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P.R. Sheard

Bio: P.R. Sheard is an academic researcher from University of Bristol. The author has contributed to research in topics: Polyunsaturated fatty acid & Tenderness. The author has an hindex of 16, co-authored 20 publications receiving 5618 citations.

Papers
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Journal ArticleDOI
TL;DR: Interest in meat fatty acid composition stems mainly from the need to find ways to produce healthier meat, i.e. with a higher ratio of polyunsaturated (PUFA) to saturated fatty acids and a more favourable balance between n-6 and n-3 PUFA.

2,166 citations

Journal ArticleDOI
TL;DR: It is shown that a major factor is the total amount of fat and that phospholipid, where 18:2n-6 is located, declines as a proportion of muscle lipid and the proportion of neutral lipid, with its higher content of saturated and monounsaturated fatty acids, increases.

2,116 citations

Journal ArticleDOI
J. D. Wood1, M. Enser1, AV Fisher1, G.R. Nute1, R. I. Richardson1, P.R. Sheard1 
01 May 1999
TL;DR: Although this increase led to greater oxidative breakdown of lipids during storage and the generation of large quantities of lipid-derived volatile compounds during cooking, there were no deleterious effects on odour or flavour.
Abstract: Meat quality describes the attractiveness of meat to consumers. The present paper focuses on two major aspects of meat quality, tenderness and flavour. Both aspects of quality can be influenced by nutrition, principally through its effects on the amount and type of fat in meat. In several countries, high levels of intramuscular fat (marbling fat), i.e. above 30 g/kg muscle weight in longissimus, are deemed necessary for optimum tenderness, although poor relationships between fat content and tenderness have generally been found in European studies, where fat levels are often very low, e.g. below 10 g/kg in UK pigs. Muscle lipid may be a marker for red oxidative (type 1) muscle fibres which are found at higher concentrations in tender muscles and carcasses. Nutritional treatment can be used to manipulate the fatty acid content of muscle to improve nutritional balance, i.e. increase the polyunsaturated (PUFA): saturated fatty acid value and reduce the n-6:n-3 PUFA value. Increasing PUFA levels may also change flavour because of their greater susceptibility to oxidative breakdown and the generation of abnormal volatile compounds during cooking. This situation particularly applies to the n-3 PUFA which are the most unsaturated meat lipids. In pigs, a concentration of 3 mg alpha-linolenic acid (18:3)/100 mg in muscle and fat tissue fatty acids can easily be achieved by including whole linseed in the diet. This level has led to abnormal odours and flavours in some studies, but not in others. In cattle and sheep, feeding whole linseed raised 18:3 concentrations in muscle fatty acids from about 0.7 mg/100 mg to > 1 mg/100 mg. As with pigs, this diet also increased levels of long-chain n-3 PUFA formed from 18:3, including eicosapentaenoic acid (20:5). Although this increase led to greater oxidative breakdown of lipids during storage and the generation of large quantities of lipid-derived volatile compounds during cooking, there were no deleterious effects on odour or flavour. When 18:3 levels are raised in lamb and beef because of grass feeding, the intensity of the flavours increases in comparison with grain-fed animals which consume and deposit relatively more linoleic acid (18:2). In ruminants, very high levels of 18:2 produced by feeding protected oil supplements cause the cooked beef to be described as oily, bland or pork-like.

413 citations

Journal ArticleDOI
M. Enser1, R. I. Richardson1, J. D. Wood1, B.P. Gill, P.R. Sheard1 
TL;DR: It is estimated that the test diet would provide 12 g of long chain n-3 PUFA to the human diet per annum at current pigmeat consumption levels in the UK, about a third of that from oily fish.

281 citations

Journal ArticleDOI
TL;DR: The results suggest that PKO and PO could be used in tropical developing countries as cheaper alternatives to SBO for the production of good quality and healthy pork, but their limits of inclusion need to be determined.

237 citations


Cited by
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Journal ArticleDOI
TL;DR: Interest in meat fatty acid composition stems mainly from the need to find ways to produce healthier meat, i.e. with a higher ratio of polyunsaturated (PUFA) to saturated fatty acids and a more favourable balance between n-6 and n-3 PUFA.

2,166 citations

Journal ArticleDOI
TL;DR: It is shown that a major factor is the total amount of fat and that phospholipid, where 18:2n-6 is located, declines as a proportion of muscle lipid and the proportion of neutral lipid, with its higher content of saturated and monounsaturated fatty acids, increases.

2,116 citations

Journal ArticleDOI
TL;DR: Strategies for increasing the content of beneficial omega-3 polyunsaturated fatty acids (PUFA) and conjugated linoleic acid (CLA) and reducing saturated fatty acid (SFA) in beef are reviewed and opportunities exist to enhance thecontent of health promoting fatty acids in beef and beef products offering opportunities to add value and contribute to market differentiation.

790 citations

Journal ArticleDOI
TL;DR: The fundamental mechanisms of lipid oxidation, the most important oxidative reactions, the main factors that influence lipid oxidisation, and the routine methods to measure compounds derived from lipid oxidation in meat are reviewed.
Abstract: Meat and meat products are a fundamental part of the human diet. The protein and vitamin content, as well as essential fatty acids, gives them an appropriate composition to complete the nutritional requirements. However, meat constituents are susceptible to degradation processes. Among them, the most important, after microbial deterioration, are oxidative processes, which affect lipids, pigments, proteins and vitamins. During these reactions a sensory degradation of the product occurs, causing consumer rejection. In addition, there is a nutritional loss that leads to the formation of toxic substances, so the control of oxidative processes is of vital importance for the meat industry. Nonetheless, despite lipid oxidation being widely investigated for decades, the complex reactions involved in the process, as well as the different pathways and factors that influenced them, make that lipid oxidation mechanisms have not yet been completely understood. Thus, this article reviews the fundamental mechanisms of lipid oxidation, the most important oxidative reactions, the main factors that influence lipid oxidation, and the routine methods to measure compounds derived from lipid oxidation in meat.

726 citations

Journal ArticleDOI
TL;DR: The potential of dietary factors to increase the mean CLA content in cow milk fat is about 300% above basal values, there is, however, a need to evaluate how the different feeding strategies could change the other aspects of milk fat quality.
Abstract: After a brief survey of metabolic pathways and nutrient fluxes involved in mammary lipogenesis, this review summarises the known effects of diet on ruminant milk fat composition. Special attention is given to fatty acids that could play a positive role for human health, such as butyric acid, oleic acid, C18 to C22 polyunsaturated fatty acids and conjugated linoleic acid (CLA). The efficiency of the transfer of C18:2, C18:3, C20:5, C22:5 and C22:6, from the duodenum to the milk, is reviewed. The main dietary factors taken into account are the nature of forages, including pasture, and the supplementation of dairy rations with protected or unprotected vegetable or fish oils. Dose-response curves of milk CLA are reviewed for different fat supplements, as well as the non-linear relationship between milk CLA and trans C18:1. The potential of dietary factors to increase the mean CLA content in cow milk fat is about 300% above basal values. There is, however, a need to evaluate how the different feeding strategies could change the other aspects of milk fat quality.

700 citations