Sensory Quality, Physicochemical Attributes, Polyphenol Profiles, and

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Agricultural and Environmental Chemistry

Sensory quality, physicochemical attributes, polyphenol profiles and residual fungicides in strawberries from different disease control treatments Marvin Abountiolas, Katrina Kelly, Yavuz Yagiz, Zheng Li, Gail Mahnken, Wlodzimierz BorejszaWysocki, Maurice R. Marshall, Charles Sims, Natalia Peres, and Maria Cecilia Do Nascimento Nunes J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.8b02153 • Publication Date (Web): 21 Jun 2018 Downloaded from http://pubs.acs.org on June 22, 2018

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Journal of Agricultural and Food Chemistry

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Sensory quality, physicochemical attributes, polyphenol profiles and residual

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fungicides in strawberries from different disease control treatments

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Marvin Abountiolasa, Katrina Kellya, Yavuz Yagizb, Zheng Lib, Gail Mahnkenb, Wlodzimierz

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Borejsza-Wysockib, Maurice Marshallb, Charles A. Simsb, Natalia Peresc, and Maria Cecilia do

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Nascimento Nunes*, a

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a

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University of South Florida, 4202 E. Fowler Avenue, Tampa, Florida 33620, USA.

Food Quality Laboratory, Department of Cell Biology, Microbiology and Molecular Biology,

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b

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Gainesville, FL 32611, USA

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c

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672, Wimauma, FL 33598, USA.

Department of Food Science and Human Nutrition, University of Florida, 520 Newell Drive,

Gulf Coast Research and Education Center, University of University of Florida, 14625 Co. Rd.

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*Corresponding author: Tel: 1-813- 974-9307; fax: 1-813-905-9919

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E-mail address: [email protected] (C.N. Nunes).

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1 ACS Paragon Plus Environment


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ABSTRACT: Using alternative agricultural practices in combination with proper postharvest

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handling has become a major goal to improve fresh produce quality. Here, two different

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strawberry (Fragaria × ananassa) genotypes were used as a model to study the impact of

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repeated, reduced-fungicide or no-fungicide applications on the sensory quality, physicochemical

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attributes, polyphenol profiles and residual fungicide in strawberries. Strawberries grown under

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reduced-fungicide applications had similar or better physicochemical quality than conventionally

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and organically-grown fruit and lower levels of fungicide residues than conventional fruit.

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Overall, flavor- and health-related attributes of strawberries from reduced-fungicide applications

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were intermediate between conventional and organic fruit. Thus, growing strawberries with

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reduced-fungicide applications can be an alternative to conventional or organic agricultural

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practices.

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KEYWORDS: Fragaria×ananassa, storage, sensory quality, bioactive compounds, sugars,

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fungicides

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INTRODUCTION

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Strawberries are amongst the most popular fruits consumed worldwide and are recognized for

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their exceptional nutritional qualities. Strawberries have been the focus of many studies for their

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health benefits due to high levels of bioactive compounds, including phenolic acids, flavonoids,

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and vitamin C.1-4 However, overall strawberry quality and, the levels of bioactive compounds, is

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greatly influenced by genotype5-12, agricultural practices13-16 and by postharvest conditions.17 In

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order to control strawberry diseases, current control measures involve repeated fungicide

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applications which may impact strawberry quality. Indeed, several studies showed that organic

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strawberries, in general, have similar or higher levels of polyphenols and vitamin C compared to

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fruit grown under conventional agricultural practices.18-24 Some have suggested that eliminating

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or limiting the use of synthetic pesticides results in increased pest pressure and thus organic

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production methods induce plants to develop more robust defense mechanisms such as

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increasing the synthesis of polyphenols.13-14, 20, 24-26

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There is a critical need to provide alternative agricultural practices that in combination with

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proper postharvest practices will produce “healthier” strawberries. Hence, production will be less

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harmful to the environment while resulting in lower costs for growers and consumers. From

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previous work on the impact of different agricultural practices on disease control and yield, and

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produce quality, it is apparent that much potential exists for reducing the amount of fungicides

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used and offer the consumer a strawberry with lower fungicide residues and, with equal or

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superior sensory and nutritional quality as an alternative to organic fruit. While few studies have

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shown that quality of organic strawberries may be superior compared to that of fruit organically-

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grown or from integrated pest management18,

21-22, 24

there are no studies that document how



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strawberries grow under a reduced-fungicide application regime perform comparatively to fruit

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gown under conventional or organic disease control measures. Also, only one study reported

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comparative changes in color, polyphenols and ascorbic acid content in organic as opposed to

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conventional strawberries during cold storage.19 Thus, the rationale for conducting this work was

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that by reducing the amount of fungicides used to control strawberry diseases through accurately

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targeting the right application time the overall postharvest quality of strawberries can be

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maintained or enhanced providing an alternative to health-aware consumers. The overall

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objective of this study was to determine the impact of repeated, reduced-fungicide or no-

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fungicide applications on the sensory quality, physicochemical attributes, polyphenol profiles

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and residual fungicides in strawberries.

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MATERIAL AND METHODS

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Plant Material and Disease Control Treatments. ‘Florida Radiance’ and ‘Strawberry

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Festival’ strawberries were obtained from commercial fields in Florida, USA, and grown under

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the following disease management conditions: conventional, reduced-fungicide using a disease

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forecasting system27 and organic. Conventional and reduced-fungicide ‘Florida Radiance’ and

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‘Strawberry Festival’ strawberries were harvested from commercial fields in Plant City and

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Floral City, respectively. Organic ‘Strawberry Festival’ was obtained from a commercial field in

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Duette. Organic ‘Florida Radiance’ strawberries were not available in same geographical area,

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therefore only organic ‘Strawberry Festival’ strawberries were tested against conventional and

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reduced-fungicide disease control treatments. Tables 1 and 2 show the types of fungicides and

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application dates for conventional and reduced-fungicide strawberries grown in Plant City and


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Floral City, respectively. Organic strawberries were grown according to the United States

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Department of Agriculture National Organic Program (NOP) guidelines.28

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Postharvest Treatments. Strawberries were harvested twice during the 2014 production

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season: conventional and reduced-fungicide ‘Florida Radiance’ were harvested on January 21

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(Harvest 1) and on February 18 (Harvest 2). Conventional, reduced-fungicide and organic

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‘Strawberry Festival’ were harvested on February 7 (Harvest 1) and March 7 (Harvest 2). Fruit

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were brought to the laboratory, selected for uniformity of size, color and freedom of defects,

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carefully packed into 0.453 kg-clamshells and stored at 1.5 °C and 85% RH inside a temperature

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and RH-controlled chamber (Forma Environmental Chambers Model 3940 Series, Thermo

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Electron Corporation, OH, USA). These conditions simulated the lowest temperature and highest

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RH measured during strawberry handling.29-31 Strawberry samples (3 clamshells containing 15

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fruit each per treatment) were evaluated for physicochemical quality at harvest and daily during a

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7-day storage period. Sensory quality was evaluated after 3 days of storage, and fungicide

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analysis was performed at harvest and after 3 and 7 days of storage.

