The Effect of Different Processing Techniques on the Proximate and Organoleptic Quality of Stored Soymilk
Objectives of the Study
This study aims to determine the effects of different processing techniques on the proximate and organoleptic quality of soymilk processing and storage.
Soybean (Glycine max L.)
Botanically, soybean belongs to the order Rosaceae, family Leguminosae or Papillonaceae or Fabaceae, subfamily Papilionoidae, the genus Glycine and the cultivar Glycine max. In October 26th, 1999, the Food and Drug Administration (FDA) in USA approved a health claim based on the role of soybean protein in reducing the risk of coronary heart disease. This claim establishes that soybean protein included in a diet low in saturated fat and cholesterol may reduce the risk of coronary heart disease. The available researches showed that frequent soybean protein consumption lowers the cholesterol levels (FDA, 1999; Henkel, 2000).
The results from recent researches suggest that soybean dietary fibre plays a role in the reduction of cholesterol levels in some hyperlipidemic individuals and has a major protective effect on cardiovascular disease (Anderson et al., 2005; Anderson et al., 1999; Kushi et al., 1999; Lukaczer et al., 2006; Reynolds et al., 2006). Moreover, it improves the glucose tolerance in some diabetic patients; (Messina, 1999; Chandalia et al., 2000; Jenkins et al., 2003) it increases the wet faecal weight and reduces the caloric density in some foods (Liu, 1999). Dietary fibre seems also to have a positive effect on diarrhoea and constipation and as a therapy of irritable bowel syndrome; (Bosaeus, 2004) it has anti- inflammatory and anti-carcinogenic effects on digestive system (Scheppach, 2004).
Origin of Soybean (Glycine Max L.)
It is widely believed that the origins of soybean are in China, probably in the north and central regions, 4,000-5,000 years ago. Soybean was introduced in Europe about 1712 by a German botanist, Engelbert Kaempfer. Later Carl von Linné, gave soybeans a genetic name, Glycine max. However, due to the poor climate and soil conditions, soybean production has been limited in Europe (Liu, 1999; López-Bellido, 2002).
Classification of Soybean (Glycine max L)
The soybean is a member of the family Leguminosae and the subfamily Papilionoideae. Cultivated soybeans have been known by several botanical names but in 2008 Ricker and Morse presented evidence that the correct botanical name should be Glycine max (L.), Merril (Ricker and Morse, 2008). Their conclusion has been generally accepted, and Glycine max has been used almost exclusively in scientific literature since 2008.
The genus Glycine is subdivided into three subgenera: GlycineBracteata and Soja G. max has not been found growing wild. It probably originated from G, soja, which grows wild in the Yangtze River Valley, the northern and northeastern provinces of China and adjacent areas of the USSR, and in Korea and Japan (Hinson and Hartwig, 2007).
- max and G. soja have diploid chromosome numbers of 40. Crosses between them are easily made, and Fl hybrids are fertile. However, G. soja has a twining growth habit, small hard seed, and low productivity. These traits make G. soja an undesirable parent in breeding programmes 9 unless the breeder identifies some specific trait in G. soja that he wishes to transfer into the more productive species, G. max
The subgenus Bracteata contains only one species – G. wightii which is subdivided into five subspecies. They are viny perennials that are used as tropical forages, and have diploid chromosome numbers of 22 and 44. They have not been hybridized -with G. max.Species within the subgenus Glycine are perennials. They appear to have limited value in intensive agriculture. Diploid chromosome numbers for four species are either 40 or 80. However, none has been hybridized with G. max (Hinson and Hartwig, 2007).
Nutritional Composition of Soybean (Glycine max L.)
Soybean is a singular food because of its rich nutrient content. Soybean contains vegetable protein, oligosaccharides, dietary fibre, phytochemicals (especially isoflavones), and minerals (Anderson et al., 1999; Messina, 1999; Liu, 1999).
MATERIALS AND METHODS
Soybean (Glycine Max L.) was obtained from the local market in Owo, Ondo State. The soybean was processed into soymilk in food processing laboratory in the department of Food Science and Technology, Rufus Giwa Polytechnic, Owo, Ondo State.
Methods of Preparation
Soymilk was prepared in the Processing Laboratory of Food Science and Technology using the following 2 (two) methods:
- Wet milling process of producing soymilk
- Dry milling process of producing soymilk
RESULTS AND DISCUSSION
Table 4.1: Physicochemical Composition of Soymilk Samples
CONCLUSION AND RECOMMENDATIONS
From the study, it is concluded that the methods of processing or preparation affect the quality and deterioration pattern of soymilk during processing. Hence numbers of processing techniques have been adopted for soymilk processing in order to extend its shelf life. It is noted from the study that the use of dry milling method of soymilk production helps contribute in shelf life of the soymilk. Although the WMS (wet milled soymilk) is preferred in terms appearance, colour, taste and aroma compared to DMS (Dry milled soymilk). The nutritional attributes of DMS is greater than that of WMS in terms of protein and fat content while WMS retain its ash (mineral composition) content compared to DMS.
Based on the findings revealed in this study it is therefore recommended that the use of drying milling and wet milling processing of soymilk should be encouraged. Though, WMS was more preferred to DMS in their sensory attributes but DMS has higher content of protein, fat and considerable amount of other nutrient. Dry milling processing of soymilk s it is not popularly available in our locality should be encouraged because it extends the shelf life of food products and also retain some major nutrients required by body for metabolism for proper functioning of the body system. There should be a way of improving the organoleptic properties of DMS product.
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