Preparation and Taste Profiling of the Enzymatic Protein Hydrolysate from a by-Product of Red Snow Crab Processing as a Natural Seasoning Compound

Novel umami-enhancing peptides of beef M. Semimembranosus hydrolysates and interactions with the T1R1/T1R3 taste receptor

The taste mechanisms of beef umami and umami-enhancing peptides are not well understood. Therefore, novel umami and umami-enhancing peptides from beef M. semimembranosus hydrolysates were explored. Beef hydrolysates treated with Flavourzyme® showed an overall strong umami intensity compared to those treated with Alcalase®, papain, or Protamex®. The peptides were isolated via consecutive separation processes, and 31 potential umami peptides were identified. Molecular docking results showed that WGSEPIRIQ and TERGYSF had considerably low docking energies with the T1R1/T1R3 taste receptor through potential key binding sites for hydrogen bonding, including Ser48, Gly49, and Gln278 in T1R1, and Ser67, Asn68, and Arg247 in the T1R3 subunit. The taste of the identified peptides dissolved in ultrapure water was dominated by sourness. Instead, they demonstrated an umami-enhancing effect in the presence of monosodium glutamate. These results broaden our understanding of the taste mechanisms of beef umami-enhancing peptides and their potential applications as flavoring agents.

Effects of Sodium Alginate on the Physical Properties and Storage Stability of Freeze-Dried Tofu Coagulated with Crab Shell Extract

The amount of processed by-products such as crab shells is increasing, but industrial utilization is insufficient. In our previous study, crab shell extract (CSE) acted as a coagulant for tofu manufacturing. This study aimed to reduce freeze-dried (FD) tofu breakdown by improving its physical properties through adding sodium alginate (SA). FD state in tofu helps increase storage and availability, but FD tofu frequently fractures during processing, which is a concern for manufacturers. Tofu samples were prepared with either crab shell extract (CSE) or MgCl2, and SA, and freeze-dried. In the yields of FD tofu samples, there were no significant differences (p < 0.05). The brokenness of FD tofu samples was lower in CSE than in MgCl2 and was significantly reduced by SA in both tofu samples, which was affected by hardness. The water-holding capacity decreased after freeze-drying, and CSE reduced this decrease, regardless of SA addition. The microstructures differed depending on the coagulant and were dense upon SA addition. The FD tofu was packed into a multilayer film and stored at 25 °C or 45 °C for 6 months to investigate storage stability. During the storage, brokenness was unchanged in all tofu samples, indicating that they maintained their original structure. There were no significant differences in the volatile base nitrogen and thiobarbituric acid values according to the coagulant type and SA addition (p < 0.05). In conclusion, SA reduced FD tofu breakdown by improving the network structure, which may help increase FD tofu quality and decrease economic loss.