Changes of Physicochemical Property during Liuyang Douchi Fermentation
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Abstract:
Dynamic changes in physicochemical indexes, microbiological indicators, and flavor during natural fermentation of Liuyang douchi were studied. Samples were obtained from the Liuyang Tianmashan Lobster Sauce Factory. Culture-based methods were used to determine changes in the bacterial and fungal counts, and total acid, amino acid nitrogen, protein, and water content were measured. The results indicated that during the production of Liuyang douchi, the total bacterial count reached a maximum (3.8×1011 CFU/g) on the fourth day, and the maximum fungal count was 1.5×105 CFU/g. Changes in total acid and amino acid nitrogen showed similar trends, and the content of total acid and amino acid nitrogen in the finished product were 2.15% and 1.37%, respectively. The total nitrogen content changed slightly during the fermentation process. The protein content in the finished product was 40.08%. The moisture content showed a downward trend during the fermentation and reached 14.30% in the finished product. Principal component analysis of the data obtained using an electronic nose could distinguish samples taken at different stages of the fermentation process. The electronic tongue could stably and efficiently detect differences in taste of the lobster sauce at various stages of the fermentation, mainly reflected in the bitterness, umami, richness and saltiness. The maximum intensities of bitterness and umami were found after 17 d of fermentation, and the maximum intensities of saltiness and richness were found after four days of fermentation.
