Nutritional Quality and Consumer Acceptability of Soy (Glycine Max) Cheese (Tofu) Compared With Beef (Bos Taurus)
The Objective of the study
Thus, the objective of the study was to study the nutritional quality and consumer acceptability of soy cheese (tofu), then compared the nutritional quality with that of beef.
History of Soybean (Glycine max)
The soybean has a long history as a food source. In fact, the first recorded usage of soybeans dates back as far as the 11th century B.C. soybeans were a crucial crop in east Asia long before written records began domestication between 7000 and 6600 B.C in China, between 5000 and 3000 B.C in Japan and 1000 B.C in Korea (Lee, 2011). It is believed that the soybean has originated from China nearly 4000-5000 years ago and was used as a popular product in Chinese cuisine (Watanabe, 2000). China was the world’s largest producer of soybeans and its exports till 1954 until United States succeeded them (Penarad et al., 2001). More than one third of U.S. soybeans are exported while the rest are used domestically mainly for production of food oil, feed meal, soy flours, soy protein concentrates and isolates. Countries such as China, Taiwan, Japan, Korea and other Asian countries import soybeans from the U.S. for preparation of traditional soy foods e.g.; soymilk and for oil and meal production (Liu and Chang, 2004).
Soybeans are rich in protein (30-40%) and oil (20%) (Wilson, 2005). Soybeans are good source of protein, lipid and other nutrients. Soybean protein is considered to be a good substituent for animal protein (sack et al., 2006). Soybean is regarded as equal in protein to animal foods. It has been found to be excellent for a number of different conditions such as high blood pressure diabetes related diseases and many other (Witf, 2004, Osho and Dashiell, 2008). Researches on rats indicated that the biological value of soy protein is similar to many animals’ protein such as casein if enriched with the Sulphur containing amino acid methionine (Hajos et al., 2006). It is reported that soybean which has less purchase cost has about 40% protein, 30% carbohydrate, 20% oil and 10% mineral. It is very useful in improving the menu of malnourished children and revitalizing heart and breast cancer patients and has no cholesterol. Protein content is approximately 40% and fat 20% (Glami, 2002) with considerable vitamins about 15.65% saturated fatty acids, 22.78% monounsaturated fatty acids and 57.74% polyunsaturated fatty acids (7% linoleic acid and 54% linoleic acid) (Wolke, 2007).
More than half of the annually harvested soybean crop is crushed to produced oil which is used extensively in commercial products such as cooking oils, margarine, processed food and other industrial product such as paints, linoleum, oil cloths, printing inks, soaps, insecticides and disinfectants (Islam et al., 2007). Soybean were traditionally used for consumer food products such as tofu, soymilk, soy sprouts, and natto in the far east and crushed for oils and meal in the west (Liu, 2007). Soybean proteins are made up of two major fractions 75(a-conglycinin) and 115 (glycinine). 75 subunits of a soluble protein while, 115 exists in a particulate form (Peng et al., 2016).
Strategies to Improve Consumer Liking
In order to prevent a gritty mouth feel (Sedimentation of large particles) and ultimately obtain a soy-PBCS with a smooth texture, alternate methods include the adoption of fermentation techniques. Specifically, the incorporation of lactic acid bacteria (LAB) softens the rough particulates in order to achieve a smoother texture when blended (Jianming et al., 2013). Two studies (Li et al., 2013) and (Li et al., 2020) compiled both hedonic and descriptive testing methods to the evaluate whether modified fermentation improved the sensory attribute and acceptance PBCS. (Li et al., 2020) initially soaked the soybeans in a 0.5% (wt /vol) sodium carbonate solution for 20minutes before creating the soymilk.
Blending different ratios of plant-based milks with soymilk results in an improved flavor profile compared to 100% soymilk PBCS. While no study specifically evaluated off-flavors or perception of beany flavor in any product, it is suggested that this attribute is reduced as a result of blending soymilk with alternative non-dairy milks. Adejuyitan et al. (2014) created soft PBCS prepared using fermented soybeans prior to blending soy and coconut milks at 5 different ratios to combat the naturally beany flavor of soymilk. (Balogun et al., 2019) created soft PBCS by blending soy and tiger nut milks prepared with six different ratios to combat the naturally beany flavor of soymilk.
