Production of seafood flavour formulations from enzymatic hydrolysates of fish by-products

© 2015 Published by Elsevier Ltd. Amino acid-rich extracts derived from fish by-products were utilised to generate flavour model systems with added glucose and/or fish oil. Combination of endo and exo peptidases resulted in the most marked increased in free amino acids, particularly for leucine, lysine and glutamic acid (48.3 ± 3.4 to 1423.4 ± 59.6, 43.3 ± 1.2 to 1485.4 ± 25.6 and 143.6 ± 21.7 to 980.9 ± 63.6 μg/g respectively).Main volatile products formed after heating the systems were 4-heptenal, 2,4-heptadienal, and some pyrazines. Increased concentrations of 1-octen-3-ol or 1-hepten-4-ol were also observed in the heated systems compared to the controls. All of these volatile compounds have been identified among the volatile profile of cooked seafood. Conversion of low value fish derived materials such as fish powder, into more valuable products such as flavour precursors and subsequently flavour compounds might be a commercially viable proposition for the fish industry

Effects of water availability on free amino acids, sugars, and acrylamide-forming potential in potato

Irrigation is used frequently in potato cultivation to maximize yield, but water availability may also affect the composition of the crop, with implications for processing properties and food safety. Five varieties of potatoes, including drought-tolerant and -sensitive types, which had been grown with and without irrigation, were analyzed to show the effect of water supply on concentrations of free asparagine, other free amino acids, and sugars and on the acrylamide-forming potential of the tubers. Two varieties were also analyzed under more severe drought stress in a glasshouse. Water availability had profound effects on tuber free amino acid and sugar concentrations, and it was concluded that potato farmers should irrigate only if necessary to maintain the health and yield of the crop, because irrigation may increase the acrylamide-forming potential of potatoes. Even mild drought stress caused significant changes in composition, but these differed from those caused by more extreme drought stress. Free proline concentration, for example, increased in the field-grown potatoes of one variety from 7.02 mmol/kg with irrigation to 104.58 mmol/kg without irrigation, whereas free asparagine concentration was not affected significantly in the field but almost doubled from 132.03 to 242.26 mmol/kg in response to more severe drought stress in the glasshouse. Furthermore, the different genotypes were affected in dissimilar fashion by the same treatment, indicating that there is no single, unifying potato tuber drought stress response

Acrylamide-forming potential of potatoes grown at different locations, and the ratio of free asparagine to reducing sugars at which free asparagine becomes a limiting factor for acrylamide formation

Acrylamide is produced from free asparagine and reducing sugars during high-temperature cooking and food processing, and potato products are major contributors to dietary acrylamide intake. The present study analysed twenty varieties of potatoes grown at two sites (Doncaster and Woburn) in the United Kingdom to assess the effect of location of cultivation on acrylamide-forming potential. Analysis of variance revealed a full site by variety nested within type (French fry, boiling and crisping) by storage interaction for acrylamide (p < 0.003, F-test), reducing sugars and total sugars (p < 0.001, F-test). There was much greater free asparagine in potatoes grown at the Doncaster site compared with the Woburn site. Modelling of the relationship between the ratio of free asparagine to reducing sugars and the levels of acrylamide identified a value of 2.257 ± 0.149 as the tipping point in the ratio below which free asparagine concentration could affect acrylamide formation

Chemical composition, antioxidant activity and sensory evaluation of five different species of brown edible seaweeds

© 2014. The chemical and volatile composition as well as sensory profile of five brown edible seaweeds collected in the United Kingdom, was evaluated. The ash content was 190-280. mg/g, NaCl 35.1-115.1. mg/g, protein 2.9-6.0. g/g, and fat 0.6-5.8. g/g (dry basis). Fucus vesiculosus, Fucus spiralis and Ascophyllum nodosum showed higher antioxidant activities (DPPH and FRAP). Nucleotide concentrations were of the same order of magnitude as reported in other foods such as tomatoes or potatoes, except for F. vesiculosus where levels of nucleotides were 10 times higher. The fatty acids profile was dominated by oleic acid (21.9-41.45%), followed by myristic (6.63-26.75%) and palmitic (9.23-16.91%). Glutamic and aspartic acids (0.15-1.8. mg/g and 0.05-3.1. mg/g) were the most abundant amino acids. Finally, sensory and volatile analyses illustrated that Laminaria sp. had the strongest seaweed and seafood-like aroma and taste

Sugars and related compounds as flavour precursors in meat

Sugars and related substances, namely sugar phosphates and ribonucleotides, are important meat flavour precursors. In particular, ribose and ribose 5-phosphate have been shown to be important in aroma development in heated model systems. There are few quantitative data on the concentrations and the variations of sugars and related substances in meat. This paper will report on the analysis of glucose, fructose, ribose, ribose 5-phosphate, fructose 6-phosphate, glucose 6-phosphate and inosine 5'-monophosphate (IMP) in aged beef. Sugars and related compounds were extracted from lean meat and derivatised to the corresponding TMS ethers. Analysis and quantitation of the sugars and sugar phosphates were performed using GC and GC/MS, while IMP analysis was performed using capillary electrophoresis (CE)

The effect of cooking on acrylamide and its precursors in potato, wheat and rye

The relationship between acrylamide and its precursors, namely free asparagine and reducing sugars, was studied in simple cakes made from potato flake, wholemeal wheat and wholemeal rye, cooked at 180 degrees C, from 5 to 60 min. Between 5 and 20 min, large losses of asparagine, water and total reducing sugars were accompanied by large increases in acrylamide, which maximized in all three products between 25 and 30 min, followed by a slow linear reduction. Acrylamide formation did not occur to any extent until the moisture contents of the cakes fell below 5%. A comparison of each type of cake with a commercial product, made from the same food material, showed that acrylamide levels in all three commercial products were well below the maximum levels in the cooked cakes

Measurement of acrylamide and its precursors in potato, wheat, and rye model systems

The relationship between acrylamide and its precursors, namely, free asparagine and reducing sugars, was studied in cakes made from potato flake, wholemeal wheat, and wholemeal rye, cooked at 180 degreesC, from 5 to 60 min. Between 5 and 20 min, major losses of asparagine, water, and total reducing sugars were accompanied by large increases in acrylamide, which maximized in all three products between 25 and 30 min, followed by a slow linear reduction. Acrylamide formation did not occur to a large degree until the moisture contents of the cakes fell below 5%. Linear relationships were observed for acrylamide formation with the residual levels of asparagine and reducing sugars for all three food materials

Water-soluble precursors of beef flavour I: effect of diet and breed

The effects of diet and breed on the concentration of water-soluble flavour precursors, namely sugars, free amino acids, ribonucleotides, creatinine, carnosine and creatine, were studied in beef longissimus hanborum muscle. Diet had a significant effect on the concentration of free amino acids, with animals fed on grass silage having higher free amino acid levels than animals fed on a concentrate diet, whereas animals fed concentrates had a higher total reducing sugar content. Differences between a beef breed (Aberdeen Angus x Holstein-Friesian) and a dairy breed (Holstein-Friesian) were generally small. (C) 2007 Elsevier Ltd. All rights reserved