This study was undertaken to evaluate the effects of liquid smoked flavorings and wood smoke on the sensory, color, texture, and lipid stability of smoked mackerel fillets for four weeks chilled storage. Fish fillets were smoked by two methods: (1) immersed in brine (1:1) containing 100 g/L NaCl at 0-5 °C for 3 hours, allowed to drain at room temperature (~20 °C) for 2 hours and smoked directly with wood smoke in a smoking chamber at 25 °C for 3 hours; (2) immersed in brine (1:1) containing 5 mL/L commercial liquid smoke flavorings and 60 g/L NaCl for 16 hours at 0-5 °C then dried at 25 °C for 2 hours in an oven. Smoked samples were then vacuum packed and stored chilled at -1 °C for one week, followed by 4±1 °C for three weeks. The quality changes in sensory, color, texture, and lipid stability were observed after 0, 1, 2, 3 and 4 weeks of storage. The results showed that, smoked mackerel using commercial liquid smoked flavorings was higher in rancid flavor, lightness, redness, and yellowness but had less bitter odor and was softer than the wood smoked mackerel. The lipid oxidation was higher after the wood smoke process but was however rather stable during the chilled storage. In contrast, lipid oxidation in the liquid smoked products increased significantly during chilled storage.
Tag: Texture
Contact
Margrét Geirsdóttir
Project Manager
mg@matis.is
The main objective is to effectively denature the autolysis enzymes C. frondosa on the premise of avoiding the quality deterioration caused by overheating. The effects of the different thermal treatments (blanching at 40–80 °C for 45 min, boiling and steaming at 100 °C for 15–120 min) on the cooking yield, moisture content, protein degradation, texture, and enzyme inactivation were studied , and the inner relationship was investigated by multivariate analysis. The autolysis enzymes too C. frondosa were thermally stable and cannot be denatured completely by blanching. Boiling and steaming could efficiently inactivate the enzymes, but overheating for 60–120 min reduced the cooking yield and texture quality. Boiling at 100 °C for 45 min was suitable for pre-treatment, with cooking yield of 70.3% and protein content of 78.5%. Steaming at 100 °C for at least 30 min was preferable for long-term storage and instant food, in which the relative activity was only 3.2% with better palatability.
Contact
Guðjón Þorkelsson
Strategic Scientist
gudjon.thorkelsson@matis.is
Technological meat quality and sensory attributes of fresh and frozen lamb meat were compared. Samples were collected from two abattoirs (one small-scale, one large-scale) that use different slaughter methods in terms of chilling regime and electrical stimulation. The fresh and frozen meat samples included products from both slaughter systems. Ten twin pairs of ram lambs were used in the study, with one of each twin slaughtered at each abattoir. Fresh meat was analyzed after chilling and frozen meat was stored frozen for three months and analyzed after thawing. The Musculus longissimus thoracis et lumborum was analyzed for colour, cooking loss, sensory attributes, Warner-Bratzler shear force (WBSF) and distribution of water and lipid within each meat sample. Meat samples analyzed after frozen storage were darker, less red and more yellow than the fresh meat. Freezing and frozen storage increased fluid loss and WBSF compared with the fresh meat, due to protein denaturation. Frozen storage affected sensory attributes by increasing fatty odor, frying flavor, sour flavor, fatty flavor and liver flavor, and by reducing juicy texture and mushy texture.
Contact
Valur Norðri Gunnlaugsson
Research Group Leader
valur.n.gunnlaugsson@matis.is
Improved quality of herring for human consumption
Herring is one of the most important fish species in the North Atlantic and the Baltic Sea. Although a large part of the catch goes to human consumption, about 85% of herring is processed into fish oil and flour. There is a general desire to increase the consumption of herring for human consumption. It was important to study the different factors that affect the quality of herring and especially how they are controlled by biological conditions. The main reason for the quality problems in herring is the high content of compounds that promote development, and affect the color and texture changes, as well as the loss of nutrients. Better quality results in increased competition for herring production in the Nordic countries, as well as a positive consumer attitude towards herring products. The main goal of the project was to improve the quality and quantity of herring, for consumption, by researching the quality of the raw material after fishing. Emphasis was placed on quality immediately after fishing and the quality of the raw material after varying periods of frost. Factors such as fishing location and fishing time did not affect the quality of the herring. However, freezing at -20 ° C had a significant effect on the quality of the raw material.
Herring is one of the most important fish species in the North Atlantic and Baltic Sea, with an annual catch exceeding 2 million tonnes. Although a large part of these fish is used for human consumption, as much as 85% of the herring is used for industrial production of fish meal and fish oil. There is a general wish to increase the utilization of herring for human consumption. Thus, it was important to study the various parameters which influence the quality of herring, and in particular how these paramenters are controlled by biological factors. A major reason behind quality problems arising during post-harvest handling of herring is its high content of compounds that efficiently catalyzes the development of rancidity, pigmentation, texture changes and loss of nutritional value. Improved quality will result in increased competitiveness of the Nordic fish processing industry and would improve the attitude among consumers towards herring products. The general objective of the project was to improve the quality and quantity of herring to be used for food production by investigating how natural variation in raw material characteristics affects post-harvest quality. Attention was given to the quality immediately after landing and the quality after period of frozen storage. The results indicated no clear differences in the quality of herring regarding catching place or season. The frozen storage for a prolonged time had the major influence on the quality of herring fillets.
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Contact
Valur Norðri Gunnlaugsson
Research Group Leader
valur.n.gunnlaugsson@matis.is
Effect of high pressure processing in reducing Listeria spp. and on the textural and microstructural properties of cold smoked salmon (CSS)
The main objective of the project was to investigate the effect of hypertension (400-900 MPa) on the death of the bacterium Listeria monocytogenes and quality factors (image structure, texture and color) in cold smoked salmon after treatment for 10, 20, 30 and 60 seconds. Effects on the total number of aerobic bacteria, lactic acid bacteria and Bacillus spores were also studied. Two experiments were performed, one in July 2005 and the other in November 2006. The study showed that short-term hypertension treatment was effective in improving the quality and safety of cold-smoked products. Due to changes in the appearance and texture of the products, further research is needed. This new method promises to meet the requirements for longer shelf life of smoked salmon. The study is of great value to the industry, due to the innovation of using high pressure for a short time (seconds) to eliminate the bacterium Listeria in smoked salmon and thus increase the shelf life of this valuable product.
The main object of this research was to study the effects of high pressure processing (400-900 MPa) on the survival of Listeria monocytogenes and the characteristics (microstructure, texture and color) of cold smoked salmon when it was processed for 10, 20, 30 and 60 seconds. The changes in counts of total aerobic bacteria, lactic acid bacteria and Bacillus spores were also studied. Two experiments were carried out, one in July 2005 and the second in November 2006. It is concluded here that the combination of high pressure and short time treatment is very effective to improve the quality and safety of cold smoked products. However, because of the changes in the visual appearance and texture, further studies are necessary. This new development is promising to meet requirements for extended shelf life of ready-to-eat cold smoked salmon with high microbiological quality and safety. This study is of high industrial relevance because it combines the innovative approach of using high pressure processing for short time (seconds) to reduce the number of Listeria in cold smoked salmon and thereby extend the shelf life of this valuable product.