Recovery Potential of Cold Press Byproducts Obtained from the Edible

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Recovery Potential of Cold Press By-Products Obtained from Oil Industry: Physicochemical, Bioactive and Antimicrobial Properties Safa Karaman, Salih Karasu, Fatih Tornuk, Ömer Said Toker, Ümit Geçgel, Osman Sagdic, Nihat Özcan, and Osman Gul J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/jf504390t • Publication Date (Web): 03 Feb 2015 Downloaded from http://pubs.acs.org on February 18, 2015

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Journal of Agricultural and Food Chemistry

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Recovery Potential of Cold Press By-Products Obtained from Oil Industry:

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Physicochemical, Bioactive and Antimicrobial Properties

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Safa Karamana, Salih Karasub,*, Fatih Tornukb, Omer Said Tokerb, Ümit Geçgelc, Osman

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Sagdicbd, Nihat Ozcand, Osman Güle a

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Erciyes University, Engineering Faculty, Food Engineering Department, 38039, Kayseri, Turkey

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Yildiz Technical University, Chemical and Metallurgical Engineering Faculty, Food Engineering Department,

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34210, Istanbul, Turkey c

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Namik Kemal University, Agricultural Faculty, Food Engineering Department, 59000, Tekirdag, Turkey d

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TÜBĐTAK MAM, Food Engineering Institute, 41470, Gebze-Kocaeli, Turkey

Ondokuz Mayıs University, Yeşilyurt Demir Celik Vocational School, Food Technology Program, 55139, Samsun, Turkey

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Corresponding Author, E-mail: [email protected], Tel: 090 212 383 4580, Fax: 090 212 383 4571

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ABSTRACT

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Physicochemical, bioactive and antimicrobial properties of the different cold press oil by-

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products (almond (AOB), walnut (WOB), pomegranate (POB) and grape (GOB)) were

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investigated. Oil, protein and crude fiber content of the by-products were found between 4.82-

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12.57%, 9.38-49.05% and 5.87-45.83%, respectively. GOB had very high crude fiber content,

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therefore, it may have potential for use in as a new dietary fiber source in the food industry.

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As GOB, POB and WOB oils were rich in polyunsaturated fatty acids, AOB was rich in

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monounsaturated fatty acids. Oil by-products were found as also rich in dietary mineral

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contents especially potassium, calcium, phosphorous and magnesium. WOB had highest total

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phenolic (802 ppm), flavonoid (216 ppm) and total hydrolyzed tannin (2185 ppm) content

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among the other by-products. Volatile compounds of the all by-products are mainly composed

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of terpenes in concentration of approximately 95%. Limonene was the dominant volatile

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compound in all of the by-products. Almond and pomegranate by-product extracts showed

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antibacterial activity depending on their concentration while those of walnut and grape by-

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products showed no antibacterial activity against any pathogenic bacteria tested. According to

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the results of the present study, walnut, almond, pomegranate and grape seed oil by-products

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possess valuable properties which can be taken into consideration for improvement nutritional

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and functional properties of many food products.

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Key words: Almond, grape, pomegranate, walnut, cold press oil, by-products

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INTRODUCTION

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Various oils have been obtained by different extraction methods and used as functional food

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ingredients/supplements since ancient times. Cold pressing, one of the most ancient oil

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extraction techniques is one of the seed oil production method where any heat treatment,

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refining processes and/or solvent extraction is not included1. As known, cold pressing does

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not give an extraction yield as much as solvent extraction technique and high temperature

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processing and a much quantity of oil after pressing cannot be recovered from the oil source;

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however, it has a major advantage of minimizing degradation of nutritive oil constituents2.

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The residual oil part is also significant for storage stability, functionality, and nutritional

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characteristics of the by-products of cold press oil.

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A huge number of plants are used for oil production and processed with different extraction

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techniques in all over the world. Cold processing constitutes a considerable part of this

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process and is especially demanded by organic food industry where use of petroleum derived

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solvents is restricted3. A main disadvantage related to oil production is release of by-

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products/wastes formed during processing to environment, constituting around 10 to 30% of

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incoming total raw material and posing some environmental problems4. Therefore, it is crucial

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for food industry to develop appropriate waste disposal and by-product management systems

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and thereby to decrease environmental risks. Several strategies such as composting,

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bioremediation and feedstock production for anaerobic digestion have been suggested for

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food waste management5. Recovery potential of by-products is based on their chemical and

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some other properties such as functional and antimicrobial properties. By this way, the

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intended use of the by-products could be determined. They could be used as enrichment of

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different food products or a source for production of different food ingredients such as

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colorants, antimicrobials, dietary fibers. Recovery of nutritional constituents from food wastes

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have been suggested as an alternative way of utilization since they have been demonstrated to 3 ACS Paragon Plus Environment


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have high amounts of active compounds with bioactive properties such as antioxidant and

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antimicrobial6. Seeds of pomegranate and grape and fruits of almond and walnut are rich

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sources of oils and used for oil production to be used as food ingredients and/or specific uses.

