61B-29 |
Effects of water activity and oleic acid contents on sensory changes, volatile compounds and oxidation in peanuts during storage |
K. A. Reed1, C. A. Sims2, and S. F. O'KEEFE1. (1) Department of Food Science and Technology, Virginia Tech, 121 Food Science Building, Blacksburg, VA 24061, (2) Department of Food Science and Human Nutrition, University of Florida, Food Science Building, Gainesville, FL 32611 The development of off-flavor compounds can have adverse effects on the consumer acceptability of roasted peanuts and peanut products. These undesirable components are created by lipid oxidation reactions that occur during the storage period prior to consumption. The storage of peanuts at low relative humidities can accelerate these oxidation reactions. Recently lines of runner peanuts with high oleic and low linoleic traits have been developed (up to 80% oleic acid and 2-4% linoleic acid). Levels of pyrazine compounds responsible for desirable peanutty flavors in some studies have been shown to remain constant during storage yet in others has been shown to decrease. Objectives of this study were to identify changes in desirable and undesirable flavor compounds of normal and high oleic peanuts during storage at low and moderate water activities. Storage studies were conducted on roasted high oleic peanuts (HOP) and normal oleic peanuts (NOP). Each peanut type was stored at aw 0.19 and aw 0.60 water activities. Samples were removed at two-week intervals for chemical oxidation measurement (peroxide value), sensory evaluation (quantitative descriptive analysis), and gas chromatographic analysis of flavor volatiles (solid phase microextraction). High oleic peanuts had better oxidative stability after 7 weeks compared to NOP, which had peroxide values 7-10 times higher. Sensory evaluation showed HOP also retained roasted peanutty characteristics and resisted off-flavor development over storage. Normal oleic peanuts developed significant painty flavors after storage. Flavor analysis of HOP with SPME-GC revealed that pyrazines, which are the compounds responsible for roasted peanutty notes, remained at higher levels after storage than in NOP. HOP also showed less development of aldehydes, which give rise to off-flavors. Loss of flavor in peanuts appears to be associated with loss of pyrazine compounds during storage.
Session 61B, Food Chemistry: Flavor and aroma chemistry
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