Microwave Vacuum Drying Effect on Peanut Quality1

Abstract

Abstract Florunner peanuts (Arachis hypogaea L.) were grown during the 1984 season near Tifton, Georgia. Two planting dates spaced one month apart were used to obtain four weekly digging dates. Peanuts from each harvest were windrow dried for 4 days, mechanically harvested and placed into a ventilated wagon for 1 to 4 days. Peanuts were subsequently removed from the wagon, shelled at 8 to 22% moisture (wb), and microwave vacuum dried at nominal rates of 4, 8, 16, and 32 times the normal rate of conventional wagon drying. Harvest group, microwave treatment level, and order of processing were configured in a Latin Square design. Concurrent with each microwave run (MV), a separate portion of the shelled peanuts was deep bed dried (CS) and another portion was similarly dried but within shell (CH). Analyses of variance were performed to determine the significance of treatment type, microwave level, harvest group, and processing order differences on splitting and skin slippage tendencies, mold growth, and germination potential. No significant (p> .05) differences were observed among treatment types for splitting and skin slippage potential, though slight (p< .05) differences existed among microwave treatment levels (damage increasing with increasing microwave drying rate), and drying order within microwave treatment (damage decreasing with increasing drying order). Larger (p< .01) splitting and skin slippage differences existed among harvest groups. MV treatments had significantly (p< .01) higher presence of A. flavus than the CS and CH treatments though aflatoxin was not detected in any sample. The percentage of normal strong germinated kernels from MV treatments was significantly (p<.01) lower than from the CS and CH treatments, with germination decreasing with increasing microwave process rate.