No abstract

Indonesia has many fermented beverages, and yeast become one of the agents in fermented process. Yeasts has a role to transform carbohydrate complex into simple compounds with release secondary metabolism to environment like amylase enzyme. This study aims to get the isolate of yeast that can potentially produce amylase enzyme. This research conducted in October 2018 until March 2019 in Microbiology Laboratory of Universitas Negeri Jakarta. The screening test of potential isolate producing amylase enzyme was performed on yeast isolate from eight source of indigenous fermented beverages that can grow in YMA medium with pH 2. Screening was carried out on YPSA medium with diffusion agar method. From 50 Isolates, 16 isolates with the codes IB4, IB15, IB20, IB21, IB26, IB36, IL78, IL80, IL81, IL86, IL88, IL97, IL113, IL136, IL146, and IL150, were able to form clear zone after 1-day incubation in room temperature. The highest amylolytic index was produced by IL86 (1,019 mm). Forming the clear zone is proof that yeast can transform starch become simpler sugar like maltose as iodine-starch reaction is resulting amylose helix and iodine become I3 − that filled main core helix. In addition to this, iodine forms complexes with starch molecules showed a dark purple colour.

No abstract

Contamination by pathogenic mold in postharvest cocoa beans becomes a significant concern by most Indonesian farmers. Pathogenic mold can cause damage to cocoa beans by such as rotting diseases in fruit. One alternative that can be used to control pathogenic mold is using biological agents such as yeasts. Some group of yeasts can produce cellulase enzyme that can degrade cellulose, and it can possibly break the cell wall with of mold which composed of semi-crystalline chitin, p-need, and cellulose. This study aims to determine the yeast originated from fermented cocoa beans which can produce cellulase enzymes and their potential ability as a biocontrol for pathogenic molds in chocolate fruit. This study includes yeast isolation from fermented beans, screening of yeast isolates that produce cellulase enzymes, and in-vitro antagonistic testing against pathogenic molds on chocolate fruit. The results showed that there were 21 yeast isolates from fermented cocoa beans, and among all, there were five isolates which can produce cellulase enzymes, namely isolate C4.-3.3, C4.-3.13, C4.-4.9, C4.-4.10, and C4.-5.9. Yeast isolate C4.-4.10 can produce cellulase enzymes with an index of 0.32 U/mL. This research showed that the 5 yeast isolates have the low category of cellulase enzyme, and further study is needed to be done to confirm their ability to act as a biocontrol agent.