Jaocs news feature

110

AND SUMMARYLegumes contain unsaturated lipids that are susceptible to oxidative deterioration. Enzymic and nonenzymic deterioration of these lipids results in the development of off-flavors. The primary objective of this review is to summarize what is currently known about lipid-derived flavors of soybeans and underblanched pea seeds (Pisum sativum). Identifying the numerous volatile compounds arising from breakdown of lipid hydroperoxides coupled with organoleptic evaluation defines the flavor problem. Major contributors to the green-beaniness of soybeans were found to be 3-cis-hexenal, 2-pentyl furan, and ethyl vinyl ketone. Oxidized phosphatidylcholines cause some of the bitter taste. The interaction of lipid breakdown products 'with proteins, carbohydrates, and other constituents can affect flavor characteristics and also increase the problems of their removal from soy protein products. To prepare bland products, it will be necessary to develop processes that effectively remove bound flavor components and prevent formation of derived flavors. Solvent systems based on alcohol have been used to extract flavor principles from soybeans; aqueous alcohol treatment of the intact seed or blanching with hot water or steam inhibits formation of off-flavors in peas and soybeans. A new approach involving infusion of antioxidants into the intact seed to control lipid deterioration during processing and storage is proposed to minimize flavor formation without subsequent undesirable changes in protein which occur with alcohol treatments.

Section: Volatile Falvor Compoundsmentioning

confidence: 99%

Lipid‐Derived flavors of legume protein products

Sessa

Rackis

1977

110

“…Various studies have shown that oxidized Ln forms four (from ground state oxygen) or six (from singlet oxygen) monohydroperoxides (11,12). It is the decomposition of those hydroperoxides to volatile compounds that probably are, at least in part, responsible for the objectionable odors and flavors of oils containing Ln (13,14).…”

Section: Introductionmentioning

confidence: 99%

“…Staph and Daubert (9) identified three aldehydes via their dinitrophenylhydrazones (DNPH) from unhardened SBO oxidized at 200 C. The aldehydes reported are associated with oxidized oleic and linoleic acids and not linolenic acid. Hoffmann (13) also used the DNPH methodology to isolate volatiles from SBO heated at 120 C. He observed 3hexenal and 2,4-hepta-and octadienals and concluded that the precursor of these compounds was Ln. The most detailed study on oxidation of Ln at elevated temperatures was reported by Lomanno and Nawar (15).…”

Section: Introductionmentioning

confidence: 99%

Volatile components from trilinolenin heated in air1

Selke

Rohwedder

1983

Headspace volatiles derived from trilinolenin heated to 192 C in air were collected, separated and identified using a microroom/GC‐MS/ computer system. Data from four analyses indicated more than 80 volatiles were present. Of these volatiles, 38 have been identified, and their combined GC peak areas represent 90% of the total integrated Chromatographic area. Dominant volatiles identified included: ethanal (2%), 2‐pentene (3%), ethanol (0.5%), 2‐propenal (20%), propanal (7%), ethyl furan (13%), 2‐butenal (4%), 2‐pentenal (4%), 2,4‐heptadienal (21%), 4,5‐epoxy‐2‐heptenal (3%) and 2,4,7‐decatrienal (2%). Most of the dominant and some of the minor volatiles are the predicted decomposition products of the four linolenin monohydroperoxides. However, the ratios of the predicted volatiles do not correspond to the monohydroperoxide ratios observed from autoxidized linolenate. Other primary and minor volatiles are present that are not predicted from the classical hydroperoxide decomposition hypothesis, which suggests that trilinolenin and some of the volatile compounds undergo further oxidation.

“…Much of the research on objective instrumental tests has been focused on gas chromatography (GC) to provide indications of food quality and/ or shelf life stability. Methods of headspace and direct analysis by GC both with and without prior enrichment have been developed by Evans et al~ (1), Selke et al (2), Nawar and Fagerson (3), Hoffmann (4), and Dupuy et al (5)(6)(7).…”

Section: Introductionmentioning

confidence: 99%

“…Smouse and Chang (13) identified 71 volatile flavor compounds in reverted soybean oil. Hoffmann (4) reported that 3-cis-hexenal caused the "green bean" flavor in soybean oil. Evans et al (14) found that the addition of 2-pentyl furan to bland oil produced buttery, rancid, and grassy flavors.…”

Section: Introductionmentioning

confidence: 99%

Flavor score correlation with pentanal and hexanal contents of vegetable oil

Warner

Evans

List

et al. 1978

Samples of commercially processed soybean, cottonseed, and peanut oils were stored under controlled conditions then evaluated for flavor by a 20‐member trained, experienced oil panel and for pentanal and hexanal contents by direct gas chromatography. The oils, which contained citric acid and/or antioxidants, were either aged from 0 to 16 days at 60 C or exposed to fluorescent light for 0 to 16 hr. The simple linear regressions of flavor score with the logarithm of pentanal or hexanal content in aged soybean oil gave correlation coefficients of −0.96 and −0.90, respectively; for cottonseed oil, −0.60 and −0.85; and for peanut oil −0.74 and −0.75. Addition of peroxide values to the linear regressions increased the correlation coefficients. Flavor scores of cottonseed and peanut oil can be predicted from pentanal and hexanal contents, but the technique is slightly more reliable for soybean oil based on the treatments used for these oils.