Minh Van Nguyen

Influence of smoking and packaging methods on lipid stability and microbial quality of Capelin (Mallotus villosus) and Sardine (Sardinella gibossa).

Lipid and microbial quality of smoked capelin (two groups differing in lipid content) and sardine was studied, with the aim of introducing capelin in the smoked sardine markets. Lipid hydrolysis (phospholipid and free fatty acids) and oxidation index (hydroperoxides and thiobarbituric acid-reactive substances), fatty acid composition, and total viable count were measured in raw and packaged smoked fish during chilled storage (day 2, 10, 16, 22, 28). Lipid hydrolysis was more pronounced in low lipid capelin, whereas accelerated lipid oxidation occurred in high lipid capelin. Muscle lipid was less stable in sardine than capelin. Essential polyunsaturated fatty acids (eicosapentaenoic acid and docosahexaenoic acid) constituted 12% of fatty acids in capelin and 19% in sardine. Vacuum packaging as well as hot smoking retarded bacterial growth, recording counts of ≤log 5 CFU/g compared to ≥log 7CFU/g in cold smoked air packaged. Smoked low lipid capelin was considered an alternative for introduction in smoked sardine markets.

Effects of Different Temperatures on Storage Quality of Heavily Salted Cod (Gadus morhua)

The aim of this study was to compare the effects of different storage temperatures (+2°C, -4°C, -12°C, -18°C and -24°C) and time (0, 1, 3 and 6 weeks) on the quality of heavily salted cod. The color, water content, water holding capacity (WHC), cooking yield, total volatile basic nitrogen (TVB-N) and trimethylamine (TMA) of the samples were determined. Results showed that the whiteness of the salted cod decreased slightly, whereas the yellow/orange color increased during the storage period. The WHC and cooking yield increased and were inversely related to water content. The TVB-N value increased slightly, whilst a lightly decrease in TMA value was observed. Storage at -4°C and lower temperatures had a detrimental influence on the color of the product which is the main quality criterion for salted cod. Therefore, it is not suitable to store the product at -4°C or lower temperatures.

Lipid Degradation of Cod Liver During Frozen Storage as Influenced by Temperature, Packaging Method, and Seasonal Variation

ABSTRACT Lipid degradation of cod liver during frozen storage was studied, where the effects of storage temperatures (−18/−24°C), packaging methods (vacuum packing/regular plastic bag and waxed cardboard box), and seasonal variations (March/June/September) were evaluated. For this, the formations of free fatty acids (FFA) and peroxide value (PV) were analyzed. Lipid degradation within different parts of the liver (middle/surface) was also investigated. Increase in FFA and PV was observed for most of the samples throughout the frozen storage period. Vacuum packaging and lower storage temperature had a significantly stronger preservative effect on lipid degradation in all seasons. Higher FFA content was observed in cod liver captured in June than in its counterparts from September and March. More intense increase in PV was observed for liver collected in June compared to September. Furthermore, significant difference in PV was observed in different layers of the liver while FFA showed minimum variation between the surface and the middle part of the cod liver. Based on the present results, packaging method and storage temperature have a significant effect on lipid hydrolysis and oxidation in frozen cod liver.

Near infrared spectroscopy for seafood process optimisation and monitoring–A shrimp case study

12 Introduction F ish and seafood are complex materials and the quality of seafood is influenced from both ante-mortem and post-mortem factors. Raw material characteristics are crucial factors with regard to final product quality. These characteristics not only vary with species but also with season, place of catch, the catching technique and general handling during processing. As a general rule, quality that is lost in a value chain cannot be regained and good handling and processing procedures through the whole value chain from catch to consumer are therefore essential to ensure good quality in a finished product. Quality preservation, therefore, calls for increased monitoring of the most essential quality parameters. Standard laboratory methods for the determination of physicochemical properties of seafood are not only complex, time-consuming and expensive, but are also generally destructive of the sample and may require the use of dangerous or corrosive solvents to isolate the compound of interest. Rapid, non-destructive measuring methods would therefore be an advantage for in-line, on-line or at-line monitoring to assess the quality of seafood during processing. Near infrared (NIR) spectroscopy is an optimal method for quality monitoring of several physicochemical properties of fish and seafood, since NIR absorption is dependent on the physical, chemical, structural and biological properties of a molecule and its environment. NIR spectroscopy has, in combination with multivariate chemometrics, proven to be an excellent tool for the quantitative determination of all four major food constituents of seafood—water, protein, fat and carbohydrate—and has also shown high correlations with important sensory attributes, fish freshness and ice fraction of glaze in superchilled salmon, to mention just a few applications. The properties of water are here of special importance, since it is the most abundant component in muscle food and its content and properties influence the quality of seafood with regard to texture, sensory attributes and shelf-life. The production of cold water shrimp (Pandalus borealis) is complex and therefore represents a challenging process in which to assess the application of NIR spectroscopy as a quality monitoring method. This process includes steps in which muscle structure is affected by both chemical, physical and mechanical treatment, involving salt and phosphate addition during pre-brining, cooking, mechanical peeling, brining, freezing and glazing. This article therefore deals with the application of NIR spectroscopy for monitoring processing of cold water shrimp, with a focus on its water properties and retention.