Effects of storage conditions on the total aerobic and yeast/mold bacterial counts of rough rice during on-farm storage

Total aerobic plate counts (APC) and yeast/mold counts on farm-stored rice (Oryza sativa L.) were evaluated as a function of sampling position within a bin, storage treatment (aeration technique), and storage duration. Rough rice (cv. Cypress) was stored for 15 wk and sampled at time 0 and at 4-wk intervals thereafter. No significant differences were found for either APC or yeast/mold counts between sample locations within a bin. The APC were significantly lower in all bins after 15 wk (p < 0.05) by 1.5 log cfu/g, corresponding to the temperature decrease of the rice in the storage bins. Yeast/mold data varied significantly over storage duration in a pattern similar to the moisture content data. Aeration treatment did not affect yeast/mold counts, but APC were significantly lower at 15 wk for rice from controlled aeration. Results indicate that storage efforts aimed at reducing grain temperature can reduce microbial loads.