Effects of roasting and storage on proteins and oil in peanut kernels

Peanut kernels, untreated or soaked in salt solution, were roasted at 160 degrees C for 30 min in a hot air oven or oil roasted at 147 degrees C for 2 min and, stored at 27 degrees C and 5 degrees C up to 150 days. The heat treatments significantly decreased methionine, tryptophan and in vitro protein digestibility (IVPD) and, increased the soluble proteins and acid value of kernel oil. Storage of heated peanuts caused an increase in water-soluble proteins, IVPD, acid value and saponification value and a decrease in methionine, tryptophan and iodine value. The oil roasting was found to be more detrimental to nutritional quality and storage stability of peanuts as compared to dry roasting. The storage of heated peanuts at 5 degrees C was found to be beneficial in lowering the undesirable nutritional changes in the peanut kernels.