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MEAT 418-518: Meat Technology

Revision Notes

MEAT-418-518 was originally issued in 2007. It was created with funding provided by the Sheep CRC supported by MLA and AWI. The module was revised in 2013. Updates since it was issued in 2007 are relatively minor.

Topic 1: Origins of the Meat Industry

This topic provides a definition of ‘meat’ and background information on the history of the production, consumption and trade in meat.

On completion of this topic you should be able to:

  • describe the evolution of meat processing from hunting to industrialisation;
  • summarise the development of meat trading; and
  • identify some of the factors regarding changes in meat consumption from pre-history to the industrial age.

Topic 2: World Meat Consumption and Trade, Australian Markets and the Australian Meat Industry

Consumption of the various types of meat varies from country to country, and changes with time. Most of the world’s meat is consumed in the country of origin and only a small proportion is traded on international markets. This topic provides background information on current world meat consumption and trade, markets for Australian meat and some of the characteristics of the Australian meat industry.

On completion of this topic you should be able to:

  • discuss the link between consumption and meat trading patterns;
  • identify major world trade patterns in beef and sheepmeats;
  • list Australia’s major markets for beef, sheepmeat and pork; and
  • describe how these markets have changed over time.

Topic 3: Muscle Structure, Contraction and Energy Metabolism

Most of the “edible” protein of an animal is present in muscle, of which there are three distinct types – skeletal, smooth and cardiac muscle. Economically, skeletal muscle is by far the most important due to the quantity present, and will therefore be the major focus of this topic.

This topic provides an introductory understanding of the structure of skeletal muscles in terms of the factors that affect the quality of meat obtained from them. The biochemistry of muscular contraction is also introduced.

By the end of this topic you should know:

  • The composition of muscle including water, lipid, carbohydrate, and protein;
  • The organisational structure of muscle, including the grouping of fibres into bundles, and bundles into entire muscles;
  • Myofibre structure within muscle, including the basic layout of the sarcomere; and
  • Mechanisms of contraction, the proteins and organelles involved, and how it is regulated.

Topic 4: Connective Tissue

The aim of this topic is to provide a basic understanding of the structure and role of connective tissue, particularly in terms of its association with the muscular system.

By the end you should know:

  • The broad categorisation of different types of connective tissue;
  • The different types of connective tissue cells;
  • What constitutes the connective tissue matrix, and the type of connective tissue fibres within this matrix;
  • The importance of the protein collagen, its different types, and how tropocollagen is synthesised;
  • The role of collagen cross-links; andThe different types of connective tissue within muscle.

Topic 5: Muscle Type

The aim of this topic is to examine the characteristic structural and metabolic differences of various muscle groups, and how this influences the quality of meat obtained from them.

By the end of this lecture you should know:

  • The composition of muscle including water, lipid, carbohydrate, and protein;
  • The organisational structure of muscle, including the grouping of fibres into bundles, and bundles into entire muscles;
  • Myofibre structure within muscle, including the basic layout of the sarcomere; and
  • Mechanisms of contraction, the proteins and organelles involved, and how it is regulated.

Topic 6: Early Post-Mortem Biochemical Events

This topic provides an understanding of the biochemical events that occur in muscle early post-mortem and their significance on subsequent meat quality.

By the end of this chapter you should:

  • Understand that cells continue to metabolise after an animal is dead;
  • Recognise that this metabolism can affect meat quality;
  • Know the sources of cellular energy following slaughter;
  • Recognise that the amounts of cellular energy can affect meat quality; and
  • Understand why rigor mortis occurs.

Topic 7: Muscle, Bone and Fat in the Body

The objective of this topic is to describe the effect of breed and sex on growth curves, mature composition and the maturing patterns of body tissues. Attention is also given to nutritional and growth path effects on the changes in body composition.