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Although several bioactive properties of extracts of oil by-products of grape and pomegranate

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seeds and almond have been studied by different researchers7-9, to the best of our knowledge,

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no investigation is available on bioactive and physicochemical properties of those by-products

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in detail and no investigation has been focused on properties of extracts of walnut. Therefore,

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this study was aimed to investigate physicochemical (crude fat, protein, fiber contents,

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mineral, phenolic, fatty acid and volatile aroma composition and color properties),

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antimicrobial (against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli

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O157:H7 and Salmonella Typhimurium), bioactive properties (hydrolysable tannin, total

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phenolic and flavonoid contents) and volatile composition of those by-products in detail.

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Results of the present study could provide information about where these by-products could

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be used in the food industry to achieve economic gain.

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MATERIALS AND METHODS

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Materials

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Oil by-products obtained by cold pressing of grape, walnut, pomegranate and almond seeds

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were provided from Neva Food Co, Istanbul, Turkey and coded as GOB, WOB, POB and

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AOB, throughout the manuscript, respectively. Air-dried and powdered samples were

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subsequently transferred to laboratory and stored in damp-proof plastic bags at room

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temperature until being analyzed.

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Physicochemical properties

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Determination of color, browning index (BI) and bulk density

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The color properties of the by-products were measured using a colorimeter (Konica Minolta,

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CR-400, Mississauga, ON, Canada) and the color values were expressed as L (whiteness/ 4 ACS Paragon Plus Environment

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darkness), a (redness/greenness), and b (yellowness/blueness). Browning index (BI) analysis

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was carried out according to a method described by Palombo, et al.

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values of the centrifuged clear filtrates were measured at 420 and 550 nm by

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spectrophotometer (8453E UV-Vis, Spectroscopy System, and Agilent, USA). Distilled water

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was used as the blank and browning index which was expressed as optical density/g dry solids

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and was calculated as follows:

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= −

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where A420 and A520 are absorbance values of the samples measured at 420nm and 520nm,

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respectively. Bulk density of the byproducts samples was determined according to method

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described by Chegini and Ghobadian 11.

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Determination of dry matter, oil, protein, crude fiber and ash contents

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Dry matter, ash, protein, crude fiber and oil content of the by-products were determined

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according to the method reported by official procedures12. Dry matter contents of the samples

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were analyzed by drying at 105°C for 4h in a drying oven (FN 120, Nuve, Ankara, Turkey).

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Ash content was determined by incineration of the samples at 550°C for 6h while protein

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content was tested using an automatic nitrogen analyzer (FP 528, Leco, USA), performing

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based on the Dumas method. Total protein contents were calculated by multiplying the

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obtained nitrogen values by 6.25. Crude fiber contents of the samples were determined using

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an automatic fiber analyzer (ANKOM Technology Corp. Fairport, NY, USA). Oil content of

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the by-products was determined using a Soxhlet extraction system in which hexane was used

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as a solvent.

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Determination of water activity and pH values

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Water activity meter (AquaLab, 2.0, USA) was used for determining water activity value of

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the samples. Samples were placed into plastic cups to cover the surface and transferred into

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the equipment. The results were measured at 25°C.The pH of the sample was measured with a

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. Briefly, absorbance

(1)



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pH meter (WTW-Inolab, Weilheim, Germany) in a suspension of 10% (w/v) powder in

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distilled water at 25ºC.

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Determination of fatty acid composition

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Fatty acid composition of the extracted oil samples was determined using fatty acid methyl

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ester (FAME) according to the method described by Yalcin, et al.

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acid composition of the samples, the samples were subjected to oil extraction procedure

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carried out by hexane using Soxhlet extraction system for 6 h. GC(Agilent 6890, Agilent,

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USA) equipped with a FID and 100 × 0.25mm ID HP-88 column was used. Injection block

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temperature was adjusted at 250°C. The oven temperature was hold at 103°C for 1min and

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heated to 170°C at 6.5°C/min, 170°C to 230°C for 12 min 2.5°C/min and then hold at 230°C

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for 5 min. Helium was used as a carrier gas with a flow rate 2mL/min: split rate was 1/50.

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To determine the fatty

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Determination of mineral composition

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Mineral analysis of samples was performed according to the methods with some modification

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described by AOAC

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vessels and incorporated with 5mLof concentrated nitric acid and 1mL of hydrogen peroxide.

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Vessels were closed and placed into microwave oven. The initial oven temperature was

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adjusted to 25°C for, then heated to 90°C for 5min, from 90 to 120°C at 6°C/min, and from

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120 to 150°C at 6°C/min, finally increased to 175°C at 6°C/min and held at this temperature

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for 5min. After cooling the vessels clear digested samples were transferred to 50 ml

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volumetric flask and diluted to mark with deionized water. Minerals were determined using a

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Perkin Elmer AAS 700 in flame mode. Following wavelengths and slit widths were used to

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quantify minerals. Calcium wavelength 422.7, slit: 0.7 H, Sodium wavelength 589.0, slit: 0.2

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H, Iron wavelength 248.3, slit: 0.2 H, Zinc wavelength 213.9, slit: 0.7 H, Manganese

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wavelength 279.5, slit: 0.2 H, Potassium wavelength 766.5, slit: 0.7 H, Magnesium

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wavelength 285.2, slit: 0.7 H, Copper wavelength 324.8, slit: 0.7 H.

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. 0.5 gram sample was weighed into Teflon microwave digestion


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Bioactive properties

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Extraction procedure

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Methanol was used for the extraction of the bioactive compounds from the by-products.