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Sensory Analysis. Fungicide treatments for each cultivar and harvest were subjected to

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acceptability testing by a panel of 100 strawberry consumers. The panelists were selected based

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on their consumption frequency of strawberries and availability for all panels. Two strawberries

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from each treatment were presented to panelists for evaluation. Each treatment was coded by a

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three-digit random number, and all possible orders of presentation were presented approximately

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an equal number of times. Panelists rated their level of acceptability for overall, appearance,

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texture, and flavor using the 9-point hedonic scale where 1 = dislike extremely, 5 = neither like

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nor dislike, and 9 = like extremely. Evaluations were conducted in a sensory testing lab, with 10

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individual booths and a computer data entry system using Compusense®.



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Instrumental Color and Texture Analysis. A total of two color measurements were taken

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on the opposite sides of the fruit in the equatorial region. A hand-held tristimulus reflectance

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colorimeter (Model CR-400, Minolta Co., Ltd., Osaka, Japan) was used following the procedure

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described by Kelly et al.8 Firmness of each strawberry was measured using a TA.XT Plus

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Texture Analyzer (Texture Technologies Corp., NY, USA) as described by Whitaker et al.32

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Weight loss and Dry Weight. Weight loss of three replicated samples of 15 strawberries

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each was calculated from the initial weight of the fruit and every day during a 7-day storage

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period. Concentrations of chemical constituents were expressed in dry weight to show the

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differences between treatments that might be obscured by differences in water content.8 To

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compensate for water loss during storage, chemical compounds were expressed in g kg-1 on a dry

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weight basis.

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Acidity and Soluble Solids Content (SSC). Three replicates of fifteen individual fruit per

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treatment were homogenized in a laboratory blender at high speed for 2 min and the resulting

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puree immediately frozen and kept at -30 °C until used. Titratable acidity and SSC were

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determined according to Nunes et al.33

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Ascorbic Acid Analysis. The ascorbic acid analysis was conducted using a Hitachi

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LaChromUltra UHPLC system with a diode array detector and a LaChromUltra C18 2µm

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column (2 × 50 mm) (Hitachi, Ltd., Tokyo, Japan) as described by Nunes.34

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Total Phenolics and Anthocyanins. Total phenolic compounds were measured using the

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Folin-Ciocalteau reagent as described by Nunes et al.35 Anthocyanins were extracted in 0.5%

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(v/v) HCl in methanol and measured using the procedure described by Nunes et al.35

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Extraction of Polyphenols. Triplicates of 5 mL of strawberry puree from each treatment

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were mixed with 15 mL of acetone, sonicated for 10 minutes and filtered through Whatman


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paper No.4. The filtrate was concentrated to 5 mL in a rotary evaporator (Buchi Rotavapor R-

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114, Birkmann Instruments, Inc., USA) and passed through a classic C18 Sep-Pack cartridge

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(Waters Technologies Corp., USA) previously activated with methanol, followed by water and

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3% formic acid. Anthocyanins and other phenolics were absorbed onto the column whereas

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sugars, acids, and other water-soluble compounds were eluted with acidified water. The

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polyphenols were then recovered by passing 2.0 mL of methanol containing 3% formic acid

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through the cartridge. The extract was filtered through a 0.20 µm syringe filter into 2 mL

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autosampler vials and stored at -30 °C until used.

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Identification and Quantification of Polyphenols. Individual polyphenol compounds

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were identified and quantified using the extracts prepared as described above. Analysis of

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phenolic compounds was conducted using a Hitachi LaChroma Ultra HPLC system coupled with

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a photodiode array detector (Hitachi, Japan).36 Samples were injected at 40°C onto a reverse-

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phase Hypersil Gold C18 column (100 × 2.1 mm; particle size, 1.9 µm) (Thermo Fisher Scientific

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Inc., USA). The mobile phase was acidified water containing 0.5% formic acid (mobile phase A)

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and 0.1% formic acid in acetonitrile (mobile phase B) in an isocratic mixture. The flow rate was

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0.3 µL/min, and the wavelength detection was set at 250, 280, 360 and 520 nm. Sample injection

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volume was 10 µL. Retention times and spectra were compared with pure standards of 16

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compounds from different polyphenol classes: flavonoids (anthocyanidins: cyanidin and

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pelargonidin; anthocyanins: cyanidin 3-glucoside and pelargonidin 3-glucoside; flavonols:

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quercetin, kaempferol, quercetin 3-glucoside, kaempferol 3-glucoside and myricetin; flavanols:

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catechin and epicatechin), phenolic acids (p-coumaric acid, ferulic acid, caffeic acid and

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chlorogenic acid) and hydrolysable tannins (ellagic acid). Afterwards a mixture containing all 16

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polyphenol standards was analyzed to obtain the retention times. The retention times from the



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mixture were used to analyze strawberry samples instead of the individual standards to account

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for shifts in retention times by polyphenolic interaction. The optimum wavelength absorbency

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was determined by comparing the chromatograms of each sample and using the strongest peak

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wavelength. Quantification of individual polyphenols was based on surface area (%) of each

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peak.

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Sugar Analysis. Quantification of sucrose, fructose and glucose was conducted using a

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Hitachi HPLC with an refractive index detector and a 300 mm × 8 mm Shodex SP0810 column

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(Shodex, Colorado Springs, CO) with an SP-G guard column (2 mm x 4 mm) as described by

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Kelly et al.8

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Fungicide Analysis. Strawberry samples were extracted for multiresidue determination of

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fungicides based on the QuEChERS method developed by Lehotay et al.37 and slightly modified

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by Lesueur et al.38 Captan was analyzed using a GC/MS system (6890N GC coupled with a

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MSD 5973, Agilent Technologies, USA) with a ZB-5MSi (30 m x 0.32 mm x 0.25µm,

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Phenomenex, USA) capillary column under the following conditions: constant helium flow of

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1.3 mL/min; inlet temperature starting at 100 °C and after one min, ramped at 15.2 °C min-1 to a

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temperature of 235 °C, held 5 min, and ramped at 15 °C min-1 to a final temperature of 300 °C

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with holding time of 5 min. Injection volume of 1 µL in splitless mode, ion source temperature

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(230 °C) and MS Quad temperature (150 °C). Captan was quantified at 149 m/z (quantification

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ion) and 79 m/z (confirmation ion) with selected ion monitoring mode.

