Evaluation of physico‐chemical characteristics and microstructure of tofu containing high viscosity chitosan

Abstract

Tofu, containing high viscosity chitosan dissolved in a δ‐gluconolactone solution, was prepared and physico‐chemical properties, microstructure, textural properties and sensory characteristics were investigated. Moisture content and pH of the chitosan tofu were slightly lower than those of the control tofu. The textural properties of tofu such as hardness, cohesiveness, gumminess and chewiness measured by an instrumental method were not significantly changed by the addition of chitosan to tofu. Springiness of chitosan tofu, however, was significantly higher than that of the control tofu. All characteristics except the roasted nutty aroma and yellowness in the sensory evaluation, did not exhibit significant differences between the chitosan tofu and control tofu. Therefore, the quality of tofu was little affected by the addition of the chitosan content employed in this experiment.

Influence of calcium chloride concentration on the physicochemical and sensory characteristics of tofu

“…Positive correlations at P ≤ 0.05 were significant between cohesiveness and firmness and between pH and adhesiveness. Kim and Han (2002) indicated that the pH of tofu can be significantly correlated with the textural characteristics, which was confirmed by the results of this study.…”

“…Noh et al (2005) suggested that tofu made from frozen soybeans has a firmer texture behavior, which coincides with the highest score for firmness reported in Table 2. Kim and Han (2002) reported tofu firmness values of 6.70 ± 1.92; elasticity 7.34 ± 2.28; and adhesiveness 6.96 ± 2.27. The same authors claimed no major differences among the sensory characteristics of tofu.…”

“…The results were similar to those reported in other investigations. According to Kim and Han (2002), moisture in tofu varies from 80.63 to 83.40%. In a separate study examining the effect of soybean variety on tofu quality, Wang et al (1983) reported humidity between 84.2 and 85.6%.…”

“…In the present investigation, the pH varied between 6.13 and 6.20. Kim and Han (2002) reported a pH of 5.70 when examining clotting. The difference with respect to the optimal pH is likely due to the addition of calcium chloride (Okigbo et al, 1985), because the pH can strongly affect the binding degree of Ca +2, causing hydrogen ions to compete with calcium ions for the same binding sites in the protein molecule (Kroll, 1984).…”

Effect of chitosan and microbial transglutaminase on the gel forming ability of horse mackerel (Trachurus spp.) muscle under high pressure

“…There have been a few studies describing addition of chitosan to foods, mainly for its antioxidant, antimicrobial and texturizing properties. Chitosan has been used in biscuits (Maezaki et al, 1993), in tofu (Kim & Han, 2002), in meat products (Jo, Lee, Lee, & Byun, 2001;Lin & Chao, 2001) and in fish muscle (Benjakul, Visessanguan, Phatchrat, & Tanaka, 2003;Benjakul et al, 2001;Kataoka, Ishizaki, & Tanaka, 1998).…”