Study of microbiological, biochemical and nutritional changes in tinabal molmol (Scarus spp.) fermentation

Microbiological examination revealed a mixed type of fermentation. The lactic acid bacteria consisted of Pediococcus pentosaceus and Streptococcus equinus which were isolated from zero day up to 21 and 15 days of fermentation, respectively. Leuconostoc and Lactobacillus species were isolated only on day 9 when the count for the lactic acid bacteria was high and constitutes 68 percent of the total plate count. The non-acid producing and/or the proteolytic types include the genera Bacillus, Staphylococcus, Pseudomonas and Alcaligenes. Aspergillus and Deparyomyces were also isolated at a very low level. The growth of pathogenic and spoilage organisms such as Staphylococcus, Pseudomonas and Alcaligenes were inhibited at the early stage of fermentation by the antagonistic effect of lactic acid produced by the species of Pediococcus, Streptococcus, Leuconostoc and Lactobacillus. Tritable acidity (2.72 percent dry weight) was high at the initial stage of fermentation probably due to post-mortem conversion of glycogen to lactic acid in fish. The pH during fermentation ranged from pH 5.93-6.65. Volatile acids and alcohol were produced at a very low value of 0.03 to 0.62 percent and 0.097 to 0.51 percent, respectively. Non-volatile acids increased with fermentation time with the highest value of 2.49 percent attained at the end of fermentation. Glutamic and aspartic acids were the non-volatile acids found in addition to lactic acid and were observed in considerable amount during the second week of fermentation. The total nitrogen content of the sample was unchanged. However, the amino acids of the fermented sample decreased. Vitamin B6 (pyridoxine) was the only B vitamin present in the sample and was observed to decrease during fermentation. Niacin was only present from samples fermented for two days up to the last day of fermentation, showing that niacin was synthesized by microorganisms during fermentation. Sensory evaluation results revealed that tinabal molmol had developed flavor characteristics of the product in the second week of fermentation. The two-week-old sample was most preferred. Inoculation studies showed that B. cereus improved the flavor and amino acid content particularly the essential amino acids of the product.