Meat quality : how well do we monitor and assure quality?

Abstract

Animal Production in Australia 1998 Vol. 22 CONTRACT REVIEW MEAT QUALITY HOW WELL DO WE MONITOR AND ASSURE QUALITY? B.B. CHRYSTALL 57 Orchard Avenue, Hamilton, New Zealand For the purposes of this paper I would like to define quality as fit for purpose and I will, in the main, consider only table cuts of meat rather than all meat products. The arguments can however be applied across the full spectrum of products. I will not restrict myself to any particular species. Quality, judged from the Consumers viewpoint, is their expectation and experience. When they sit down to a meal with meat what do they expect? I believe they expect to experience the meaty aroma, perhaps tinged with those of herbs and spices and they expect to see a piece of meat that has the colour they associate with the degree of doneness they have asked for or tried to produce. If they want a rare steak they do not expect it to be grey throughout, but want it showing the purplish red colour in the centre. Most do not want the meat to be oozing blood. Then when they eat it they expect to experience the textural characteristics that match their expectations. If they are eating fillet they will expect a much more tender bite than they expect from rump steak. The textural characteristics include the hardness to bite and also the residue that must be swallowed. Juiciness is also expected because few like to eat something that is dry and mealy. Juiciness is not just expressed juice, but is a combination of the expressed juice and salivary stimulation. Consumers also expect to enjoy the flavour. This may be the flavour of the meat itself or the overall flavour of the meat with the spices, herbs and sauces. Some consumers may also be interested in the nutritional content of the meat and, often, whether it comes from an animal which has been given growth promotants. How well do we monitor what the consumer experiences? If we judge quality as perceived by the customer, what is expected? I realise that there are many different types of customer but for this exercise consider the customer as the home person. What determines which piece of meat that person purchases? To some extent it will be driven by price, in part because of the notion that price reflects quality attributes. Fillet steak for example will be more expensive than crosscut blade steak and is generally regarded as having characteristics that many consumers consider as quality attributes. Fillet will be more tender, but within a cut type how do they judge quality? They judge by the source, packaging, colour, the amount of drip in the pack, the fat cover and the amount of bone. Some customers will add the information supplied into their own judgement of quality. How well do we monitor what the customer experiences? Many of the supermarkets and retailers make their judgement of quality at the carcass stage. What do they consider as quality? In many cases they judge quality on basis of carcass weight, age of the animal from which the carcass came and the degree of fatness. Conformation might also be in their list of criteria but until recently there was no interest in any other characteristics which might provide a guide to ultimate quality. How well do we monitor the delivery of quality to the retailer? A processor might judge quality by looking at the animal they purchase. Generally they are only concerned with conformation, weight, fatness and expected yield. Do they consider the quality of the product they will produce? From a legal standpoint they will take account of the possibilities of disease, residues, presence of growth promotants and animal cleanliness. How well do we monitor the quality perceived by the processor and how does it relate to the quality required by the consumer? The producer often considers his or her animals are the best. The criteria used to judge quality are growth rate, size, conformation, breed characteristics and perhaps temperament. How well do these characteristics indicate quality and how well do we monitor them? I believe we need to integrate the many facets of quality over all phases because the end purpose of all the production, processing and marketing, is delivery of a pleasurable eating experience to the consumer while ensuring the profitability of all necessary parts of the chain. Table 1 lists quality-related measurements that may be made and the overall purpose of those measurements. 47 Animal Production in Australia 1998 Vol. 22 Table 1. Quality-r elated measur ements of meat Location of measurement Farm Measurement Breed Sex Live weight Fat cover Visual conformation Age Nutrition Carcass weight Yield Cleanliness Fat thickness Muscle colour Fat colour Muscle area Marbling score Muscle pH Microbiological counts Temperatures Origin Residue levels Cut weights Shear force Temperature Time Cut weight Meat colour Fat colour Fat cover Weight Fat cover Temperature Microbiology Tenderness Weight Meat colour Fat colour Marbling Aroma Juiciness Appearance Texture Purpose Predict carcass weight Predict grade Predict yield Grade Payment Payment Penalties Grade payment Market grade Market grade Market grade Market grade Stress, colour, tenderness Hygiene Hygiene, process control