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Identification of Volatile Compounds in Codfish(Gadus) by a Combination of Two Extraction Methods Coupled with GC-MS Analysis

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Journal of Ocean University of China 2016年第3期15卷 509-514页

作者： CHANG Yufei HOU Hu li bafang College of Food Science and Engineering Ocean University of China

Codfish is a kind of abyssal fish species with a great value in food industry. However, the flavor of codfish, especially the unpleasant odor, has caused serious problems in its processing. To accurately identify the volatile compounds in codfish, a combination of solid phase micro-extraction(SPME) method and simultaneous distillation extraction(SDE) method was used to extract the volatiles. Gas chromatography-mass spectrometry(GC-MS) along with Kovats indices(KI) and authentic standard compounds were used to identify the volatiles. The results showed that a total of 86 volatile compounds were identified in codfish, of them 24 were extracted by SDE, 69 compounds by SPME, and 10 compounds by both SDE and SPME. Seventy volatile compounds were found to have specific odors, of them 7 typical compounds contributed significantly to the flavor of codfish. Alcohols(i.e.,(E)-2-penten-1-ol and 2-octanol), esters(i.e., ethyl butyrate and methyl geranate), aldehydes(i.e., 2-dodecenal and pentadecanal) contributed the most to fresh flavor while nitrogen compounds, sulphur compounds, furans, as well as some ketones(i.e., 2-hydroxy-3-pentanone) brought unpleasant odor, such as fishy and earthy odor. It was indicated that the combination of multiple extraction methods and GC-MS analysis can enhance the accuracy of identification, and provide a reference for the further study on flavor of aquatic products.

关键词： codfish volatile flavor compound SDE SPME GC-MS Kovats index

The Effect of Hydrolysis with Neutrase on Molecular Weight,Functional Properties,and Antioxidant Activities of Alaska Pollock Protein Isolate

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Journal of Ocean University of China 2018年第6期17卷 1423-1431页

作者： liU Chuyi MA Xiaoming CHE Shuai WANG Changwei li bafang College of Food Science and Engineering Ocean University of ChinaQingdao 266003China Marine Biomedical Research Institute of Qingdao Qingdao 266073China

In this study, the Alaska pollock protein isolate(APPI) was hydrolyzed by Neutrase for 20, 40, 80, 120, 160, 200, and 240 min. Hydrolysates with different molecular weights were produced and they were named as H1–H7. Furthermore, the effects of hydrolysis on the average molecular weights, functional properties(solubility, oil-holding capacities, foaming activities, and emulsifying properties), and antioxidant activities(1, 1-diphenyl-2-picrylhydrazyl, superoxide, and hydroxyl free radical-scavenging activities) were determined. It was found that when the degree of hydrolysis(DH) increased, the average molecular weights of the hydrolysates decreased significantly. The functional properties of APPI were also significantly improved. The hydrolysates of APPI exhibited better solubility, emulsifying activities, and foaming activities. Hydrolysates with low molecular weights(lity, oil-holding capacities, and emulsifying activities, while hydrolysates with higher molecular weights(>1 kDa) had better foaming activities. In addition, the hydrolysates exhibited excellent antioxidant properties, while the inhibition values of 1, 1-diphenyl-2-picryl hydroxyl(DPPH), superoxide, and hydroxyl free radical-scavenging activities, were 85.22%, 53.56%, and 75.00% respectively, when the concentration of the hydrolysates was 5.0 mg mL^(-1). The lower the average molecular weight was, the higher was the antioxidant activity. These results indicated that hydrolysis with Neutrase is an effective method for improving the functional and antioxidant properties of APPI. The hydrolysates of APPI displayed great potentials to be used as natural antioxidants in protein-rich aqueous foods such as nutrient supplements and sports beverages.

关键词： Alaska Pollock protein isolate(APPI) solubility enzymatic hydrolysis functional properties

Isolation and Characterization of a Fucoidan-Degrading Bacterium from Laminaria japonica

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Journal of Ocean University of China 2014年第1期13卷 153-156页

作者： WANG Ying li bafang ZHAO Xue PIAO Meizi College of Food Science and Engineering Ocean University of China College of Food Science and Engineering Qingdao Agricultural University

Fucoidan, a polysaccharide containing abundant fucose and sulfate ester group, was prepared from Laminaria japonica. In order to obtain fucoidan-degrading enzyme, bacteria capable of degrading fucoidan were screened from kelp. A bacterial strain named RC2-3 was obtained, which degraded fucoidan by the maximum extent of 54% ± 1.3%, the highest among all bacterial isolates. High-performance size exclusion chromatography(HPSEC) showed that the molecular weight of fucoidan was gradually reduced by RC2-3 with culturing time, suggesting the production of fucoidan-degrading enzyme by RC2-3. Phylogenetic analysis of partial 16S ribosomal RNA gene(16S rDNA) sequence showed that RC2-3 belonged to the family Flavobacteriaceae. However, it showed different physiological and biochemical characteristics from the known Flavobacteriaceae members producing fucoidan-degrading enzyme, thus RC2-3 was proposed to be a new member of this family.