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During the extraction process, 1g of sample was weighed into the test tube and mixed with

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10mL of methanol. Obtained mixture was stirred by vortex and then by a shaker for 1 h at

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ambient temperature (Simsek Labor Teknik, Ankara, Turkey). Following the extraction

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process, solution was centrifuged at Universal 320, Hettich, Germany) at 5000 × g for 5min,

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(Universal 320, Hettich, Germany), and the supernatants were filtered using a 0.45 µm filter

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(Sartorious Stedim Biotech, Gottingen, Germany). Obtained extracts were kept at -18 °C for

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further analysis.

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Determination of total phenolic contents (TPC)

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Total phenolic contents (TPC) of the methanolic extracts were determined according to the

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modified method described by Singleton and Rossi

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spectrophotometer (Agilent, 8453E UV-Vis, Spectroscopy System, USA) using Folin

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Ciocalteau’s phenol reagent. TPCs of the samples were calculated as mg gallic acid

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equivalents (GAE) per 100 g of dried samples.

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Determination of total flavonoid content (TFC)

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Total flavonoid contents (TFC) of the methanolic extracts were determined according to the

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method described by Zhinsen, et al.

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nm. The results were expressed as mg catechin (CE)/100g dried sample.

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Determination of total hydrolysable tannin content (HTC)

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Total hydrolysable tannin contents (HTC) of the methanolic extracts were determined

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according to the method of Willis and Allen 17. The absorbance of the samples was recorded

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at 550 nm and the results were calculated as mg tannic acid (TA)/100 g dried sample.

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. TPC was determined at 760 nm by a

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. TFC was determined spectrophotometrically at 510

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Determination of phenolic composition

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Phenolic profile of the samples was determined according to the modified method described

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by Schieber and Carle18 using a HPLC system (Shimadzu, Kyoto, Japan) equipped with a

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degasser DGU-20A5, a gradient pump LC-20AT, an autosampler SIL-20A, column oven

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CTO-10A5 VP and diode array detection (DAD) system SPD-M20A. The column used was

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Luna 5µ C18 100A (250x4.6 mm) from Phenomenex (Torrance, CA, USA). Column

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temperature was set to 25°C. The mobile phase A was 2% (v/v) acetic acid prepared in double

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distilled water; eluent B was 0.5% acetic acid in double distilled water and acetonitrile (50:50,

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v/v). The gradient was as follows: 90 to 55% of A within 40min, 55 to 0% of A within 5 min,

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and returning to the initial 90% of A within 5 min. Among of each analysis 15 min of

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equilibration treatment (90% of A) was performed. The flow rate was 1mL/min and the

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injection volume was 20µL.

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Antibacterial activity

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Antibacterial activity was assessed using the extracts of the by-products prepared for

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determination of bioactive properties. Four bacterial strains were used to assess antibacterial

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activity of the extracts of oil by-products, two Gram positive (Staphylococcus aureus ATCC

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25923 and Listeria monocytogenes ATCC 19118) and two Gram negative bacteria

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(Escherichia coli O157:H7 ATCC 33150 and Salmonella enteric subsp. Enteric serovar

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Typhimurium ATCC 14028). All bacterial strains were activated twice in Nutrient Broth

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(Merck, Darmstadt, Germany) and inocula were prepared by 18h culture in Nutrient Broth at

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37°C.

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The agar diffusion method was used to determine the antibacterial effect based on the method

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described by Özkan, et al.

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Germany) was inoculated with each 18h-bacterial strain targeting a final cell concentration of

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106-107 CFU/mL at 43-45°C and poured in petri plates. After the solidification of agar, four

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wells were made in the agar using sterile cork pores (4mm). A 50 µL of different

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. For this aim, autoclaved Nutrient Agar (Merck, Darmstadt,


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concentrations (50%, 20% and 4% v:v in 95% ethanol) of the extracts was pipetted in each

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well. 95% ethanol was used as the negative control. Petri plates were incubated at 37 °C for

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24h. The antibacterial activity was expressed as the mean of inhibition diameters (mm)

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produced by the extract minus that for the negative control.

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Volatile composition

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Volatile profile of the oil by-products was determined using a gas chromatography–mass

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spectrometry (Agilent 7890A GC system, Agilent, Avondale, Arizona USA) using a mass

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selective detector (Agilent Technologies, Agilent, Avondale, AZ, USA) and DB-WAX

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column (60m×0.250mmi.d.; film thickness, 0.25µm). The oven temperature was adjusted to

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40°C for 10 min, then heated to 110°C at 3°C/min, from 110 to 150°C at 4°C/min, and from

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150 to 210°C at 10°C/min, finally increased to 210 °C/min and held for 15 min. Helium was

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used as a carrier gas with a flow rate of 1.0 mL/min and the voltage of the electron ionization

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detector was 70eV. The compounds adsorbed by the SPME fiber (75 µm, 23 ga,

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carboxen/polydimethylsiloxane (CAR/PDMS)) (Supelco, Bellefonte, PA, USA) at 40°C for 1

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h were desorbed from the injection port for 15 min at 50°C in the splitless mode. The

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compounds were identified by comparison with spectra from the libraries Flavor 2, NIST 05,

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and Wiley 7n. Analyses were conducted in duplicate.