By the end you should:

  • Know the relative pattern of tissue deposition as the animal matures from birth to maturity;
  • Understand how the differential pattern of tissue growth in the body impacts on body composition at any weight;
  • Understand how breeds of different mature size rank in body composition when compared at the same body weight, age and stage of maturity;
  • Understand how sex effects impact on mature size, composition at maturity, relative rates of tissue deposition and finally comparisons at the same weight and age;
  • Understand how castration impacts on mature size, composition at maturity, relative rates of tissue deposition and finally comparisons at the same weight and age; and
  • Know what impact restricted growth at early or later stages of growth has on body composition of slaughter animals.

Topic 8: The Musculature of the Body

The objective of this topic is to describe the pattern of growth and development of the musculature in the carcase. The scope for manipulation of muscle distribution patterns by genetic and nutritional means is also examined.

By the end you should:

  • Know the relative importance of function and genetics in controlling muscle distribution patterns in the body;
  • Know the different phases of muscle distribution as the animal matures from birth;
  • Know the effect of sex on both mature muscle distribution and the relative rates of maturity for the anatomical muscle groups;
  • Know the effect of breed on both mature muscle distribution and the relative rates of maturity for the anatomical muscle groups;
  • Know the effect of weight loss on distribution of anatomical muscle groups in the carcase; and
  • Understand what causes double muscling in the body and the consequences on production and metabolism of the animal.

Topic 9: Fat Partitioning and Distribution

This topic examines the pattern of fat deposition in the body of animals and the scope for manipulation by either management or genetic means.

By the end you should:

  • Know the important steps in the genesis of fat cells in the embryo and postnatal development;
  • Understand the metabolic differences between white and brown adipose tissue;
  • Know how total fat is partitioned within the body and the relative rates of deposition;
  • Understand the effect of nutritional restriction on fat mobilisation in the body;
  • Understand the effect of sex on fat partitioning in the body; and
  • Understand the genetic variation fat partitioning (both between and between breeds).

Topic 10: The Biochemistry of Fat

This topic examines the biochemical pathways by which fat is digested, absorbed and deposited in both ruminants and monogastrics and the scope for manipulation by either management or genetic means.

At the end you will:

  • understand the importance of fat to the meat and food industries;
  • know the principles of digestion of fat in monogastrics and ruminants;
  • understand the metabolic pathways for fat absorption, synthesis and catabolism in the body;
  • understand the effect of genetic variation on fatty acid composition in ruminants (both between and within breed); and
  • know the importance of environmental effects on fat composition in ruminants (diet, temperature and seasonal effects).

Topic 11: Animal Welfare, Ritual Slaughter and Slaughter Floor Operations

Abattoir slaughter and dressing procedures have evolved from early practices which were relatively slow, unpleasant and unhygienic by to-days standards, which are efficient, clean and hygienic components of the meat supply chain. This topic provides an overview and basic understanding of what happens pre-slaughter and on the slaughter floor of an abattoir—stunning, exsanguination (bleeding) and carcase dressing procedures. The criteria for humane slaughter and ritual slaughter are also outlined.

By the end you should be able to:

  • describe the steps in the slaughter chain from lairage to by-products;
  • discuss the operational issues within the slaughter process; and
  • debate the benefits of different technologies on the slaughter chain.

Topic 12: Chilling, Freezing and Boning

The meat industry uses refrigeration for food preservation. In many countries, animals slaughtered for meat were, and in some cases still are, immediately distributed, sold and consumed. Preservation was therefore unnecessary. As producers began to produce surplus meat, however, preservation methods were required so that excess product could be held and used at a later time, or in a distant location. Chilling meat was an early form of preservation that could be used without changing the form or state of the products. Freezing meat was a logical progression from chilling that gave longer preservation times

At the end of this topic you should be able to:

  • demonstrate a thorough understanding of heat transfer mechanisms and how they affect product cooling in the meat industry;
  • discuss relevant literature relating to grazing management and sustainability;
  • predict chilling and freezing times for meat products; and
  • understand hot and cold boning and the advantages and disadvantages of each of these processing methods.

