Submitted to: American Peanut Research and Education Society Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/19/2003
Publication Date: 7/12/2003
Citation: SANDERS, T.H., HELMS, D. THE EFFECT OF DEGREE OF ROAST ON SHELF-LIFE QUALITY OF IN-SHELL PEANUTS. PROCEEDINGS OF AMERICAN PEANUT RESEARCH AND EDUCATION SOCIETY 35:44 (2003). Interpretive Summary:
Technical Abstract: External peanut pod appearance is a critical factor when consumers make purchase decisions. Pod color is affected by degree of roasting. In a study designed to evaluate the quality characteristics of roasted in-shell peanuts, three degrees of roasting were imposed on peanuts to produce measurable differences in pod color. Peanuts were roasted at 347, 354, and 358 C in a Proctor & Schwartz, Inc. commercial roaster for ca. 25 min to produce pods with significantly different mean Hunter L values of 43.5, 42.1, and 40.2, respectively. Roasted pods were placed into 21 or 30 C temperature controlled storage 3 d after roasting and samples were taken weekly for 2 wk and then biweekly through 16 wk. Moisture content was higher in the lighter roasted peanuts and moisture increased approximately 1.5% in all pods during storage. Oxidative stability index (OSI) indicated the relative stability of oil from the peanuts to increase from dark to light roast. Significant differences in OSI were noted after one wk and all treatments were significantly different over the storage period. Peroxide values indicated the same relationship among roast treatments. Descriptive sensory analysis revealed significantly higher intensity of roasted peanutty from dark to light roast and the differences persisted over the storage period. Dark roast flavor intensity was found to be almost two intensity units higher in the darker roasted samples while raw beany flavor was higher in the lighter roasted samples. Painty descriptor, commonly associated with lipid degradation, began to increase after 2 wk at 30 C and after 8 wk at 21 C. At both storage temperatures, the lighter roast samples had significantly higher painty intensity. The study demonstrated that light roasting of in-shell peanuts to preserve a lighter color results in decreased shelf life quality.