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validated at 0.025 and 0.25 ppm captan fortification levels. An HPLC with mass spectrometry

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(TSQ Quantum Ultra LC/MS/MS, Thermo Finnigan, USA) was used to quantify fludioxonil,

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penthiopyrad, cyprodinil, cyflufenamid, azoxystrobin and pyraclostrobin.37-38 The method was

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first validated at 0.025 and 0.25 ppm fortification levels on strawberry matrix before sample

The method was


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analysis. Spike recoveries should fall in the acceptable range of 70 to 120%. Both fortified and

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unfortified control samples were analyzed concurrently with each sample set to demonstrate the

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absence of significant interferences and adequate recoveries. Organic ‘Strawberry Festival’ was

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used as a control.

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Statistical Analysis. The Statistical Analysis System computer package (SAS Institute, Inc.,

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2004) was used for the analysis of the data. Although there was a significant difference between

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harvests for several of the physicochemical attributes measured, the trend for the different

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treatments was the same within cultivar and harvest. Therefore, for ease of interpretation,

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physicochemical data from the two harvests were combined. The data was treated by two-way

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analysis of variance (ANOVA) with harvest, cultivar and disease control treatment as main

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effects. Significant differences between cultivars and disease control treatments were detected

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using the least significant difference (LSD) at the 5% level of significance. Data from sensory

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quality and residual fungicides from the two different harvests were analyzed separately.

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Acceptability data from sensory analysis were subjected to a two-way analysis of variance to

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determine whether significant differences exist between the fungicide treatments. If significant

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differences were indicated, means were separated by Tukey’s HSD (p>0.05).

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RESULTS AND DISCUSSION

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Sensory Quality. In the first harvest, the appearance of organic ‘Strawberry Festival’

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received higher scores than that of fruit from the reduced-fungicide treatment and similar scores

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to that of conventional strawberries (Table 3). However, the appearance of conventional

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strawberries was not significantly different from that of reduced-fungicide or organic fruit.

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‘Strawberry Festival’ scores for texture, flavor and overall liking were not significantly different



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between treatments. Conventional ‘Florida Radiance’ received higher scores for texture and

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flavor and similar scores for appearance and overall liking compared to fruit from the reduced-

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fungicide treatment. Overall, fruit from the first harvest was not significantly different for overall

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liking. Results from the second harvest showed that there were no significant differences

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between the disease control treatments for any of the sensory attributes evaluated. A previous

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study showed that consumer preference for organic, as opposed to conventional strawberries, is

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cultivar dependent.39 That is, overall acceptance, flavor, sweetness, and appearance of organic

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strawberries ‘Lanai’ and ‘San Juan’ were not different than conventional fruit whereas organic

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‘Diamante’ strawberries received higher scores for the same sensory attributes compared to

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conventional fruit.18

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Color and Texture. ‘Strawberry Festival’ were lighter (higher L*) and less red (higher hue)

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than ‘Florida Radiance’, regardless of the disease control treatment (Figure 1). At harvest,

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organic ‘Strawberry Festival’ was slightly lighter (higher L*) but redder (lower hue) compared to

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fruit from the other treatments whereas no significant difference was found between the color of

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conventional and reduced-fungicide ‘Florida Radiance’. In a previous study, external color

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intensity was similar between organic and conventional ‘Diamante’, ‘Lanai’ and ‘San Juan’

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strawberries however organic fruit was darker red compared to conventional strawberries.18

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Others have also reported that surface color of ‘Selva’ organic strawberries was darker, less vivid

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and tended to be redder than conventional fruit but no significant differences were found in the

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color of the flesh between organic and conventional fruit.20 In a study conducted at the retail

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level, conventional strawberries tended to have higher L* (less dark) and lower or similar hue

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(redder) than organic fruit. Unlike reported by Crecente-Campo et al.20, the internal color of

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organic ‘Strawberry Festival’ was redder than that of fruit from conventional or reduced-


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fungicide treatments (data not shown). During storage, L* of both strawberry cultivars declined,

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as the fruit became darker, but after 7 days no difference was found in the L* of Strawberry

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Festival’ from the different disease control treatments (Figure 1). On the other hand, after

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storage, ‘Florida Radiance’ from the reduced-fungicide treatment was significantly lighter and

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less red (higher L* and hue) than conventional fruit. After storage, organic ‘Strawberry Festival’

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were redder (lower hue) than conventional fruit but less red (higher hue) than reduced-fungicide

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treatments. Overall, differences in color of strawberries did not result in appearance preferences

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by consumer-sensory panels between organic and conventional fruit (Table 3).

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‘Florida Radiance’ was slightly firmer at harvest compared to ‘Strawberry Festival’ (Figure

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2). At harvest, organic ‘Strawberry Festival’ was softer than fruit from other treatments. Also,

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when compared to conventional fruit, reduced-fungicide strawberries also tended to be softer at

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harvest. A previous study showed no significant difference between firmness of organic and

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conventional strawberries.18 Such differences may be related to genotype variability and possibly

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to maturity of the fruit at harvest. The firmness of strawberries decreased during storage,

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regardless of cultivar or treatment. However, compared to initial values at harvest, ‘Strawberry

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Festival’ and ‘Florida Radiance’ from the reduced-fungicide treatment softened less during

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storage (10.7 and 12.3% decrease, respectively) than fruit from the conventional treatment (14.5

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and 20.5% decrease, respectively). The least decrease in firmness during storage was measured

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for organic ‘Strawberry Festival’ (9.7%). Overall, differences in texture did not result in a

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preference for the texture of organic versus conventional and reduced-fungicide strawberries by

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consumer-sensory panels except for conventional ‘Florida Radiance’ that were preferred for

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texture over fruit from the reduced-fungicide treatment (Table 3).



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Weight Loss. Although after storage there was no significant difference in the weight loss of

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‘Strawberry Festival’ from all treatments, organic and reduced-fungicide strawberries lost

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slightly less weight (8.5 and 8.9%, respectively) than conventional fruit (9.1%) (Figure 2).

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Reduced-fungicide ‘Florida Radiance’ lost significantly less weight than conventional fruit. In a

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previous study, Reganold et al.18 also reported lower weight loss in organic strawberries

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compared to conventional fruit and suggested that slower dehydration in organic fruit may result

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from a thicker cuticle and expansion of epidermal cell walls.

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Overall, there was a decline in strawberry chemical compounds during storage regardless of

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the treatment (Figures 1-5). The decrease in chemical compounds during storage is likely related

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to water loss that results in reduced turgor pressure of the cells leading to membrane breakdown.

