利用外源蛋白酶和曲霉菌YL001加速沙丁鱼鱼露的发酵

该研究旨在利用外源蛋白酶和曲霉菌YL001缩短沙丁鱼鱼露的发酵周期.将沙丁鱼鱼肉分为2组,一组仅用外源蛋白酶发酵(鱼露A),另一组用外源蛋白酶和曲霉菌YL001复合发酵(鱼露B).2组样品先在35℃下发酵30 d,然后在室温下继续发酵150 d.结果表明,发酵180 d后,鱼露A、B中氨基酸态氮含量分别为7.6和10....     

Effect of functional edible films and high pressure processing on microbial and oxidative spoilage in cold-smoked sardine (Sardina pilchardus)

The present experiment was an attempt to improve the shelf-life of cold-smoked sardine (Sardina pilchardus) using, singly or in combination, high pressure (300 MPa/20 °C/15 min) and gelatin-based functional edible films enriched by adding an extract of oregano (Origanum vulgare) or rosemary (Rosmarinus officinalis) or by adding chitosan. The uncoated muscle itself exhibited a certain level of antioxidant power (as measured by the FRAP method) ensuing from the deposition of phenols during smoking. Coating the muscle with the films enriched with the oregano or rosemary extracts increased the phenol content and the antioxidant power of the muscle, particularly when used in association with high pressure, due to migration of antioxidant substances from the film. The edible films with the added plant extracts lowered lipid oxidation levels (as measured by the peroxide and TBARS indices) and also, to a lesser extent, reduced microbial growth (total counts), whereas the gelatin–chitosan-based edible films lowered microbial counts (total counts, sulphide-reducing bacteria). Neither luminescent bacteria nor Enterobacteriaceae were detected in any of the batches. The combination of high pressure and edible films yielded the best results in terms of both preventing oxidation and inhibiting microbial growth.     

Extraction and fractionation of lipolytic enzyme from viscera of Monterey sardine (Sardinops sagax caerulea)

In this study, lipolytic activity of a semi-purified lipolytic enzyme (SLE) from the viscera of sardine ( Sardinops sagax caerulea ) was screened on the lipolysis of olive, Menhaden and sardine oil. A lipolytic enzyme was partially purified from the crude extract of sardine viscera by fractional precipitation followed by ultrafiltration (30 kDa). The main tissues found in sardine viscera were pyloric caeca (19.0% w/w), digestive tract (13.0% w/w), liver (4.8% w/w) and pancreas (1.5% w/w). Results show that pancreas had the highest lipolytic activity. There were no significant differences in lipolytic activity between pyloric caeca, intestine and liver ( P  < 0.05). Specific activity of the SLE increased 47.0-fold after extraction and fractionation, with a yield of 0.34% calculated for the whole viscera weight. Lipolytic activity of SLE from sardine viscera increased threefold when sardine oil was used as substrate. The results of this study confirm the potential importance of lipases from marine sources.     

Quality assessment of whole and gutted sardines (Sardina pilchardus) stored in ice

The quality and shelf life of whole ungutted and gutted sardines ( Sardina pilchardus ) stored in ice were studied. The changes in the fish were investigated by sensory assessments, chemical analyses and microbiological analyses. The sensory scores of uneviscerated and gutted sardines stored in ice at +4 °C were 7 days. The chemical indicators of spoilage, total volatile basic nitrogen and trimethylamine values of gutted sardine increased very slowly, whereas for whole ungutted samples higher values were obtained reaching a final value of 15.03–29.23 mg per 100 g and 2.36–4.16 mg per 100 g, respectively (day 9). Peroxide and thiobarbituric acid values remained lower for whole ungutted sardine samples until day 9 of storage, whereas for gutted fish were higher. The level of histamine exceeded the legal limit in whole ungutted sardine after 7 days of storage in ice, during which sardines were rejected by the sensory panel. Mesophilic aerobic bacteria count, H₂S-producing bacteria, sulphide reducing anaerobe Clostridias, Enterobacteriaceae count of whole ungutted sardine samples are higher than gutted sardine samples during the storage. Psychrotrophic bacteria counts of the two groups were not different. The limits of microbiological data were not exceeded throughout the storage in both the groups' samples.     

Stereospecific analysis of triacyl-sn-glycerols in Docosahexaenoic acid-rich fish oils

This paper presents the positional distribution of fatty acids in docosahexaenoic acid (22∶6n-3)-rich fish oil triacyl-sn-glycerols (TG). Stereospecific analysis of TG was carried out by a nonenzymatic method. The TG of bonito head oil, obtained after a winterization process, contained 22∶6n-3 at concentrations of 28,7, and 49 mole % in thesn-1,sn-2, andsn-3 positions, respectively. In the TG of oil before the winterization process, 22∶6n-3 was concentrated in thesn-3 position, followed evenly by thesn-1 andsn-2 positions. Tuna orbital oil, obtained after winterization, showed the preferential association of 22∶6n-3 to thesn-3 position, followed by thesn-1 position. This distribution pattern was similar to that observed for seal oil TG rather than sardine oil TG. The bonito head and tuna orbital oils are useful as fish oils with characteristics different from those of common fish oils, such as menhaden, sardine, and herring oils.     

Purification of a lipase from the hepatopancreas of oil sardine (Sardinella longiceps linnaeus) and its characteristics and properties

Lipase has been purified from the hepatopancreas of oil sardine (Sardinella longiceps) by defatting, water extraction, ammonium sulphate fractionation and chromatography on DEAE Sephadex and Sephadex G-100. The preparation was homogeneous on polyacrylamide disc gel electrophoresis and on gel filtration through Sephacryl S-200. The enzyme showed a molecular weight of 54000±57000 with 6.1% of carbohydrate. The pH and temperature optima of purified sardine lipase were 8 and 37°C respectively. Sardine lipase remained stable up to 45°C (15 min) and in the pH range 5 to 9.5. The K_m values obtained for the substrates tributyrin and triacetin were 4 × 10^?2 and 30 × 10^?2, respectively. The effect of halogens and various metal ions on sardine lipase activity, substrate specificity, amino acid and carbohydrate composition are also reported.     

Lipid composition and palatability of canned sardines. Influence of the canning process and storage in olive oil for five years

Lipid variations of canned sardines in olive oil, both quantitative and in fatty acid composition, have been studied during various stages of the canning process: raw sardines (RS), precooked sardines (PS), just canned sardines (CS) and sardines stored for 6 months (6MS), 12 months (12MS) and 5 years (5YS). The effect of maturation on the palatability of sardines has also been observed by means of triangle tests using a panel of 60 tasters. Our results show a significant loss of SFA in fish during the canning process (C16: 0, 273±6 g kg⁻¹ of fat in RS and 169±11 g kg⁻¹ of fat in CS) and a rise in MUFA (C18:1 207±2 g kg⁻¹ of fat in RS and 506±14 g kg⁻¹ of fat in CS); PUFA showed almost no variation. The maturation and canning processes both yielded similar qualitative modifications. The palatability of the sardines was significantly higher after 6 months of maturation than immediately after canning, and this quality was maintained, for at least 5 years of storage. © 1998 SCI.