Modified Processing of Soybeans
In order to eliminate the beauty flavor, blanching and grinding soybeans at or above 80 oC has shown to reduce lipoxygenase activity in order to improve these sensory properties (Li et al., 2013). Additionally, incorporating sodium bicarbonate results in the softening of soybean seed coat (Jayasen et al., 2010) in order to reduce the gritty mouth feel expressed (Jeewanthi and Paik, 2018). In the following studies, the methods of sodium bicarbonate, blanching, or blending a variety of plant-based milks at different ratios were utilized in order to improve sensory characteristics of soy-based PBCS. This section review studies that performed modified processing, which often entails blending soybeans with other non-dairy milks.
Nutritional Profile of Soybean
Nutrient composition can be influenced not only by the genetics, the cultivar or the growth condition, but also by the processing and refinement; therefore, significant variations can be detected in the soybean and soy-based foods nutritional profile (Grieshop and Fahey, 2001; Grieshop et al., 2003). Nevertheless, Sulphur-amino acids (Cysteine and especially methionine), tryptophan and valine are limiting amino acids in say (Aletor, 2010; Anuonye et al., 2010). Nowadays, there is a clear increase in the amounts of commercial soy-based foods so that the soy consumption has risen greatly. Lipid raffinose, fraction. Dietary fibre, as non-starch polysaccharides, is mainly found in the hulls and the content range between 9 and 16% of whole soy seed (Estevez et al., 2010).
MATERIALS AND METHOD
Soybeans (Glycine max) and beef (Bos taurus) used for this research was collected and purchased from Oba market, Owo, Ondo state, Nigeria and taken to the Laboratory of the laboratory of the department of Food Science and Technology, Rufus Giwa Polytechnic, Owo, Ondo state.
Processing of Fresh Tofu Coagulated with Alum
The processing of soybean includes manual sorting of the beans, washing and it was soaked with hot water for 30 minutes until they are completely hydrated, the soaked soybean was washed in water to remove the Testa. The unabsorbed water remaining was drained off after washing of soybean. The hydrated soybean are combined with fresh water and wet milled. The resulting slurry was flittered using a muslin cloth, washed with fresh water and pressed to remove any remaining soymilk and insoluble residue (Okara). The Okara was pressed washed and then pressed again to remove any remaining soymilk. It was then cooked at 100oc for a period of time, usually 7-10 minutes. The soymilk was then coagulated with some sour liquid or residue from making pap (Steep water).
To produce the finished tofu, the curds are separated from the whey, poured into a muslin cloth pressing box, pressed for a period of time and then most important phases in tofu production. The tofu was further divided into two: one part was cold water as fresh firm tofu while the other part was stored for further processing.
RESULTS AND DISCUSSIONS
Table 4.1: Proximate Composition of Soy cheese (Tofu) and Beef (in %)
CONCLUSION AND RECOMMENDATIONS
The results obtained from this study showed high protein and fat content in boiled beef followed by tofu coagulated with lime. All mineral content (Iron, Zinc, Sodium, Potassium, Phosphorus, Magnesium and Calcium) are predominantly present in the samples, although boiled beef has the highest content in all mineral accept in potassium and zinc, thus, the entire mineral are safe in limit as required for the body. Tofu coagulated with lime could be a substitute for beef in terms of protein and fat as required in the body especially for vegetarian which will helps to reduced malnutrition (i.e. kwashiorkor and marasmus) and also helps to repair their worn out tissues. There is no significant difference between tofu coagulated with alum and boiled beef in all parameter investigated but tofu coagulated with lime is significantly different.
Tofu coagulated with alum is the most acceptable in all samples, thereby encouraging the consumption of soybeans, enhancing and improving the utilization of tofu production. This will serve as an advantage to both children’s and adults as its contain low cholesterol and adequate minerals. It can be for direct consumption or commercially for sales which can serve as a means of poverty eradication among peoples.
Tofu utilization and consumption should be encouraged into our diet since the proximate, minerals and sensory evaluation can be compared well with boiled beef (animal protein). Further studies should be done on the processing method and fortification of soybeans with some legumes for the production of tofu to increase its nutrients bioavailability.
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