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Statistical Analysis

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All of the results were expressed as mean ± SD. ANOVA was performed to determine the

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differences among the samples using SPSS Statistical Software Program (SPSS Statistics

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17.0, Armonk, NY, USA). Duncan multiple comparison test was conducted to determine the

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differences between the parameters at the probability level of 0.05.

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RESULTS AND DISCUSSION

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Physicochemical properties

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Physical properties 9 ACS Paragon Plus Environment


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Color (L, a, b), browning index and bulk density values of the oil by-products are shown in

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Table 1. As can be seen in the Table 1, L, a and b values of the by-products were found to

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between 42.01-68.39, 5.71-12.72 and 18.19-23.27, respectively. Color values of the WOB,

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POB and GOB samples were very close to each other; however, those of AOB, especially L

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and a values were quite different from the others. As known, color of a certain food is one of

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the main factors affecting its consumer preference. Use of different additives may change

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color properties of foods. In this respect, these oil by-products, if they are used, may affect

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foods' color. Color of the by-products is related with pigments, carotenoids and phenolic

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pigments (anthocyanins, flavonols, and proanthocyanins). Therefore, variation in type or

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amount of these compounds results in different color values. Browning index (BI) values of

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the by-products analyzed in the present study changed between 0.042 and 0.520. Browning of

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the food and agricultural material and their by-products are occurred by the formation of some

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colored pigments due to enzymatic and non-enzymatic reaction and, concentration changes

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The highest BI value was belonged to WOB while AOB had the lowest BI. In addition to

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color properties, bulk densities of the samples were also analyzed. Bulk density of the cold

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pressed oil by-products were found between 1.33 and 1.53. When considering the fact that

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powder forms of these by-products could be used for any aim, their bulk density values are

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also important in this respect. Among the samples, WOB had the lowest bulk density value

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indicating that it can be compressed easily when compared with the others.

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Some chemical properties

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Chemical properties of the oil by-products are presented in Table 2. pH and aw values of the

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samples ranged from 4.25 to 6.14 and from 0.391 to 0.498, respectively. Dry matter contents

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of the by-products were very close to each other and it varied between 90.55% and 93.71%.

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Protein contents of the samples varied in a wide range, from 9.38% to 49.05%. Among the

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samples, AOB had the highest protein content followed by WOB, POB and GOB,


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respectively. As seen from the results, WOB, POB and AOB had significant amounts of

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protein; therefore, they might be used to enrich protein content of different food products.

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Cam, et al.

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samples enriched with by-products had higher protein content than that of control ice cream.

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Enrichment of different food products with AOB could be preferred since it has high protein

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content and almond proteins can provide all essential amino acids except for methionine in

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equal or greater quantities recommended by the FAO21.

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Oil content and fatty acid composition

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Oil contents of the by-products ranged from 4.82% to 12.57%. Except for GOB, the other

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seed by-products had approximately 10% oil, indicating that relatively low cold pressing yield

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which can be considered as a general problem for cold press oil industry. The high oil content

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of the by-products could lead to problem due to oxidation of oil, which might cause some

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problems during storage of the by-products or food products enriched with them. However, as

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it will be seen in subsequent sections, this problem might be prevented due to high phenolic

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composition of the samples. Fatty acid composition of the oils extracted from the by-products

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is presented in Table 3. As seen from the Table 3, significant differences were observed

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among the fatty acid compositions of the oil by-products. Dominant fatty acid of the oil

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extracted from GOB was found to be C18:2, followed by C18:1, C16:0 and C18:0,

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respectively. Saturated fatty acid content of the GOB was determined as 13.08%. Mono- and

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polyunsaturated fatty acid content was found as 18.67% and 68.26%, respectively. Beveridge,

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et al. 22 studied fatty acid composition of oil extracted from different grape seed varieties with

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supercritical carbon dioxide and they revealed that saturated, mono- and polyunsaturated fatty

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acid composition of the oils ranged between 11.21-13.85%, 12.77-18.59%, and 68.10-

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73.67%, respectively. As seen, our results were in accordance with the literature findings. The

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oil extracted from AOB contained the fatty acid types in decreasing order: C18:1, C18:2,

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added pomegranate by-products to ice cream and they reported that ice cream



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C16:0, C18:0, C18:3n6 and C14:0. The findings of the present study were in accordance with

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the previous study 23. Fatty acid profile of POB oil is also presented in Table 3 and the most

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abundant fatty acid determined was C18:3n6 which was followed by C18:2, C18:1, C16:0,

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C18:0, C18:3n3 and C14:0, respectively. POB oil comprised saturated, mono- and

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polyunsaturated fatty acid in concentrations of 7.47%, 6.48% and 86.25, respectively. C18:3

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was found as dominant fatty acid in POB oil. The results of the present study was consistent

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with the findings of Fadavi, et al.