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For example, collapse of cellular membranes allows for the interaction of degrading enzymes,

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such as polyphenol oxidase and ascorbate oxidase, to come into contact with polyphenols and

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ascorbic acid, respectively.34,35

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Acidity and Soluble Solids Content. At harvest, the acidity of organic ‘Strawberry Festival’

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was higher compared to fruit from the conventional or reduced-fungicide treatments whereas

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acidity of conventional ‘Florida Radiance’ was higher than that of fruit from the reduced-

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fungicide treatment (Figure 3). Reganold et al.18 reported no consistent trend in the acidity of

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organic versus conventional strawberries. That is, organic ‘Diamante’, ‘Lanai’ and ‘San Juan’

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strawberries had higher, similar or lower acidity, respectively, than their conventional

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counterparts. Acidity declined during storage, regardless of the treatment or cultivar but after 7

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days, there was no significant difference in the acidity of ‘Strawberry Festival’ whereas

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conventional ‘Florida Radiance’ had lower acidity compared to reduced-fungicide strawberries.


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Initial values for SSC were significantly different between cultivars and between disease

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control treatments and (Figure 3). ‘Strawberry Festival’ from reduced-fungicide had higher SSC,

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followed by organic and conventional fruit while conventional ‘Florida Radiance’ had, at

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harvest, higher SSC compared to fruit from the reduced-fungicide treatment. Reganold et al18

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reported higher SSC for organic ‘Diamante’ strawberries but similar SSC for organic and

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conventional ‘Lanai’ and ‘San Juan’ strawberries. During cold storage, SSC of ‘Strawberry

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Festival’ and ‘Florida Radiance’ declined significantly. Within each cultivar, the highest

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decrease in SSC was for reduced-fungicide ‘Strawberry Festival’ (58.0%) and conventional

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‘Florida Radiance’ (52.1%). Though, after storage there was no significant difference between

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SSC of organic and reduced-fungicide ‘Strawberry Festival’, SSC of conventional strawberries

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was significantly lower compared to other treatments. After 7 days, there was no significant

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difference in the SSC of ‘Florida Radiance’ from both treatments. Results from this and other

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studies suggest that cultivar variability might have a greater impact on fruit acidity and SCC than

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disease control treatments.

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Ascorbic Acid Content. At harvest, ascorbic acid (AA) content of organic ‘Strawberry

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Festival’ was significantly higher compared to fruit from the conventional or reduced-pesticide

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treatments (Figure 4). Initial AA contents of ‘Florida Radiance’ from conventional and reduced-

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pesticide treatments were not significantly different. Others reported that the difference in the

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levels of AA between conventional and organic strawberries is cultivar dependent and that

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genotype and environmental conditions may have a greater impact on AA levels than cultivation

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methods. Therefore, controversial reports have been published with some showing no difference

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or significantly higher levels of AA in organic compared to conventional strawberries.22-23, 40 For

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example, Hakala et al.40 showed no significant difference in the levels of vitamin C of organic



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‘Jonsok’, ‘Polka’ and ‘Honeoye’ strawberries compared to conventionally-grown fruit. Olsson et

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al.22 reported that AA and vitamin C contents of organic ‘Cavendish’ strawberries were similar

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to conventional fruit, but AA levels of organic ‘Honeoye’ were higher compared to

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conventionally-grown fruit. Several recent studies showed that organic strawberries tend to have

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higher levels of AA compared to conventional fruit.18,

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‘Diamante’, ’Lanai’ and ‘San Juan’ organic strawberries was on average 9.7% higher compared

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to conventional fruit.18

20, 41

For example, AA content of

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After cold storage, AA content of ‘Strawberry Festival’ from the conventional and reduced-

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fungicide treatments declined by approximately 47.9 and 51.3%, respectively whereas a decrease

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in AA content of organic fruit was approximately 49.1%. Although after storage AA content

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remained significantly higher in organic ‘Strawberry Festival’, AA content of fruit from other

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treatments was not significantly different. Similarly, AA content of conventional and reduced-

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fungicide ‘Florida Radiance’ was not significantly different after storage. One previous study

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also showed that organic ‘Earligow’ and ‘Allstar’ strawberries had higher levels of AA

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compared to conventional strawberries at harvest and after 7 days at 0, 5 or 10 °C.19 Unlike in the

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present study, Jin et al.19 reported that AA levels increase during storage, regardless of the

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cultivation method, and that AA levels were higher in fruit exposed to 5 or 10 °C compared to 0

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°C. However, AA was reported on fresh weight, and it is possible that the increase reported by

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Jin et al.19 was caused by a concentration effect due to loss of water rather than to an actual

315

increase.

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Total Phenolic and Anthocyanin Contents. Total polyphenol (TPC) and anthocyanin

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(ANC) contents of ‘Strawberry Festival and ‘Florida Radiance’ showed similar patterns (Figure

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4). At harvest, TPC was significantly higher in organic ‘Strawberry Festival’ (25.6 g kg-1),


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followed by reduced-fungicide and conventional strawberries (21.1 and 20.2 g kg-1,

320

respectively). Anthocyanin content (ANC) was also higher in organic ‘Strawberry Festival’

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compared to other treatments, yet there was a less marked difference in ANC between organic

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and reduced-fungicide fruit (Figure 4). The levels of ANC in conventional ‘Strawberry Festival’

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were 21% lower compared to fruit from both organic of reduced-fungicide treatments. At

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harvest, TPC and ANC of ‘Florida Radiance’, from conventional and reduced-fungicide

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treatments were similar (17.4 and 16.5 g TPC kg-1; 1.8 and 1.7 g ANC kg-1, respectively). One

326

single study reported that strawberry cultivars from integrated pest management had lower TPC

327

and ANC compared to organic fruit

328

higher TPC and ANC than conventional fruit.18-20, 22

21

. Others have also shown organic strawberries having

329

After cold storage, there was a significant decline in TPC of ‘Strawberry Festival’, yet TPC

330

of organic fruit remained the highest compared to the other treatments. After 7 days, there was

331

no significant difference between the TPC of conventional and reduced-fungicide ‘Strawberry

332

Festival or ‘Florida Radiance’ (Figure 4). A significant decline in ANC was also observed during

333

storage, with organic ‘Strawberry Festival’ having the lowest decline (38.7%) compared to fruit

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from conventional and reduced-fungicide treatments (48.6 and 60.8%). ANC of ‘Florida

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Radiance’ from conventional and reduced-fungicide also declined during storage, but the levels

336

remained comparable. Jin et al.19 reported that TPC and ANC levels increase during storage,

337

regardless of the cultivation method, and were higher in fruit exposed to 5 or 10 °C compared to

338

0 °C. However, like for AA, TPC and ANC were reported on fresh weight, and it is possible that

339

the increase reported by Jin et al.19 was caused by a concentration effect due to loss of water

340

during storage, rather than to an actual increase. In fact, Shin et al.42 reported that the marked

341

decline in total flavonoid and phenolic concentrations in strawberries after 12 days of storage at



Page 16 of 47

342

10 °C paralleled the increase in water loss and a decrease in anthocyanin concentration. Thus, in

343

shelf life studies to determine the actual changes in chemical compounds, and to show the

344

differences between treatments that might be obscured by differences in water content,

345

concentrations of chemical constituents should be expressed in dry weight.

