低酸素濃度密封貯蔵におけるレタスの品質 Quality of Lettuce Stored in a Low Oxygen Closed System
For the low cost vegetable transportation, the applicability of a low O<SUB>2</SUB> closed system was examined under ambient temperature. Heads of leaf lettuce grown under the controlled climate of a commercially operated plant factory individually placed in airtight containers filled with normal air or with low O<SUB>2</SUB> mixed gas (5% 0<SUB>2</SUB>+95% N<SUB>2</SUB>) were stored for 11 d and 13 d at 15°C and for 7 d at 20°C. Populations of mesophilic aerobic bacteria from levels of 10<SUP>7</SUP> to 10<SUP>9</SUP> CFU/g were detected at the end of storage on lettuce heads in control treatment (normal air). Contrary to this, final populations on lettuce heads in low O<SUP>2</SUP> treatment were 10<SUP>2</SUP>- to 10<SUP>5</SUP>-fold less than those in control treatment. As the final populations were less than 1 x 10<SUP>7</SUP> CFU/g, leaves of lettuce heads in low O<SUB>2</SUB> treatment were not spoiled for all storage experiments. Supplementary examinations indicated that low O<SUB>2</SUB> treatment was not effective to suppress bacterial populations on lettuce heads having large populations as about the level of 10<SUP>5</SUP> CFU/g or more at the beginning of storage. Hence, the low O<SUB>2</SUB> closed system can be applied exclusively to the leaf lettuce grown in plant factory that can normally assure small populations of bacteria. Adding to this bacterial point of view, cumulative quantity of CO<SUB>2</SUB> showed a reduction in respiration of lettuce head in low O<SUB>2</SUB> treatment. Moreover, large amount of ascorbic acid was lost in control treatment as compared to that in low O<SUB>2</SUB> treatment. However, no significant difference was observed in weight loss regardless of treatment.
植物工場学会誌 14(4), 204-211, 2002-12-01
JAPANESE SOCIETY OF AGRICULTURAL, BIOLOGICAL AND ENVIRONMENTAL ENGINEERS AND SCIENTISTS