การผลิตน้ำส้มสายชูหมักจากผลลำไยอบแห้งทั้งเปลือก

Abstract

Acetic acid bacteria were isolated from some fermented fruit juices and fruits by enrichment culture technique using sterile distilled water supplemented with 4% ethanol (v/v). One hundred and one isolates of acetic acid bacteria were obtained from 18 varieties of fruits and 4 fermented fruit juices. Morphological and overoxidation examinations revealed that 99 isolates were in the genus Acetobacter and 10 isolates were in the genus Gluconobacter. Fifty-five isolates were A. aceti as determined by biochemical tests. Nineteen isolates ; P1, P4, P6, P8, P12, K4, K5, K6, K7, K8, S1, S2, S3, S4, S5, S6, S7, S8 and S11 gave the yellow zone diameter over 3.5 cm on bromocresol green ethanol agar. They were selected for acetic acid production and compared with Acetobacter aceti TISTR354 in ethanol-yeast extract medium supplemented with 2% (v/v) ethanol. It was found that P1, P4, P6, P8, S3, S8, S11 and A. aceti TISTR354 gave the highest yield of acetic acid at 17.76, 17.94, 18.06, 16.92, 18.12, 16.98, 17.22 and 18.12 g/l respectively. All the isolates were tested for their growth tolerance in 4-12% (v/v) ethanol and 1-3% (v/v) acetic acid. It was found that 18 isolates except S7 were able to grow at 4-12% ethanol and P12 was able to grow at 3% acetic acid. Eight isolates ; P1, P4, P6, P8, P12, S3, S8 and S11, which gave high yield of acetic acid and were able to grow at 12% ethanol, were selected for acetic acid production in ethanol-yeast extract medium supplemented with 4, 6, 8 and 10% (v/v) ethanol and compared with Acetobacter aceti TISTR354. It was found that at the concentrations of ethanol 6 and 8%, P1, P4, P6 and P12 produced higher amount of acetic acid than other isolates. The yield of acetic acid was between 37.86-44.40 g/l

In the vinegar production from whole dried longan, Saccharomyces cerevisiae V1116 was used in the first step of fermentation. The total soluble solid was adjusted to 20°Brix. After fermentation, the yield of alcohol was 9.53% ± 0.34, the total soluble solid was 8.33°Brix ± 0.24 and the reducing sugar was 40.09 ± 0.55 g/l. Vinegar fermentation using whole dried longan wine was carried out by Rapid-Tray-Culture Method with P1, P4, P6 and P12 with A. aceti TISTR354. It was found that they gave the highest yield of acetic acid 49.76 ± 0.89, 47.72 ± 3.67, 51.20 ± 3.00, 50.92 ± 2.56 and 37.20 ± 4.43 g/l respectively. Isolates P1, P4, P6 and P12 were identified to be Acetobacter tropicalis as determined by biomolecular technique.