346

Polyphenol Profiles of ‘Strawberry Festival’ from Different Disease Control

347

Treatments. Polyphenol profiles were only obtained for ‘Strawberry Festival’ due to

348

unavailability of ‘Florida Radiance’ organic strawberries. Regardless of the disease control

349

treatment or storage period, pelargonidin 3-glucoside was the major polyphenol measured in

350

conventional, reduced and organic fruit (9.8, 16.7 and 19.8%, respectively), followed by

351

quercetin (4.0, 3.5 and 3.2%, respectively), quercetin 3-glucoside (3.6, 4.5 and 2.9%,

352

respectively), kaempferol 3-glucoside (2.3, 1.9 and 2.4%, respectively) and coumaric acid (1.0,

353

1.8 and 2.0%, respectively) (Figure 6). Other polyphenols were also detected but at levels lower

354

than 2%. Overall, there were significant differences in the levels of each polyphenol measured

355

between disease control treatments. At harvest, organic strawberries had significantly higher

356

levels of pelargonidin 3-glucoside, catechin and coumaric acid compared to fruit from

357

conventional or reduced-fungicide treatments (Figure 6A). Crecente-Campo et al.20 also reported

358

higher levels of pelargonidin 3-glucoside and cyanidin 3-glucoside in organic strawberries than

359

in conventional fruit. In this study, compared to conventional ‘Strawberry Festival’, strawberries

360

from the reduced-fungicide treatment had significantly higher levels of cyanidin 3-glucoside,

361

pelargonidin 3-glucoside, coumaric, chlorogenic and ellagic acids. A previous study reported that

362

organic ‘Cavendish’ strawberries had higher levels of cyanidin and pelargonidin but lower levels

363

of flavonols compared to conventionally-grown fruit whereas organic ‘Honeoye’ had lower

364

levels or ellagic acid, cyanidin and pelargonidin than conventional fruit.22 Others have reported


Page 17 of 47


365

mixed or no differences in kaempferol, quercetin, ellagic and p-coumaric acids between organic

366

and conventional strawberry cultivars18-19, 24. It appears that the levels of specific polyphenols,

367

other than the major anthocyanins, are more influenced by cultivar than by cultivation method.

368

However, there seems to be an agreement among published data that pelargonidin 3-glucoside

369

and cyanidin 3-glucoside are higher in organic than in conventional fruit.19-20,

370

strawberry cultivars from integrated pest management cultivation also showed lower levels

371

pelargonidin 3-glucoside and cyanidin 3-glucoside than organic fruit.21 Some have suggested that

372

in organic agriculture, the limited use of pesticides contributes to increased pest pressure and

373

induces plants to develop more robust defense mechanisms such as increasing the synthesis of

374

polyphenols.

375

may affect plant growth, nutritional composition an synthesis of polyphenols.13

13-14, 20, 24-26

22

Different

In addition, soil composition, particularly the availability of nitrogen,

376

After cold storage, the major differences in the polyphenol profiles were the increase in

377

levels of epicatechin and ellagic acid in organic fruit compared to other treatments and

378

significantly higher levels of quercetin in conventional fruit compared to other treatments (Figure

379

6B). Some other individual polyphenols also increased or decreased during storage depending on

380

the treatment. For example, in conventional strawberries, pelargonidin 3-glucoside increased

381

during storage whereas it decreased in reduced-fungicide and organic fruit. Jin et al.19 showed

382

that cyanidin 3-glucoside increased in organic and conventional ‘Allstar’ after storage at 0 °C but

383

no significant increase in cyanidin 3-glucoside or pelargonidin 3-glucoside was reported for

384

organic or conventional ‘Earliglow’ strawberries. In addition, no significant increases were

385

reported for ellagic acid, quercetin 3-glucoside and kaempferol 3-glucoside in organic and

386

conventional ‘Allstar’ and Earliglow’ strawberries after 7 days of storage at 0 °C.19 On average,

387

at harvest, and based on the sum of individual polyphenols measured, there was no significant



Page 18 of 47

388

difference between organic and reduced-fungicide fruit whereas conventional fruit had

389

significantly lower percentage of polyphenol compounds (Figure 6C). Compared to data

390

obtained from TPC (Figure 4) the results agree as the levels of TPC were significantly lower in

391

conventional fruit and similar between reduced-fungicide and organic fruit. However, after 7

392

days there was an increase in the sum of individual polyphenols measured in conventional fruit

393

whereas there was no change in other treatments compared to initial values (Figure 6C). These

394

results are not in agreement with those from TPC where there was a significant decreased in TPC

395

during storage, regardless of the treatment (Figure 4). This discrepancy may be due to a

396

concentration effect resulting from the loss of moisture during storage rather than an increase or

397

no change in the polyphenol profiles. In fact, to compensate from water loss, TPC was expressed

398

in dry weight while the data (Area %) for individual polyphenols were based on fruit fresh

399

weight. Because area percentage was used to estimate the levels of individual polyphenols

400

detected in strawberries, it did not seem accurate to calculate these values in dry weight.

401

Sugar Profiles. Although there is quite some variability in sugar content amongst strawberry

402

cultivars, in general sucrose has the lowest contribution to the total sugar content whereas

403

concentrations of glucose and fructose are approximately on 1:1 ratio.43 At harvest, sucrose

404

levels of conventional ‘Florida Radiance’ were approximately 3-fold higher than in conventional

405

‘Strawberry Festival’ (Figure 5). However, sucrose contents of ‘Strawberry Festival’ and

406

‘Florida Radiance’ from the reduced treatment were not significantly different. Within cultivars,

407

conventional ‘Strawberry Festival’ had significantly lower sucrose levels at harvest compared to

408

fruit from the reduced or organic treatments (Figure 5). Reduced and organic ‘Strawberry

409

Festival’ had similar sucrose levels at harvest. Conversely, at harvest, sucrose content was

410

significantly higher in conventional ‘Florida Radiance’ compared to the fruit from the reduced


Page 19 of 47


411

treatment. After 7 days, sucrose levels decreased significantly, regardless of the cultivar or

412

treatment. Conventional ‘Strawberry Festival’ showed the highest decrease in sucrose content

413

(91%) followed by fruit from the reduced and organic treatments (80 and 74% %, respectively).

