Cyanide is a toxic substance found in several tubers such as cassava (Manihot esculenta), wild yam (Dioscorea hispida Dennts), some cerealia and legumes. In the plants, it can be in the form of cyanogenic glycosides, acetone cyanohydrin, and hydrogen cyanide (HCN). Cyanogenic glycosides such as linamarin and lotaustralin belong to the product of secondary metabolism. The characteristic of cyanogenic glycosides is intermediately polar, water-soluble, and often accumulated in the vacuoles of plant cells. Acetone cyanohydrins are intermediates product from cyanogenic glycosides and cyanide acid in plant tissues. HCN, hydrogen cyanide, is a volatile and water-soluble compound. The toxic effect of cyanide in humans is inactivation of cytochrome oxidase, respiratory disorders, sore throat, dizziness, limpness, convulsions, and lethal effects. Cyanide can be removed by several processes before consumption. Methods such as peeling, washing, heating, drying, fermenting and chemical treatment are used to remove or reduce cyanide. The treatment can damage the structure of the cell and hydrolyzed the cyanogenic glycosides to acetone cyanohydrin and glucose by endogenous enzyme like linamarase. A second enzyme, hydroxynitril lyase, can dissociate acetone cyanohydrins to HCN, ketone and aldehyde compound. The maximum safe level for total cyanide in food is 10 ppm. This review aims at updating the available knowledge on the various detoxification cyanide in food.

Dioscoreaceae or yam is a family of tuber that comprises many members with variability in utilization and their intensity of consumption. This family has wide variability and is used not only as food but also for medical purposes due to their bioactive compounds. One of the Dioscoreaceae family is wild yam (Dioscorea hispida Dennst), rich in carbohydrates but has an obstacle of high cyanide level. Historically, along with cassava, wild yam is the staple food in some places in Indonesia. There is a long history of traditional detoxification methods of wild yam with slightly different steps among different places. The shifting of staple food to rice excludes wild yam consumption. One of the remaining products from wild yam is chips. Wild yam chips are a traditional snack that is also produced by traditional detoxification. This paper is aimed to review the scientific basis for each step in traditional wild yam chips processing to remove cyanogenic compounds. This review was based on the observations of traditional wild yam tuber chip processing and unstructured interview with the wild yam tuber chip maker at 6 locations in East Java, Indonesia. Relevant literature was used to explain the scientific basis of the detoxification methods based on the definite inclusion and exclusion criteria. Also, the variability of processing methods was compared among different locations. In general, the steps of traditional detoxification during wild yam tuber chips processing are slicing the peeled wild yam tubers, mixing with the rubbing ash, pressing, drying, soaking, boiling/steaming, and sun drying. Slicing, rubbing, and pressing in chips processing is aimed to convert cyanogenic glycoside into acetone cyanohydrin. The alkaline pH due to ash rubbing makes spontaneous decomposition of acetone cyanohydrin into HCN. HCN is easily removed by dissolution and heating (drying and steaming/boiling). Thermal treatment also spontaneously decomposes cyanohydrin into free HCN. All of the cyanogenic compounds are water-soluble which soaking and washing are aimed to remove all compounds. Consecutive, complicated, and time-consuming processing completely removes cyanogenic compounds and produces safe wild yam tuber chips. The key finding of this review is the purpose of every step in wild yam tuber detoxification has a scientific basis to reduce cyanogenic compounds gradually. This process produces a very low cyanide level in the final product. In conclusion, traditional detoxication reduces cyanogenic compounds to a safe level.

Kefir is an acidic-alcoholic fermented milk product with little acidic taste and creamy consistency and has a distinctive yeasty aroma. Bacteria in the grain produce lactic acid and flavor components, carbon dioxide, and alcohol. Increased alcohol levels can occur with longer storage. The optimal temperature for the growth of alcohol-producing microorganisms can be at room temperature, whereas low temperatures can inhibit microbial growth and biochemical processes. This study aimed to determine the effect of temperature and storage time on the alcohol content of cow milk kefir. The research method used Randomized Block Design Factorial with two factors and three levels. The first factor was the storage time that consists of 7, 14 and 21 days. While, the second factor was storage temperature that consists of freezing storage (-10°C), refrigerator storage (15°C), and room storage (20°C). Data were analysed using ANOVA, then the further test DMRT with a 95% confidence interval. The best treatment result was tested using Zeleny. The best treatment result was attributed to freezing storage (day 7) at -10°C, with physical parameters include pH of 4.47 and total soluble solids of 10.00% Brix. Then, chemical parameters are total sugar (3.07%), total acid (0.26%), and alcohol content (0.04%). Lastly, microbiological parameters include the total of lactic acid bacteria (5.91 Log CFU/ml) and the total of yeast (6.56 Log CFU/ml). Kefir with the best treatment could decrease the alcohol level and safe for consumption.