Improvement of gel properties of mackerel mince by phlorotannin extracts from sporophyll of Undaria pinnatifidai and UVA induced cross-linking

The effects of phlorotannin extracts (PTE) (from sporophyll of Undaria pinnatifida) added at different concentration (0, 1.6, 8, and 40 mg/g protein) with and without ultraviolet A (UVA) irradiation treatment on gel properties of mackerel (Scomberomorus niphonius) mince (MM) were investigated. The results indicated that both the breaking force and water-holding capacity (WHC) of the MM gel increased with addition of PTE, and the highest breaking force and WHC were observed with 40 mg/g PTE under UVA irradiation. Low-field nuclear magnetic resonance revealed that free water significantly decreased in this PTE-MM gel as well. UVA irradiation treatment led to reduction of total sulfhydryls and free amines in the PTE-MM gel, indicating more cross-linking between proteins. Electrophoresis results indicated that myosin heavy chains were aggregated in the UVA-treated PTE-MM gel. The microstructure of the UVA-treated PTE-MM gel showed that protein formed more evenly distributed cross-linked structures and was more compact than the untreated control gel. As a conclusion, PTE addition with UVA irradiation is shown to improve gelling properties of mackerel mince.     

The effects of rosemary extract combination with vacuum packing on the quality changes of Atlantic mackerel fish burgers

The effects of the use of antioxidant technology on the quality of mackerel burgers stored at 4 °C were investigated in terms of sensory, biochemical [thiobarbituric acid (TBA), total volatile basic nitrogen (TVB‐N), peroxide value (PV) and free fatty acids (FFA)] and microbiological analyses [total viable count (TVC)]. Fish meat was divided into three groups; the control (C) without rosemary extract, the second group with 0.4% rosemary extracts (Group A) and the third with 0.8% rosemary extracts (Group B). Results showed that the TVB‐N level did not exceed acceptability limit (30–35 mg 100 g^?1) for all groups. TBA value for the control significantly increased from 1.47 to 4.80 MA kg^?1 whereas it slightly increased in treatment groups as the storage time increased. Significantly higher PV and FFA (P < 0.05) were obtained from the control group. Rosemary extract, in combination with vacuum pack was effective in controlling the growth of bacteria and biochemical indices.     

Pediococcus pentosaceus L and S Utilization in Fermentation and Storage of Mackerel Sausage

ABSTRACT During 72 h fermentation at 37 °C, rapid increase in lactic acid bacteria count (LAB), dramatic decline in pH and suppression in the growth of contaminating Pseudomonas, Staphylococcus, and Enterobacteriaceae of mackerel minces with Pediococcus pentosaceus strains L and S were observed (p < 0.05). When the mackerel mince was processed into Chinese style sausage with 4% sucrose, no significant changes in pH, growth of LAB, Aerobic Plate Count, and Pseudomonas of the fermented mackerel sausage with Pediococcus pentosaceus strains L and S were obtained (p > 0.05) during 3 wk storage at 4 °C, however, the growth of Enterobacteriaceae and Staphylococcus were effectively suppressed. The residual nitrite in sample decreased during processing and fermentation, and was minimally detected after 72 h fermentation. Suppression of VBN and psychrophilic microflora, and lowering residual nitrite suggest the potential of using these 2 strains in the fermented fish products.     

Effect of Combining Proteolysis and Lactic Acid Bacterial Fermentation on the Characteristics of Minced Mackerel

ABSTRACT: To improve the quality of fish muscle, mackerel muscle protein was hydrolyzed by proteases from Aspergillus oryzae , and then fermented by lactic acid bacteria (LAB). The highest protease activities were obtained from A. oryzae after 72 h incubation at 25°C. Acidic protease activity was much higher than neutral and alkaline proteases. SDS-PAGE indicated the degradation of muscle proteins after 1 or 2 h hydrolysis by A. oryzae proteases at 50°C. During 48 h fermentation by Pediococcus pentosaceus L and S at 37°C, rapid growth of LAB, decline in pH, and suppression in the growth of microflora, Enterobacteriaceae, Staphylococcus , and Pseudomonas , occurred while increases in whiteness, nonprotein nitrogen, sensory quality, and free amino acids were observed. These data suggested that the acceptability of LAB -fermented mackerel hydrolysates could be substantially improved.     

Comparison of Gelation Mechanism of Surimi between Heat and Pressure Treatment by Using Rheological and NMR Relaxation Measurements

ABSTRACT: The stress-relaxation and nuclear magnetic resonance (NMR) proton spin-spin relaxation time (¹H T₂) measurements were performed to elucidate the gelation mechanism of heated and pressurized surimi gels. Numerical inverse Laplace transformation of the stress-relaxation data showedlarge distributions of stress-relaxation times and the Kohlrauch-Williams-Watts (KWW) equation described well the stress-relaxation process for each gel. NMR measurement gave information about the content of the exposed protein surface. From these results it is considered that the heat treatment induces the denaturation and re-aggregation of protein, which contribute to the formation of strong network structure. On the other hand, the pressure treatment contributes to the formation of weak cross-links made by the aggregation of protein in native form.     

A novel compound, 7,10-dihydroxy-8(E)-octadecenoic acid from oleic acid by bioconversion

Sixty-two cultures from the Agricultural Research Service (ARS) Culture Collection and 10 cultures isolated from soil and water samples in Illinois were screened for their ability to convert agricultural oils to value-added industrial chemicals. A new compound, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD), was produced from oleic acid at a yield of greater than 60% by bacterial strain PR3 which was isolated from a water sample in Morton, IL. To our knowledge, DOD has not been previously reported. The optimum time, pH and temperature for the production of DOD were 2 days, 7.0, and 30°C, respectively. The production of DOD is unique in that it involves hydroxylation at two positions and rearrangement of the double bond of the substrate molecule.     

鲭鱼在中餐的运用探讨

本文阐述了鲭鱼的种类、营养、功用,同时探讨了利用传统中式烹调技法结合西餐菜肴风格,烹制出具有外形美观、色泽丰富、香味浓郁、营养时尚等特点的鲭鱼特色菜肴。     

Production of eicosapentaenoic acid by a bacterium isolated from mackerel intestines

Optimization of culture conditions for the growth rate, 5,8,11,14,17-cis-Eicosapentaenoic acid (EPA) content and EPA productivity of a bacterium isolated from Pacific mackerel intestines was investigated by use of a culture medium containing 1.00 wt% peptone and 0.50 wt% yeast extract in an artificial sea water (ASW). Cultivation temperature affected the growth rate and cellular EPA content of the bacterium. The cellular EPA content at 8°C was as great as 16.8 mg/g of dry cells, which was more than two times greater than that at 25°C (7.3 mg/g of dry cells), although the growth rate showed a maximum at 25°C. Both the yield of bacterial cells and the cellular EPA content at 25°C reached maximum values when the pH of the culture medium was nearly 7.0 and when the concentration of ASW was 100% (v/v). Under optimum culture conditions [25°C pH 7.0 and 100% (v/v) ASW], the amount of EPA accumulated in the cellular lipids reached 45.6 mg/L of culture broth after 8 hr.