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fatty acid contents of the 25 different pomegranate seed oils varied between 4.8-26.8%, 0.4-

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17.4% and 55.8-92.1%, respectively. C18:2 was determined as the dominant fatty acid in

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WOB oil when compared to the other fatty acid types, which was consistent with the study in

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which saturated, mono- and polyunsaturated fatty acid content of walnut seed oil was reported

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to be 11.76%, 15.28% and 72.96%, respectively23. As expected, slight differences among the

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results of the present study and previous studies were observed for each by-product oil, which

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might be resulted from genetic and environmental factors such as production year and

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growing location25. As known, consumption of the vegetable oils is currently increasing due

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to their high polyunsaturated fatty acid content which possesses natural preventive role in

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cardiovascular disease and promotes reduction of total and HDL cholesterol26. Therefore,

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enrichment of different food products with these oil by-products could be suggested regarding

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their fatty acid composition, which also gain economic benefit as well as health benefit.

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Crude fiber contents

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Crude fiber contents of the by-products varied between 5.87% and 45.83% as shown in Table

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2. Among the by-products analyzed in the present study, the highest crude fiber content was

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observed in GOB (45.83%) while POB, WOB and AOB had crude fiber in concentrations of

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25.10%, 6.65% and 5.87%, respectively. As known, sufficient dietary fiber consumption

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could reduce the risk of cardiovascular disease, colon cancer and obesity

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who reported that saturated, mono- and polyunsaturated


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. Hereby,

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consumption of the dietary fiber enriched products is very important for health of people of all

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age. Enrichment of the food products with GOB or POB should be suggested considering

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beneficial effects of the dietary fiber. Moreover, these by-products can be used as a new

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source for production of different dietary fiber types, which can provide important economic

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benefit since in recent years; people tend to consume products with high fiber content. Chau

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and Huang

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ingredients and have encouraged researchers to search out new fiber sources.

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Determination total ash and mineral composition

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Ash contents of the oil by-products varied between 3.07% and 4.50%. AOB had the highest

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ash content followed by WOB, POB and GOB, respectively. Mineral composition profile of

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the by-products analyzed is summarized in Table 4. GOB was found to be a rich source of

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potassium (832.27 mg/100 g sample) and calcium (670.03 mg/100 g sample). AOB and WOB

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sample had significant amount of potassium, calcium, phosphorous, sulfur and magnesium.

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POB was rich in potassium, calcium, phosphorous and sulfur. In general, all of the by-

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products were rich in macro elements, namely, potassium, calcium, phosphorous and

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magnesium while these elements were all the most abundant minerals found in AOB. These

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by-products also contained dietary trace minerals (iron, manganese, copper and zinc) in

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different quantities. As known, calcium is required for bone growth, nerve and muscle

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functions, protection against high blood pressure; phosphorous for bone growth, acid base

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balance, structure of nucleic acids; magnesium for also bone growth, regular functions of

320

nervous and muscular system; potassium for regulation of blood pressure and muscular

321

contraction. Among the trace elements, iron is required for use of oxygen in body, building of

322

blood cells, structuring of hemoglobin; copper for absorption of iron, structuring of

323

hemoglobin and production of energy. For these reasons, people of all ages require these

324

minerals in order to keep their healthy life and in this respect, incorporation of the oil by-

28

reported that products rich in dietary fibers have attracted attention as food



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products into different food products have potential to improve their nutritional quality by

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enriching their mineral profile. For instance, if any AOB is incorporated to any food product

327

in concentrations of 1%, it provides approximately 12.07 mg potassium, 8.96 mg calcium,

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5.22 mg phosphorous and 2.56 mg sulfur per 100g food to person who consumed this

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enriched food product. As seen enrichment of the products with these by-products can induce

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significant increase in mineral composition.

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Antibacterial activity

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In this study, almond and pomegranate showed antibacterial activity while grape and walnut

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extracts showed no antibacterial activity against any pathogenic bacteria tested. Table 5

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showed the antibacterial activity of AOB and POB as inhibition zone. As can be seen from the

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table, AOB showed no antibacterial activity on tested microorganism except L.

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monocytogenes at the lowest concentration. It is clear from the table that antibacterial activity

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of the AOB and POB extracts was concentration dependent and lower concentrations of the

338

extracts exhibited weak or no antibacterial activity. AOB extract was more effective against

339

Gram positive bacteria (L. monocytogenes and S. aureus) than POB extract while stronger

340

antibacterial activity on S. Typhimurium and E. coli O157:H7, Gram negative ones, was

341

exhibited by pomegranate. Baydar, et al.

342

antibacterial activity against fifteen bacteria. They also stated that lower concentrations of

343

grape seed extracts were ineffective. Hammer, et al.

344

dulcis) oil did not inhibit any organisms even at the highest concentration, which was 2.0%

345

oil. De, et al. 31 reported antimicrobial activity of pomegranate seeds against Bacillus subtilis,

346

E. coli and Saccharomyces cerevisiae. The peel extract has shown highest antimicrobial

347

activity compared to other extracts while the seed extracts exhibited variable antimicrobial

348

activities to the bacteria except for B. coagulans. It can be understood from the literature that

29

reported that grape bagasse extracts did not show

30

showed that sweet almond (Prunus


Page 14 of 30

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349

antimicrobial activity of plant extracts depends several factors such as plant part, extraction

350

method, solvent used and extract concentration.

