Yuting Ding

Determination of the effects of different washing processes on aroma characteristics in silver carp mince by MMSE-GC-MS, e-nose and sensory evaluation.

The present study investigated the volatile compounds of silver carp mince and the effects of washing processes on the integral aroma characteristics and aroma-active compounds (AACs) of the mince. 57 volatile compounds were identified by monolithic material sorptive extraction (MMSE) and GC-MS analysis, and 13 volatile compounds with odor activity values greater than 1 (OAVs > 1) were further selected as AACs contributing primarily to the integral aroma profile of silver carp. Washing methods affected the overall aroma profiles of fish samples by washing away or facilitating the release of AACs but to different extents. Compared with water washing, washing with saline and weak alkaline solution removed more AACs. Washing with water three times (T2) exhibited a relatively stronger removal effect on most AACs compared to washing with water twice (T1). Washing with a high concentration of saline (T4) produced a strong removal effect on AACs. The results of sensory evaluation and electronic nose (e-nose) detection for distinguishing the aroma characteristics of different samples demonstrated good agreement with those obtained by OAV analysis.

Combined Effect of Ozonized Water Pretreatment and Ozonized Flake Ice on Maintaining Quality of Japanese Sea Bass (Lateolabrax japonicus)

The effect of the combined application of ozonized water pretreatment and ozonized flake ice (O+OIce) as compared with traditional flake ice (CK), ozonized flake ice (OIce), and ozonized water pretreatment and traditional flake ice (O) was investigated for the storage of Japanese sea bass. Microbiological, chemical, and sensory analysis and moisture content were carried out throughout a storage period of 18 days. A slower increase of total viable mesophilic count (TVC), total volatile base nitrogen (TVB-N), and thiobarbituric acid reactive substances (TBARS) was observed for O+OIce as compared with OIce, O, and CK. Treatment of O+OIce also allowed a better control of pH as compared with OIce, O, and CK. None of the treatments resulted in a significant difference in myofibrillar protein extractability and moisture content. The shelf life of Japanese sea bass treated with CK, OIce, O, and O+OIce, determined by sensory evaluation, was 9, 15, 12, and more than 18 days, respectively. Principal component analysis results showed that the treatments significantly affected the fish quality during storage, and the sensory attributes had a significant correlation with TVB-N, TVC, and TBARS. In conclusion, the combined application of ozonized water and ozonized flake ice had the best effect on fish quality maintenance.

Effect of slaughter methods on the quality of Chilean jack mackerel (Trachurus murphyi) during refrigerated storage.

The main objective of this study was to assess the influence of slaughter methods on the quality of Chilean jack mackerel (Trachurus murphyi) during refrigerated storage on board. Fishes were slaughtered by asphyxia in air (AA), asphyxia in ice water (AI) or stunning fish heads (SH), and the rigor mortis, pH, total volatile basic nitrogen (TVB-N), trimethylamine (TMA), 2-thiobarbituric acid reactive substances (TBARS) and sensory properties for the fishes were analyzed. On day 0, Chilean jack mackerel samples of AI group displayed higher pH values than those of AA and SH groups. TVB-N, TMA and TBARS values of all samples increased with the storage time, and these values of AI had a lower increase than AA and SH. Moreover, samples of AI had a better sensory score than AA and SH during storage. It can be concluded that slaughter method of asphyxia in ice water for Chilean jack mackerel exhibit the better efficiency on maintaining the fish quality during refrigerated storage on board.

Inhibitory Effects of Spices on Biogenic Amine Accumulation during Fish Sauce Fermentation

The presence of high levels of biogenic amines is detrimental to the quality and safety of fish sauce. This study investigated the effects of ethanol extracts of spices, including garlic, ginger, cinnamon, and star anise extracts, in reducing the accumulation of biogenic amines during fish sauce fermentation. The concentrations of biogenic amines, which include histamine, putrescine, tyramine, and spermidine, all increased during fish sauce fermentation. When compared with the samples without spices, the garlic and star anise extracts significantly reduced these increases. The greatest inhibitory effect was observed for the garlic ethanolic extracts. When compared with controls, the histamine, putrescine, tyramine, and spermidine contents and the overall biogenic amine levels of the garlic extract-treated samples were reduced by 30.49%, 17.65%, 26.03%, 37.20%, and 27.17%, respectively. The garlic, cinnamon, and star anise extracts showed significant inhibitory effects on aerobic bacteria counts. Furthermore, the garlic and star anise extracts showed antimicrobial activity against amine producers. These findings may be helpful for enhancing the safety of fish sauce.

Comparative study of basic characteristics of ordinary and dark muscle in skipjack tuna (Katsuwonus pelamis)

Differences between ordinary and dark muscle of skipjack tuna (Katsuwonus pelamis) including proximate composition, flavor, color, texture, and freshness were investigated. Ordinary muscle had a higher crude protein content, but a lower crude lipid content than dark muscle. Alcohols (30.41%) and aldehydes (25.56%) were the prominent flavor compounds present in ordinary muscle, whereas hydrocarbons (39.51%) and ketones (21.81%) were more abundant in dark muscle. Different L*, a*, and b* values were also observed. Texture profile analysis (TPA) showed that dark muscle had higher values for adhesiveness, and lower values for cohensiveness, chewiness, and resilience. After mechanical breaking, large myofibril fragments were observed in ordinary muscle under phase contrast microscopy, but not in dark muscle. Freshness indices, including K values, total volatile basic nitrogen (TVB-N), and thiobarbituric acid (TBA) values of dark muscle were higher than for ordinary muscle.

Decrease of Lipid Oxidation for Dried Shrimp (Acetes chinensis) Preservation Using Alkaline Lipase Hydrolysis Technology

ABSTRACT In this study, the degreasing technology using alkaline lipase hydrolysis for Chinese dried shrimp (Acetes chinensis) was investigated, with the purpose of decreasing lipid oxidation during dried shrimp preservation. The salt, moisture, and lipid contents of the shrimp were 6.01, 32.51, and 2.95%, respectively. The optimum enzymatic hydrolysis condition for effective decrease of shrimp lipid was obtained: lipase concentration 40 U/mL, pH 10, soaking time 60 min, soaking temperature 30°C, and shrimp/liquid ratio 1:20 (w:v). Under this optimum condition, the residual lipid of the shrimp was reduced to 2.28%, and the degreasing rate reached 49%. During 30-day preservation, the thiobarbituric acid-reactive substances (TBARS) value (0.185 mg/kg of dried shrimp and 0.131 mg/kg of degreased dried shrimp at Day 30) of degreased shrimp was lower than the shrimp without degreasing, indicating alkaline lipase hydrolysis could effectively prevent lipid oxidation and inhibit oxidative rancidity during dried shrimp preservation.