Ya Wei

The effects of different extraction methods on composition and storage stability of sturgeon oil.

The objective of this study was to assess the effect of different extraction methods on oil yield, colour attributes, oxidative stability, fatty acids composition and production of volatile compounds in sturgeon oil during storage. The supercritical fluid extraction (SFE) method with carbon dioxide resulted in higher oil yields, better colour attributes, and higher oxidative stability compared to other traditional extraction methods such as enzymatic extraction, amino, and wet reduction. After storage at 4 °C for 33 days, the aldehyde content in oil extracted by the enzymatic extraction and wet reduction methods was twice as high as that obtained by the other methods. There was a significant reduction in the content of total acids in oils extracted by the enzymatic extraction and wet reduction methods (p<0.05), whereas amine compounds were mainly detected in oil extracted by the amino method. The oil extracted by SFE exhibited higher UFA and lower SFA. Significant diffidence among PUFA with C above 20 was observed in oil extracted with SFE.

Effect of Ultrastructure on Changes of Textural Characteristics between Crisp Grass Carp (Ctenopharyngodon Idellus C.Et V) and Grass Carp (Ctenopharyngodon Idellus) Inducing Heating Treatment

The research studies the ultrastructure effect on texture of crisp grass carp (CGC) and grass carp (GC) fillets inducing heating for 15, 25, and 40 min with boiling water. After heating, the hardness, fracturability, springiness, chewiness, resilience, and cohesiveness of CGC were higher than that of raw CGC, whereas the all textural characteristics of heating GC were lower obviously than that of raw GC. The hardness, fracturability, springiness, chewiness, resilience, and cohesiveness of CGC for heating 15 min were higher by 6.3%, 9.0%, 27.0%, 71.8%, 9.4%, and 23.9%, respectively, than that of raw CGC (RCGC). The hardness increasing of CGC flesh with the extension of heating time related closely to more coagulating connective tissue in interstitial spaces, especially relating to smaller muscle fiber diameter and denser muscle fiber density. The more and larger spaces between fiber and fiber with the extension of heating time results in the decrease of cohesiveness and resilience of CGC flesh. For chewiness, the stronger chewiness of cooked CGC associated with more detachment of myofiber-myocommata and fiber-fiber. Overall, the results show that the changes of texture characteristics of CGC fillet with extension of heating time correlates positively with the ultrastructure.

Extraction of Fish Oil from the Muscle of Sturgeon Using Supercritical Fluids

This study evaluated the extraction of oil from sturgeon (Acipenser baeri) muscle using supercritical fluids. Response surface methodology (RSM) was used to identify and quantify the variables, namely extraction pressure, extraction time and CO2 flow rate on the yield of oil. Statistical analysis indicated that for all three variables, the quadratic terms and interactions between the variables had significant effects on yield (p < 0.05). Polynomial regression model predictions were in good agreement with the experimental results, with a coefficient of determination of 0.9936 for yield. Maximum yield from sturgeon muscle was 26.83% with a pressure of 315.8 bar, extraction time of 10.8 min and CO2 flow rate of 3.5 l/min, which closely matched the predicted value (26.70%). The characteristics of the fish oil extracted with the supercritical fluids were superior to those of oil obtained by other methods.

Effects of Inoculating Compound Lactic Acid Bacteria on the Quality of Cured Fish

Inoculation with compound lactobacillus in the low-salt pickled fish, fermented and dried to produce cured fish. The paper studied the effects of inoculating compound lactobacillus on the pH, total volatile basic nitrogen (TVB-N), amino acid nitrogen content (AA-N) and total acid content of salted fish quality. The results showed that, compared with the non-vaccinated groups (CK), The cured fish inoculated lactobacillus had a lower pH and TVB-N content, higher the amino acid nitrogen content and total acid content. Inoculated compound lactic acid bacteria into salted fish, to a certain extent, could improve the nutritional value and edible value, which had positive effects on the fish quality.

Comparison of the Effect of Sterilization Pretreatment Using Four Different Bacteriostatic Agents on the Quality of Penaeus vannamei

Four different bacteriostatic agents H2O2, NaClO, ClO2, and ozone water (O3) were used to the sterilization pretreatment of fresh muscle of penaeus vannamei. The bactericidal effect of these bacteriostatic agents were evaluated by aerobic bacterial count method, sensory evaluation and chromatic aberration analysis. The results showed that the optimum pretreatment concentrations of sterilization pretreatment by H2O2, NaClO, ClO2 and ozone water (O3) were 3.0 g/kg, 50 mg/kg, 150 mg/kg and 1.0 mg/kg respectively. The optimum pretreatment time of sterilization pretreatment by H2O2, NaClO, ClO2 and ozone water (O3) were 60 s, 300 s, 300 s and 300 s respectively. Furthermore, the bactericidal coefficients of sterilization pretreatment by H2O2, NaClO, ClO2 and ozone water (O3) were 91.6%, 95.1%, 92.3% and 99.6% respectively. The effects of color and flavor of fresh muscle treated by these four bacteriostatic agents were compared. The results showed that the color and flavor of fresh muscle was less effected by ozone water (O3) method used for sterilization pretreatment method than other three methods. The total number of bacterial colony of sample treated 600 s by 1.0 mg/kg of ozone water (O3) method was reduced to 3.4 lgCFU/g, and the advantages of this method are significant sterilization effect as well as the low influences of color and sensory quality.