Topic 13: Measurement of Carcase Characteristics

This lecture examines a range of subjective and objective carcase measurements and their relationship to carcase composition and meat quality.

By the end of this section you should be able to:

  • describe the various measurements taken on carcases;
  • explain the purpose of these measurements in terms of product description, marketing, quality assurance and meat quality;
  • debate the advantages and disadvantages of the various measurements, in terms of accuracy, reliability, repeatability and usefulness; and
  • discuss the impact on the industry of the introduction of new measurement technology.

Topic 14: Sensory Measurement of Meat Quality

The assessment of meat quality can be done subjectively by humans using their senses (sensory measurement) or by machines. There are advantages and disadvantages of both approaches. This lecture presents the various methods used for sensory assessment of meat quality, and how they are applied.

At the end of this topic you will be able to:

  • describe how meat quality traits are assessed by human senses;
  • describe the major frameworks within which this assessment is done; and
  • discuss the benefits and disadvantages of these methods.

Topic 15: Objective Analysis of Tenderness

Whilst humans are the final arbiters of eating quality, there are a number of drawbacks to their use (eg, cost, time, variability). Over the years a number of mechanical devices have been developed for the objective measurement of tenderness. They are consistent, relatively cheap, repeatable, reliable, and not influenced by human bias, preference or by external irrelevancies. This lecture will cover their usage and how well they correlate to sensory assessment.

At the end you will be able to:

  • Describe the tests available for objective measurement of tenderness;
  • Interpret the results from these tests; and
  • Discuss their usefulness.

Topic 16: Designs to Exploit Reproductive Technology

Reproductive technologies such as AI and MOET can be used to greatly increase fecundity. This increases selection intensity and, in turn, genetic gains

On completion of this topic you should:

  • Have an understanding of the different reproductive technologies available to animal breeders; and
  • Have an understanding of how each technology can affect genetic progress.

Topic 17: Marbling

Marbling is a term used to describe the appearance of intramuscular fat between the muscle fibres in meat. This topic describes the development of marbling, the genetic and environmental effects on its level in the muscles and its impact on palatability.

By the end you should be able to:

  • Understand how marbling fat develops in the carcase;
  • Know the magnitude and importance of genetic effects on expression of marbling; and
  • Know how marbling impacts on the palatability of beef.

Topic 18: Meat Flavour

Tenderness is the most important determinant of consumer acceptability of meat, especially beef. This has led to the development of the World-leading grading system, Meat Standards Australia. However, once meat is tender, the primary determinant of acceptability is flavour.

At the end of this topic you should be able to:

  • demonstrate an understanding of the effects of cooking on flavour;
  • demonstrate an appreciation for the complexity of flavour causing compounds and flavour analysis;
  • be able to list common meat flavour descriptors; and
  • demonstrate a thorough understanding of major factors causing differences in meat flavour between species and some important flavour issues.

Topic 19: On-Farm Factors Affecting Meat Quality – Beef

The objective of this topic is to understand the importance of the production factors, including breed, HGPs and growth path on meat quality.

By the end you should understand:

  • The magnitude of the Bos indicus effect on palatability and how it interacts with cut;
  • The importance of genetic variation both within and between breeds on the palatability of beef;
  • The importance of Hormonal Growth Promotants (HGPs) on palatability and how it interacts with cut;
  • The effect of the growth path effect, both within and between groups of cattle, on the palatability of beef; and
  • Biological mechanisms by which production effects impact on palatability of beef.

Topic 20: On Farm Quality Assurance for Sheepmeat

This topic describes the practical on-farm quality assurance measures that producers should consider to minimise the risk of the customer being dissatisfied with the sheepmeat product supplied.

At the conclusion of this unit , students should:

  • Understand that simple preventative on-farm measures can be put in place that will minimise the ‘nasty surprises” that customers may find in the Australian sheepmeat;
  • Understand that these procedures need to be documented to provide evidence to customers on request that they have been followed; and
  • Be aware of the industry wide quality assurance programs in which Australian sheepmeat producers may participate.

