Growth and survival of Aeromonas hydrophila in rice pudding (milk rice) during its storage at 4
D. K. Papageorgiou, D. S. Melas, A. Abrahim and K. Koutsoumanis
Food Microbiology Volume 20, Issue 4 , August 2003, Pages 385-390
2003
บทคัดย่อ
Rice pudding (rice milk) was inoculated with Aeromonas hydrophila strains NTCC 8049 or wild isolate (food strain) at levels of ca. 2.5×102–4.0×102 cfu/g and stored at 4°C and 12°C. Average moisture content of rice pudding was 74.12%, fat in dry matter 11.79%, total carbohydrates 18.75%, total proteins 3.31%, and initial pH 6.60–6.67. The pH values dropped gradually to between 6.07 and 6.23 for the trials stored at 4°C and 4.60–5.38 for the trials stored at 12°C. Duplicate samples of rice pudding were tested for numbers of A. hydrophila and pH. Aeromonas counts were obtained by surface plating onto starch ampicillin agar. Selected colonies were confirmed biochemically. A lag phase of ca. 81 h and 14–15 h was observed during storage at 4°C and 12°C, respectively. The generation times of A. hydrophila food strain (20.38 h) was significantly longer than those of the type strain NTCC 8049 (17.75 h) at 4°C. Generation times of 4.12 h for the type strain and 4.20 h for the food strain were observed at 12°C. Maximum populations of A. hydrophila were reached after 22 d at 4°C and after 6–9 d at 12°C and ranged from 8.00 to 9.23 log10 cfu/g. Maximum populations were significantly lower in rice pudding stored at 4°C.