Huixing Shen

Effects of different freezing treatments on the biogenic amine and quality changes of bighead carp (Aristichthys nobilis) heads during ice storage

The effects of different freezing treatments on the quality changes of bighead carp heads were evaluated in terms of pH value, TBARS, TVB-N, K-value, biogenic amine, total aerobic counts (TACs), drip loss, cooking loss and electrical conductivity (EC) during ice storage. Fish heads were stored at -40°C (T1), -40°C for 12h and then -18°C (T2), -18°C (T3) for 3months prior to ice storage. No significant differences were observed among T1, T2 and T3 for drip loss, cooking loss and EC (p>0.05). T2 showed lower TACs, pH value, TBARS and TVB-N than T3 did. Significant lower value of spermine and spermidine were observed in T1, T2 and T3 than those of control group (fresh) from 9th to 18th day (p<0.05). Drip loss was significantly correlated with TBARS, pH value, TVB-N, and TACs in groups T1, T2 and T3 (p<0.05).

Biochemical, sensory and microbiological attributes of bream (Megalobrama amblycephala) during partial freezing and chilled storage

BACKGROUND Bream is one of the main farmed freshwater fish species in China. This study aimed to examine the nucleotide degradation of bream during partial freezing and chilled storage and to assess the possible usefulness of nucleotide ratios (K, Ki, H, P, Fr and G values) as freshness indices in comparison with sensory assessment and total viable counts. RESULTS Total viable counts were 5.74 and 4.66 log(colony-forming units g(-1)) on the day of sensory rejection under chilled storage and partial freezing storage respectively. The inosine 5-monophosphate decrease and inosine increase were faster in chilled storage than in partial freezing storage. Hypoxanthine levels increased continuously with time under both storage regimes. Among the nucleotide ratios, the K, Ki, P, G and Fr values were superior to the H value and provided useful freshness indicators for both storage conditions. CONCLUSION Bream in chilled storage were sensorially acceptable only up to 10 days, compared with 33 days for bream in partial freezing storage. Partial freezing delayed the nucleotide degradation of bream.

Changes in biogenic amines of silver carp (Hypophthalmichthys molitrix) fillets stored at different temperatures and their relation to total volatile base nitrogen, microbiological and sensory score.

BACKGROUND Biogenic amines have received considerable attention owing to their undesirable effects in humans. There are few studies of changes in biogenic amine contents related to freshwater fish. Silver carp is an important freshwater fish species in China. This study aimed to investigate the changes in biogenic amines and their relation to total volatile base nitrogen (TVB-N), microbiological and sensory score of silver carp fillets stored at 0, 3 and 15 °C. RESULTS The total biogenic amine contents of all silver carp fillets (regardless of storage time and temperature) ranged from 13.05 to 318.10 mg kg(-1). Putrescine and histamine were the main biogenic amines in silver carp fillets during storage. Cadaverine was only detected after 12 days at 3 °C and after 2 days at 15 °C. Spermidine and spermine contents increased during the early storage period and then slightly decreased. CONCLUSION Low temperature could control the quality of silver carp fillets by inhibiting the contents of biogenic amines. Putrescine showed significant correlation with TVB-N, total aerobic content, sensory score, tryptamine and phenylethylamine. Putrescine was a good quality marker of silver carp fillets in the cold chain.

Antioxidant activities and functional properties of grass carp (Ctenopharyngodon idellus) protein hydrolysates