Topic 21: Lairage – Beef, Sheep and Pigs

The pre-slaughter period consists of the period of time from when animals are organised into a consignment, on the property where they have been “finished”, to the time when they are slaughtered at an abattoir. This period consists of a number of phases which will be discussed below and can be a critical period affecting carcase yields and ultimate meat quality.

At the end of this topic you should be able to:

  • Be able to identify and describe the different phases of the pre-slaughter period;
  • Understand how livestock management during the pre-slaughter period can affect food safety, animal welfare, meat yield and meat quality; and
  • Appreciate the differences between the different livestock species (pigs, cattle and sheep) in relation to the pre-slaughter period.

Topic 22: Processing Technology I

Electric stunning is used in most Australian sheep-processing plants.

At the end of this topic you should be able to:

  • Demonstrate an understanding of the various electrical inputs that may be applied during the animal/carcase stages of meat processing;
  • Discuss the possible relationships between electrical inputs and carcase and meat quality; and
  • Understand the Occupational Health and Safety aspects of the various electrical inputs.

Topic 23: Processing Technology II

The period immediately following slaughter can have a dramatic effect on meat quality. Consequently, considerable effort has been expended in the development of specifications and control measures that can be reliably used in the abattoir to ensure that eating quality, particularly tenderness is maximised. The focus has centred on minimising the degree of myofibrillar shortening and optimising the degree of proteolysis.

This topic discusses the application of pre-rigor stretching of muscles to minimise myofibrillar shortening.

By the end you should be able to:

  • Describe the biochemical causes of myofibrillar shortening;
  • Understand the relationship between sarcomere length and tenderness 3. Describe the processes by which muscles may be stretched pre-rigor; and
  • Discuss how stretching the muscle pre-rigor impacts on palatability

Topic 24: Ageing Vacuum-Packing and Storage

Meat is a highly perishable food. The meat industry in its current form would not exist if methods of preserving meat during transport and distribution had not been developed. In the early days of the meat industry in Australia, cattle were grown for their tallow and hides and sheep were grown for wool. Most of the meat was discarded because there was no way of getting it to overseas markets in an acceptable condition.

At the end of this topic you should be able to:

  • Explain how shelf life of chilled vacuum packed is extended compared with the storage life of chilled meat stored in air;
  • Understand the processing factors that affect the colour and microbial condition of vacuum-packed meat; and
  • Understand the changes in meat quality that occur during ageing of meat.

Topic 25: The Effect of Cooking on Palatability

Cooking impacts on the tenderness, flavour and juiciness of meat. Changes in meat tenderness with cooking occur from alterations in both the connective tissue and myofibre proteins in the meat. The application of heat solubilises collagen which increases tenderness, whereas heat denatures the myofibre protein and this results in toughness. Therefore the resultant tenderness of meat depends upon the relative contribution of both the connective tissue and myofibre components and their interaction with time and temperature of the cooking process.

This topic describes the physical and chemical changes which occur in the cooking of meat.

At the end you should:

  • understand the physical and chemical changes which occur in connective tissue and myofibres when meat is cooked;
  • know what the Maillard reaction is and how it contributes to flavour and colour attributes of meat;
  • know what factors impact on degree of doneness of meat and its importance to the consumer;
  • how does low temperature cooking impact on meat quality; and
  • what is warmed over flavour in meat and what are the factors which contribute to its incidence.

Topic 26: Specifications and Grading Systems for Beef: Japan, USA, Korea and Australia

Japan, the United States and Korea all have grading systems based on yield and quality grade, as assigned by end point assessment of the carcase. This differs from Meat Standards Australia (MSA), Australia’s new domestic grading scheme, which is covered in a separate topic.