351

Bioactive properties

352

Total TPC, TFC, and HTC contents

353

Figure 1 represents TPC, TFC and HTC values of the oil by-product extracts. TPC values of

354

the samples varied from 5.21 to 801.89 mg GAE/100g. TFC and HTC values of samples were

355

found to be 71-216 mg CE/100 g and 364.97-2184.60 mg TA /100g, respectively. Among the

356

extracts, WOB extract had the highest TPC, TFC and HTC levels.

357

Grape seeds have attracted considerable attention due to high abundance of bioactive

358

compounds, especially various types of phenolics. It has been reported that grape seed

359

contains higher levels of phenolics than skin and pulp32. As expected, TPC of GOB was found

360

to be lower than those of their studies, probably caused by the cold pressing process. TPC

361

value of GOB was also lower than that of the grape wine by-products previously reported

362

from literature33. Growth environment of grape cultivars might also influence their TPC

363

values. TFC value of GOB was comparable with grape skin while it was higher than that of

364

the grape pulp as reported from literature.

365

In present study, considerable amount of the bioactive compounds was found in the walnut

366

waste obtained after cold press oil processing (Figure 1). It was reported that walnut bioactive

367

compounds have antioxidant activity and potential beneficial health effects such as anti-

368

inflammatory, anti-mutagenic and anti-atherogenic34. Almond HTC was

369

54.7mg EA and 27.4mg GA 100 g-1 for different almond varieties

370

tannins and other phenolics compounds found in almond could be beneficial for health due to

371

their antioxidant and anti-inflammatory effects 35.

372

Pomegranate seeds are by-products of pomegranate fruits. In presents study, moderate levels

373

of bioactive compounds were found in POB as compared to other by-products (Figure 1). It


35

reported to be

.It was reported that


374

can be concluded that by-products analyzed in this study could be considered as a valuable

375

waste materials which may have potential food applications due to presence of high amounts

376

of bioactive compounds.

377

Phenolic profile of the by-products

378

Rather than TPC, distribution of the specific phenolics in a certain media is very important

379

due to balanced intake of essential materials into the body. Phenolics distribution may vary

380

depending on several factors such as plant origin, cultivar, harvesting time, and soil types. In

381

this study, phenolic compositions of the cold press oil by-products are presented in Table 5.

382

As expected, distribution and ratios of phenolic compounds were variable and influenced

383

from the origin of the by-products. Epigallocatechin, gallocatechin and epicatechin were

384

predominate phenolics in GOB (Table 6). Epicatechin was also found to be the most abundant

385

phenolic compound in the grape seed extracts as reported by Baydar, et al. 36. Gallocatechin

386

was found to be major phenolics among the AOB phenolics. Gallic acid, Epigallocatechin and

387

p-cumaric acid were determined to be other major phenolics detected in AOB (Table 6).

388

Epicatechin had the highest level of phenolics in POB followed by p-cumaric acid quarcetin

389

and gallocatechin. There were sight differences between p-cumaric acid quarcetin and

390

gallocatechin contents of POB (Table 6). Gallocatechin was the highest phenolic in WOB

391

while epicatechin and quercetin were other major phenolics found in WOB. WOB contained

392

higher levels of catechin, chlorogenic acid, and resveratrol than the other by-products (Table

393

6). Ellagitannins (ETs) have been reported to be the main phenolic compounds found in the

394

seed of J. regia 37. Gallotannins and ellagitannins, which are classified as hydrolysable tannin,

395

were also reported to be at high amounts in the walnut kernel38.

396

397


Page 16 of 30

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398

Volatile composition

399

Approximately 35 different volatile compounds were identified in the oil by-products.

400

However, their concentrations higher than 0.1% are shown in Table 7. As seen from the Table

401

7, terpenes were found as the predominant volatile compounds of the by-products. Terpenes

402

are composed of 95% of the volatile compounds. Total terpen content of AOB and POB was

403

found to be similar (p>0.05). Among the volatile compounds identified, limonene which is a

404

terpen was found to be major compound in all of the samples analyzed with varying amounts

405

ranging from 90.2% to 93.7%. The highest limonene level was determined in POB and GOB

406

while the lowest was in WOB. Limonene is known as a natural and functional monoterpene.

407

Limonene is considered as safe (GRAS) and used as flavoring agent and food preservative39.

408

Gerhäuser, et al.

409

activities of limonene. Therefore, usage of these by-products which are rich in limonene in the

410

different food products may be important for human health. In addition, the oil by-products

411

had myrcene and β-pinene compounds in concentrations which changed between 1.22%-

412

1.56% and 0.84%-1.29%, respectively. Trans limonene oxide is another volatile compound

413

found in AOB and WOB with concentrations higher than 1.0%. In addition, the percentage of

414

citral in WOB was determined as 2.45%.

415

In a conclusion, in cold press oil industry, remarkable amounts of by-products are arisen after

416

production of the oil. Recovery of these products is important regarding economical gain.

