Effect of processing conditions on trace elements in fish roe from six commercial new zealand fish species

The concentrations of trace elements in fish roes and the effect of processing conditions (karasumi-like or karashi mentaiko) were investigated in six commercial fish species from New Zealand. The studied elements were As, Cd, Cr, Cu, Hg, Pb, and Zn, and the roes were from the following species: chinook salmon ( Oncorhynchus tshawytscha), hoki ( Macruronus novaezelandiae), southern blue whiting ( Micromesistius australis), hake ( Merluccius australis), blue warehou ( Seriolella brama), and barracouta ( Thyrsites atun). The concentrations of As, Cd, Cr, Hg, and Pb in the roes were lower than literature values for fish muscles. Only Zn in barracouta roe and Cu in salmon roe and their products were relatively higher than the generally accepted levels in fish muscles and could be of safety concern. Hence, the consumption of barracouta and salmon roes among certain parts of the population needs to be monitored and assessed. Dry salting (karasumi-like) processing increased ( P < 0.001) the concentrations of the studied trace elements while salting fermentation (karashi mentaiko) processing tended to decrease the levels of trace elements. Fermentation may be a useful process to decrease the level of toxic trace elements.     

Optimisation of a dehydration process for potato cubes using an intermediate puffing step

Summary Factors affecting the volume expansion of potato cubes during puffing in a fluidised bed were examined. It was found that puffing temperature, initial size, pre-drying time and puffing time influenced the degree of expansion of the cube during the puffing step. Blanching alone was found not to influence expansion, but in conjunction with the other factors it was found that blanched samples showed greater volume expansion than unblanched samples. The optimum conditions for maximum volume expansion were found to be; blanching for 80 s, cube size between 7.5–12.5 mm, pre-drying time of 90 min. at 90°C and a puffing time of 270s at 130°C.     

Particulate metmyoglobin reducing activity and its relationship with meat color

There is controversy about the effect of storage time on metmyoglobin (MetMb) reducing activity in the sarcoplasmic fraction of meat and the role of this reducing activity in maintaining the color of red meat. The presence of metmyoglobin reducing activity in the myofibrillar fraction of muscle extracts was investigated as a possible reason for this controversy. NADH-dependent MetMb reducing activity was found in the particulate fraction of meat following sedimentation of a meat homogenate at 35 000g. There was 5.8 times more MetMb reducing activity in the particulate fraction compared with that of the sarcoplasmic (supernatant) fraction. The presence of metmyoglobin reducing activity in the myofibrils (MMRA), defined as the activity in the sediment after centrifugation of a meat homogenate at 2 000g, was confirmed. The myofibrillar fraction contained 63% of the total MetMb reducing activity available in the meat. The relationship between muscle MetMb reducing activities and meat color parameters was investigated in a beef patties system. The particulate MetMb reducing activity (PMRA) in beef patties was found to be a good indicator of the total metmyoglobin reducing activity in meat and was positively correlated with the color parameters of the patties, suggesting that PMRA may be associated with red meat color of meat patties.     

Purification and characterization of a rhamnose-binding chinook salmon roe lectin with antiproliferative activity toward tumor cells and nitric oxide-inducing activity toward murine macrophages

In this study, a rhamnose-binding lectin from the roe of chinook salmon (Oncorhynchus tshawytscha) was purified and characterized, and its biological activities were examined in several model systems. Chinook salmon roe lectin had a molecular mass of 30 kDa and agglutinated rabbit and bovine erythrocytes. The hemagglutination activity of the lectin was not affected by metal ions. The lectin was stable up to 70 °C and between pH 4 and pH 11. Chinook salmon roe lectin did not exert antifungal activity toward the fungal species tested and did not exhibit mitogenic response toward mouse splenocytes up to a concentration of 5 mg/mL. The lectin had selective antiproliferative activity toward human breast cancer MCF-7 cells and hepatoma Hep G2 cells. It also induced the production of nitric oxide from mouse peritoneal macrophages. This is the first report that demonstrates these biological activities from chinook salmon roe lectin.     

Rigor temperature and meat quality characteristics of lamb longissimus muscle

The present experiment was conducted to determine the effect of muscle temperature during the prerigor and early postrigor period on meat tenderness, postmortem proteolysis, calpain system activity, water-holding capacity, and color. Lamb longissimus muscle (n = 14) from the right and left carcass sides was excised immediately after dressing, divided into an anterior and posterior sample, vacuum-packaged, and stored overnight at 5 to 35 degrees C. Further storage, up to 14 d postmortem, was at 2 degrees C. Tenderness at 1 d postmortem, tenderization during further storage, and postmortem proteolysis were negatively affected by overnight incubation above 25 degrees C. This effect could be explained by an effect of temperature on muscle contraction and activity of the calpain system. Muscle contraction was at a minimum after incubation at 15 degrees C. Water-holding capacity was negatively affected by incubation above 25 degrees C. Color scores improved with increasing incubation temperature at 1 d postmortem. However, after 14 d of postmortem storage, no differences in color scores were observed. Based on the present results and results of other groups, a temperature around 15 degrees C at the onset of rigor seems optimal to maximize tenderness without having detrimental effects on water-holding capacity or color.     