The objective of this topic is to outline the main features of the grading systems of our major trading partners, Japan, United States and Korea. At the end you will be able to:

  • describe the Japanese, Korean and USA grading schemes; and
  • compare the various attributes which are considered important in assigning grades in the different countries.

Topic 27: Setting Grade Standards and the Carcase Pathways Scheme

The objective of this topic is to describe the consumer testing system and how it has been used to set grade standards. In addition the development of the pathways carcase grading scheme is described.

By the end you should understand:

  • the principles in the sensory tasting protocol used by MSA;
  • the principles of how the sensory data is used to derive the combined palatability scores and the grade boundaries;
  • the importance of demographic effects on consumer responses; and
  • the principles behind the development of the MSA carcass pathways system.

Topic 28: The MSA Cuts-Based Grading Scheme

This topic describes the development of the cuts based grading scheme. The cuts-based-grading model is described and examples are given of the magnitude of the various production, processing and value adding inputs on the palatability of beef using the cuts based model. In addition the potential benefits of a cuts-based grading system to the various sectors of the industry are discussed.

By the end you should:

  • Understand how the cuts based model differs from the carcase pathways grading system;
  • Know the predictors used in the cuts based model and their relative impact on palatability;
  • Know the accuracy of the cuts based model in predicting palatability; and
  • Understand the unique features of the labelling system used by MSA.

Topic 29: Sheepmeat Grading Systems MSA for Lamb and Sheep

Meat and Livestock Australia (MLA) has as its mission “World Leadership for the Australian Red Meat Industry” and MLA’s vision for the sheepmeat eating quality (SMEQ) research program is to deliver on this promise for lamb and other sheepmeats. MLA and the Sheepmeat Council of Australia (SCA) have undertaken research and development into defining and improving lamb and sheepmeat eating quality.

On completion of this topic you should be able to understand the importance of SMEQ to sheep meat production.

Topic 30: Meat Inspection

The term or phrase “meat inspection” refers to a set of standards or rules used for producing meat for consumption by Man and animals. On completion of this topic you will understand and appreciate the general philosophy for the practice of meat inspection (Veterinary Public Health) at meat export abattoirs

Topic 31: Game Meats I

The use of wild animals as a source of protein for human ancestors has been identified as long as 5 million years ago. The appearance of Homo sapiens around 250,000 years ago ushered in an era in which animals were hunted for sources of both meat for food and skins for clothing.

On completion of this topic you should have an understanding of:

  • The species that are used for game meat consumption both in Australia and the rest of the world;
  • The characteristics of meat for each species that are different from those in the major commercial meat animals, cattle, sheep and pigs;
  • Methods of farming and harvesting that are unique to each species;
  • Export legislation and quality control standards;
  • The utilisation of Australia’s own game meat animal;
  • An example of turning non-conventional farming into mainstream farming in Australia;
  • Effects of stunning methods on carcase and meat quality; and
  • The importance of shelf life and colour stability of fresh meat and its relation to temperature and nutritive value.

Topic 32: Game Meats II

Just as the quality attributes of the meat game species offer is important, so too is the health and disease risk and status of these species. Potential disease risks should always be taken into account when developing new and exotic meats for human consumption; this will become apparent in this topic.

On completion of you should have an understanding of:

  • The commercial potential for species other than kangaroo and deer to contribute to the supply of animal protein for human food;
  • Methods of farming and harvesting that are unique to each species.
  • Quality control and potential risks to human health associated with different species; and
  • The sources of information available on game meat production and factors influencing its quality.

Topic 33: Hazard Analysis of Critical Control Points (HACCP)

Hazard Analysis Critical Control Point (HACCP) is a systematic approach to the control of potential hazards in food industry operations. It aims to identify problems before they occur and establish measures for their control at the stages in production that are critical to ensuring safety or quality. Control is proactive because remedial action is taken in advance. Many QA processes are HACCP based. Such processes are a key to attaining good manufacturing practices.

This topic covers the basis of a HACCP system for controlling potential hazards in the food industry.