414

Sucrose levels of ‘Florida Radiance’ also decreased after storage. However, the decrease was

415

significantly higher in fruit from the reduced-fungicide treatment compared to the conventional

416

(68 and 61%, respectively).

417

Although in a previous study Reganold et al.18 reported no difference in reducing (glucose

418

and fructose) or total sugars between conventional and organic strawberries, in this study glucose

419

and fructose were higher in ‘Strawberry Festival’ from the conventional or reduced treatments

420

and lower in fruit from organic treatments (Figure 5). ‘Florida Radiance’ from the reduced-

421

fungicide treatment had higher glucose and fructose contents than conventional fruit. Within

422

cultivars, there was no significant difference in glucose and fructose contents of conventional

423

and reduced ‘Strawberry Festival’ both at harvest and after storage. Although organic fruit had

424

lower glucose and fructose levels at harvest compared to the other treatments, there was no

425

significant difference between treatments after storage. Nonetheless, after cold storage, organic

426

‘Strawberry Festival’ had the lowest decrease in glucose and fructose contents (45 and 48%,

427

respectively) compared to fruit from the conventional (52 and 55%, respectively) and reduced

428

treatments (57 and 60%, respectively). A similar trend was observed for ‘Florida Radiance’

429

where fruit from the reduced treatment had significantly higher glucose and fructose levels at

430

harvest but no difference after cold storage.

431

Residual Fungicides. Organic ‘Strawberry Festival’ was used as a control as no detectable

432

levels for any of the fungicides were measured in the fruit (data not shown). Eight different

433

active fungicide compounds namely, captan, fludioxonil, penthiopyrad, fenhexamid, cyprodinil,



Page 20 of 47

434

cyflufenamid, azoxystrobin, and pyraclostrobin, were measured (Tables 4 and 5). There was

435

significant variability between harvests and cultivars regarding the presence and levels of these

436

compounds in the fruit but pyraclostrobin was never detected in the fruit. In the first harvest,

437

only fludioxonil and cyprodinil were detected in conventional and reduced-fungicide ‘Strawberry

438

Festival’ (Table 4). On average, cyprodinil was detected at higher levels (0.398 and 0.260 ppm

439

in conventional and reduced fruit, respectively) than fludioxonil (0.143 and 0.113 ppm in

440

conventional and reduced fruit, respectively). There was no trend observed in the levels of

441

fludioxonil and cyprodinil between the day of harvest and after 3 and 7 days of storage most

442

likely due to sample variability. Even so, levels of these two fungicides were on average higher

443

in conventional fruit than in fruit from reduced-fungicide treatment. In ‘Florida Radiance’

444

strawberries from the first harvest other than fludioxonil and cyprodinil, fungicides captan,

445

fenhexamid and cyflufenamid were also detected (Table 5). However, only cyflufenamid was

446

measured on both fruit from the conventional and reduced-fungicide treatments, but the levels

447

were not significantly different between treatments. Conventional strawberries had higher levels

448

of captan and fenhexamid compared to fruit from the reduced-fungicide treatment, which

449

showed no detectable levels. In contrast, strawberries from the reduced-fungicide treatment had

450

higher levels of fludioxonil and cyprodinil compared to conventional fruit, which showed no

451

detectable levels. In the second harvest, captan, fludioxonil, penthiopyrad and cyprodinil were

452

measure in ‘Strawberry Festival’ (Table 4). Captan was higher in conventional strawberries

453

compared to the reduced-fungicide fruit, which showed no detectable levels. Unlike in the first

454

harvest, levels of fludioxonil and cyprodinil were slightly higher in ‘Strawberry Festival’ from

455

the reduced-fungicide compared to the conventional treatment. Levels of penthiopyrad were not

456

significantly different between disease control treatments. Although there was no trend in the


Page 21 of 47


457

levels of these compounds during storage, captan tended to be higher in conventional

458

‘Strawberry Festival’ at harvest than after 7 days of storage (Table 4). In ‘Florida Radiance’ from

459

the second harvest, captan, fludioxonil, penthiopyrad, fenhexamid, cyprodinil cyflufenamid and

460

azoxystrobin were measured in the fruit (Table 5). On average, conventional strawberries had

461

higher levels of captan, fludioxonil, cyprodinil, and azoxystrobin compared to the reduced-

462

fungicide fruit which had higher levels of penthiopyrad, fenhexamid and cyflufenamid. In an

463

earlier analysis of pesticide residue data from organic and non-organic fresh fruits and

464

vegetables, Baker et al.44 also found higher levels of captan in conventional strawberries (1.1084

465

ppm) compared to fruit from integrated pest management (0.1200 ppm). In the second harvest,

466

the residual levels of fenhexamid and cyflufenamid in conventional ‘Florida Radiance’ were

467

slightly lower than that measured in fruit from the reduced-fungicide treatment most likely

468

because in conventional strawberries Elevate was applied on February 4 (14 days before harvest)

469

whereas in the reduced-fungicide treatment Elevate was applied on February 10 (8 days before

470

harvest). Thus, it seems that the levels of fungicides in the fruit were more influenced by when

471

the fungicide was applied, relative to the sampling date, than to how much or how many times it

472

was applied. The United States Environmental Protection Agency (USEPA) establishes 20 ppm

473

for captan, 3 ppm for fludioxonil, penthiopyrad and fenhexamid, 5 ppm for cyprodinil, 0.2 ppm

474

for cyflufenamid, 10 ppm for azoxystrobin, and 1.2 ppm for pyraclostrobin.45 Therefore, the

475

levels of fungicides found in all strawberry cultivars from any disease control treatments used in

476

this study were well below the tolerances established by the USEPA. Others have suggested that

477

the benefits or reducing human exposure to pesticides by substituting conventional by organic

478

produce is insignificant because the exposure to pesticide residues from consuming a standard

479

diet poses minimal risk to humans.46



Page 22 of 47

480

In summary, ‘Strawberry Festival’ and ‘Florida Radiance’ strawberries grown under

481

reduced-fungicide applications had at harvest similar or better physicochemical quality than

482

conventionally-grown fruit. Organic ‘Strawberry Festival’ had higher phenolics, anthocyanins

483

and ascorbic acid contents but lower levels of glucose and fructose compared to conventional or

484

reduced-fungicide strawberries. After cold storage, consumer-sensory panels did not show liking

485

preference between organic, reduced-fungicide and conventional fruit. Physicochemical quality

486

of reduced-fungicide ‘Strawberry Festival’ and ‘Florida Radiance’ was comparable to that of

487

conventional and organic fruit. Organic strawberries were softer after storage but maintained its

488

higher levels of phenolics, anthocyanins and ascorbic acid. On average, strawberries from the

489

reduced-fungicide treatment had lower levels of fungicides than conventional fruit. Overall,

490

results showed that flavor- and health-related attributes of strawberries from the reduced-

491

fungicide treatment were intermediate between conventional and organic fruit. Thus, growing

492

strawberries with reduced-fungicide applications can be an alternative to conventional disease

493

control or organic practices.

