Studies On The Effects Of Irradiation Preservating On The Safety And Quality Of Boiled Dumplings

The effects of irradiation and storage on the survival of total bacteria, E. coli, the sensory,nutritional and physicomical characteristics of the dumpling under chill state (0～4℃ ) were studied. The results showed as the followings: The total bacteria, E.coli, thiobarbituric acid reactive substances (TBA), POV, volatile basic nitrogen, and total acidity of dumpling showed a increasing tendency under chill state (0～4℃ ). The value of pH, Aw, moisture, color difference and sensory evaluation showed a tendency of decrease. The shelf life of boiled dumpling was 7 d under chill state. The total bacteria and E. coli of the treated boiled dumplings were decreased significantly by irradiation. The values of D10 and D for the total bacteria in boiled dumplings under chill state were 2.04 kGy and 4.00 kGy, the value of D10 and D for E. coli were 1.25 kGy and 2.00 kGy. TBAS were increased significantly and excessed the trade standard by 5 kGy γ-irradiation. However, the TBAS would be decreased with addition of antioxidants. Lipid peroxide,volatile basic nitrogen, "a" value of color and "b" value of color showed a tendency of increase, and moisture content and Aw showed a tendency of decrease, which did not achieve a significant level(p<0.05) by 1 to 5 kGy doses of γ-irradiation. Total acidity, amino acid nitrogen and free fatty acid showed no significant differences between treated and control samples. Sensory evaluation values were decreased and were all well within the acceptable level by 1 to 5 kGy doses of γ- irradiation. 4 kGy dose of γ-irradiation decreased content of vitamin B1 significantly and did not had a significant effect on the content of vitamin E, protein, fat, amino acid and unsaturate fatty acid. The results of x-ray diffract grams revealed that the relatively diffraction intensity tended to decrease and the diffraction angle (2θ) tended to increase with the increase of irradiation dose. γ- irradiation treatment restrained the degree of crystallinity of starch in dumpling's skin. The dose of γ-irradiation had significant influences on shelf life of boiled dumplings under chill state. The value of volatile basic nitrogen of control sample excessed the trade standard after one week. The value of total acidity of control sample excessed the trade standard after four weeks.However ,except TBA of sample treated with 5 kGy excessed the trade standard after irradiation, other properties of treated sample were all well within the acceptable level throughout storage period. The shelf life of control sample was 7 days and the shelf life of 2 and 3 kGy irradiated samples were 14 days for its sensory quality decreased, and the shelf life of 4 kGy irradiated sample was 21 days. According to the research results, the suitable dose of γ-irradiation for the boiled dumpling under chilled state should be 4kGy and it may extend the shelf life of boiled dumpling from 7d to 21 d.