BACKGROUND Grass carp, with an annual production exceeding 4 × 10(6) t in China in 2009, has not been developed into a high-value product. In this study the antioxidant activities and functional properties of grass carp protein hydrolysates prepared with Alcalase 2.4L (HA) and papain (HP) were investigated. The hydrolysate with strongest radical-scavenging activity and reducing power was assessed further for changes in its antioxidant activity during simulated gastrointestinal digestion. RESULTS As the degree of hydrolysis (DH) increased, the metal-chelating activity of both HA and HP increased while their reducing power and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH(•) )-scavenging activity decreased (P < 0.05). At the same DH, HP possessed higher DPPH(•) -scavenging activity and reducing power than HA (P < 0.05). The metal-chelating activity of HP with 10% DH was significantly increased after in vitro gastrointestinal metabolism (P < 0.05). Regarding their functional properties, all hydrolysates were more than 81% soluble over a wide range of pH (3-8). At the same DH, HP showed higher emulsion activity index but lower solubility and foaming capacity than HA. CONCLUSION Grass carp protein hydrolysates showed high solubility over a wide pH range and could be used as natural antioxidants in food systems.

Formation of biogenic amines in crucian carp (Carassius auratus) during storage in ice and at 4°C.

The formation of eight biogenic amines (BAs), total volatile base nitrogen (TVB-N), aerobic plate counts (APC), and sensory evaluation in crucian carp (Carassius auratus) during storage in ice and at 4°C were investigated. The sum of contents of all eight biogenic amines (SBA) in crucian carp increased from 49.82 to 197.09 mg/kg on day 36 when stored in ice and from 49.82 to 219.35 mg/kg on day 24 when stored at 4°C. TVB-N content increased with storage time; good relationships between TVB-N content and SBA were observed during storage in ice and at 4°C (R(2) = 0.95 and 0.93, respectively). APC of all samples significantly (P < 0.05) increased with storage time in the first 12 days and toward the end of the storage period, there were only minor changes; good relationships between APC and SBA were observed during storage in ice and at 4°C (R(2) = 0.96 and 0.58, respectively). According to sensory evaluation results, the crucian carp became unacceptable on days 24 and 16 during storage in ice and at 4°C, respectively. Putrescine and tyramine contents could be good quality evaluation indices for crucian carp during storage.

Effects of Chitosan Coatings Enriched with Different Antioxidants on Preservation of Grass Carp (Ctenopharyngodon idellus) During Cold Storage

To investigate the effects of chitosan composite coatings for maintaining the quality of grass carp portions, indictors of microbiology (total bacteria count, TBC), chemistry (pH; total volatile basic nitrogen, TVB-N; 2-thiobarbituric acid, TBA; K-value), and sensory characteristics were analyzed periodically. The results showed that chitosan (1.5%, w/v) + acetic acid (1.0%, v/v) + tea polyphenol (TP, 0.5%, w/v) coating significantly (p ≤ 0.05) reduced growth of microorganisms as reflected in TBC, lipid oxidation as displayed in TBA, chemical spoilage as reflected in pH, TVB-N, K-value, and sensory characteristic scores compared to the control samples. The effect of chitosan (1.5%, w/v) + acetic acid (1.0%, v/v) + vitamin C (VC, 0.5%, w/v) coating was better than chitosan (1.5%, w/v) + acetic acid (1.0%, v/v) coating. Chitosan together with acetic acid and TP can be used as a type of preservative coating for grass carp portions under chilled storage.

Effects of different concentrations of salt and sugar on biogenic amines and quality changes of carp (Cyprinus carpio) during chilled storage

BACKGROUND Biogenic amines have gained a great deal of attention due to their toxic potential in humans. Carp is one of the most important freshwater fish species in China. Salt and sugar are capable of preserving food. There is a limited amount of information on the changes of biogenic amines in freshwater fish influenced by salt and sugar. This study aimed to detect the changes in biogenic amines, sensory attributes, total volatile basic nitrogen (TVB-N) and total viable counts (TVC) of carp influenced by different concentrations of salt and sugar stored at 4 °C. RESULTS TVB-N and TVC increased with storage time, which was in accordance with the changes of sensory scores. The eight biogenic amines were detected in fresh carp. Putrescine and cadaverine were the main biogenic amines found in carp fillets stored at 4 °C; they had a significant (P < 0.05) correlation with TVB-N. CONCLUSION Salt processing was found to inhibit the increase of TVB-N, TVC, putrescine and cadaverine in carp. High salt concentration had a positive effect on extending the shelf-life of the carp, compared to low salt concentration.