Disease status, traceback Overall performance Yield Tenderness Hygiene Inventory control Pricing Grade some markets Grade some markets Grade Pricing Yield Regulations Safety Payment Assess freshness Assess source and age Fat content Enjoyment Processor Wholesaler Retailer Customer Consumer Many measurements are made on the animal, its carcass and its products, for various purposes. Not all of these contribute to quality assurance but this does not mean they are unimportant. For example, measurements made as a basis for payment to producers may have nothing to do will ultimate product quality, but are vitally important economically. What do we measure along the complete production and marketing chain and how well do the measurements assist in the assurance of quality to the end user? 48 Animal Production in Australia 1998 Vol. 22 WHICH MEASUREMENTS ARE IMPORTANT FOR ASSURANCE OF QUALITY IN THE CONSUMERS EYES? Measurements that assure food safety are critically important. However the question of which measurements assure the other quality attributes is more difficult to answer. Can a consumer obtain a high quality steak if many of the measurements are not taken? The answer is probably yes, but not on a reliable assured basis. To assure the quality means that this must be delivered practically 100% of the time and not have a mere 50% chance of success. To assure quality it becomes important to minimize variability arising from any unmeasured or unmonitored factors. By controlling processing it is possible to get the large proportion of product to meet a defined tenderness standard, but there will be the 15 to 20% that is still too tough. This has been achieved with New Zealand lamb processed according to the accelerated conditioning and aging (AC&A) specifications. However, even 15 to 20% unaccounted for variability will not assure quality. It is therefore imperative to take a Hazard Analysis Critical Control Point (HACCP) approach to tenderness. This approach becomes the Palatabilty Analysis Critical Control Point (PACCP) approach, conceived in the USA and recently discussed by Webster (1997). In taking this approach it makes sense to step through the process of raising an animal and taking that animal through the full processing and marketing sequence to the ultimate consumer. Where are the control points and are they critical to the delivery of product? ANIMAL CHARACTERISTICS All of the major animal characteristics (Table 1) are considered by some to influence ultimate quality. Some of the characteristics have been used to restrict the type of animal that can be used to supply certain markets. For example, in the UK, Marks & Spencer sell beef only from Angus and some Angus crossbreeds but not from the continental European breeds. There has been a continuing argument that Brahman animals are tougher than Bos taurus animals (Wheeler et al. 1990). I do not believe that the animal conformation has any bearing on quality at the consumer end point, although it could be argued that the shape of a cut is influenced by the conformation of the animal. This would certainly be the case for the loin where a poor conformation can lead to a thin and narrow loin muscle, which is not what the customer expects of a top quality steak. What about fatness, live weight or carcass weight? Carcass weight is an important attribute as far as payment is concerned. It is a factor that can be measured early and provides a base from which to compare animals free from the complication of variable gut fill, common in cattle. I do not consider these are critical points in the assurance of end point quality especially if one considers lean grass-fed beef. However there are those who would argue that grass-fed beef and quality meat are oxymorons. They argue that it is impossible to have quality beef unless it has been grain fed! I do not accept that argument. In fact, there is plenty of anecdotal evidence of high praise being given to properly handled grass-fed beef. Animal age has an effect on texture and tenderness and the effect is not uniform across all muscles. If one is concerned only with the loin it might be possible to ignore animal age, but if other hind and fore quarter cuts are of importance then age is important (Harris and Shorthose 1988). It is interesting that tenderness determined by shear force measurements may not totally reflect the age effects that are detected by a sensory panel (Wenham et al. 1973). The difference due to age is a result of connective tissue changes that occur as the animal matures. It is important to recognise that the connective tissue changes are correlated with physiological age, not necessarily chronological age. Mere acknowledgement of years since birth may not be much value in assuring quality. There also appear to be some subtle effects that may be age related or may be a reflection of environmental effects that have been confounded with animal age. There is anecdotal information that beef animals of the same age can be very different in tenderness if one group has overwintered whilst the other was killed before winter. Similar examples can be found for lambs that are born late in the season and are killed at ages similar to the normal thoughput. They are likely to be tougher than