Microbial Succession and Chemical Characteristics in Fermentation of Ambonese Arrack (Sopi), Traditional Beverage from Maluku

Ambonese arrack is one of the traditional fermented beverage product in Maluku, Indonesia. The microbiological research of this beverage that is processed using coconut sap as raw material has never been done before. The research aimed to analyze the microbial succession and chemical characteristics during fermentation of Ambonese arrack. The sample of coconut sap was taken from traditional producer in Mahia village, Ambon. The dominant microbes in the fermentation of Ambonese arrack were Pichia polymorpha and Kloeckera javanica. The highest numbers of these two microbes was obtained after 15 hours fermentation (9.6 log Cfu/mL and 9.9 Cfu/mL, respectively). The sugar content decreased from 593.3 mg/L to 474.3 mg/L, whereas ethanol content increased from 0.0018 g/L to 0.0100 g/L. The pH value decreased from 4.70 to 3.10. The research has isolated indigenous microbes in Ambonese arrack fermentation which was considered as novelty. The bacteria that play a role in fermentation can be used as a starter in the fermentation of various beverage products, especially Ambonese arrack. The results of this research can improve the quality of this fermentation product in the future.

The optimization of the Ambonese arrack fermentation using co-culture Pichia polymorpha and Kloeckera javanica

Mahulette F, Astuti DI. 2020. The optimization of the Ambonese arrack fermentation using co-culture Pichia Polymorpha and Kloeckera javanica. Biodiversitas 21: xxxx. The fermentation process of the Ambonese arrack is still uncontrollable. As various microbes are involved in the fermentation, which causes inconsistent production of ethanol content. This research aimed to optimize the production of the Ambonese arrack using Pichia polymorpha and Kloeckera javanica in inoculum ratios of 1:1, 1:2, and 1:3. The number of yeast cells and chemical characteristics was observed every three hrs up to 24 hrs. The ethanol content of the fermented coconut sap and the arrack was measured using the titration and Gas Chromatography-Mass Spectrophotometry (GC-MS) methods, respectively. The numbers of P. polymorpha and K. javanica cells at 15 hrs of fermentation were 9.9 log CFU/mL and 10.7 log CFU/mL, respectively. The reducing sugar content decreased from 525 mg/L to 296 mg/L, while the pH from 6.46 to 4.82. The highest ethanol production rate was 1.4 mg/L.3hrs. (ratio 1:1), observed at 12 hrs of the fermentation, while the highest ethanol contents in the fermented coconut sap and the arracks were 11.3 mg/L and 300.400 mg/L, respectively. Different inoculum ratios affect the sensory characteristics of Ambonese arrack. The highest average value of sensory testing was 4.6 (ratio 1:2). Thus, the inoculum ratios of P. polymorpha and K. javanica 1:2 and 1:3 has the best quality in controlled Ambonese arrack processing.

Chemical and enzymic analyses of Pichia polymorpha cell walls

Conventional techniques of chemical analysis have shown that the cell walls of the yeast Pichia polymorpha, at early stationary growth phase, consisted of carbohydrate (about 85%), protein (8%), and lipid (7%). Glucose and mannose were the only neutral sugars and glucosamine the sole amino sugar present among the cell wall components. Paper and gas–liquid chromatographies of acid hydrolysates of purified cell walls and cell wall fractions proved that mannan and alkali-insoluble glucans, in that order, were the major polysaccharide components, accounting for 83% of the total carbohydrate content. The isolation of an alkali-soluble glucan, non-precipitable with Fehling's solution, has been achieved. Treatments of whole cell walls and their fractions with purified cell wall lytic enzymes have shown the presence of both 1, 3- and 1, 6-β-D-linkages in all the glucan fractions. 1, 3-α-Glucan was not detected. Mannan–glucan complexes have been found containing about 50% each of mannose and glucose. All polysaccharides exhibited different turnover rates when cells were grown in the presence of D-[U-14C]glucose. The morphogenetic implications of these results are discussed.