Carotenoid-Derived Aroma Compounds - ACS Publications

Chapter 15

Carotenoid Degradation Products in Paprika Powder

Downloaded by UNIV OF CINCINNATI on February 18, 2015 | http://pubs.acs.org Publication Date: November 21, 2001 | doi: 10.1021/bk-2002-0802.ch015

G. E. Krammer, P. Werkhoff, H. Sommer, C. O. Schmidt, I. Gatfield, and H.-J. Bertram Flavor Division, Haarmann and Reimer GmbH, P.O. Box 1253, D-37601 Holzminden, Germany

The color and the characteristic flavor of red paprika powder (Capsicum annuum L.) is highly appreciated for savory food products. During processing, treatment and storage of paprika powder numerous degradation and rearrangement products are formed. In this work 29 new carotenoid derived compounds in paprika powder are reported. In addition the presence of 12 previously described carotenoid degradation products was confirmed. Furthermore the influence of individual compounds on the sensorial profile of paprika powder was investigated by means of gas chromatography-olfactometry together with enantioselective gas chromatography.

Capsicum, also called chili or red pepper, is the dried fruit of certain New World relatives of the tomato (Lycopersicum esculentum, Solanaceae). Most are the varieties of two species, Capsicum annuum (Solanaceae) and the frequently smaller, hotter Capsicum frutescens (Solanaceae). One variety of Capsicum annuum has become well established in Hungary as sweet bell pepper or paprika (1). In many cuisines paprika is known as spice for its color and flavor. It is applied to food in the form of powder, flakes or oleoresins, which are of growing interest in food industry. The composition of the carotenoid pigments produced in red paprika have been studied thoroughly (2-4). In the following all

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© 2002 American Chemical Society

In Carotenoid-Derived Aroma Compounds; Winterhalter, P., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2001.

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previously identified carotenoid degradation products from paprika powder are mentioned with Roman numerals. In parallel newly identified degradation products are listed with Arabic numerals. Studies on the volatiles of red pepper, conducted in the early eighties, revealed the presence of β-ionone (I) as an important flavor compound with typical floral notes (5, 6). The importance of β-ionone for the flavor profile of paprika powder was emphasized recently by Zimmermann and Schieberle (7). Parallel to our work, Cremer and Eichner observed a significant increase of βionone during heating of paprika powder (8). Additional publications on volatile compounds in Spanish paprika (9) and paprika oleoresin (10) revealed the presence of other carotenoid degradation products such as dihydroactinidiolide (II). On the one hand these compounds indicate the close relation between color and flavor in dried products like paprika powder. On the other hand carotenoid derived aroma compounds represent paprika-typical sensory properties like, e.g., floral, hay-like and tobacco-like notes. It is well-known that the stability of the main carotenoids depends on the drying conditions and other industrial processes (11). In order to receive an overview about carotenoid derived volatiles in paprika powder several different qualities of paprika powder were analyzed for this work.

EXPERIMENTAL SECTION Paprika powder. Samples obtained from three different harvest periods (1997-1999) in Hungary were analyzed. Additionally paprika powder of harvest 1999 with and without steam treatment were analyzed. Sample preparation. For the study of carotenoid degradation products we tested different sample clean-up techniques, for example liquid-liquid extraction, simultaneous distillation extraction (SDE), thermodesorption and extraction with supercritical C 0 (SFE). A specific procedure starting with a SFE step revealed interesting results both for semi-polar and polar degradation products. Amounts between 300 g and 2000 g of paprika powder were extracted for 4 hours at 40°C and 150 bar with supercritical C 0 (SITEC System, Switzerland). The obtained extract was subjected to partitioning with two portions of 250 ml distilled water. The next step comprised the extraction of the aqueous phase with dichloromethane and subsequent concentration. A l l con centrated extracts were analyzed using G C / M S , GC/FTIR and G C / O , as well. Instrumental analysis. Instrumentation (capillary gas chromatography, spectroscopy) as well as analytical and preparative conditions have been described in a previous publication (12). For chiral separations a fused silica column (25 m χ 0,25 mm, film thickness 0,25 μηι) from M E G A capillary columns laboratory (Legnano, Italy) was used. The column was coated with a solution of 30% diacetyl tert. butyl silyl^-cyclodextrin with 70% OV-1701. 2

