Water Soluble Antioxidant in Supernatant Fraction of Okara, a By-product of Tofu Manufacturing

Takenaka, Tohru; Tamura, Yoshiyuki; Takenaka, Yoko

doi:10.3136/fsti9596t9798.2.19

Cited by 4 publications

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References 25 publications

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“…However, Okara still contains about 25% protein (dry basis) with high nutritive quality. Studies on the utility of Okara (Takenaka et al, 1996;Miyamura et al, 1998;Tamura & Takenaka, 1999) have been done, but utilization of the substance is still in the developmental stage. Antioxidative activity has recently been detected in peptides from the proteolytic hydrolysis of many food proteins (Suetsuna et al, 2000;Chen et al, 1995).…”

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Antioxidative Activity of Peptides Prepared from Okara Protein.

Yokomizo

Takenaka

2002

FSTR

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Protease hydrolyses of an Okara protein yielded antioxidative activity against the peroxidation of linoleic acid in an aqueous system at pH 7.0. Four antioxidative peptides were isolated from the hydrolysate prepared with Protease N by size exclusion chromatography and reversed-phase HPLC. The peptides were composed of two and three amino acid residues, including aromatic amino acid at the C terminal end. Their amino acid sequences were determined to be Ala-Tyr, Gly-Tyr-Tyr, Ala-Asp-Phe, and Ser-Asp-Phe, respectively. The antioxidative activity of Gly-Tyr-Tyr is nearly equal to that of carnosine.Keywords: antioxidative activity, amino acid, peptide, hydrolysate, OkaraIn the manufacturing of soymilk and tofu, the soymilk residue, Okara, is produced as a by-product with little market value. However, Okara still contains about 25% protein (dry basis) with high nutritive quality. Studies on the utility of Okara (Takenaka et al., 1996;Miyamura et al., 1998;Tamura & Takenaka, 1999) have been done, but utilization of the substance is still in the developmental stage. Antioxidative activity has recently been detected in peptides from the proteolytic hydrolysis of many food proteins (Suetsuna et al., 2000;Chen et al., 1995). In this study, we examined the antioxidative effects of enzymatic hydrolysates of Okara protein with seven different proteases. Materials and MethodsMaterials The Okara protein was prepared using the method of Yamauchi et al. (1984). Proteases were purchased from Amano Enzyme Co., Ltd (Nagoya, Japan): Protease A from Aspergillus oryzae, 10,000 u/g, pH 7.0; Protease M from Aspergillus oryzae, 150,000 u/g, pH 7.0; Protease N from Bacillus subtilus, 30,000 u/g, pH 7.0; Protease P from Aspergillus melleus, 30,000 u/g, pH 8.0; Protease S from Bacillus sp. 10,000 u/g, pH 7.0; Prolezer from Bacillus subtilus 10,000 u/g, pH 9.0; and Papain W-40 from Carica pancreas, 400 u/g, pH 8.0.Preparation of the Okara protein hydrolysate Okara protein (10 g) was dissolved in 200 ml of distilled water, and heated at 100˚C for 10 min. Protease (0.2 g) was added to the protein solution after the pH was properly adjusted. Enzymatic hydrolysis was performed under optimum pH conditions as the manufacturer recommended. After digestion, hydrolysates were heated in boiling water for 5 min to inactivate proteases, then neutralized and centrifuged (20,000¥g for 10 min). The supernatants were lyophilized and stored in 4˚C until use.Measurement of antioxidative activity Linoleic acid (10 mg) in 0.5 ml of ethanol, samples in 4.0 ml of 0.2 M phosphate buffer (pH 7.0), and 0.15 ml of 20 mM 2,2¢-azobis(2-amidinopropane) dihydrochloride (AAPH) were placed in a vial, which was then sealed tightly and kept at 50˚C in the dark. At regular intervals, an aliquot of the reaction mixture was withdrawn for measurement of the oxidation using the ferric thiocyanate method (Mitsuda et al., 1966). The time taken to attain an absorbance of 0.3 was defined as the induction period. The relative antioxidative activity was calculated by dividing the indu...

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Antioxidative Activity of Peptides Prepared from Okara Protein.

Yokomizo

Takenaka

2002

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“…This fact indicates that the protein contributes to the DPPH radical scavenging activity in the extracts, which agreed with several published reports. [4,7,20] .…”

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confidence: 99%

Properties of Extract from Okara by Its Subcritical Water Treatment

Wiboonsirikul¹,

Mori²,

Khuwijitjaru³

et al. 2013

International Journal of Food Properties

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Okara was treated with subcritical water at temperatures ranging from 170 to 260 o C for various times. After clarification, the extracts were analyzed for their protein and carbohydrate contents, DPPH radical scavenging activity and antioxidative activity. The carbohydrate content significantly decreased with the increasing treatment temperature and time. The protein content, however, increased with the increasing treatment temperature and slightly decreased with a heating time longer than 10 min. The extract obtained from the subcritical water treatment at 240 o C for 5 min, which would be used to evaluate the antioxidative activity, provided the relatively highest radical scavenging activity and the activity decreased with the prolonging heating time and temperature. The extract also exhibited a suppressive activity to the autoxidation of linoleic acid with the increasing weight ratio of the extract to linoleic acid. The results clearly showed okara still contained highly valuable substances for human consumption.

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“…Chip specimens are designated by N3 or N5 specimen for Inconel X-750 alloy and by A2 or A4 according to shear strain imposed by machining in this study. The approximate shear strain (g) of the chip specimens was calculated by the following theoretical equation for two-dimensional cutting, 21,22) although the cutting condition was not two-dimensional for producing long N3 and A2 specimens (more than about 20 mm in length). Figure 2 shows the scanning electron micrographs of N3 chip specimen (shear strain, gϷ3) of Inconel X-750 alloy.…”

Section: Microstructures and Properties Of High-strength Alloys Severmentioning

confidence: 99%