expected. As researchers get closer to understanding mechanisms of quality development, it is likely that there will be probes that can detect different characteristics which determine the end quality potential. It is important not to consider tenderness as the only quality parameter, but rather consider all of the quality characteristics. Tenderness is undoubtedly a major factor but as prices increase all attributes will need to be right to get the customers cash and then continue to get the repeat purchases. There can be considerable between animal variability and, if we are to assure quality such variability should be minimized. It may be that tight specifications are required on animal categories that can meet specific end 49 Animal Production in Australia 1998 Vol. 22 product characteristics. I would like to think that it should be possible to tailor processing to account for raw material variability. If process A is appropriate to convert a young, well-grown animal into product of premium class, it may or may not be the process suitable to convert older well grown animals to the same quality product. These might require process B. We do not have the information that allows this form or level of selective processing to take place. Early identification of animal characteristics is essential to selectively process the carcasses. There is no measurement that will currently allow this and we do not know how much difference we can accommodate through selective processing. PROCESSING What about the processor, do they measure the appropriate things and even if they do, do they control the process according to the requirements? Processors measure and/or record a lot of data from a wide range of variables. This is done to control processes, to determine what payments are required, to comply with regulations and sometimes to assure quality. Which of their measures are important and necessary to assure quality? The processes that affect the product must be monitored. These start with the stress on animals imposed by handling. Then there is the time/temperature history of the product and its effect on microbial growth. It must ensure no toughening but the achievement of optimum tenderness and colour. Grading may provide some quality information but probably not to the degree that some processors and producers accept. Grade as normally judged, at least in the New Zealand context, is based on weight, fatness and to a small degree on conformation. For markets such as Japan there are also fat and meat colour scores and a marbling score. How do these affect quality? For the Japanese buyer, but not necessarily the end consumer, the fat and lean colour at time of grading is important but these change during storage, and therefore the colour at time of sale can be quite different (Powell 1997). The higher priced Japanese meat is certainly well marbled; in fact one wonders if it is meaty fat or fatty meat. However to the average New Zealander and Australian consumer the appearance of a heavily marbled steak is not synonymous with quality. If you placed a series of steaks on display ranging from no marbling through to heavily marbled, the average New Zealander and Australian would choose to purchase a steak close to the non-marbled end of the scale. However, if commenting on the juiciness of cooked steaks the same consumers are likely to favour some marbling. In assuring quality it is important to be sure what level of quality is being assured. There is no reason why there should not be different levels that are assured. If the animal has arrived at the processing plant, what factors that affect quality can be controlled? These are especially important to monitor and control. Control may be in form of exclusion from a category, or a direction to use a modified process. The ultimate pH of meat has a pronounced effect on its keeping quality, colour, tenderness and waterholding capacity, and it is one measure that is often used to exclude product. In the Meat Standards Australia (formerly EQS) programme (Webster 1997), beef is expected to be within the pH 5.3 to pH 5.7 range. To qualify for the New Zealand Qmark, beef must have an ultimate pH less than 5.8 (Fraser 1997). Meat with ultimate pH above 6.0 is often excluded from the vacuum packed chilled meat trade. Although a producer and processor may take all possible care with their animal handling, they may still have some carcasses exhibiting elevated ultimate pH levels. Nothing can be done about this once the animal has been slaughtered. There is a need for a method to measure the animal condition prior to slaughter and predict the ultimate pH. If an animal were identified as likely to give a high ultimate pH, it could be diverted to be re-fed and rested, and processed on a later day. The stunning system used may exert an influence on the subsequent performance of the processing operations. In the New Zealand context, where electrical stunning of sheep and cattle is common and where there may be other applications of electricity during processing it is important that the full use be known and factored into tailoring the electrical stimulation of the carcass process for the individual animal. Captive bolt stunning systems may have a much lesser influence on the