15D-23 |
Controlling dongchimi fermentation with chitosan to prevent over-ripening |
H. I. OH1, W. J. Lee2, E. J. Chang1, and Y. H. Lee1. (1) Dept. of Food Science & Technology, Sejong University, Kunja-Dong 98, Kwangjin-Ku, Seoul, 143-747, South Korea, (2) Sama Venture Co., Hanshin officetel 618, Shinchun-Dong 11-9, Songpa-Ku, Seoul, 138-733, South Korea The effects of addition of chitosan prepared at 140oC in 50%(w/v) NaOH solution to dongchimi ( whole-radish juicy winter kimchi ) have been studied during fermentation at different temperatures of 4, 10 and 20oC. Total viable cell counts of Leuconostoc spp. in the 1000ppm chitosan added dongchimi dropped at the initial stage and bottomed out at 103-104 CFU/ml, and then increased to the same level as the other samples at middle stage, and finally decreased slightly at the terminal stage. Total viable cell counts of Lactobacillus spp. in the 1000ppm chitosan added dongchimi dropped at the initial stage and then bottomed out at 102-104 CFU/ml, and then leveled off at the final stage. During dongchimi fermentation, the chitosan added at higher dosage prolonged the palatable fermentation period. During 4oC fermentation, the 1000ppm chitosan added dongchimi did not reach pH 4.2 throughout the whole fermentation stage, while the control reached the palatable titratable acidity of 0.13% as lactic acid in 11 days. The 1000ppm sample did not show over-ripened acidity of 0.21%, while the control reached that acidity on 18th day. During 10oC fermentation, the 1000ppm chitosan added dongchimi reached the palatable pH 4.2 on 18th day, delaying 6 days in over-ripening as compared to that of the control. During 20oC fermentation, the 1000ppm chitosan added dongchimi delayed the time to reach the palatable pH 4.2 and never reached pH 3.7 throughout the whole fermentation stage. It also took 4 days to reach the palatable titratable acidity and 5.8 days to reach the over-ripened acidity in the 1000ppm chitosan added dongchimi, while 2.2nd and 3.2rd days, respectively, in the control. Addition of 1000ppm of chitosan-140 to dongchimi fermentation seemed to inhibit the growth of lactic acid bacteria, thereby lowering the acid content. It, therefore, caused the shelf-life to be extended and gave a prolonged palatable period in the dongchimi.
Session 15D, Food Microbiology: Fruits and vegetables
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