An alkane-assimilating yeast Candida maltosa had been studied in order to establish systems suitable for biotransformation of hydrophobic compounds. However, functional expression of heterologous genes tested for this purpose had not been successful in several cases. On the other hand, it had been reported that the codon CUG, a universal leucine codon, is read as serine in C. cylindracea. The same altered codon usage had also been suggested by in vitro experiments in some Candida yeasts which are phylogenetically closely related to C. maltosa. In this study we have shown that the failure in functional expression of a heterologous gene is due to the fact that the codon CUG is read as serine in C. maltosa. This conclusion was drawn from the following experimental results: (1) when a cytochrome P450 gene of C. maltosa containing a CTG codon was expressed in C. maltosa, the corresponding amino acid was found to be serine, and not leucine; (2) a tRNA gene with an almost identical structure to that of the tRNASerCAG gene of C. albicans could be isolated from the genome of C. maltosa; (3) the Saccharomyces cerevisiae URA3 gene, which has one CTG codon, could not complement the ura3 mutation of C. maltosa as itself, but when the CTG codon was changed to another leucine codon, CTC, the mutated gene could complement the ura3 mutation. The last result is the first example of succeeding in functional expression of a heterologous gene in Candida species having an altered codon usage by changing the CTG codon in the gene to another codon.

Antioxidant properties of brown seaweed (Sargassum siliquastrum) extracts were evaluated using various antioxidant measurements, i.e., inhibitory effect on thiobarbituric acid-reactive substances (TBARS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, metal chelating effect, reducing power effect, and total phenolic compounds. When the extraction solvents n-hexane, chloroform, ethanol, and water were compared, the water extract showed the highest yield in extracted mass. Total phenolic compounds were the highest in the ethanol extract, with 127.4 mg/g. The TBARS inhibition of chloroform and ethanol extracts at 10 mg/mL was 90.9% and 80.9%, respectively. DPPH radical scavenging capacity was more than 90% in all extracts at 1 mg/mL. The chloroform extract exhibited the highest metal ion chelating ability of 69.6% at 10 mg/mL. The reducing power was found to be the highest in the ethanol extract at 10 mg/mL, showing an effect similar to ascorbic acid. Thus, the ethanol extract of S. siliquastrum has potential as a natural antioxidant.

The common squid (Todarodes pacificus) is one of the most widely consumed food ingredients in East Asian countries, especially Korea and Japan. It is generally marketed raw, which leads to inconvenient preparation, less commercial value, and short shelf life. Therefore, in order to handle these problems, superheated steam roasting (260°C heater, 240°C steam for 4 min) in combination with smoking treatment (15 min) using sawdust from the oak tree was used to process squid before mixing with vegetables and special sauce to make a ready-to-eat squid dish in an effective packaging. The processed squid product showed favorable sensory characteristics (appearance, odor, color, flavor, and texture) and physicochemical properties including maintained pH level (pH > 6.4), low microbial activity (4.74 ± 4.27 log CFU/g), low VBN level (18.27 ± 0.52 mg%), and good texture profile during storage for 10 days at 10°C. Results were significant at the significance level of p<0.05. Findings of this study suggest that the superheated steam-roasting treatment was the best method to maintain nutritional value of the common squid. It also showed favorable sensory and physicochemical properties, while smoking treatment prolonged the shelf life through enhancing antioxidant and antimicrobial activities and enriched flavor of the squid product.

The adductor muscle of the pen shell Atrina pectinata (AMPS) is a popular protein‐enriched food item in Asian Pacific countries, and has only been marketed in the frozen condition, as a result browning and decreased sensory attributes occur. To overcome these problems, superheated steam roasting (at 270°C for 4 min) combined with the hot smoke (10 min) using a selective Oak sawdust was employed to develop a new AMPS product yielding high physicochemical properties during storage periods (0–13 days) especially at 10°C. The processed AMPS showed high sensory preferences because of good odor, color, and textural properties. It also significantly inhibited bacterial growth, volatile basic nitrogen, thiobarbituric acid‐reactive species, and pH changes, and eventually possessed higher nutritional composition with low trimethylamine N‐oxide level. Results indicate that saturated steam allows AMPS at good physicochemical conditions, whereas hot smoke‐derived aroma compounds prolong its shelf life through antioxidant and antimicrobial activities.

The hagfish (Myxine glutinosa), an eel‐shaped demersal fish, is a potential protein source with a distinctive flavor. Additionally, the consumption of hagfish is believed to exert aphrodisiac activity. This study attempted to evaluate the effect of steaming and hot smoking treatment combination on the quality characteristics of hagfish under optimal conditions. There was a significant increase in the sensory attributes such as color, taste, aroma, and texture of processed hagfish (p < .05). Cooking the hagfish with this combination resulted in acceptable physicochemical and microbial properties. Additionally, the processed hagfish exhibited good nutritional value with high contents of protein (10.8 g), fat (5.4 g), carbohydrate (12.1 g), and calorie (140.2 kcal/100 g). The processed product can maintain its quality for 22 days at 10°C. These results indicated that the ready‐to‐eat hagfish can be an alternative for healthy consumption of processed food and for the diversification of processed marine products. Practical applications Conventional foods are increasingly popular as they are ready‐to‐eat and simple to cook. The quality and nutritional value of these foods are important for the production process. Our study revealed that steaming in superheated steam roaster (SS) and hot smoking (HS) treatment combination improved the quality characteristics of hagfish meat, a popular fish in Korea. We optimized the temperature and duration of steaming and smoking for cooking hagfish. The processed hagfish exhibited acceptable sensory properties and marketable physicochemical and microbial properties. Our investigation resulted in a shelf‐life improvement of the new ready‐to‐eat seafood product. The results of this study revealed that treating the hagfish with the combination of SS and HS can preserve its quality for 22 days when stored at 10°C. Hence, this study establishes the procedures for preparing this product, which can be readily marketed.