ultimate quality but this has been poorly researched. It is important that the performance of the stunning operation be monitored for humane reasons if nothing else. Electrical stimulation of carcasses is widely used, but how many operators really know what they are doing or whether they are using a sledgehammer to crack the walnut? Electrical stimulation is one of a series of tools that can be used in the quest for a better quality product. It is not, per se, the answer to the maidens prayer (Law 1972). How many processors monitor their electrical stimulation and know the current levels, the variability of response and the variability in end product? I suspect very few! 50 Animal Production in Australia 1998 Vol. 22 There is a number of characteristics of electrical stimulation that should be measured. The importance of the measurements increases as the voltage used decreases. The characteristics that I consider important are: time and muscle temperature at time of application, current level, pulse characteristics and frequency, and duration of stimulation. At low voltages, the current levels are extremely dependent on the contact resistance. A recent paper by Sparrey and Wotton (1997) stresses the importance of contact resistance and impedance of electrical stunning tongs. The same is equally, if not more true for stimulation systems. Many plants I have seen claim to be using electrical stimulation, yet have no idea of the current levels through the carcass or the effects they are expecting or are achieving. Effective stimulation is a valuable processing aid ensuring an increased uniformity of pH fall and a more uniform commencement of aging. However unless the stimulation is controlled it can increase variability because it fails to accommodate differences in electrical resistance and difference in animal response. Throughout the dressing process the focus should be on measures that are used to control the hygiene of the operation. The cleanliness of the product, affected by both visual soiling and unseen microbiological contaminants, has a major affect on quality. It is of little value trying to control a process with assessments for which the answers are not available until several days later. There is need for immediacy if change is to be made on the basis of a measurement. For microbiological hazards it is more likely that monitoring the process control will have more affected than will end-product monitoring. This means that attention should be directed to ensuring that workers know why their operations must be carefully conducted, and that they use good hygienic operations for themselves and their implements. Mechanisation should allow more complete cleaning and sterilization of tools between operations. It is easier to wash and use high-pressure steam to sterilize a machine than it is to achieve the same level of hygiene with a manual worker. The New Zealand MAF have the philosophy that product should be kept clean by avoiding contamination, rather than allowing contamination but expecting removal of it before sale. This has benefited the New Zealand industry. However in trying to get to an even cleaner situation the use of a pasteurizing or sterilizing treatment might be required, even though some (Jay 1996) would argue that product can be too clean and provide no competition for some of the unusual nasties. A quality product demands safety to be assured. To achieve this it is therefore important to use the appropriate methods to ensure production of a hygienic product, rather than control the subsequent processes to maintain that assurance. Temperature, time, environment and available nutrients all influence microbiological growth rates. It is these factors that can be controlled for safety of product, and product safety must be assured right up to the time of consumption. The extent to which a processor must go to ensure safety is a matter of debate, and even legal argument. At present it appears that the processor is liable should one of their products cause a problem. Food products are perishable and changes will occur from time of sale until time of consumption. Consider this scenario: I buy some minced beef from the local supermarket at 9am, I leave it on the back seat of my car for the day before taking it home. I season the meat and form it into a patty and grill it until it looks slightly brown in the centre. Who is responsible if I get food poisoning? Is it the supermarket? Is it the processor or am I responsible? I must admit I am inclined to absolve the supermarket and the processor from all responsibility provided they are able to assure me that the product their product at point of sale is assured safe until its used by date under reasonable handling practices. Traceback of product is becoming important as a means of assuring customers that producers, processors and supermarkets know what they are processing and selling and can, in case of a problem, know where it originated. I am not convinced that it should be necessary to be able to trace every steak back to its animal of origin and thus back to its source, but there is definitely a push towards that position. The situation becomes more difficult if you expect the same for smaller animals. Perhaps the argument is that