Oil yield, physicochemical characteristics, oxidative stability and microbial safety of perilla seeds stored at different relative humidity

Abstract

(T)his work investigated the effect of different relative humidity (RH) on the oil yields, physicochemical characteristics, oxidative stability, and microbial safety of perilla seed (PS) stored for 12 weeks. The PSs stored at 11 % RH gave the highest oil yield (34.24 g/100 g PSs), about 7.5-times higher compared with the yield from PSs stored at 93 % RH. During storage at 69-93 % RHs, the lightness (L*) decreased and the redness (a*) and yellowness (b*) increased, indicated a dark-brownish color. The PSs stored at 33-43 % RHs had higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (85.74 %) and iodine value (190 g/100 g sample) and lower acid value (1.40 mg KOH/g sample) and peroxide value (4.35 meq/kg sample) as compared with other PSs samples. During storage, the aerobic bacterial contents (3.08 log10 cfu/g) in PSs were plateaued at 11-69 % RHs, and significantly increased at 81-93 % RHs. Yeasts and molds were found only for those of the PSs stored at 69-93 % RHs. At higher RH (81-93 %), the microbial contents were uncountable due to too much growth after two weeks. This study could be useful for an appropriate storage condition to maintain quality in terms of oxidative stability and retarding microbial growth of PS.