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result(s) for
"Thorkelsson, Gudjon"
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A Comparison of Fresh and Frozen Lamb Meat—Differences in Technological Meat Quality and Sensory Attributes
by
Thorkelsson, Guðjón
,
Stenberg, Elin
,
Ólafsdóttir, Aðalheiður
in
Animals
,
cooking loss
,
Food Science
2022
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 analysed after chilling and frozen meat was stored frozen for three months and analysed after thawing. The Musculus longissimus thoracis et lumborum was analysed for colour, cooking loss, sensory attributes, Warner-Bratzler shear force (WBSF) and distribution of water and lipid within each meat sample. Meat samples analysed 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 odour, frying flavour, sour flavour, fatty flavour and liver flavour, and by reducing juicy texture and mushy texture.
Journal Article
A Comparison of Two Different Slaughter Systems for Lambs. Effects on Carcass Characteristics, Technological Meat Quality and Sensory Attributes
by
Thorkelsson, Guðjón
,
Stenberg, Elin
,
Ólafsdóttir, Aðalheiður
in
Animal and Dairy Science
,
carcass weight
,
Cold
2021
Two slaughter systems for lambs and their effects on meat quality in terms of texture, colour and sensory attributes were compared. The slaughter systems differed in methods for controlling rigor mortis and carcass chilling. One slaughter system (large-scale) used electrical stimulation and fast chilling of carcasses, while the other system (small-scale) did not use electrical stimulation and applied slower chilling, with carcass temperature decreasing over a longer period after slaughter. Ten pairs of ram lamb twins were selected, and one of each pair was slaughtered at the large-scale abattoir and the other at the small-scale abattoir. Carcass weight, conformation, fatness, pH and temperature were recorded. Musculus longissimus thoracis et lumborum was analysed for colour, cooking loss, Warner–Bratzler shear force and sensory attributes. For meat quality attributes, the only differences were found in meat colour L* (lightness; p = 0.0073), sensory attribute “appearance colour” (p = 0.0089) and “fatty flavour” (p = 0.0554). Meat from the small-scale abattoir was darker in colour and had a more fatty flavour than the meat from the large-scale abattoir. For sensory attributes (apart from colour), no significant differences were found between the two abattoir systems.
Journal Article
Characteristics of freeze-dried fish protein isolated from saithe (Pollachius virens)
by
Thorkelsson, Gudjon
,
Arason, Sigurjon
,
Shaviklo, Gholam Reza
in
Chemistry
,
Chemistry and Materials Science
,
Chemistry/Food Science
2012
Fish proteins isolated from by-products or low commercial/underutilized species using pH-shift process is a new source of proteins that may be used as wet or dried ingredients to develop value-added convenience foods. This paper reports the effects of freeze-drying on characteristics of fish protein isolates (FPI) from saithe (
Pollachius virens
) with or without lyoprotectants. Freeze-dried saithe mince from the same lot and without additives was used as a control. The resulting fish protein powders contained 71-93% protein, 1.5-3% moisture, 0-21% carbohydrate and 0.5-2% fat. Lipid oxidation (assessed by TBARS) of FPI powder groups was higher than that of fish mince powder. The results revealed that oxidation started during the pH-shift process and was increased by freeze-drying. Functional properties and sensory attributes were influenced by the advanced oxidation. However, the mince powder was less oxidized and had higher functional properties such as water binding capacity, gel forming ability, emulsification, foaming properties and colour and lower sensory scores for rancid odour and flavour than the FPI powders. Further studies on how to prevent oxidation of fish flesh during pH-shift and drying processes are recommended.
Journal Article
Quality characteristics and consumer acceptance of a high fish protein puffed corn-fish snack
by
Thorkelsson, Gudjon
,
Olafsdottir, Adalheidur
,
Shaviklo, Gholam Reza
in
Chemistry
,
Chemistry and Materials Science
,
Chemistry/Food Science
2011
Corn snack fortified with 7% fish protein powder made from saithe (
Pollachius Virens
) surimi was selected by expert panel from industry for consumer studies in Iran and Iceland. They hedonically screened products with 3%, 5%, 7% and 9% fish protein powder. Snack containing 9% fish protein powder (FP) had significantly lower liking for odour, texture, flavour, and overall acceptability than the other three prototypes. Snacks fortified with 3%, 5%, and 7% FP had similar sensory attributes. Therefore, snack with the highest level of FP (7%) was selected for acceptance tests. It was seasoned with cheese powder, vegetable oil, salt, and colorant. The amount of protein, moisture, fat, ash and salt in fortified corn snack (FCS) was 12%, 2%, 31%, 3%, and 2% respectively. Consumers’ acceptance was studied using a central location test method. Consumers were 6–16 years old children in two communities (Iceland and Iran). They liked FCS but Iranian children favoured it more than Icelandic children. Majority of parents of the participants expressed their willingness to choose this product when buying snacks.