417

Determination of physicochemical and functional properties of the products is crucial in order

418

to reveal their recovery potential in terms of economic and health aspects. In the present

419

study, physicochemical and bioactive properties, fatty acid andmineral composition,

420

antibacterial activity and volatile profiles of the cold press oil by-products of almond, walnut,

421

grape seed and pomegranate were determined. In general, the by-products were found to

422

possess significant amounts of protein and bioactive compounds including phenolic

40

reported bactericidal, antioxidant, chemo-preventative and therapeutic



423

compounds, flavonoids and tannins. GOB and POB had significant amount of crude fiber,

424

which gained them importance to be evaluated as new sources of dietary fiber.Extracts of

425

almond and pomegranate showed considerable antibacterial activity against the pathogenic

426

bacteria tested, indicating their antimicrobial potential while grape and walnut did not have

427

any inhibitory effect. Limonene was the most abundant volatile component of all the by-

428

products. In conclusion, this study revealed that pomegranate, walnut, grape seed and almond

429

cold press oil by-products possessed had valuable potentials and qualifications from different

430

aspects to be used in different areas of food industry for enrichment purposes of food

431

materials.

432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448


Page 18 of 30

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449

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450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498

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22. Beveridge, T. H. J.; Girard, B.; Kopp, T.; Drover, J. C. G., Yield and composition of grape seed oils extracted by supercritical carbon dioxide and petroleum ether: Varietal effects. J. Agric. Food Chem. 2005, 53, 1799-1804. 23. Venkatachalam, M.; Sathe, S. K., Chemical composition of selected edible nut seeds. J. Agric. Food Chem. 2006, 54, 4705-4714. 24. Fadavi, A.; Barzegar, M.; Hossein Azizi, M., Determination of fatty acids and total lipid content in oilseed of 25 pomegranates varieties grown in Iran. J. Food Compos. Anal. 2006, 19, 676-680. 25. Amaral, J. S.; Cunha, S. C.; Santos, A.; Alves, M. R.; Seabra, R. M.; Oliveira, B. P. P., Influence of cultivar and environmental conditions on the triacylglycerol profile of hazelnut (Corylus avellana L.). J. Agric. Food Chem. 2006, 54, 449-456. 26. Melgarejo, P.; Artes, F., Total lipid content and fatty acid composition of oilseed from lesser known sweet pomegranate clones. J. Sci. Food Agric. 2000, 80, 1452-1454. 27. Marlett, J. A., In Handbook of dietary fibre S. S. Cho; (Eds.), M. L. D., Eds. Marcel Dekker: New York, 2001; pp 17-30. 28. Chau, C. F.; Huang, Y. L., Characterization of passion fruit seed fibres - a potential fibre source. Food Chem. 2004, 85, 189-194. 29. Baydar; GülcanÖzkan; OsmanSağdiç, Total phenolic contents and antibacterial activities of grape (Vitis vinifera L.) extracts. Food Control 2004, 15, 335-339. 30. Hammer, K. A.; Carson, C. F.; Riley, T. V., Antimicrobial activity of essential oils and other plant extracts. J. Appl. Microbiol. 1999, 86, 985-990. 31. De, M.; Krishna De, A.; Banerjee, A. B., Antimicrobial screening of some Indian spices. Phytother. Res. 1999, 13, 616-618. 32. Yilmaz, Y.; Toledo, R. T., Major flavonoids in grape seeds and skins: Antioxidant capacity of catechin, epicatechin, and gallic acid. J. Agric. Food Chem. 2004, 52, 255-260. 33. Lachman, J.; Hejtmánková, A.; Hejtmánková, K.; Horníčková, Š.; Pivec, V.; Skala, O.; Dědina, M.; Přibyl, J., Towards complex utilisation of winemaking residues: Characterisation of grape seeds by total phenols, tocols and essential elements content as a byproduct of winemaking. Ind. Crops Prod. 2013, 49, 445-453. 34. Isabel Tapia, M.; Ramon Sanchez-Morgado, J.; Garcia-Parra, J.; Ramirez, R.; Hernandez, T.; Gonzalez-Gomez, D., Comparative study of the nutritional and bioactive compounds content of four walnut (juglans regia L.) cultivars. J. Food Compos. Anal. 2013, 31, 232-237. 35. Xie, L.; Roto, A. V.; Bolling, B. W., Characterization of Ellagitannins, Gallotannins, and Bound Proanthocyanidins from California Almond (Prunus dulcis) Varieties. J. Agric. Food Chem. 2012, 60, 12151-12156. 36. Baydar, N. G.; Babalik, Z.; Turk, F. H.; Cetin, E. S., Phenolic Composition and Antioxidant Activities of Wines and Extracts of Some Grape Varieties Grown in Turkey. Tarim Bilim. Derg. 2011, 17, 67-76. 37. Fukuda, T.; Ito, H.; Yoshida, T., Antioxidative polyphenols from walnuts (Juglans regia L.). Phytochemistry 2003, 63, 795–801. 38. Regueiroa, J.; Sánchez-González, C.; Vallverdú-Queraltb, A.; Simal-Gándara, J., Comprehensive identification of walnut polyphenols by liquid chromatography coupled to linear ion trap–Orbitrap mass spectrometry. Food Chem. 2014, 152, 340–348. 39. Sun, J., D-limonene: Safety and clinical applications. Altern. Med. Rev. 2007, 12, 259264. 40. Gerhäuser, C.; Klimo, K.; Heiss, E.; Neumann, I.; Gamal-Eldeen, A.; Knauft, J.; Liu, G.-Y.; Sitthimonchai, S.; Frank, N., Mechanism-based in vitro screening of potential cancer chemopreventive agents. Mutat. Res. Fundam. Mol. Mech. Mutagen. 2003, 523–524, 163172. 20 ACS Paragon Plus Environment

