Kigen Takahashi

Properties of gelatin film from horse mackerel (Trachurus japonicus) scale.

Optimal conditions for extracting gelatin and preparing gelatin film from horse mackerel scale, such as extraction temperature and time, as well as the protein concentration of film-forming solutions were investigated. Yields of extracted gelatin at 70 °C, 80 °C, and 90 °C for 15 min to 3 h were 1.08% to 3.45%, depending on the extraction conditions. Among the various extraction times and temperatures, the film from gelatin extracted at 70 °C for 1 h showed the highest tensile strength and elongation at break. Horse mackerel scale gelatin film showed the greatly low water vapor permeability (WVP) compared with mammalian or fish gelatin films, maybe due to its containing a slightly higher level of hydrophobic amino acids (total 653 residues per 1000 residues) than that of mammalian, cold-water fish and warm-water fish gelatins. Gelatin films from different preparation conditions showed excellent UV barrier properties at wavelength of 200 nm, although the films were transparent at visible wavelength. As a consequence, it can be suggested that gelatin film from horse mackerel scale extracted at 70 °C for 1 h can be applied to food packaging material due to its lowest WVP value and excellent UV barrier properties.

The influence of proteases on the browning of dried squid products processed by air-drying

To clarify why mantle meat from Japanese common squid (Todarodes pacificus) dried products discolor dramatically when processed by air-drying, the role of endogenous protease(s) on browning during the processing of dried squid products was studied. The involvement of endogenous protease(s) in the generation of Free Amino Acids (FAAs) participating in the Maillard reaction was characterized. The browning and myosin heavy chain degradation during air-drying were obviously mitigated by the addition of metalloprotease inhibitors, especially EGTA and 1,10-phenanthroline, followed by serine proteinase inhibitor, especially PMSF. The amount of total FAAs in dried products increased by only 0.17% with the addition of 1,10-phenanthroline and 5.0% with added EGTA. In autolysis models, protein autolysis was almost completely inhibited by 1,10-phenanthroline. The addition of, 1,10-phenanthroline inhibited the increase in total FAAs including arginine (Arg), followed by EGTA and PMSF. The results indicated that endogenous metalloproteases and serine proteases might influence the generation of FAAs including Arg, and contribute to product discoloration during air-drying.

Influence of Various Phenolic Compounds on Properties of Gelatin Film Prepared from Horse Mackerel Trachurus japonicus Scales: Properties of fish gelatin film…

Influence of various phenolic compounds on physical properties and antioxidant activity of gelatin film from horse mackerel Trachurus japonicus scales was investigated. Tensile strength (TS) of the film was enhanced whereas elongation at break was declined by adding 1% to 5% phenolic compounds. Rutin was the most effective to improve the TS compared to the other tested phenolic compounds including ferulic acid, caffeic acid, gallic acid, and catechin. Gelatin films with the phenolic compounds showed the excellent UV barrier properties. FTIR spectra exhibited that wavenumber of amide-A band of films decreased with formation of hydrogen bonding between amino groups of gelatin and hydroxyl groups of the phenolic compounds. Gelatin film incorporated with rutin which has the largest number of hydroxyl groups among the tested compounds demonstrated the lowest wavenumber for the amide-A peak. It is indicated that hydroxyl groups contained in the phenolic compounds contribute to formation of hydrogen bonds involved in improvement of the mechanical properties of the films. The incorporation of the phenolic compounds with gelatin films also led to the increasing of total phenolic contents and DPPH radical scavenging activities. Thus, it is concluded that phenolic compounds can promote the quality of gelatin film. PRACTICAL APPLICATION Properties of gelatin film derived from horse mackerel scales can be improved by adding of phenolic compounds. Phenolic compounds containing a large number of hydroxyl groups should be selected to enhance physical properties of the gelatin film. A biodegradable film prepared from horse mackerel gelatin incorporated with phenolic compounds, which has good physical properties and antioxidant properties, can solve environmental problems caused by synthetic plastic materials.

The effect of organic salts on the browning of dried squid products processed by air-drying

To control discoloration of dried Japanese common squid (Todarodes pacificus) product, influence of 0-1% organic salts, including sodium gluconate (Na-gluconate), sodium citrate (Na-citrate), sodium phytate (Na-phytate), sodium benzoate (Na-benzoate) and sodium tartrate (Na-tartrate), on Maillard browning in the squid meat during air-drying was investigated. Changes in surface color of the dried squid were mitigated by the addition of organic salts. Organic salts also showed inhibitory effects on autolysis and generation of free amino acids (FAAs), especially arginine, in both the dried squid meat and the model solution. Moreover, Maillard reaction degree of the dried squid was decreased by using organic salts. The addition of 1% Na-citrate or 1% Na-phytate well suppressed the browning of the dried squid (p < 0.05). The results indicated that organic salts having strong chelating ability, including Na-citrate and Na-phytate, can prevent the browning of the dried squid product by inhibiting the generation of FAAs.