Trial of soya milk yoghurt production and its organoleptic study in Lubumbashi, D.R. Congo

Résumé

Summary: The study focused on the preparation of yoghurt from soya milk in the city of Lubumbashi. The objective of this study is to extend the shelf life of soybeans while diversifying and preserving them in various forms, particularly soy yogurt. This product of vegetable origin is cultivated everywhere in the city of Lubumbashi but the population suffers from infantile malnutrition because it is consumed in only one form; the soya flour and the population does not have access to the various products derived from the soya. In order to produce yoghurt, the soya milk was produced by taking 1 kg of soya beans and soaking them in 1 litre of lukewarm water for 24 hours, then grinding them until a paste was obtained, to which 5 litres of lukewarm water were added. The resulting solution was homogenized, filtered, heated to 85°C for 30 minutes (pasteurization) and then left to stand for 10 minutes. The operation was repeated for a second time to accelerate coagulation. The second pasteurization of the milk allows the destruction of pathogenic bacteria. The milk was then cooled to a temperature between 42 and 48°C. Since this milk is a vegetable product, the addition of lactose is necessary to produce lactic acid. Thus, 500 ml of soy milk were taken and 500 ml of FINTA milk (cow's milk) were added. This mixture was heated to 48°C. 125ml of ferments (Streptococcus thermophilus and Lactobacillus bulgaricus) were added. The mixture was stirred and covered to ferment for 6 hours. Then 50gr of sugar was added to the mixture. Then the product was packed in plastic bottles and put directly in the refrigerator at a temperature of 2 to 4°C. Thus the yoghurt was born. In this product of vegetable origin, two organoleptic analyses were carried out with taste, colour, consistency and the personal appreciation of the taster as parameters. In the second analysis an improvement was observed on the colour, the consistency and the appreciation but for the taste, we find that it is necessary to play on the aftertaste of the legumes by adding the ingredients to hope for an improvement. Keyword: Streptococcus thermophilus and Lactobacillus bulgaricus, FINTA milk