A simple visual ethanol biosensor based on alcohol oxidase (AOX) immobilised onto polyaniline (PANI) film for halal verification of fermented beverage samples is described. This biosensor responds to ethanol via a colour change from green to blue, due to the enzymatic reaction of ethanol that produces acetaldehyde and hydrogen peroxide, when the latter oxidizes the PANI film. The procedure to obtain this biosensor consists of the immobilization of AOX onto PANI film by adsorption. For the immobilisation, an AOX solution is deposited on the PANI film and left at room temperature until dried (30 min). The biosensor was constructed as a dip stick for visual and simple use. The colour changes of the films have been scanned and analysed using image analysis software (i.e., ImageJ) to study the characteristics of the biosensor’s response toward ethanol. The biosensor has a linear response in an ethanol concentration range of 0.01%–0.8%, with a correlation coefficient (r) of 0.996. The limit detection of the biosensor was 0.001%, with reproducibility (RSD) of 1.6% and a life time up to seven weeks when stored at 4 °C. The biosensor provides accurate results for ethanol determination in fermented drinks and was in good agreement with the standard method (gas chromatography) results. Thus, the biosensor could be used as a simple visual method for ethanol determination in fermented beverage samples that can be useful for Muslim community for halal verification.

Simple and Low-Cost On-Package Sticker Sensor based on Litmus Paper for Real-Time Monitoring of Beef Freshness

Effort to improve the yield of bioetanol production from cassava peels were be carried out by separated hydrolysis fermentation (SHF) and simultaneous saccharification fermentation (SSF) using Aspergillus niger, Trichoderma viride and New Aule Instant Dry Yeast. The purpose of this research is to measure bioetanol production from cassava peels using three different culture methods i.e SHF1 (A. niger 24 hours +New Aule Instant Dry Yeast); SHF2 (T. viride 24 hours+New Aule Instant Dry Yeast); and SSF (A. niger + T. viride + New Aule Instant Dry Yeast). The research results showed SHF1 (2,58 g/l) produced higher ethanol than that of SHF2 (2,15). The methods of SSF eficiency produced ethanol (2,93 g/l) and faster (18 hours) compared the methods of SHF1 and SHF2 which need 48 hours incubation time to reach maximum level. Keywords: bioethanol, cassava peels, SHF, SSF, A.niger, T.viride, new aule instant dry yeast

Astriani A, Diniyah N, Jayus J, Nurhayati N. 2018. Phenotypic identification of indigenous fungi and lactic acid bacteria isolated from ’gatot’ an Indonesian fermented food. Biodiversitas 19: 947-954. As a traditional Indonesian food made from cassava, ‘gatot' has special attracted characters of black appearance and chewy texture, mainly as a result of certain fungi and lactic acid bacteria (LAB) during the spontaneous fermentation. However, many producers were failed to gain these typical properties since much unwanted microbial strain often appears during the spontaneous fermentation. Therefore, this study was conducted to isolate and identify the indigenous fungi and LAB which predominantly contributed in fermentation of cassava during ‘gatot’ production. Fungi and LAB were isolated from conventionally made of the ‘gatot’ followed by the phenotypic identification of the isolates based on the morphological and physiological properties. The fungi isolates were morphologically distinguished by the type of mycelia, the shape, and color of the sporangium, while the LAB strains were identified by the type of cell and colony form. In addition, the physiological behavior of the LAB isolates was characterized by their typical growth temperature, its catalase activity and its fermentation profile using BBL crystal kit test. The predominant fungi isolates were identified as Botryodiplodia theobromae, Rhizopus oligosporus, Trichoderma sp. and Aspergillus niger. B. theobromae had greyish white to black color of mycelia when it mature. R. oligosporus had globose sporangium and blackish grey color of the mature mycelia. Trichoderma sp. had green color of the mature sporangium and mycelia. A. niger had yellow color of the mycelia and black color of sporangium. Meanwhile, the indigenous LAB was majority identified as Lactobacillus manihotivorans, Bacillus licheniformis, Brevibacillus brevis and Lactobacillus fermentum. Those bacteria were gram-positive, rods shape, catalase-negative and grew optimally at 37oC. The LAB also arise frequently in many spontaneously fermented food. B. theobromae, R. oligosporus, L. manihotivorans, and L. fermentum were potential and non-pathogenic microbial, which can be used as a starter culture to produce ‘gatot’ under controlled fermentation process.

