Effect of Chitosan on Shelf Life of Cooked Rice Contaminated Artificially with Bacillus sp

This study was carried out to examine the effect of chitosan on the quality of cooked rice. Sensory quality of cooked rice added with 0.1% and 0.5% chitosan was investigated. Taste, flavor and overall acceptability of cooked rice with 0.1% chitosan solution was similar to cooked rice without chitosan. Quality characteristics of cooked rice artificially inoculated with Bacillus spore (CRB), such as number of viable cell, pH, hardness, cohesiveness and color were investigated and compared with CRB added with 0.1% chitosan (CRCB) during storage at $20^{\circ}C\;and\;30^{\circ}C$ for 3 days. The viable cell number of 0.1% chitosan contained in cooked rice inoculated with Bacillus (CRCB) was lower about $1{\sim}1.5$ log at $20^{\circ}C,\;0.5{\sim}1$ log at $30^{\circ}C$ than that of cooked rice inoculated with Bacillus (CRB). The pH of CRCB did not change during storage at $20^{\circ}C$ for 2 days, but decreased in CRCB and CRB during storage at $30^{\circ}C$. The difference of hardness was not noticeable between CRB and CRCB during storage. Cohesiveness and lightness (L value) of CRCB were higher than those of CRB during storage.

취반시 키토산 첨가가 Bacillus sp.에 오염된 쌀밥의 품질에 미치는 영향

취반시 chitosan 첨가가 쌀밥의 저장 중 품질특성에 미치는 효과를 조사하기 위해 먼저 취반시 밥물에 0.1%와 0.5%의 키토산을 첨가하여 밥을 제조하여 관능검사를 실시한 결과, 쌀밥의 종합적 기호도는 0.1% chitosan 처리구와 대조구와 유사하였으나 0.5% chitosan 첨가구의 기호성은 감소하였다. 0.1% chitosan을 첨가한 밥에 Bacillus 포자를 인위적으로 접종하여 $20^{\circ}C$와 $30^{\circ}C$에 3일 동안 저장하면서 품질변화를 조사하였다. Chitosan 첨가구의 생균수는 저장기간 동안 대조구에 비해 $20^{\circ}C$에서는 약 $1{\sim}1.5$ log cycle, $30^{\circ}C$에서는 약 $0.5{\sim}1$ log cycle정도 낮았다. 대조구와는 달리 chitosan 첨가구는 저장 2일째까지 pH의 뚜렷한 변화가 관찰되지 않았으며, $30^{\circ}C$에서는 대조구와 chitosan 첨가구 모두 pH가 점차 감소하였다. Hardness는 대조구와 chitosan 첨가구 사이에 뚜렷한 차이는 관찰되지 않았으며, 저장시간이 경과할수록 감소하였다. Cohesiveness는 chitosan 처리구와 대조구 모두 저장기간이 경과할수록 감소하였으며, chitosan 처리구의 cohesiveness가 대조구에 비해 저장 전 기간 동안 다소 높은 경향을 나타내었다. Chitosan첨가 쌀밥의 명도(L값)는 저장기간 동안 대조구에 비해 높았으며, b값은 낮게 나타났다.