Flavor formation and sensory perception of selected peanut genotypes (Arachis hypogea L.) as affected by storage water activity, roasting, and planting date

Peanuts (Arachis hypogea L.) are a major commodity throughout the world and the southeastern U.S. Planting date, maturity at harvest, initial moisture content, storage water activity, peanut variety, and fatty acid composition play a role in roasted peanut flavor and oxidative stability.; Peanut storage conditions have significant effects on overall quality. High-oleic peanuts (peanut seed with 74+% oleic fatty acid oil chemistry) maintain best product quality (low oxidation rate, maintenance of desirable flavor, and crunchiness) when stored at water activities between 0.33 and 0.44. Above this range, crunchiness decreased and oxidation increased, whereas below the range, the oxidation rate increased.; Planting date did not affect peanut flavor, sweetness, painty, or cardboardy sensory scores, with the exception of the 4-15-98 early planting date, which had lower sensory values. Early May appears to be the best time to plant peanuts as a function of sensory potential. SunOleic 97R had the highest roasted peanut scores and the lowest levels of oxidation over six months of storage, among the genotypes evaluated. Roasted peanut flavor and sweetness declined during storage regardless of variety or planting date. Fatty acid profile did not significantly change as a function of planting date. Oleic/linoleic acid ratios increased in late maturity peanuts, thus increasing oxidative stability.; Peanuts available for commercial roasting tend to be a mixture of genotypes, seed sizes, maturities, and seed composition. Color measurement is currently used to predict roasted flavor in peanuts but does not account for genotypes that have the propensity to roast to a darker color without increased formation of flavor. During peanut roasting, pyrazines and other flavor compounds are formed via Maillard reactions, and strongly correlate with roasted flavor and aroma. A rapid method for measuring pyrazine compounds using headspace solid-phase microextraction (SPME) was developed. This method was used to analyze peanuts roasted under a variety of time-temperature combinations. Florida MDR 98 formed the highest levels of pyrazines under the same roasting conditions, followed by Florunner, Georgia Greene, and SunOleic 97R, respectively. Of all pyrazines tested, 2,5-dimethylpyrazine more highly correlated to roast peanut flavor and aroma.