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549


Figure Captions

550

Figure 1. Total phenolic, flavonoid and hydrolyzed tannin content of the by-products (AOB:

551

Almond seed oil by-product, GOB: Grape seed oil by-product, WOB: Walnut seed oil by-product,

552

POB: Pomegranate seed oil by-product)

553

554

555

556

557

558

559

560

561

562

563

564

565

566

567

568



569

Table 1. Physical properties of the oil by-products Samples WOB POB GOB AOB

570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610

Page 22 of 30

Color Values

BI

L

a

b

48.33 ± 0.01b 42.01 ± 0.02c 43.41 ± 0.02c 68.39 ± 0.01a

8.45 ± 0.01c 10.15 ± 0.03b 12.72 ± 0.02a 5.71 ± 0.01d

22.11 ± 0.04b 23.27 ± 0.02a 18.19 ± 0.03c 18.76 ± 0.04c

0.520 ± 0.001a 0.221 ± 0.000b 0.074 ± 0.000c 0.042 ± 0.000d

Bulk Density 1.33 ± 0.00d 1.47 ± 0.02b 1.37 ± 0.00c 1.53 ± 0.00a

Different superscript lower case letters show differences between the samples (n=3; The results were expresses as mean ± SD) WOB: Walnut seed oil by-product POB: Pomegranate seed oil by-product GOB: Grape seed oil by-product AOB: Almond seed oil by-product BI: Browning index


Page 23 of 30

611 612 Samples WOB POB GOB AOB 613 614 615 616 617 618


Table 2. Chemical properties of the oil by-products Dry Matter (%)

Protein (%)

Oil (%)

Crude Fiber (%)

Ash (%)

90.55 ± 0.04c 93.71 ± 0.49a 93.47 ± 0.46a 92.41 ± 0.02b

34.09 ± 1.01b 24.33 ± 0.49c 9.38 ± 0.23d 49.05 ± 1.03a

10.11 ± 0.36b 12.57 ± 0.36a 4.82 ± 0.33d 8.83 ± 0.52c

6.65 ± 0.17c 25.10 ± 1.08b 45.83 ± 0.66a 5.87 ± 0.30d

4.50 ± 0.15b 3.30 ± 0.06c 3.07 ± 0.02d 5.72 ± 0.01a

pH 5.52 ± 0.05b 4.43 ± 0.00c 4.25 ± 0.11d 6.14 ± 0.02a

aw 0.498 ± 0.006a 0.431 ± 0.003c 0.391 ± 0.011d 0.486 ± 0.001b

Different superscript lower case letters show differences between the samples (n=3; The results were expresses as mean ± SD) WOB: Walnut seed oil by-product POB: Pomegranate seed oil by-product GOB: Grape seed oil by-product AOB: Almond seed oil by-product

619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 23 ACS Paragon Plus Environment


654 655

Table 3. Fatty acid composition (%) of the oils extracted from the cold press oil by-products Fatty Acid C14:0 C16:0 C18:0 C18:1 C18:2 C18:3ω3 C18:3ω6 SFA MUFA PUFA

656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689

WOB

POB

GOB a

AOB c

7.81±0.02c 3.99±0.03b 20.12±0.06b 57.33±0.11b 10.75 ± 0.00a -

0.31 ± 0.00 4.40 ± 0.02d 2.76 ± 0.01c 6.28 ± 0.02d 8.75 ± 0.02d 1.08 ± 0.00b 76.42 ± 0.07a

0.14 ± 0.00 8.65 ± 0.03a 4.29 ± 0.03a 18.67 ± 0.29c 67.50 ± 0.24a 0.76 ± 0.01b

0.20 ± 0.00b 8.35 ± 0.01b 1.73 ± 0.01d 60.18 ± 0.01a 28.79 ± 0.01c 0.75 ± 0.00b

11.80ab 20.12b 68.08b

7.47c 6.28c 86.25a

13.08a 18.67b 68.26b

10.28b 60.18a 29.54c

Different superscript lower case letters show differences between the samples (n=3; The results were expressed as mean ± SD) WOB: Walnut seed oil by-product POB: Pomegranate seed oil by-product GOB: Grape seed oil by-product AOB: Almond seed oil by-product C14:0: Butyric acid, C16:0: Palmitic acid, C18:0: Stearic acid, C18:1: Oleic acid, C18:3ω3: Linolenic acid, C18:3ω6: Conjugated linolenic acid, SFA: Saturated fatty acid, MUFA: Monounsaturated fatty acid, PUFA: polyunsaturated fatty acid -: Not detected.


Page 24 of 30

Page 25 of 30

690 691 692


Table 4. Mineral composition (mg/100 g sample) of cold press oil by-products. Minerals K Ca P S Mg Fe Si Al Cl Mn Cu Zn Sr Na Rb

693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723

WOB

POB b

1171.5 ± 3.5 665.7 ± 3.4b 377.2 ± 10.8b 187.4 ± 1.4b 437.6 ± 3.4b 11.31 ± 1.04a 29.91 ± 2.31a 26.94 ± 1.72a 38.75 ± 1.91b 10.41 ± 1.04a

Recovery Potential of Cold Press Byproducts Obtained from the Edible

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