THE EFFECTS OF DIFFERENT PROCESSING TECHNIQUES ON THE ORGANOLEPTIC QUALITY OF SOYMILK PROCESSING AND STORAGE

ABSTRACT
This study examined the effects of different processing techniques on the organoleptic quality of soymilk processing and storage. The utilization of soybean for the production of soy milk was studied. Soy milk was extracted from whole and dehulled seed, pasteurized and fermented. All soy milk samples were analyzed for proximate composition (moisture%, ash %, total solids, fat) and the organoleptic tests (color, thickness, appearance, body, texture, taste, smell, flavor and overall acceptability) of the soy milk samples were evaluated to determine the shelf-stability of the products during refrigeration and room temperature storage. The moisture, protein, fibre, fat, ash, carbohydrate and total solids of soy milk from whole and dehulled seed differed significantly (p<0.05). There was marked variation in the % fat content of the products. The results of the sensory evaluation revealed that flavor with respect to taste and smell had significant influence (p<0.05) on overall acceptability of soy milk product. The sensory properties of yam bean yoghurt samples were compared with soybean yoghurt. The sensory properties showed that sample stored at refrigeration temperature maintained good quality up to 16 days storage while samples stored at room temperature were of poor quality by the 4th day. The implication of these results is discussed. So, the soy milk manufacturers need to improve on the sensory properties in particular flavor and taste for better consumer acceptability. Also, they may improve on packaging by labeling to specifications that precisely represent the content and type. INTRODUCTION His of Soymilk: Soybeans belongs to the family leguminous, subfamily papiliondase and the genus Glycine Max. (Ricker and Morse, 1984), other normendatures which have been used include phaseolus Max, Soja Max Piper and Soja hispide moech. It is not known when this remarkable legume, soybean was first cultivated in China. However as the first legume of which a written record was made. This was in the books of the Emperor Shen hung, dated 1800BC which describes the five principal and sacred crops of China, rice, bean, wheat barely and millet, lafter in his milliohm there were chinses writing, giving expert advice on growing soybean which was cultivated more extensively in North than in Southern China, it reached Hapan and other countries in East Asia at an early date. Soybean contain about 46% protein and 18% fat, characteristics which have influenced it’s history: the ancient Chinese evolved methods of making from it’s preparations with high protein content for example, Curd and Shoyu, Shoyu is a dark brown liquid made by fermentation of a combination of soybeans and cereals (F.A.O. 1970). The Chinese also ate soybeans as a vegetable after it ahs sprouted. The soybean was first heard of in Europe in 1712 through the German Botanist Egelbant Kalmpfer who had visited Japan. In the 18th century, it was grown in some European botanical gardens (F.A.O, 1970), it is first appearance in the United States in 1804, when Commander Perry brought home two varieties from Japan (F.A.O, 1970). What was called the second stage in the history of soybeans did not begin until the first decade of the present century, when it become an important export from East – Asia at first mainly to Europe and alter to the importing countries was as a source of oil for soap making and other purposes and for the manufacture of livestock feed. Then the third stage began in the early nineteen thirties, it is silent feature has been the large stage cultivation of the soybean in the United States, combined with the application of Modern Technology which enable it to be put to a variety of uses both as food and folder and as raw materials for manufacturing processes, while soybean has to a considerable extent becomes an industrial crop in the United States, it continues to be grown in East Asia as a food crop processed for consumption by time honoured methods. (FAO, 1970). The fourth stage began during the first decade of the 20th century A.D. at the period in which this crop was first introduced of soybeans in Nigeria shows that middle belt of the country to be the best producer of soybean production (Ezedinmma, 1964). In Nigeria, nearly all of the soybean production estimated at 30,000 tons is used for human food. A response to increase in demand for soybean for soybean as a source of protein and vegetable oil, national programme in Nigeria have explained their research on the crop. Since 1987 (IITA; Annual Report 1985) currently more feather have been added to the number of products that can be obtained from soybeans in Nigeria, such products like soymilk as it had been recently demonstrated at the food investigation centuries in Enugu. Soymilk in the traditional sense is simply an aqueous extract of whole soybean, A detailed description of the technique used for the preparation of the soymilk as well as its composition will be found in chapter 3. Soymilk according to the nutritionist a possible substitute for cow or human milk particularly in the feeding of infant who are allegic to animal milk or where cows milk may be found to be two expensive or unavailable. Miller, (1962) soybean or vegetable milk or flu-changin chinse is reported to have been developed and used in china before the Christian era (paker and Morse 1943) by the philosopher who was credited with the first step in the processing of tofu and yuba. Then, the traditional milk is made by soaking the bean in water overnight, wet milling the bean, heating the wet mash to improve flavour and nutritional value and filtration. The milk produce is sold to the public in streets and canteens in china in 1984. In recent years large scale production ha evolved along with commercial marketing of soymilk in Hongkong, Taiwan, Thailand, South Korea, Sinapere, Malaysiaa and not the United States (Babara, 1984).