494


Page 23 of 47

495


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496

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Pelletier, W.; Brecht, J. K.; Nunes, M. C. N.; Emond, J.-P. Quality of strawberries

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Reganold, J. P.; Andrews, P. K.; Reeve, J. R.; Carpenter-Boggs, L.; Schadt, C.

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W.; Alldredge, J. R.; Ross, C. F.; Davies, N. M.; Zhou, J. Fruit and soil quality of organic and

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Hakala, M.; Lapveteläinen, A.; Huopalahti, R.; Kallio, H.; Tahvonen, R. Effects

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Cordenunsi, B. R.; Oliveira do Nascimento, J. R.; Genovese, M. I.; Lajolo, F. M.

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idx?tpl=/ecfrbrowse/Title40/40cfr180_main_02.tpl (accessed March 18, 2018).

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630

FUNDING SOURCES

631

This work was supported by the Specialty Crop Block Grant Program at the U.S. Department of

632

Agriculture (USDA) through grant 12-25-B-1663. Its contents are solely the responsibility of the

633

authors and do not necessarily represent the official views of the USDA. The authors would like

634

to thank Mr. Carl Grooms from Fancy Farms and Mr. Dudley Calfee from Ferris Farms, Inc. for

635

conducting the different disease control treatments and by providing the strawberry samples.

636



Page 30 of 47

637

Figure 1. Color attributes of ‘Strawberry Festival’ and ‘Florida Radiance’ strawberries from

638

different disease control treatments during storage at 1.5°C and 85% RH. Letters next to data

639

points denote significant differences between disease control treatments based on Fisher’s LSD

640

test at p ≤ 0.05. Data points are averages of two harvests; average data points with the same letter

641

are not significantly different.

642 643

Figure 2. Firmness and weight loss of ‘Strawberry Festival’ and ‘Florida Radiance’ strawberries

644

from different disease control treatments during storage at 1.5°C and 85% RH. Letters next to

645

data points denote significant differences between disease control treatments based on Fisher’s

646

LSD test at p ≤ 0.05. Data points are averages of two harvests; average data points with the same

647

letter are not significantly different.

648 649

Figure 3. Titratable acidity and soluble solids content (SSC) of ‘Strawberry Festival’ and ‘Florida

650

Radiance’ strawberries from different disease control treatments during storage at 1.5°C and 85%

651

RH. Letters next to data points denote significant differences between disease control treatments

652

based on Fisher’s LSD test at p ≤ 0.05. Data points are averages of two harvests; average data

653

points with the same letter are not significantly different.

654 655

Figure 4. Levels of bioactive compounds (total polyphenols, anthocyanins, and ascorbic acid

656

contents) of ‘Strawberry Festival’ and ‘Florida Radiance’ strawberries from different disease

657

control treatments during storage at 1.5°C and 85% RH. Letters next to data points denote

658

significant differences between disease control treatments based on Fisher’s LSD test at p ≤ 0.05;


Page 31 of 47


659

average data points with the same letter are not significantly different. Data points are averages of

660

two harvests; average data points with the same letter are not significantly different.

661 662

Figure 5. Sucrose, glucose and fructose contents of ‘Strawberry Festival’ and ‘Florida Radiance’

663

strawberries from different disease control treatments during storage at 1.5°C and 85% RH.

664

Letters next to data points denote significant differences between disease control treatments based

665

on Fisher’s LSD test at p ≤ 0.05. Data points are averages of two harvests; average data points

666

with the same letter are not significantly different.

667 668

Figure 6. Polyphenol profiles of ‘Strawberry Festival’ strawberries from conventional, reduced

669

and organic disease control treatments at harvest (A), after a 7-day storage period (B), and (C)

670

total polyphenols at harvest and after 7 days at 1.5°C and 85% RH. Letters above each bar denote

671

significant differences between disease control treatments based on Fisher’s LSD test at p ≤ 0.05.

672

Data are averages of two harvests; bars with the same letter within each polyphenolic compound

673

are statistically non-significant (ns).

674 675



Page 32 of 47

Table 1. Fungicides applied to ‘Florida Radiance’ strawberries grown in Plant City, Florida, USA, under conventional and reduced-fungicide disease control treatments. Date

Conventional

Reduced

10/29/2013

Quilt Xcel (a.ia azoxystrobin, propiconazole)

11/19/2013

11/29/2013

Captan + Thiram (a.i. captan,

Thiram (a.i. tetramethylthiuram

tetramethylthiuram disulfide)

disulfide)

Captan + Elevate (a.i. captan, fenhexamid)

12/07/2013

Switch (a.i. cyprodinil, fludioxonil)

12/19/2013

Captan (a.i. captan)

12/22/2013 12/26/2013


Captan (a.i. captan) Captan (a.i. captan)

12/30/2013


1/04/2014


1/08/2014

Captan + Thiram (a.i. captan,


tetramethylthiuram disulfide)

disulfide)

Captan + Elevate + Torino (a.i. captan,

Torino (a.i. cyflufenamid)

1/15/2014

fenhexamid, cyflufenamid)

1/21/2014

Harvest 1

1/25/2014


1/27/2014

Fontelis (a.i. penthiopyrad)

2/01/2014


2/02/2014

Captan + Quilt Xcel (a.i. captan, azoxystrobin, propiconazole)

2/04/2014

Captan + Elevate (a.i. captan, fenhexamid)

2/10/2014


Captan + Elevate (a.i. captan,


Page 33 of 47


fenhexamid) 2/15/2014


2/18/2014

Harvest 2

a

a.i = active ingredient.



Page 34 of 47

Table 2. Fungicides applied to ‘Strawberry Festival’ strawberries grown in Floral City, Florida, USA, under conventional and reduced-fungicide disease control treatments. Date

Conventional

Reduced

10/31/2013

Captec (a.ia captan)

Captec (a.i. captan)

11/8/2013



11/14/2013


11/18/2013



11/21/2013



disulfide)

disulfide)

11/29/2013

Captevate (a.i. captan, fenhexamid)

12/11/2013


12/19/2013


12/24/2013



1/2/2014



1/3/2014



1/10/2014

Fontellis (a.i. penthiopyrad)


2/1/2014



2/7/2014

Harvest 1

2/11/2014


2/19/2014


2/25/2014



3/7/2014



3/7/2014

Harvest 2

a



a.i = active ingredient.


