Oxidation in Foods and Beverages and Antioxidant Applications

Management in Different Industry Sectors

Eric A Decker, Ryan J Elias, D. Julian McClements

• Publisher: Woodhead Publishing
• Year: 2010
• Print ISBN:
  9781845699833
• eBook ISBN:
  9780857090331
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

Oxidative rancidity is a major cause of food quality deterioration, leading to the formation of undesirable off-flavours as well as unhealthy compounds. Antioxidants are widely employed to inhibit oxidation, and with current consumer concerns about synthetic additives and natural antioxidants are of much interest. The two volumes of Oxidation in foods and beverages and antioxidant applications review food quality deterioration due to oxidation and methods for its control.The second volume reviews problems associated with oxidation and its management in different industry sectors. Part one focuses on animal products, with chapters on the oxidation and protection of red meat, poultry, fish and dairy products. The oxidation of fish oils and foods enriched with omega-3 polyunsaturated fatty acids is also covered. Part two reviews oxidation in plant-based foods and beverages, including edible oils, fruit and vegetables, beer and wine. Oxidation of fried products and emulsion-based foods is also discussed. Final chapters examine encapsulation to inhibit lipid oxidation and antioxidant active packaging and edible films.With its distinguished international team of editors and contributors, the two volumes of Oxidation in foods and beverages and antioxidant applications is standard references for R&D and QA professionals in the food industry, as well as academic researchers interested in food quality. - Reviews problems associated with oxidation and its management in different industry sectors - Examines animal products, with chapters on the oxidation and protection of red meat, poultry and fish - Discusses oxidation of fish oils and foods enriched with omega-3 and polyunsaturated fatty acids

Part I

Oxidation in animal products

1

Oxidation and protection of red meat

C. Faustman, S. Yin and N. Tatiyaborworntham, University of Connecticut, USA

B.M. Naveena, National Research Centre on Meat, India

Abstract:

This chapter discusses the basis for lipid and protein oxidation in fresh and processed red meat products. These processes lead to quality degradation, and a variety of antioxidant strategies have been developed to minimize and/or prevent this quality loss. The chapter provides an overview of the field’s status to date.

Key words

red meat

lipid oxidation

myoglobin oxidation

protein oxidation

antioxidants

1.1 Introduction and compositional considerations

1.1.1 Red meat defined

Red meat includes the postmortem muscle of mammalian species. The degree of redness is proportional to the haem protein content of meat and is dependent on the specific muscles involved, the species, and age of the animal from which the meat was derived. Meat is composed of myofibres which contain the contractile apparati critical to proper functioning in vivo. For simplicity sake, myofibres can be classified physiologically as slow, fast and intermediate, or biochemically as oxidative, glycoclytic or oxidative/glycolytic. Slow, oxidative myofibres are characterized by a higher fat content, a slower contraction speed, oxidative metabolism, and greater myoglobin and mitochondrial concentrations. Fast, glycolytic myofibres contain less fat and more glycogen, contract more rapidly, rely on anaerobic metabolism and contain less myoglobin and mitochondria. Intermediate fibres contain elements that are intermediate between fast and slow myofibres. Muscles that contain a greater proportion of red myofibres than white ones will contain more myoglobin and be more red in appearance. Traditionally, the primary species that yield red meat are cattle, pigs, sheep, goats and deer. However, within these species there can be significant differences in the degree of redness of different muscles and this is most readily observed in pork. For example, within a pig carcass, the longissimus muscle contains more white fibres and is considered more white than the psoas muscle. For the purposes of this chapter we will focus on oxidation and protection of meat from the common mammalian livestock species (i.e., cattle, sheep, pigs).

The substrates in meat that influence susceptibility to oxidation are derived from the animal’s diet. It is important to note that the extent to which nutrition can influence the concentration of nutrients capable of accelerating or delaying oxidation depends, in part, on the animal’s nutritional physiology. Specifically, pigs are monogastric animals, while cattle, sheep and goats are ruminants. The fat of monogastric animals is more readily altered by dietary fat composition.

Considerable understanding of oxidation in meat can be obtained by consulting related studies of tissue oxidation in the medical literature. Some caution needs to be observed when doing this. The conversion of muscle to meat during the antemortem to postmortem transition is characterized by many biochemical changes (Greaser, 1986). Cellular integrity is lost with time and a number of physico-chemical changes occur that affect oxidation in meat. For example, mitochondrial morphology is lost with time postmortem (Cheah and Cheah, 1971, 1974; Tang et al., 2005) and this is accompanied by changes in oxygen consumption capacity. The accessibility of oxygen to fatty acids in membranes and production of radical intermediates would both be affected by these changes.

