Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/1997
Publication Date: N/A
Interpretive Summary: Understanding factors which affect roasted peanut flavor and shelf-life are important to the peanut industry. Peanuts are marketed in seed-sized grades, but a distribution of peanut maturities is found in all grades because the size-maturity relationship is not absolute. The roasted flavor of peanuts from a lot is, thus, the composite of the flavor characteristics of each maturity class and the percentage of those seed present. In this study, virginia-type peanuts were harvested on several harvest dates in two years to examine the changes in maturity that occurred. Peanuts of different maturity were classified based on pod mesocarp color, dried, shelled, roasted, and stored at 35 C. A trained sensory panel evaluated flavor characteristics of the different maturity classes and stored samples. Roasted mature peanuts had higher intensities of roasted peanutty flavor and sweet taste and lower intensity of painty (rancid) flavor than immature peanuts. In storage, painty off-flavor increased more quickly to a higher intensity in immature peanuts. Immature peanuts had overall lower flavor impact and a propensity to deteriorate faster in storage. Early harvest dates contained more immature peanuts suggesting a significant impact on flavor. Results of this research explain some of the differences in peanut flavor and shelf life and emphasize that proper harvest timing is important not only to producers, but also to manufacturers of peanut products.
Technical Abstract: Sensory and storage characteristics for maturity classes of virginia-type peanuts from two crop years were studied. Peanuts were roasted, stored at 37 C, and sampled over a twelve-week period. Higher intensities (P<0.01) of roasted peanutty and sweet taste and lower intensity of painty were found in the most mature classes. Painty increased more quickly to a higher intensity in immature classes. Oxidative stability indices and fatty acid profiles supported this change. Immature peanuts had low flavor impact and a propensity to deteriorate faster in storage. Maturity changes at progressive harvest dates indicated the significant impact of maturity class sensory characteristics in determining quality of seed-size based commercial grades.