关键词： fucoidan degradation Flavobacteriaceae 16S rDNA HPSEC

The Scavenging of Free Radical and Oxygen Species Activities and Hydration Capacity of Collagen Hydrolysates from Walleye Pollock(Theragra chalcogramma) Skin

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Journal of Ocean University of China 2009年第2期8卷 171-176页

作者： ZHUANG Yongliang li bafang ZHAO Xue College of Food Science and Engineering Ocean University of China Qingdao 266003 P. R. China

Fish skin collagen hydrolysates （FSCH） were prepared from walleye pollock （Theragra chalcogramrna） using a mixture of enzymes, namely trypsin and flavourzyme. The degree of hydrolysis of the skin collagen was 27.3%. FSCH was mainly composed of low-molecular-weight peptides and the relative proportion of 〈1000Da fraction was 70.6%. Free radical and oxygen species scavenging activities of FSCH were investigated in four model systems, including diphenylpicrylhy-drazyl radical （DPPH）, superoxide anion radical, hydroxyl radical and hydrogen peroxide model, and compared with that of a native antioxidant, reduced glutathione （GSH）. FSCH was also evaluated by water-absorbing and water-holding capacity. The results showed that FSCH was able to scavenge free radical and oxygen species significantly and to enhance water-absorbing and water-holding capacity remarkably. Therefore FSCH may have potential applications in the medicine and food industries.

关键词： walleye pollock collagen free radical-scavenging activity water-holding capacity

Enzymatic Hydrolysis of Defatted Mackerel Protein with Low Bitter Taste

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Journal of Ocean University of China 2011年第1期10卷 85-92页

作者： HOU Hu li bafang ZHAO Xue College of Food Science and Engineering Ocean University of China Qingdao 266003 P. R. China

Ultrasound-assisted solvent extraction was confirmed as a novel,effective method for separating lipid from mackerel pro-tein,resulting in a degreasing rate (DR) of 95% and a nitrogen recovery (NR) of 88.6%.To obtain protein hydrolysates with high ni-trogen recovery and low bitter taste,enzymatic hydrolysis was performed using eight commercially available *** turned out that the optimum enzyme was the ‘Mixed enzymes for animal proteolysis’.An enzyme dosage of 4%,a temperature of 50℃,and a hydrolysis time of 300 min were found to be the optimum conditions to obtain high NR (84.28%) and degree of hydrolysis (DH,16.18%) by orthogonal *** acid was the most abundant amino acid of MDP (defatted mackerel protein) and MDPH (defatted mackerel protein hydrolysates).Compared with the FAO/WHO reference protein,the essential amino acid chemical scores (CS) were greater than 1.0 (1.0 1.7) in MDPH,which is reflective of high nutritional ***,coupled with the light color and slight fishy odor,indicates that MDPH would potentially have a wide range of applications such as nutritional additives,functional ingredients,and so on.

关键词： mackerel hydrolysis ultrasound defatted bitter amino acid composition

Isolation and Characterization of Collagen from Squid(Ommastrephes bartrami) Skin

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Journal of Ocean University of China 2009年第2期8卷 191-196页

作者： YAN Mingyan li bafang ZHAO Xue College of Food Science and Engineering Ocean University of China Qingdao 266003 P. R. China

Collagen of squid （Ommastrephes bartrami） skin was examined in the present study. Histology showed that collagen fiber in the skin was partially cross-linked with muscle fiber. Acid-solubilized collagen （ASC） and pepsin-solubilized collagen （PSC） were extracted from the skin and characterized. The results of amino acid composition and electrophoretic patterns revealed that ASC and PSC were both type 1 collagen, containing α1 and α2 chains. FTIR （fourier transform infrared spectroscopy） investigations confirmed the existence of helical arrangements in PSC of squid skin. The denaturation temperature （Td） and shrinkage temperature （T5） of PSC were 29.4℃ and 52.8℃, respectively.