Study on Synthesis and Characterization of a Fluorescence Probe and its Application for Determination of Superoxide Anion Radical

A novel Schiff base, 2-(Salicylideneamino)pyridine (2-SAP) synthesized by 2-aminopyridine and salicylaldehyde was used as a fluorescence probe to determine superoxide anion radical (O2•-) in this study. The synthetic product was characterized by IR, 1H-NMR and GC-MS methods. A fluorescence quenching reaction occurs between 2-SAP and O2•-, and the fluorescence intensity decreased significantly. The effect of pyrogallol concentration (2.0×10-5 M to1.0×10-3 M) was discussed in this study. In the range from 2.0×10-5 M to 1.0×10-4 M, relative fluorescence intensity (y) and pyrogallol concentration (x) shown a good linear relationship, y=37.801x+76.854, r=0.993. Based on this phenomenon, the O2•- generated by pyrogallol autoxidation could be determined simply with high sensitivity.

Effect of Bacterial Community and Free Amino Acids on the Content of Biogenic Amines During Fermentation of Yu-lu, a Chinese Fermented Fish Sauce

ABSTRACT The main objective of this work was to investigate the effects of bacterial community and free amino acids on the content of biogenic amines in Yu-lu during fermentation. Four major biogenic amines (histamine, tyramine, cadaverine, and putrescine) were identified, and the content of tyramine was positively correlated with histamine (R value = 0.9113). Aspartic acid, glutamic acid, histidine, leucine, and lysine were the dominant free amino acids. 16S rRNA sequencing showed that the composition of the bacterial community changed significantly during fermentation of Yu-lu. Principal component analysis revealed the crucial links between microbial community and biogenic amines. For example, Halanaerobium was probably associated with the formation of putrescine, while Halomonas might be associated with the degradation of biogenic amines at the end of fermentation of Yu-lu. This study provided a detailed evaluation of the Yu-lu fermentation process, enabling development of better strategies for biogenic amine control in fish sauce.

Analysis and Evaluation of Nutrient Composition of the Factory Farming Jade Perch

Jade perch (Scortum barcoo) meat nutrition analysis and evaluation was carried out in this paper, results showed that: the protein content, fat content and total amino acid content of Jade perch are 18.4%, 9.0% and 19.99% respectively. As a balanced amino acid combination, it contains a variety of amino acids necessary for the meat, glutamic acid content of up to 3.10%, delicious amino acids in the total amino acid content 7.64%. Jade perch has a lower fat content, but rich in unsaturated fatty acids, DHA content is 3.36%, rich in Ca, Fe, Zn, Se and other trace elements, in the jade perch, the heavy metals and other toxic substances analysis showed that they are in line with national health and safety standards, the Jade Perch is a good quality, high nutritional value of edible fish.

Determination of the Malachite Green in Sediment by High Performance Liquid Chromatography with Fluorescence Detection

A new method of determination of malachite green (MG) in sediment has been developed by high performance liquid chromatography with fluorescence detection (HPLC-FLD). It is based on use of a deoxidation reaction which converts malachite green (MG) into LMG in the process of extraction. The sediment samples were extracted with a solution of formic acid and acetonitrile. Clean up and isolation was performed on MCX solid phase extraction (SPE) column. Chromatographic separation was achieved by using C18 column with an isocratic mobile phase consisting of acetonitrile and ammonium acetate buffer (0.05 M, pH 4.5) (80:20, v/v). High performance liquid chromatography with fluorescence detector (λex=265 nm and λem=360 nm) was used for the determination of LMG. The recovery values of MG in sediment samples fortified with MG were determined by measuring the amount of MG in the samples, after carrying out deoxidation reaction with potassium borohydride, which converts the MG into LMG. Under the optimized conditions, the average recoveries of MG from sediment at three levels (1.0, 10 and 50 μg/kg) were 85.0% (range from 80.8 to 87.6%). Relative standard deviations (RSD) of recoveries at all fortification levels were less than for 9.57% for MG. The method detection limit obtained for MG was 0.5 μg/kg.

Preliminary Fractionation and Derivatives Changes of Myoglobin from Tilapia (O. niloticus♀×O. aureus♂) Dark Muscle with Ammonium Sulfate

Ammonium sulfate fractionation was implicated as one of essential steps to purified Myoglobin (Mb).We adopted SDS-PAGE analysis and absorption spectra scanning to demonstrate the effect of ammonium sulfate on Mb and its derivatives. The results shown that protein with the molecular weight above 37.8kDa were dominated in myoglobin extract of tilapia, which can be precipitated with ammonium sulfate. Mb molecular weight of tilapia is about 15.8 kDa, which can be collected by the treatment of ammonium sulfate with saturation between 60%-70% to remove unwanted protein. The absorption spectra show that Mb derivatives could be transferred to met-myoglobin after preliminary fractionating with ammonium sulfate.