• The Korean Journal of Food And Nutrition
• /
• v.14 no.6
• /
• pp.562-567
• /
• 2001

In order to utilize okara protein as a food auditive, nutritional composition of soymilk okara was investigated. Protein in okara Is highly insoluble due to excessive heat treatment during soymilk processing. Protein content of okara was 37.3% as compared to 42.5 % for soybean. Carbohydrate and lipid contents of okara were 40.6% and 17.9%, respectively. Okara lipid extracted with chloroform-methanol consisted of neutral lipid, glycolipid and phospholipid, with neutral lipid making up 98.6% . Linoleic acid, ileic acid, and palmitic acids accounted for about 80% of the total fatty acids with linoleic acid sharing 50.3% of the total. Amino acid composition of okara protein was dissimilar to that of soy Protein : Cysteine was totally absent in okara while lysine, which is the limiting amino acid of soy protein, was present in higher amount in okara on dry weight basis. Both aqueous extract of okara protein and soy Protein were found to have ACE inhibitory activity.

• Korean Journal of Food Science and Technology
• /
• v.33 no.6
• /
• pp.769-773
• /
• 2001

Protein content of okara and soybean were found to be 37.3% and 42.5%, respectively by micro-Kjeldahl analysis. Solubility of okara protein in phosphate buffer (pH 8) was 10% versus soy protein of 68.4%. Insolubilization of okara protein was mostly due to disulfide bonding between cysteine residues caused by excessive heat treatment during soymilk processing: hydrophobic interactions and hydrogen bondings were involved to lesser extent. Optimum extraction temperature and time were $60^{\circ}C$ and 40 min. Typical solubility profile of soy protein disappeared for okara protein though minimum solubility of the protein was around pH 3.0. Treating okara with protease was effective in solubilizing okara protein and solubility increased to 19.2%. Optimum reaction temperature and time were $80^{\circ}C$ and 50 min, respectively. Cell wall degrading enzyme did not increase solubility of the protein, however. Through enzymatic reaction okara protein could be effectively solubilized for uses as food ingredient.

• Journal of the Korean Wood Science and Technology
• /
• v.36 no.3
• /
• pp.30-38
• /
• 2008

Petroleum-based resin adhesives have extensively been used for the production of wood panels. However, with the increase of manufacturing cost and the environmental issue, such as the emission of volatile organic compounds, of the adhesive resins, it is necessary to be developed new adhesive systems. In this study, the potential of okara, which is a residue wasted from the production of tofu, for the development of bio-based adhesives was investigated. At first, the physical and chemical properties of okara were examined. After okara was hydrolyzed in acidic and/or alkaline solutions, okara-based adhesive resins were formulated with the mixtures of the okara hydrolyzates and phenol formaldehyde (PF) prepolymer. The adhesive resins were used for the fabrication of plywood panels, and then the adhesive strength and formaldehyde emission of the plywood panels were measured to examine the applicability of the resin adhesives for the production of plywood panels. The solids content and pH of the okara used in this study were around 20% and weak acidic state, respectively. In the analysis of its chemical composition, the content of carbohydrate was the highest, and followed by protein. The shear strengths of plywood fabricated with okara-based resin adhesives exceeded a minimum requirement of KS standard for ordinary plywood, but its wood failure did not reach the minimum requirement. In addition, the formaldehyde emissions of all plywood panels were higher than that of E1 specified in the KS standard. Based on these results, okara has the potential to be used as a raw material of environmentally friendly adhesive resin systems for the production of wood panels, but further researches - biological hydrolysis of okara and various formulations of PF prepolymer - are required to improve the adhesive strength and formaldehyde emission of okara-based resin adhesives.