Journal Article
Influence of lipid content and packaging methods on the quality of dried capelin (Mallotus villosus) during storage
2017
Capelin annual catch exceeds half a million tons in Iceland, with only a small quantity (<20%) of female with roe used for human food. There is a potential to use dried male capelin as a new product for human consumption, but its lipid content varies considerably (4–20% body weight). Earlier studies were more concentrated on the influence of drying conditions than the influence of storage conditions on the quality of dried fish, as dried fish are usually considered to be stable and safe during storage. Three batches of dried male capelin differing in lipid content were packaged and studied during 5 months storage at 22 ± 2 °C to establish appropriate lipid content at harvesting and product packaging method. Lipid composition, lipid hydrolysis and oxidation, sensory attributes and microbial activity were evaluated. Batches differed in composition and stability, with low lipid capelin constituting higher proportion of polyunsaturated fatty acids (22% lipid) than high lipid (18% lipid) capelin. Lipid oxidation was influenced by lipid content and packaging method, as accelerated oxidation occurred in high lipid and open packed capelin. Lipid hydrolysis was less influenced by packaging and was greater in low lipid capelin. High lipid capelin in open bags scored the highest for rancid odor. All batches were micro-biologically stable with colony-forming unit counts increasing less than log 1 (log 5–6) during 5 months storage.
Journal Article
Studies on processing, consumer survey and storage stability of a ready-to-reconstitute fish cutlet mix
by
Shaviklo, G. Reza
,
Thorkelsson, Gudjon
,
Sveinsdottir, Kolbrun
in
Analysis
,
Chemistry
,
Chemistry and Materials Science
2013
A convenience ready-to-reconstitute cutlet mix containing 30% fish protein powder was developed to improve the nutritional quality of the product. Consumer survey was based on the home use test (HUT) method. The acceptance of the fish cutlet mix (FCM) was studied using a 9-point hedonic scale ranging from 1 (extremely dislike) to 9 (extremely like). Product’s characteristics and stability were studied during 6 months of storage at 27 ± 2 °C. The FCM packed in a polyethylene bag and cardboard box was stable during the storage period. There were no changes in colour, moisture gain and water activity, and TBARS values remained low. The FCM was accepted by the consumers in the study (
n = 85
). The average liking was high (7.5 ± 1.3) and it was influenced by frequency of fish and chicken consumption, educational level and household size. People who ate fish once a week liked the product more than other consumers. Also those with higher educational level and bigger household size. The results in this paper are important information for companies planning to develop ready-to-eat products fortified with fish proteins. The products could be means of increasing fish consumption in countries/areas where there is no tradition of consuming fresh or frozen fish.
Journal Article
Influence of smoking and packaging methods on lipid stability and microbial quality of Capelin (Mallotus villosus) and Sardine (Sardinella gibossa)
2015
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.
Effect of smoking and packaging method on capelin differing in lipid content and sardine muscle lipid and microbial stability is examined. Faster lipid hydrolysis occurred in capelin with low lipid whereas oxidation was higher with high lipid capelin. Low lipid capelin is recommended for introduction in smoked sardine markets.
Journal Article
Effects of Added Phosphates on Lipid Stability During Salt Curing and Rehydration of Cod (Gadus morhua)
by
Thorkelsson, Gudjon
,
Thorarinsdottir, Kristin Anna
,
Vu, Boi Ngoc
in
Agriculture
,
Biomaterials
,
Biotechnology
2013
Effects of added phosphates on retardation of lipid oxidation of salted cod during processing, storage and after rehydration were investigated. Lipid hydrolysis progress and development of color, primary and secondary lipid oxidation products and fluorescence intensities were determined. Added phosphates significantly retarded lipid hydrolysis and lipid oxidation progress, resulting in lower free fatty acid , lipid hydroperoxides (PV), thiobarbituric acid-reactive substances (TBARS) as well as fluorescence intensities (δF ₒᵣ and δF ₐq). Significant correlation between the lipid oxidation products (PV, TBARS, δF ₒᵣ and δF ₐq) and yellow/brownish discoloration (b* value) of salted cod was observed. Principal component analysis showed that TBARS, b* value and δF ₒᵣ were the strongest indicators of lipid oxidation during salting and storage.
Journal Article
Influence of smoking and packaging methods on lipid stability and microbial quality of C apelin ( M allotus villosus ) and Sardine ( S ardinella gibossa )
2015
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 7
CFU
/g in cold smoked air packaged. Smoked low lipid capelin was considered an alternative for introduction in smoked sardine markets.
Journal Article