Xichang Wang

Antioxidative activities of a mycosporine-like amino acid, porphyra-334

Antioxidative activities of porphyra-334, a mycosporine-like amino acid extracted from laver were evaluated. Oxidation of linoleic acid induced by an alkyl-radical 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH) was successfully suppressed by porphyra-334 (0–200 μM). The simultaneous application of 0.02 μM α-tocopherol and 50 μM porphyra-334 effectively suppressed the AAPH induced oxidation level to approximately 40% of a single application of porphyra-334 after 10 min reaction. Porphyra-334 (0–200 μM) efficiently suppressed the lipid peroxidation induced by singlet oxygen although the antioxidative effect observed was relatively moderate at the initial stage of oxidation. These results suggested that porphyra-334 may function as an antioxidant which influences the storage stability of laver.

An Online Survey Study of Consumer Preferences on Aquatic Products in China: Current Seafood Consumption Patterns and Trends

The domestic demand for aquatic products in China has increased greatly, from consumption of 4.5 kg per person in 1970 to 31 kg per person in 2009. Little attention has been paid to Chinese consumer preferences on aquatic products. This study seeks to address this question through an online survey targeting university students to investigate the family and personal consumption preferences on aquatic products. This online survey involved 1038 students who are studying in 10 universities located in coastal and inland cities on mainland China. The results showed that 49.9% of respondents’ families bought fish once a week. Fish markets (47.2%) and supermarkets (21.8%) were the main sources of purchase due to good freshness (48.6%) and shopping convenience (45.8%). Morethan half of all respondents (55.8%) preferred fish over meat. Among them, 60.4% of respondents like freshwater fish with a good awareness of freshness and taste. Regarding the selection of cooking methods, respondents showed a clear favor for braising, steaming and stewing over frying and grilling. About two thirds of respondents had no experience on eating raw fish. However, many of them showed interest in raw fish such as salmon and tuna. This study provided preliminary information of Chinese consumption patterns on aquatic products for understanding current and future consumption trends of China’s aquatic market, and may be used as a reference for aquatic product processing industry.

Odor profiles of hepatopancreas and gonad of Eriocheir sinensis by sensory analysis, electronic nose, and GC–MS analysis

The odor profiles of the hepatopancreas and gonad of Eriocheir sinensis were evaluated by sensory analysis, electronic nose, and gas chromatography-mass spectrometry (GC–MS) analysis. The results of sensory analysis and E-nose showed good correlation, which indicated that the hepatopancreas and gonad of female crabs both contributed to the overall aroma of “XieHuang”, while only the hepatopancreas of male crabs played an important part in the overall aroma of “XieGao”. For further GC–MS analysis, a total of 53 volatile compounds were identified and quantified. The quantity of volatile compounds in each category of hepatopancreas were similar to that of the mixture samples (XieHuang/XieGao). However, the differences between gonad and the mixture samples were mainly focused in aldehydes, ketones, furans, S-containing compounds, and N-containing compounds, which mainly include 2-methylbutanal, 2-methyl-2-butenal, acetone, 4-isopropylpyridine, and 2-isobutyl-4-methylpyridine in female crabs, and 2-methylpropanal, 2-methylbutanal, (E,E)-2,4-heptadienal, acetone, 1-octen-3-one, 2-butanone, dimethyl sulfide, and 4-isopropylpyridine in male crabs.

Characterization of Myosin Subfragment-1 of Summer and Winter Silver Carp (Hypophthalmichthys molitrix) Muscle

UNLABELLED Myosin subfragment-1 (S1) was prepared from myofibrils of summer and winter silver carp by chymotryptic digestion in the presence of ethylenediaminetetraacetic acid (EDTA). Two S1 heavy chain isoforms with different molecular sizes of 91 kDa and 95 kDa were detected in the fast skeletal muscle from summer and winter silver carp, respectively. ATPase inactivation assay indicated that winter S1 was about 20-fold unstable comparing to summer S1. Matrix-assisted laser desorption/ionization time-of-flight/mass spectrometry (MALDI-TOF MS) further confirmed that summer and winter myosin S1 heavy chain isoforms were homologous to myosin high-temperature type and myosin low-temperature type S1 heavy chain, respectively. Moreover, both types of myosin S1 heavy chain isoforms were identified at the intermediate stage. The results indicated that myosin was expressed in a season-specific manner; different types of myosin isomer expressed in different seasons, showing different thermostabilities. PRACTICAL APPLICATION Silver carp, Hypophthalmichthys molitrix, is one of the most abundant freshwater fish species in China. The structure thermal stability of myosin rod from silver carp was affected by season change. The gel-forming abilities of surimi prepared in different seasons were different. This study investigated the seasonal differences in structure thermal stability of myosin S1 which is vital for gel formation of myosin. The results of this study will aid understanding of the relationship between the structure and function of myosin, and effective production of surimi from freshwater fish species in different seasons.

Acceptability and its improvement of kamaboko gel derived from silver carp surimi

Sensory evaluations were conducted on kamaboko gels prepared from silver carp (SC) surimi. Different kamaboko gel specimens, produced with or without the extract from walleye pollack (WP) muscle (Ewp) or trimethylamine N-oxide (TMAO), were tested using a panel of university students for their odor, flavor, texture, whiteness, and overall acceptability. According to the sensory evaluation results done in Kyoto, there were significant differences (p < 0.005) between SC kamaboko gel and WP kamaboko gel for all sensory evaluation indices. When compared with WP kamaboko gel, kamaboko gel derived from SC surimi was unacceptable to the Japanese students especially because of its odor. A slight increase in their sensory scorings of kamaboko gels occurred when Ewp was added into SC surimi, especially when scoring the odor of SC kamaboko gels. In addition, the acceptability of kamaboko gel with the addition of TMAO has a higher scoring in its odor as compared with the control (no addition of TMAO), which is presumed as a result of a little of trimethylamine derived from TMAO additive.