Quality of non-sweetened fresh soymilk in Khon Kaen province(Thai)

Abstract

Fresh soymilk can be found in every community and is sold directly to consumers. The quality depends on the sanitation and the skill of the individual producer. This project is to study the quality of fresh soymilk for the purpose of consumer protection. In this study some physicochemical properties and quality of 18 non-sweetened fresh soymilk and 2 UHT products, purchased from vendors in Khon Kaen University campus and Khon Kaen Municipality, were investigated according to the Thailand Industrial Standard regulations. It was found that the specific gravity of 18 fresh soymilks were 0.9991-1.0111, and the residue on evaporation was between 3.59–8.17 % w/v. The sulfated ash was 3.59–6.41 % w/w of the residue on evaporation, the protein content was 1.87–3.54 % w/v and the fat content was 0.00–0.02 % w/v. Heavy metals were less than 1 ppm in 4 samples, between 1–2 ppm in 8 samples and more than 2 ppm in 6 samples. The limit of heavy metals for the Thailand Industrial Standard for soymilk or soya bean milk is less than 0.5 ppm. Total aerobic microbial count was 160–10020 cfu.ml-1 and the range of coliform was 3-23 cfu.ml-1 of sample by Most Probable Number (MPN) test. The 2 UHT products had specific gravity of 1.0301-1.0351, the residue on evaporation was 16.33-18.38 % w/v, the sulfated ash was 2.49-3.74 % w/w of the residue on evaporation, the protein content was 2.35-3.34 % w/v, fat content was 1.69-2.28 % w/v. Heavy metals were less than 1 ppm, total aerobic microbial count was not detected and coliform were less than 3 cfu.ml-1. These properties indicated the contamination of the products. There is no regulation imposed upon fresh soymilk production. However guidelines and workshops for those who wish to develop themselves in making good quality fresh soymilk should be available. Small businesses in Thailand are still very important for self–reliance of the people in communities. However consumers also need protection.