Study on the quality of fermented cocoa beans inoculated with mixed culture
1996
Boonhai Laempet
Mixed culture of yeasts (Saccharomyces cerevisiae KU-Y77, produce alcohol and pectinase enzyme; S. chevalieri KU-Y150, produce pectinase enzyme) and bacteria (Acetobacter aceti, KU-A72) were used in quality fermented cocoa bean study. The amount of yeasts were 1.50, 1.00 percent and of bacteria was 1.00 percent by weight. The study shown that more fully fermentation was observed after adding mixed culture in the first day of the fermentation period. The field test at 4 selected farms in Chumphon and Surat-Thani was conducted following the completion of the laboratory test. Results shown a better quality of fermented cocoa bean after applying the mixed culture than the natural fermentation of cocoa at the fourth and sixth days. The quality of the cocoa fermentation after applying mixed culture was shown 79-87 percent of fully fermented beans. According to the international standard the fermented beans of this fermentation process was considered to be the first grade. In the present study, the amount of organic acids, including acetic acid, lactic acid, citric acid, and oxalic acid were 0.30-2.89, 0.56-3.77, 1.75-5.80, and 0.38-8.00 mg/g respectively. The theobromine content ranged between 13.23-16.76 mg/g while the glucose content ranged between 1.05-1.87 mg/g. The pH value during the fermentation period ranged between 5.18-5.66. The amount of the total saturated (palmitic acid and stearic acid) and unsaturated (oleic acid and linoleic acid) fatty acids were 61.65-67.77 percent and 32.23-38.75 percent respectively. With sensory evaluation in the form of chocolate, the fermented beans with mixed culture for 4 and 6 days shown acceptable similar results. The decreasing of bitterness, astringency, and acid flavour were however found. Results thus indicated that mixed culture application would reduced the fermentation period and improved cocoa quality.
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