the larger animals are more likely to be traded more than once during their lifetime and be subjected to a range of operators, whereas chickens and pigs are likely to be handled as a group. Traceback is one factor that should have a role in assuring quality since it will allow identification of any producer not adhering to rules on handling of chemicals and animal remedies. The fact that they can be identified will encourage more producers to conform to the rules. There will be the few who, no matter what the rules and checks, will try to cheat the system. Traceback has some positive aspects in that it can be arranged so that the processor can track their product and have more information available to assist management of their operation. The New Zealand QMark and the AC&A control procedures have set a tenderness standard that requires tenderness testing (using the NZ Tenderometer) of product where the process deviates from the defined procedures. This provides a measure of how well the processes are operating and a means for the regulators, 51 Animal Production in Australia 1998 Vol. 22 in this case the New Zealand Meat Producers Board, to approve different processes. The important end result is the target quality rather than the means of getting that quality. However, tenderometer testing is a slow and destructive process that cannot be applied to all product. It is not as costly as sensory testing but, within a given class of stock, is an effective check of performance. There is an increasing range of technologies allowing measurements on samples from the carcass to predict tenderness. Most of these have not been found to account for enough of the variability to make them very useful, but if they are being used to segregate carcasses into different classes they may be more valuable. Most have focussed on tenderness: NIR ( Byrne et al. 1997), conductivity and impedance (Byrne et al. 1997), ultrasonics (Karam et al. 1997) but there is also a move to assess flavour, marbling and potential colour. More work is required before any of these are of value as on-line product monitoring devices, no matter where in the process they are used. WHOLESALERS The wholesaler must continue to be vigilant with respect to the time/temperature history of the product and to general hygiene to preserve safety. Time and temperature will also be important for the full development of tenderness and perhaps, at the extreme, the deterioration of flavour. In general terms the wholesaler is often not in a position to affect quality, though may do so if also cutting and repackaging the product. RETAILERS Similarly the retailers must protect the safety of product. However they have a critical role in presenting the product in a way that appeals to the potential customer. Unless the product appears to have quality it will not be sold, and all the good work up to that point is wasted. The packaging, merchandising and pricing of the product will all affect the perceived quality. Do we really know what the customer expects and for what they are willing to pay? What does the retailer measure to know what they sell, or do they depend of the supplier? Tenderness measurement (eg by Tenderometer) and other quality assessments can be used to audit quality performance but are not control measures. CUSTOMERS Customers purchase the product but do we know what they think of their purchase? Do we actually know the quality of the product they buy? Do we do anything to determine how satisfied they are with the meat they buy, or how the ultimate consumers reacted on being served the product? None of us would expect the same reaction from a customer served mince as one served up a fillet steak at a romantic dinner, but there are standards of quality that are expected in each case and the question must be: how well did we meet (meat) those expectations? The preparation of the product for consumption plays a part in the quality at consumption. I believe that we do not do a very good job of assuring quality through to the final customer, the consumer. We still need to take a more integrative approach and know exactly what drives variability in ultimate product characteristics. If we more fully understand what contributes to the variability we may then be in a position to tailor selection and processing to deliver a predictable product. The initiatives to deliver quality to the consumer, eg The Australian MSA, the New Zealand Qmark, the UK Blueprints (Warkup 1997) and the USA initiatives for pork and beef (Miller 1997) are moving us forward but there still too much variability? Someone buying a packet of breakfast cereal expects and gets something that is the same as they purchased last month and will be the same when they repurchase next month. Can we say the same for meat or do we get something that does not even come close? I believe we still have a long way to go in the quest for guaranteed quality, but we are getting closer. 