Postmortem Changes of Crucian Carp (Carassius auratus) During Storage in Ice

Postmortem catabolism of Adenosine Triphosphate and Adenosine Triphosphate-related compounds, K value, pH, and texture of crucian carp were investigated during storage in ice. ATP and Adenosine Diphosphate degraded to Inosinic acid within 48 hours postmortem. There was a good relationship between pH value and IMP concentration (r = −0.753), IMP reached a top point at 3.33 ± 0.17 μmols/g in 4 hours postmortem; meanwhile, Hypoxanthine reached a bottom point at 0.038 ± 0.0052 μmol/g. K value increased linearly (r = 0.96) from an initial value of 0.54 to 1.66% in 48 hours postmortem. Texture analyses results suggested that rigor mortis lasted about 1 hour postmortem, after resolution of rigor, hardness, gumminess, and chewiness decreased in accordance with storage time (r = −0.88,−0.78, and −0.78, respectively). Those results indicated that it was better to effectively utilize the crucian carp in 2–4 hours postmortem. The K value might not be a good indicator to monitoring the loss of freshness of crucian carp during storage in ice since the K value was much lower than marine fish.

Functional Properties of Water-soluble Proteins from Silver Carp (Hypophthalmichthys molitrix) Conjugated with Five Different Kinds of Sugar

Water-soluble proteins (WSP) from silver carp denature easily during thermal processing, leading to the reduction of functional properties. In order to improve the functional properties of WSP and to utilize its resources efficiently, five different kinds of sugars (i.e., xylose, glucose, galactose, oligo-isomaltose, and dextran-10) were used to conjugate with WSP by Maillard reaction. Results suggested that the use of the Maillard reaction improved the solubility, heat stability, and emulsifying properties of WSP. With the increase of molecular weight (MW) of the sugars, the solubility, emulsifying properties, and total sulfhydryl (SH) groups of WSP increased, while the surface hydrophobicity decreased. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of the five Maillard reaction products (MRPs) showed that xylose reacted easily with WSP than did the other four kinds of sugar. Dextran-10 conjugated to WSP could efficiently improve the functional properties of WSP during heat processing.

Changes in Biogenic Amines and ATP-Related Compounds and Their Relation to Other Quality Changes in Common Carp (Cyprinus carpio var. Jian) Stored at 20 and 0°C.

Biogenic amines, ATP-related compounds, sensory attributes, total volatile basic nitrogen, microbial flora (total viable bacteria, Pseudomonas, Aeromonas, and H2S-producing bacteria), and free amino acids were determined in common carp (Cyprinus carpio var. Jian) stored at 20 and 0°C. Pseudomonas and H2S-producing bacteria became the dominant bacteria in carp stored at 20 and 0°C, whereas Aeromonas rapidly increased only in carp stored at 0°C. Inosine monophosphate, which is responsible for flavor and freshness, increased to a maximum of 2.37 l mol/g after 12 h at 20°C and to 4.72 l mol/g after 3 days at 0°C. Putrescine and cadaverine were the dominant amines in carp and their concentrations were significantly correlated (P < 0.05) with total volatile basic nitrogen and sensory scores in all samples during the storage. Significant correlations also were observed between histamine and total volatile basic nitrogen and sensory scores only in samples stored at 20°C. Arginine decreased while putrescine increased in all samples. A significant decrease (P < 0.05) in histidine was observed after 24 h of storage, which coincided with an increase in histamine after 36 h in samples stored at 20°C. Hypoxanthine concentrations were significantly correlated with the microbial species (P < 0.01) and sensory scores (P < 0.05) and seems to be a reliable marker for quality of carp fillets stored at 20 and 0°C.