Properties of transglutaminase-induced myofibrillar/wheat gluten gels.

Gelation properties of myofibrillar protein (MP)/wheat gluten (WG) induced by glutamine transaminase (TGase) were studied. Results showed that the inclusion of transglutaminase increased the gel strength, water-holding capacity (WHC), and nonfreezable water (Wnf) of MP/WG mixture. Circular dichroism (CD) analysis showed that the ß-sheet and random coil content of the MP/WG treated with TGase addition increased by 12.1% and 3.7%, while the α-helix and ß-turn content decreased by 14.2% and 1.8%. Rheological measurements showed that TGase induced higher energy storage modulus value during the MP/WG gel heating-cooling cycle. the hydrogen bond and hydrophobic interaction content of the MP/WG gels increased by 80 and 120 ug/L, and the disulfide bond decreased by 200 ug/L, with TGase addition was increased from 0 to 120 U/g protein. Scanning electron microscope (SEM) showed that MP/WG gel with TGase had uniform and dense network structure. PRACTICAL APPLICATION: The properties of myofibrillar/wheat gluten gel induced by TGase crosslinking was studied. The gel structure and water holding capacity of MP/WG were improved by the cross-linking of TGase. The study of the gel properties of MP/WG induced by TGase crosslinking also can provide a theoretical basis for analyzing the effect of TGase on the application of gluten protein in complex meat emulsion system.

Effect of high-intensity ultrasound soymilk pretreatment on the physicochemical properties of microbial transglutaminase-catalyzed tofu gel.

Tofu prepared by conventional methods often has a bitter taste and poor water-holding capacity (WHC). To improve the quality of the product, alternative processes must be developed. Herein, the effect of ultrasound pretreatment on the properties of soymilk and tofu gel derived thereof were investigated. Treatment of soymilk with ultrasound gave rise to a reduction in the particle size and an enhancement in the surface hydrophobicity, whereby optimum values were obtained after 15 min treatment. Subsequently, microbial transglutaminase (MTG) was added to ultrasound-treated soymilk to promote the soy protein crosslinking. The gel strength, WHC, and nonfreezable water content of MTG-catalyzed tofu gel obtained from treated soymilk increased with the extension of the ultrasound pretreatment time, whereas the free sulfhydryl content decreased because of the formation of disulfide bonds. Fourier transform infrared spectroscopy demonstrated variations in the secondary structure of MTG-catalyzed tofu gel. Furthermore, soymilk's exposure to high-intensity ultrasound pretreatment led to a tofu gel with a dense, homogenous, and stable network structure, as evidenced by scanning electron microscopy. Therefore, this study answers for the theoretical support of the industrial production of MTG-catalyzed tofu gel from ultrasound-treated soymilk. PRACTICAL APPLICATION: High-intensity ultrasound pretreatment improved the texture properties of MTG-catalyzed tofu gel. The resulting MTG-catalyzed tofu gel has potential application in industrial production.