52 Animal Production in Australia 1998 Vol. 22 MONITORING AND ASSURING QUALITY OF AUSTRALIAN PORK H.A. CHANNON, C.D. HOFMEYR and R.D. WARNER Victorian Institute of Animal Science, Agriculture Victoria, Private Bag 7, Werribee, Vic 3030 As a consequence of consumer demand for lean, tender and juicy pork products with acceptable flavour, the Australian pig industry is continuing to strive towards producing pork which meets these requirements. This paper will discuss quality problems facing the Australian pork industry and provide details of current industry initiatives focussed on improving eating quality by reducing the incidence of pale soft and exudative pork (PSE). PALE, SOFT AND EXUDATIVE PORK Problems associated with inconsistent meat quality, particularly pale soft and exudative pork (PSE), have been shown to cost the Australian pig industry up to $20 million per year (Whan 1993). Recent studies have identified that the incidence of soft, exudative pork in Australia was between 41 and 64%, with an average of 51% (Eldridge et al. 1995; King 1996). The pork quality defects of PSE and dark, firm and dry meat (DFD) can be determined on the carcass using objective measurements of muscle pH and colour. The development of PSE meat results from a rapid pH decline post-slaughter while the muscle temperature is high (> 38_C). It is associated with a deterioration in the appearance of fresh pork due to higher drip loss, softer texture and paler colour than normal meat. Processing losses are also experienced when cooked, cured hams and bacon are manufactured from PSE rather than normal meat. The recognition of the importance of the high incidence of PSE in the Australian industry led to the National Pork Quality Improvement Program. The aim of this initiative was to develop, refine, validate and implement standards of management of pigs and their carcasses to achieve a 50% reduction in the incidence and commercial impact of pale, soft, exudative meat in abattoirs that implemented and maintained these standards. Over a period of sixteen months, this program achieved an overall reduction of 38% in the incidence of soft, exudative pork in four participating abattoirs (Eldridge et al. 1995). Similar results were achieved in the State-wide programs which were run concurrently (Hofmeyr 1996). It was demonstrated in this Program that a reduction in the incidence of PSE could result from low-cost changes to pre-slaughter management of pigs and post-slaughter chiller management. As the rapid rate of pH decline at a high muscle temperature is largely responsible for the production of PSE pork, several rapid chilling systems have been installed as a method of reducing its incidence. Warner (1997) presented results under Australian conditions and discussed the problem of rapid chilling to reduce PSE and improve colour resulting in unacceptably tough pork. Unfortunately, the impact of post-slaughter management strategies used to reduce PSE incidence have not been widely documented in terms of potential effects on tenderness of fresh pork. This issue is of particular importance as the industry continues its move towards producing leaner pigs to satisfy changing consumer requirements for lean pork products. Dikeman (1996) stated that reducing fat depth at the P2 site to less than 14 mm may result in cold-shortening, particularly when rapid chilling systems are used. TENDERNESS The pork quality characteristics of tenderness, juiciness and flavour are used to describe the eating quality of fresh pork. Although many studies have documented the effects of PSE/DFD in terms of reduced acceptability, paler colour and increased drip loss, less attention has been concentrated on determining both the potential impact of these pork quality defects on eating quality and the variability in eating quality of fresh pork. A survey of tenderness of pork loins purchased from retail outlets in Melbourne from December 1996 to June 1997 found that 31% of all pork loins purchased would have been considered tough by consumers (Hofmeyr 1998). Furthermore, it was found that 65% and 58% of pork loins purchased in December 1996 and January 1997, respectively, recorded Warner-Bratzler values greater than 6 kg. Possible reasons for the high levels of tough pork found in this study are not clear. The incidence of PSE did not markedly differ between pork loins purchased over the seven month period. This is in contrast to Warner (1994) who indicated that PSE pork may be tougher and drier compared with normal pork. As stated by Hofmeyr (1998), 53 Animal Production in Australia 1998 Vol. 22 the high incidence of tough pork identified in the survey should be of considerable concern to the Australian pork industry, particularly with the introduction of the Australian Pork Industry Quality Program. As sensory evaluations were not conducted as part of this study, it is not known whether this product was acceptable in terms of juiciness and flavour. JUICINESS Dikeman (1996) stated that selection and production of pigs with reduced levels of subcutaneous fat is likely to have negative effects on pork eating quality due to a reduction in intramuscular fat content. Bennett (1997) considered that eating quality problems with Australian pork are related to insufficient intramuscular fat. Strategies that include castrate production and the introduction of the Duroc breed into pig herds, to increase the intramuscular fat content of pigs without influencing subcutaneous fat levels or feed conversion efficiencies, are currently under investigation. PORK FLAVOUR Flavour of pork, p