Probiotic drink like yoghurt from dairy milk is one of the most popular functional food. However, some people are not able to consume dairy milk due to lactose intolerance. Thus, a substitute substrate such as fruit juice, is needed. It refers to prebiotic compounds that are found in some of fruits like banana and guava. The aim of this research was to determine the effect of fermented banana and guava juices on the viability of fecal microflora. The juices were made from banana or red guava fermented by Lactobacillus casei (15% v/v). In vitro test was conducted using indigenous human fecal bacteria (1% w/v). The viability of enteropathogens, lactic acid bacteria (LAB), and total microbes was determined by enumeration as well as the prebiotic index of the fermented juices. The in vitro test results showed that both fermented juices could elevate the total microbes and LAB as compared to control sample. The viability of the total microbes and LAB increased by 2.16 log CFU/mL and 2.90 log CFU/mL for fermented banana juice (FBJ), respectively. The same trend was also observed in fermented guava juice (FGJ) with an increase by 1.92 log CFU/mL for total microbes and 2.99 log CFU/mL for LAB. Interestingly, both fermented juice could decrease the population of most enteropathogens compared to control sample. FBJ could decrease the population of E. coli, Klebsiella sp. and Salmonella as low as 3.78, 3.32, and 1.37 log CFU/mL respectively. Meanwhile, FGJ could drop the number of E. coli (1.44 log CFU/mL), and Klebsiella sp. (1.29 log CFU/mL). Moreover, the prebiotic index for FBJ and FGJ were 2.57 and 2.16. In conclusion, both FBJ and FGJ were potential substrate for probiotic drink and had good effect for fecal microflora health.

Urbahillah A, Jayus J, Nurhayati N. 2021. Improving SCOBY starter using co-culture of tapai and bakery yeast. Biodiversitas 22: 4617-4624. Kombucha is a beverage fermented by a symbiotic bacteria and yeast known as SCOBY (Symbiotic Culture of Bacteria and Yeast). Bacteria and yeast contribute to the formation of organic acids, aroma, taste, and flavor of kombucha. The commercial yeasts used in Indonesian are baker’s yeast and tapai yeast. This study was conducted to develop SCOBYco-culture with tapai yeast and baker’s yeast and evaluate its activity. The ingredients for the kombucha were cascara, water, and sugar, which were fermented with three formula starter, i.e. original SCOBY 10% w/v (SN), co-culture SCOBY 10% w/v with 0.1% w/v of baker’s yeast (SNR), and co-culture SCOBY 10% w/v with tapai yeast 0.1% w/v (SNT). The starter activity were determined based on the OD (Optical Density) value. Yeast screening was carried out on the dominant starter population. Furthermore, morphologically yeast was identified based on colony type, color, and shape of cell. Then yeast was identified by their fermentation profile using API 20C Aux Kit. Isolate A showed white colony with convex elevation and the cell was round-shaped. Colony of isolate B and isolate C were creamy in color and oval cell shaped. The API results revealed that the first isolate was identified as Candida famata, second isolate was as Candida krusei, and the third isolate was as Candida magnoliae. Three types of fungi were found from SCOBY, namely Mucor sp., Trichoderma sp., and Fusarium sp. Mucor sp. has non-septate hyphae, and round black spores. Trichoderma sp. has septate hyphae, greenish-white spores, and the conidia have the shape of globose to ellipsoidal Fusarium sp. has a mold with septate hyphae, yellowish-white colonies, and the conidia have the shape of obovoid. Bacteria, yeast, and mold present in the medium form a powerful symbiosis for produce metabolite.