关键词： isolation characterization collagen thermal stability squid

Protective Effect of Gelatin and Gelatin Hydrolysate from Salmon Skin on UV Irradiation-Induced Photoaging of Mice Skin

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Journal of Ocean University of China 2016年第4期15卷 711-718页

作者： CHEN Tiejun HOU Hu LU Jiaohan ZHANG Kai li bafang College of Food Science and Engineering Ocean University of China

The objective of this study was to investigate the effect of gelatin(SG) isolated from salmon skin and its hydrolysate(SGH) on photoaging skin, and the mechanism responsible for anti-photoaging. The average molecular weights of SG and SGH were 65 k Da and 873 Da, respectively. The amino acid compositions of SG and SGH were similar. Both of them were abundant in hydrophobic amino acids. Twenty-five peptides were identified from SGH. SG and SGH could improve UV irradiation-induced pathological changes of macroscopical tissue texture and skin morphology. Hydroxyproline content is an indicator of matrix collagen content, SG and SGH could inhibit the decrease of hydroxyproline content in photoaging skin in a dose dependent manner. In addition, SG and SGH could alleviate UV irradiation-induced oxidative damages to skin by increasing the activities of total superoxide dismutase(T-SOD), glutathione peroxidase(GSH-Px) and catalase(CAT), increasing the content of glutathione(GSH) and decreasing the content of malonaldehyde(MDA). Moreover, SG and SGH could enhance immune regulation system by increasing the thymus index. Thus, the anti-photoaging mechanisms of SG and SGH were by inhibiting the depletion of antioxidant defense components, involving in the synthesis of collagen and enhancing the function of immune system. Besides, SGH showed a better result in protecting skin from photoaging than SG.

关键词： glutathione collagen superoxide hydroxyproline inhibiting irradiation thymus peroxidase antioxidant gelatin

Screening of Extraction Methods for Glycoproteins from Jellyfish (Rhopilema esculentum) Oral-Arms by High Performance liquid Chromatography

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Journal of Ocean University of China 2009年第1期8卷 83-88页

作者： REN Guoyan li bafang ZHAO Xue ZHUANG Yongliang YAN Mingyan HOU Hu ZHANG Xiukun CHEN li Food and Bioengineering Department Henan University of Science and Technology Luoyang 471003 P. R. China College of Food Science and Engineering Ocean University of China Qingdao 266003 P. R. China

In order to select an optimum extraction method for the target glycoprotein （TGP） from jellyfish （Rhopilema esculentum） oral-arms, a high performance liquid chromatography （HPLC）-assay for the determination of the TGP was developed Purified target glycoprotein was taken as a standard glycoprotein. The results showed that the calibration curves for peak area plotted against concentration for TGP were linear （r= 0.9984, y=4.5895x＋47.601） over concentrations ranging from 50 to 400mgL^-1. The mean extraction recovery was 97.84% （CV2.60%）. The fractions containing TGP were isolated from jellyfish （R esculentum） oral-arms by four extraction methods： 1） water extraction （WE）, 2） phosphate buffer solution （PBS） extraction （PE）, 3） ultrasound-assisted water extraction （UA-WE）, 4） ultrasound-assisted P/3S extraction （UA-PE）. The lyophilized extract was dissolved in Milli-Q water and analyzed directly on a short TSK-GEL G4000PWXL （7.8 mm×300 ram） column. Our results indicated that the UA-PE method was the optimum extraction method selected by HPLC.

关键词： HPLC glycoprotein jellyfish extraction method

Study on the Free Radical Scavenging Activity of Sea Cucumber (Paracaudina chinens var.) Gelatin Hydrolysate

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Journal of Ocean University of China 2007年第3期6卷 255-258页

作者： ZENG Mingyong XIAO Feng ZHAO Yuanhui liU Zunying li bafang DONG Shiyuan College of Food Science and Engineering Ocean University of China Qingdao 266003 P. R. China

Gelatin from the sea cucumber(Paracaudina chinens var.) was hydrolyzed by bromelain and the hydrolysate was found to have a high free radical scavenging activity. The hydrolysate was fractionated through an ultrafiltration membrane with 5 kDa molecular weight cutoff(MWCO). The portion(less than 5 kDa) was further separated by Sephadex G-25. The active peak was col-lected and assayed for free radical scavenging activity. The scavenging rates for superoxide anion radicals(O2·-) and hydroxyl radi-cals(·OH) of the fraction with the highest activity were 29.02% and 75.41%,respectively. A rabbit liver mitochondrial free radical damage model was adopted to study the free radical scavenging activity of the fraction. The results showed that the sea cucumber gelatin hydrolysate can prevent the damage of rabbit liver and mitochondria.

关键词： Paracaudina chinens var. gelatin hydrolysate free radical scavenging activity mitochondria