The effects of storage and processing on the properties of Arachis hypogeae (peanut).

 

The project was part of a Knowledge Transfer Partnership between Sunscoop Products Ltd. and the University of Wales Institute, Cardiff. The processing parameters of (dry

roasting) peanuts were mapped and improvements made, increasing product throughput and energy efficiency. A cross sample of peanuts were compared for their ash, moisture,lipid, protein and carbohydrate, only protein and carbohydrate showed significant differences. Free amino groups and reducing sugars were also compared, country of origin and size of peanut showed significant differences, and correlations were observed between development of colour during heat processing and reduction in the content of free amino groups and reducing sugars.

High oleic peanuts (HOP) showed higher oxidative stability than conventional peanuts

(CP) in both nibbed (<2mm3 pieces) and whole kernels. Temperature and processing format influenced the oxidative stability of both varieties, more than the addition of

nitrogen to the packaging. Antioxidant assays correlated with the rate of lipid oxidation, where antioxidant levels decreased during storage and peroxide value increased. Rates of tocopherol oxidation followed those of previous reported data, except α-tocopherol levels increased in CP whole kernels during 7 weeks, no other increases were observed.

The characterisation of oil bodies from two varieties of peanut, HOP and CP, showed

small differences in the particle size of the oil bodies and zeta potential. Significant differences were observed between the protein contents, and SDS-PAGE showed higher concentrations of high molecular weight proteins in HOP oil bodies. CP showed higher amounts of α-tocopherols than HOP and CP showed higher concentrations of tocopherols in the oil bodies rather than the extracted oil. In vivo cross sections of peanuts indicated some body stability during processing.