Sang Moo Kim

Antioxidant effect of Phaeodactylum tricornutum in mice fed high-fat diet

High-fat diet (HFD)-induced obesity is associated with oxidative stress. The purpose of this study was to examine the antioxidant effect of Phaeodactylum tricornutum extract in mice with diet-induced obesity. Four-week-old C57BL/6J mice were fed a normal diet or HFD with and without 0.7% P. tricornutum lipid extract corresponding to 0.2% fucoxanthin for 8 weeks. P. tricornutum significantly decreased body weight and epidydimal white adipose tissue in mice fed the HFD. Serum triglyceride, glucose, insulin, and leptin levels, as well as homeostasis model assessment for insulin resistance (HOMA-IR) values, were significantly lower in the P. tricornutum group than in the HFD group. P. tricornutum significantly decreased thiobarbituric acid reactive substances (TBARS) and increased glutathione and the activities of superoxide dismutase, catalase, and glutathione peroxidase in the liver compared with the HFD group. Thus, P. tricornutum could exert antiobesity and antioxidant effects in mice fed a HFD.

Quality Properties of Giant Squid (Dosidicus gigas) Surimi-Based Product Manufactured with Amorphophallus konjac Flour

A giant squid has not been utilized in the manufacture of the surimi-based product because of its strong fishy smell and weak gel forming ability. In this study, Amorphophallus konjac flour (AKF) was used to improve the quality of giant squid surimi-based products. The response trace plots showed that the gel texture and water retention ability (WRA) of surimi gel increased as the contents of AKF and surimi increased, whereas the water content decreased. Meanwhile, the whiteness of surimi gel increased as the contents of water and surimi increased, and AKF content decreased. Based on a sensory evaluation, giant squid surimi-products with AKF was inferior in color and taste compared to commercial surimi-based products, This inferiority could be improved by the addition of seasoning ingredients such as sweeteners. AKF successfully removed the fishy smell and improved the surimi gel properties. Therefore, AKF could be used as a food ingredient in surimi-based products.

Quality Properties of Fermented Squid Seasoning Manufactured with Fermentation Accelerator

Squid was fermented with fermentation accelerators to develop a natural complex seasoning. The quality properties of fermented squid were determined at different fermentation periods. Squid fermented with 10% Aspergillus oryzae koji for 10 days had the highest amino-N, acidity, and total viable cell content during fermentation periods, whereas volatile basic nitrogen content and pH were the lowest. Based on the amino-N content, squid with 10% koji fermented for 10 days was selected for further analyses. The inosine and glutamic acid contents of the fermented squid were highest innucleotide composition, their related compounds, and free amino acids, respectively. The IC50 values of the fermented squid on DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging and α-glucosidase inhibitory activities were 6.20 and 4.41 mg/mL, respectively. Based on the results of a sensory evaluation, the fermented squid seasoning was similar to other natural complex seasonings such as anchovy, cowmeat, and fisheries seasonings.

Biofunctional Properties of Enzymatic Squid Meat Hydrolysate

Squid is one of the most important commercial fishes in the world and is mainly utilized or consumed as sliced raw fish or as processed products. The biofunctional activities of enzymatic squid meat hydrolysate were determined to develop value-added products. Enzymatic squid hydrolysate manufactured by Alcalase effectively quenched 1,1-diphenyl-2-picrylhydrazyl radical, hydroxyl radical, and hydrogen peroxide radical with IC50 values of 311, 3,410, and 111.5 μg/mL, respectively. Angiotensin I-converting enzyme inhibitory activity of squid hydrolysate was strong with an IC50 value of 145.1 μg/mL, while tyrosinase inhibitory activity with an IC50 value of 4.72 mg/mL was moderately low. Overall, squid meat hydrolysate can be used in food or cosmetic industries as a bioactive ingredient and possibly be used in the manufacture of seasoning, bread, noodle, or cosmetics.

Optimization and Biochemical Characteristics of an Enzymatic Squid Hydrolysate for Manufacture of a Squid Complex Seasoning

Enzymatic hydrolysis of squid meat was optimized and the biochemical properties of solubility, amino acid composition, and contents of nucleic acid related compounds were determined. Optimal hydrolysis conditions were a pH of 7.0, a hydrolysis time of 5.9 h, a temperature of 55°C, and an enzyme/substrate ratio of 2.4%. More than 75% of squid meat hydrolysate was soluble in a wide pH range. The sweet and savory tasting amino acid contents of the squid hydrolysate were higher than the contents of bitter tasting amino acids. The hydrophilic amino acid content of squid meat was lower than the content of hydrophobic amino acids. The inosine monophosphate content of squid hydrolysate was highest among nucleic acid related compounds. Based on a sensory evaluation, squid complex seasoning was similar or superior to commercial complex seasonings. A squid hydrolysate can be used as an ingredient for manufacture of food products.