Page 35 of 47


Table 3. Sensory quality of ‘Strawberry Festival’ and ‘Florida Radiance’ strawberries from conventional and reduced-fungicide disease control treatments after 3 days storage at 1.5°C and 85% RH. Appearancea

Texturea

Flavora

Overall likinga

Conventional

6.71 abb

6.90 a

6.36 a

6.49 a

Reduced

6.39 b

6.83 a

6.19 a

6.30 a

Organic

6.93 a

6.63 a

6.19 a

6.44 a

Conventional

7.29 a

7.38 a

7.30 a

7.34 a

Reduced

7.15 a

6.90 b

7.00 b

7.02 a

Conventional

6.46 a

6.83 a

6.21 a

6.42 a

Reduced

6.62 a

6.85 a

6.29 a

6.41 a

Organic

6.73 a

6.65 a

5.93 a

6.14 a

Conventional

6.75 a

6.54 a

6.10 a

6.34 a

Reduced

6.38 a

6.46 a

5.99 a

6.22 a

Cultivar/Treatment Harvest 1 ‘Strawberry Festival’

‘Florida Radiance’

Harvest 2 ‘Strawberry Festival’

‘Florida Radiance’

a

1 = dislike extremely; 5 = neither like nor dislike; 9 = like extremely.

b

Letters after averages denote significant differences (p < 0.05) between disease control

treatments based on Tukey’s HSD test; averages followed by the same letter are not significantly different.



Page 36 of 47


Page 37 of 47


Table 4. Residual fungicides on ‘Strawberry Festival’ from conventional and reduced-fungicide disease control treatments at harvest (day 0) and after 3 and 7 days of storage at 1.5°C and 85% RH. Captan

Fludioxonil

Penthiopyrad

Fenhexamid

Cyprodinil

Cyflufenamid

Azoxystrobin

Pyraclostrobin

(ppm)

(ppm)

(ppm)

(ppm)

(ppm)

(ppm)

(ppm)

(ppm)

Harvest 1 Conventional 0

N.D.

0.152 ab

N.D.

N.D.

0.340 b

N.D.

N.D.

N.D.

3

N.D.

0.119 b

N.D.

N.D.

0.367 ab

N.D.

N.D.

N.D.

7

N.D.

0.159 a

N.D.

N.D.

0.488 a

N.D.

N.D.

N.D.

-

-

0.398 A

-

-

-

Average

a

c

-

0.143 A

0

N.D.

0.099 b

N.D.

N.D.

0.204 b

N.D.

N.D.

N.D.

3

N.D.

0.129 a

N.D.

N.D.

0.293 a

N.D.

N.D.

N.D.

7

N.D.

0.112 b

N.D.

N.D.

0.285 a

N.D.

N.D.

N.D.

Average

-

0.113 B

-

-

0.260 B

-

-

-

0

4.023 a

0.002 a

0.021 a

N.D.

0.006 a

N.D.

N.D.

N.D.

3

3.937 a

0.002 a

0.018 a

N.D.

0.005 a

N.D.

N.D.

N.D.

7

3.476 b

0.002 a

0.026 a

N.D.

0.006 a

N.D.

N.D.

N.D.

Average

3.812

0.002 B

0.022 A

-

0.006 B

-

-

-

Reduced

Harvest 2 Conventional

Reduced



Page 38 of 47

0

N.D.

0.004 a

0.026 a

N.D.

0.006 b

N.D.

N.D.

N.D.

3

N.D.

0.005 a

0.023 a

N.D.

0.008 a

N.D.

N.D.

N.D.

7

N.D.

0.004 a

0.021 a

N.D.

0.006 b

N.D.

N.D.

N.D.

Average

-

0.004 A

0.023 A

-

0.007 A

-

-

-

a

N.D. = Not detected.

b

c

Means separations are within disease control treatments and days of storage and within columns by the Fisher’s LSD test at P ≤ 0.05.

Means separations are within harvests and within columns by the Fisher’s LSD test at P ≤ 0.05.


Page 39 of 47


Table 5. Residual fungicides on ‘Florida Radiance’ from conventional and reduced-fungicide disease control treatments at harvest (day 0) and after 3 and 7 days of storage at 1.5°C and 85% RH. Captan

Fludioxonil

Penthiopyrad

Fenhexamid

Cyprodinil

Cyflufenamid

Azoxystrobin

Pyraclostrobin

(ppm)

(ppm)

(ppm)

(ppm)

(ppm)

(ppm)

(ppm)

(ppm)

Harvest 1 Conventional 0

3.144 ba

N.D.b

N.D.

0.224 b

N.D.

0.015 b

N.D.

N.D.

3

4.596 a

N.D.

N.D.

0.320 a

N.D.

0.025 a

N.D.

N.D.

7

3.638 b

N.D.

N.D.

0.220 b

N.D.

0.019 b

N.D.

N.D.

-

-

0.254

-

0.020 A

-

-

Average

3.792

c

Reduced 0

N.D.

0.027 a

N.D.

N.D.

0.018 ab

0.016 a

N.D.

N.D.

3

N.D.

0.025 a

N.D.

N.D.

0.016 b

0.016 a

N.D.

N.D.

7

N.D.

0.026 a

N.D.

N.D.

0.019 a

0.015 a

N.D.

N.D.

Average

-

0.026

-

-

0.017

0.016 A

-

-

0

3.008 a

0.388 a

N.D.

0.105 b

0.474 a

N.D.

0.019 a

N.D.

3

2.066 b

0.162 c

N.D.

0.194 a

0.282 c

N.D.

0.011 b

N.D.

7

2.175 b

0.232 b

N.D.

0.090 b

0.397 b

N.D.

0.018 b

N.D.

Average

2.416 A

0.261 A

-

0.130 B

0.384 A

-

0.016

-

Harvest 2 Conventional

Reduced



Page 40 of 47

0

1.493 a

0.125 a

0.010 a

0.204 b

0.110 b

0.009 a

N.D.

N.D.

3

1.796 a

0.135 a

0.009 a

0.271 a

0.138 a

0.001 b

N.D.

N.D.

7

1.360 a

0.084 b

0.010 a

0.113 c

0.099 b

0.007 a

N.D.

N.D.

Average

1.550 B

0.115 B

0.010

0.196 A

0.116 B

0.006

-

-

a

Means separations are within disease control treatments and days of storage and within columns by the Fisher’s LSD test at P ≤ 0.05.

b

N.D. = Not detected.

c

Means separations are within harvests and within columns by the Fisher’s LSD test at P ≤ 0.05.


Page 41 of 47


'Strawberry Festival'

'Florida Radiance'

40 38

Conventional Reduced

[

a

L* value

36

]

b

34

[

a

32

b Conventional Reduced Organic

30

p

Sensory Quality, Physicochemical Attributes, Polyphenol Profiles, and

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