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RESULTS AND DISCUSSION The intensity of the red color is one of the most important parameters that determines the commercial quality of paprika powder. The main carotenoids, which are responsible for the red color spectrum are capsanthin and capsorubin characterized by one and two κ-end groups, respectively. The red xanthophylls mainly occur as esters with lauric, myristic and palmitic acid. β-Carotene as well as cryptoxanthin, zeaxanthin and violaxanthin are progenitors of red pigments and contribute to the yellow color spectrum. The fatty acids esterifying yellow xanthophylls are linoleic, myristic and palmitic acid. Consequently the red xanthophylls show higher stability than yellow xanthophylls and β-carotene itself at temperatures below 60°C. Above 60°C the situation was found to be inverted (75). The degradation of β-carotene follows different pathways, always with oxygen playing a key role. A welldocumented reaction is photo-oxygenation, induced by singlet oxygen (14). The so called "en"-mechanism and the (2+2) cyclo-addition are important reaction mechanisms. Furthermore, intensive research work revealed the presence of minor constituents with interesting structural properties in varieties of Capsicum annuum. Carotenoids with 3,6-epoxy end groups such as cyclo-violaxanthin, cucurbitaxanthin A , 3,6-epoxyxanthin were found together with (8S)~ capsochrom, which shows a 5,8-epoxy group (15). Recently the occurrence of 5,6-di-epi-karpoxanthin and 5,6-di-epicapso-karpoxanthin, two derivatives with two and one 3,5,6-trihydroxy-5,6-dihydro β-end groups was reported (16).

Nor Compounds Derived from Acyclic Isoprenoids In accordance with the work of Guadayol et al. (10), we found 6-methyl-5hepten-2-one (III) and (E)-6-methyl-3,5-heptadien-2-one (IV) as well as geranyl acetone (V) and farnesyl acetone (VI) in the extracts prepared by the above mentioned clean-up procedure. The formation of compound III was also described by Luning et al. in 1994 (17). Geranyl acetone, farnesyl acetone and methyl heptenone are formal degradation products of phytofluene (Figure 1). The formation of methyl heptenone from ξ-carotene and lycopene follows the same scheme. In tomato, as a related fruit, Buttery and Ling suggested an oxidative process for the formation of geranyl acetone, while methyl heptenone (III) also seems to be generated from a glycosidically bound precursor (18). Furthermore (E)-6-methyl-3,5-heptadien-2-one (IV) was found amongst the products of hydrolysis of a tomato glycoside fraction by the same authors. A second pathway to methyl heptadienone was observed by Hohler during S D E treatment of lutein (14).


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Table I MS-data and retention index data of cyclohexanone and cyclopentenone derivatives No. 23a


23b

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Compound name 4-hydroxy-2,2,6trimethyl-cyclohexanone (trans-isomer) 4-hydroxy-2,2,6trimethyl-cyclohexanone (cis-isomer) 3,4,4-trimethyl-2cyclopentenone

RI(DB-l) 1207

1196

1016

MS-data (m/z, %) 56(15), 83 (100), 57 (58), 69 (45), 41 (39), 82 (38), 74 (37), 88 (37), 55 (30) 156(14), 83 (100), 57 (64), 69 (50), 41 (46), 88 (41), 74 (38), 82 (36), 43 (32) 124(37), 109 (100), 81 (47), 39 (30), 41 (20), 79 (16), 53 (13), 40(10)

lycop

Carotenoid-Derived Aroma Compounds - ACS Publications

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