Tong Chang

Effects of starches on the textural, rheological, and color properties of surimi-beef gels with microbial tranglutaminase.

In order to evaluate effects of starches (corn starch, potato starch, and tapioca starch) on the characteristics of surimi-beef gels with microbial transglutaminase, the cooking loss, gel strength, color and rheological properties of samples were investigated. Results demonstrated that starches gave negative effects on the cooking loss of surimi-beef gels. The gel with corn starch had the highest cooking loss while that with tapioca starch showed the lowest value. The gel with potato starch obtained the highest gel strength. During the sol-gel transitions, surimi-beef complexes with 3% corn starch exhibited the highest storage modulus value, while that with 3% tapioca starch had the lowest one. The addition of starch caused the increase of L* values of surimi-beef gels. Results showed that the excessive amount of starch resulted in the decrease in gel strength of surimi-beef gels.

Effects of salts on physicochemical, microstructural and thermal properties of potato starch.

The objective of this study was to determine the effects of salts on the physicochemical, microstructural and thermal properties of potato starch. The salting-out ions were able to decrease the solubility, swelling power, transparency and particle size of potato starch significantly (p<0.05), while the salting-in ions increased these properties significantly (p<0.05). The microstructure of potato starch granules, observed by a light microscopy at 50°C and 70°C, was consistent with the above results. Differential scanning calorimetry (DSC) analysis demonstrated an increase in gelatinization temperature and enthalpy with the addition of salting-out ions, whereas there was a reverse trend for the addition of salting-in ions. The effects of anions on these properties of potato starch follow the order of SCN(-)>I(-)>NO3(-)>Br(-)>Cl(-)>SO4(2-)>F(-), while effects of the cations follow the order of Li(+)>Na(+)>K(+), matching to the order of the Hofmeister series.

Effects of the Acid- and Alkali-Aided Processes on Bighead Carp (Aristichthys nobilis) Muscle Proteins

The objective of this study was to investigate the effects of the acid- and alkali-aided processes on bighead carp (Aristichthys nobilis) muscle protein as compared with the conventional washing method. Acid- and alkali-aided processes resulted in higher protein recoveries than conventional washing method. In textural profile analyses, the highest hardness and cohesiveness were observed in the gels prepared by conventional washing and alkali-aided processing (p < 0.05). No endothermic peak was found in the differential scanning calorimetry thermogram of protein isolates after acid- and alkali-aided processes. The hydrophobic interactions and disulfide bonds were the main chemical bonds to maintain the stability of the gel matrix, while the sulfhydryl group in bighead carp muscle was apt to be activated during alkali-aided processing. The α-helical content of actomyosin decreased remarkably after the acid- and alkali-aided processes (p < 0.05). Overall, there is a potential to apply the alkali-aided processing to extract proteins from bighead carp muscle for the production of surimi-based seafoods.

Comparison of Conventional Washing Processing and pH Shift Processing on Gelation Characteristics of Bighead Carp (Aristichthys nobilis) Muscle Proteins

ABSTRACT In this study, gelation characteristics of bighead carp (Aristichthys nobilis) protein isolates prepared by pH shift processing were investigated as compared with those of surimi prepared by conventional wash processing. Results showed that the gel from alkali-aided protein isolate exhibited a higher breaking force than that from conventional washed surimi (p < 0.05). However, the gel from conventional washed surimi had higher whiteness (p < 0.05) and lower expressible moisture (p < 0.05). The rheological study showed that protein isolates exhibited different storage modulus and loss tangent patterns from conventional washed surimi during heating. Acid-aided processing could lead to higher denaturation and dissociation for fish muscle myosin and a coarser gel network from the sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) pattern and the scanning electron microscopy (SEM). Overall, there is a potential to apply pH shift processing, especially alkali-aided processing, to extract more proteins from bighead carp muscle for the production of surimi-based food.

Seafood Processing By-products: Collagen and Gelatin

With the rapid development of the fish processing industry, large amounts of fish skin, scales, and bone are produced and considered as waste every year around the world. However, this waste, such as the fish skin, contains collagen in abundance, which can be used as ingredients for food, medicine, cosmetics, etc. Thus, the utilization of waste from the fish processing industry can not only produce value-added products from low-cost resources, but also reduce pollution to the environment. This chapter focuses on the production and utilization of fish collagen and gelatin, as well as their structural, compositional, physicochemical, and functional properties.