91E-17 |
Changes in volatile compounds and sensory quality of fermented soybean paste, chungkukjang, by high dose irradiation |
B. S. AHN and C. H. Lee. Graduate School of Biotechnology, Korea University, #1, Anam-dong, Sungbuk-ku, Seoul, 136-701, South Korea The Joint FAO/IAEA/WHO Study Group on High-Dose Irradiation held in Geneva, September 1997, recommended the elimination of maximum dose limit(currently 10 kGy) for food irradiation. It was based on the fact that the sensory quality changes to unpalatable by high dose(10-70 kGy) irradiation, before any toxic substances are produced. In this study, we have determined the effect of high dose(up to 120 kGy) irradiation treatment on the quality of traditional fermented soybean product, chungkukjang, in order to find the optimal radiation dose for the sterilization. Volatile flavor compounds in chungkukjang irradiated by Co60 irradiation(10-120 kGy) were analyzed by using a purge and trap method, and identified with GC/MSD. Seventy-eight volatile flavor compounds including 13 ketones, 10 alcohols, 8 aldehydes, 5 heterocyclic compounds, 8 esters, 3 thiol compounds, 4 acids, 19 hydrocarbons, and 8 others were found in irradiated chungkukjang. The number of volatile flavor compounds detected in chungkukjang was 43 and new 32 volatile compounds detected in irradiated chungkukjang. The characteristic compounds of irradiated chungkukjang were ketones such as 2,3-butanedione, 2-butanone, and 5-methyl-2-hexanone, and hydrocarbons such as 2,4-dimethyl-heptane, 2,3-butanediene and 4-octyne. The largest number of new volatile compounds were found in 120 kGy irradiated chungkukjang. The color and odor of chungkukjang were not significantly affected by irradiation up to 40 kGy. Unpalatable odor(p<0.01), off-flavor(p<0.001) and fish-odor(p<0.001) increased, and brown intensity(p<0.05) and acceptability(p<0.001) decreased as dose levels increased over 40 kGy. Irradiation with 20-40 kGy dose could inactivate most of microorganisms in chungkukjang, and prevent the deterioration of the product quality.
Session 91E, Nonthermal Processing: Nonthermal processing of foods
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