The Alteration of Physicochemical and Thermal Characteristics of Peanut by Salting-Roasting Process

Abstract

Peanut as nutritious food containing high protein, high fat, carbohydrate, and bioactive substance is usually processed in order to enhance palatability and consumer preference. One of the thermal processes, a traditional salting-roasting process used by BIMARAM SME in Gunungkidul to add the value of peanut, was predicted to be able to alter the properties of peanut, i.e., physicochemical and thermal characteristics. This research investigated the alteration, and the comparison of salted-roasted peanut and raw peanut properties was essentially needed to be conducted. Physicochemical characteristics were represented by parameters such as moisture content, ash content, fat content, protein content, antioxidant activity, color, mean geometric peanut kernel diameter, kernel size distribution, hardness, and fracture parameter. Meanwhile, thermogravimetric analysis (TGA) result described thermal characteristic. The salting-roasting process produced the decreasing of moisture, protein, fat, antioxidant activity expressed by antiradical power, and CIE Lab color values (lightness (L*), redness (a*), and yellowness (b*)), compared with that of raw peanut. Meanwhile, the ash content of the peanut was increased by the process. All of the changes were significant (p<0.05) statistically. The process reduced the mean geometric peanut kernel diameter (p<0.05) and yielded a narrower kernel size distribution. According to TGA result, the roasted peanut was more stable thermally, which was shown by the shifting of endothermic peak to the higher temperature. The enhancing of palatability of peanut by salting-roasting was proven by hardness decreasing (p<0.05), although the fracture was insignificantly increased (p>0.05).