Oxidation of meat lipids, specifically unsaturated fatty acids in triacylglycerols and phospholipids, and of cholesterol, is a critical concern. The generation of peroxides, radical species and secondary oxidation products has implications for flavour, colour and loss of myofibrillar protein functionality. Protein oxidation generally leads to decreased functionality relevant to processed meat texture and water-holding capacity. All oxidative reactions generally result in compromised sensory quality and an undesirable sensory experience for the consumer. Antioxidant mediation of oxidative events has been adopted strategically to lessen the undesirable effects of oxidation reactions in red meat. Delivery of antioxidants has been accomplished by dietary intervention and ingredient addition, and resulted in shelf-life extension. In addition, packaging technologies that alter the atmosphere in which meat resides has also been employed to minimize the undesirable consequences of oxidation.

The goal of this chapter is to provide a summary review of relevant studies published in the literature. Our emphasis will be on the more applied aspects of red meat oxidation because the fundamental aspects are covered in earlier sections of this book. The reader should recognize that results from studies of oxidation very much depend on the experimental conditions employed by specific investigators. Space limitations preclude us from recounting specific details of conditions for all of the work cited and we encourage the reader to carefully consult the original investigations for these critical components when considering related work.

1.2 Lipid oxidation in red meat

1.2.1 Substrates for lipid oxidation

Triacylglycerols, phospholipids and cholesterol are the three major substrates for lipid oxidation in red meat. The fatty acids esterified to meat triacylglycerols and phospholipids can be saturated or unsaturated. In general, oxidative susceptibility is directly proportional to the degree of unsaturation in the constituent fatty acids. Selected nutrient profiles including fatty acids are presented in Table 1.1. Phospholipids are the major components of cell membranes and sub-cellular organelles in meat. They contain two fatty acids and the fatty acid at the sn-2 position is commonly unsaturated. The oxidation of fatty acids in phospholipids, more so than in triacylglycerols, has been attributed as the cause of sensory quality deterioration in foods (Pearson et al., 1977). As noted previously, the fatty acid profile of fresh meat from monogastric animals is more easily manipulated than that from ruminants. The production of comminuted red meat products can utilize raw meat materials differing in fatty acid unsaturation to achieve products with a specific level of unsaturated fat.

Table 1.1

Selected nutrient profile of red meats (value per 100 g; USDA, 2008)

^aBeef, rib, shortribs, separable lean only, choice, raw, trimmed to 0” fat;

^bPork, fresh, loin, centre rib (chops or roasts), boneless, separable lean only, raw;

^cLamb, Australian, imported, fresh, rib, separable lean only, trimmed to 1/8” fat, raw;

^dGoat, raw;

^eGame meat, deer, raw;

^fVeal, rib, separable lean only, raw;

^gGame meat, buffalo, water, raw.

The process of lipid oxidation in red meat leads to the production of a complex mixture of primary and secondary oxidation products that reflect the degree and location of unsaturations in the fatty acid substrates (Belitz et al., 2004). Aldehydes and ketones are produced in measurable quantities and are responsible for many of the odours and flavours associated with rancidity in red meat (Pearson et al., 1977). The most well-known secondary product of lipid oxidation in red meat is malondialdehyde (MDA). Some products of lipid oxidation are sufficiently reactive that they bind with other macromolecules. Previous research has suggested that MDA is predominantly complexed with protein in foods (Piche et al., 1988; Giron-Calle et al., 2002). α, β-Unsaturated aldehydes are reactive products of lipid oxidation (Witz, 1989) and in particular, 4-hydroxy-2-nonenal (HNE) is very reactive. HNE is produced from oxidation of linoleic acid in membranes (Pryor and Porter, 1990) and has been identified in beef and pork (Munasinghe et al., 2003; Sakai et al., 1995, 1998, 2004, 2006).

The fundamental bases of lipid oxidation have been addressed in the literature and are not discussed in this chapter. However, a critical consideration when assessing oxidation as a function of fatty acid unsaturation is that of methodology. Methods may be qualitative or quantitative, and can focus on consumption of oxygen or the production of primary or secondary products from the fatty acid substrate. The commonly used thiobarbituric acid (TBARS) assay (Fernandez et al., 1997) is more sensitive to the generation of 3-carbon secondary oxidation products, specifically MDA, than to other oxidation products. Also, the profile of oxida...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributor contact details
• Woodhead Publishing Series in Food Science, Technology and Nutrition
• Part I: Oxidation in animal products
• Part II: Oxidation in plant-based foods and beverages
• Part III: Antioxidant delivery in foods and beverages
• Index