Effect of preslaughter feed withdrawal period on longissimus tenderness and the expression of calpains in the ovine

The objective was to study the role of calpains in meat tenderness. Lambs were fasted for various periods of time to generate differences in meat tenderness and to determine in tandem the expression of calpain 1, calpain 2, calpain 3, and calpastatin. The assumption has been that increased calpain expression associated with an increase in tenderness indicates a role for calpain in the tenderization process and vice versa. Fasting lambs for 1 day caused a significant improvement in longissimus (LD) tenderness compared to the control. Correlations between the tenderness of the LD and the expression of the calpains and calpastatin were significant for calpains 1 and 3 but not for calpain 2 or calpastatin. Consequently, this study supports a role for calpains 1 and 3, but not for calpain 2, in the tenderization of the LD from fasted lambs during post-mortem aging.     

Physicochemical Properties and Bioactivity of Extracts from the Roe of New Zealand Hoki and Southern Blue Whiting

ABSTRACT

Various physicochemical properties of New Zealand hoki and southern blue whiting (SBW) roes and the biological activities of their extracts were investigated. Protein, moisture, and ash contents in both roes were similar; however, the lipid content of hoki roe was higher (p < 0.05) than SBW roe (11.0 ± 0.9 and 2.5 ± 0.1, respectively). Both fish roe extracts contained active protease inhibitors toward trypsin and papain. Neither of the roe extracts agglutinated erythrocytes, indicating the absence of lectins. Both fish roe extracts at 5 mg/mL concentration exhibited slight inhibitory effects on the proliferation of breast cancer cells, but neither of the roe extracts exhibited RNase or antifungal activity.     

Effect of calcium chloride, zinc chloride, and water infusion on metmyoglobin reducing activity and fresh lamb color

Calcium chloride (CaCl2), zinc chloride (ZnCl2), or water infusions were used to investigate the biochemical factors that affect fresh lamb color, and to examine the role of metmyoglobin-reducing activity in regulating this important quality attribute. Immediately after exsanguination, lamb carcasses (n = 6 per treatment) were infused (10% of BW) with 0.3 M CaCl2, 0.05 M ZnCl2, or water via a catheter inserted into the left carotid artery. The right LM was excised at 24-h postmortem and divided into two halves. The caudal portion was cut into 2.5-cm-thick chops and displayed for 6 d under 1,076 lx of white fluorescent lighting at 2 degrees C, whereas the cranial half was vacuum-packaged and stored at 2 degrees C for 3 wk before retail display. Objective color measurements and samples for biochemical analysis were taken at 0, 1, 3, and 6 d of display. In infused carcasses, pH decline was more rapid (P < 0.05) than in untreated controls, and it was greatest for CaCl2-infused carcasses. Calcium chloride-infused carcasses had lower (P < 0.01) NAD and higher (P < 0.001) NADPH concentrations than water- and ZnCl2-infused or untreated control carcasses. The negative effects of calcium infusion on fresh lamb color, higher (P < 0.01) metmyoglobin accumulation rate, and lower (P < 0.01) L*, a*, and b* color measurements could be explained by the lower amounts of unbound water (P < 0.01), shorter sarcomere length (P < 0.01), lower NAD concentrations (P < 0.01), and higher lipid peroxidation (P < 0.01). Zinc and water-infusions produced less (P < 0.01) lipid oxidation and improved the color and color stability of fresh lamb (P < 0.001). Rate of lipid oxidation in LM chops was greater (P < 0.01) after 3 wk of vacuum-packaged storage than 24-h postmortem. Metmyoglobin-reducing activities (sarcoplasmic and myofibrillar) were decreased in response to infusion treatments (P < 0.001), and ZnCl2 infusion resulted in the lowest metmyoglobin-reducing activities (P < 0.001). A significant association between the myofibrillar metmyoglobin-reducing activity and lipid peroxidation was observed, but metmyoglobin-reducing activities were not associated with any improvement in lamb color. Strategies to increase the antioxidant levels in lamb are very important to improve lamb quality, especially during vacuum-packaging storage.