Microbiological Quality of Skin-on Goat Carcases and Meat

Transcription

1 Attachment 2 Microbiological Quality of Skin-on Goat Carcases and Meat Suite 2, 150 Victoria Rd, Drummoyne, NSW 2047 Ph: (02) Fax: (02) mintrac@mintrac.com.au Website: mintrac.com.au ABN NO ACN

2 Contents Attachment Microbiological Quality of Skin-on Goat Carcases and Meat... 1 Introduction... 3 Methods... 3 Macro and Micro Contamination of Goat carcases and meat... 3 Impact of Bristle and Skin Pigmentation on Carcase Hygiene... 3 Results and Discussion... 6 Micro Contamination of Goat carcases and meat... 6 Macro Contamination of Goat carcases... 8 Impact of Bristle and Skin Pigmentation on Carcase Hygiene... 9 Conclusions References Appendix Appendix

3 Introduction While a relatively small producer of goat meat Australia is the world s largest exporter (GICA, 2016). The slaughter number in 2014 was 2.13 million head, with goat meat production up 4% on the previous year to 32,900 tonnes carcase weight (Mathews et al, 2015). The major market for goat meat in 2014 was the US; 19,090 tonnes (shipped weight) up 23% from the previous year. The majority of goat meat exported to the US is as whole carcases (75% of the total shipment to the US in 2014), with skin-on carcases comprising about 10% of production. While skin-on carcases have traditionally been a small part of the export market the demand is growing and skin-on product is attracting a significant premium in markets like the USA. Recent issues with export of skin-on carcases to the US has highlight a general lack of knowledge of contamination on skin-on carcases. The purpose of the current study was to review macro and micro contamination on skin-on goat carcases and to determine the possible impact on carcase hygiene of bristle and skin pigmentation. Methods Macro and Micro Contamination of Goat carcases and meat Information on the level of contamination on carcases, both visible and microbial, are collected by companies under the supervision of offices of the Department of Agriculture and Water Resources (DAWR, the Department). These data form part of the Product Hygiene Indicator (PHI) program and are collated by the Department and reported monthly to industry and peak industry councils. Microbial data includes aerobic plate count and generic E. coli. Briefly, a total of 75 cm 2 of carcase surface from 3 sites (mid-loin, flank and brisket) is sampled after chilling using a sponge (Anon, 2003). Sponging has been shown to produce a higher recovery than other non-destructive sampling techniques when compared to excision methods (Gallina et al, 2015). Sampling is verified weekly by Department officers and all samples are analysed at Department approved laboratories using Department approved methods that have been internationally validated. The data used in this study were summarized and provided by the Department. Data are compared with published data on the microbiological load on carcases and in meat. Information on macro contamination of skin-on coat carcases is generally lacking. Data collected by Department officers as part of daily verification activities is summarized in the PHI. These data are generalised and do not provide information on specific types of contamination. Data have been summarized by the Department and provided for reference in this report. Impact of Bristle and Skin Pigmentation on Carcase Hygiene The impact of bristle and skin pigmentation on the microbiological load on carcases was determined experimentally at Wodonga abattoir. Effect of bristle on carcase hygiene Carcases were selected from those available immediately prior to the final trim. This allowed selection of carcases with higher levels of bristle that might otherwise not have been available immediately prior to boning. Areas on the carcase representing both high and low bristle density were selected. An example of a high bristle density area is shown in Figure 1. Sample sites were reasonably adjacent to ensure that they had been similarly exposed to external contamination sources during processing. Samples were collected from the 3

4 hindquarters of the carcase to avoid confounding of data from sites where contamination might have been influenced by pre-washing steps. Figure 1: Areas (100 cm 2 ) of high (left) and low (right) bristle density sampled as part of this study. To obtain a representative sample of both high and low bristle density, 20 paired sites were sampled using the procedure detailed in the E. coli Salmonella Monitoring program (ESAM) Meat Notice (Anon, 2003). In an effort to minimize variability within each population 100 cm 2 rather than 25 cm 2 samples were collected. Samples were collected by a single trained member of the Wodonga abattoir Quality Assurance staff who was familiar with the ESAM procedures and aseptic sampling techniques. Samples were appropriately labelled and couriered to an external NATA accredited laboratory for analysis for aerobic plate count (APC) and E. coli/coliforms using Petrifilm TM. The laboratory was instructed to plate sufficient dilutions to ensure that a countable result was obtained for all samples. Samples were analysed no later than on the day following sample collection i.e. no samples were collected on a Friday. Results for each sample were reported by the laboratory as a count per cm 2. The effect of bristle load on the microbiological quality of carcases was assessed using the paired t-test in Minitab TM Release 14 (Minitab Inc.; State College, Pennsylvania). 4

5 Effect of skin pigmentation on carcase hygiene Carcases were selected from those carcases retained for 'burning' (flaming of the carcase surface to produce smokies ) or from those that clearly showed pigmentation on the majority of their surface. An examples of a pigmented area sampled is shown in Figure 2. Figure 2: Example of pigmented carcases sampled as part of this study Samples were also collected from the same number of carcases with a normal appearance and at a similar time in the production process. Both pigmented and normal carcases were collected from the same lot of animals to reduce animal effects and allow comparison of results for the two carcase types. To obtain a representative sample of each population, 20 pigmented and 20 'normal' carcases were sampled following the ESAM protocol (Anon, 2003). Samples were collected by a single trained member of the Wodonga abattoir Quality Assurance staff who was familiar with the ESAM procedures and aseptic sampling techniques. Samples were sent to an external NATA accredited laboratory and analysed for APC and E. coli/coliforms using Petrifilm TM. The laboratory was instructed to plate sufficient dilutions to ensure that a countable result was obtained for all samples. Samples were analysed no later than on the day following sample collection i.e. no samples were collected on a Friday. Results for each sample were reported by the laboratory as a count per cm 2. The effect of pigmentation on the microbiological quality of carcases was assessed using the ANOVA function in Minitab TM Release 14 (Minitab Inc.; State College, Pennsylvania). Part of this work also looked at traceability of product through the process from the live animal to final product. 5

6 Results and Discussion Micro Contamination of Goat carcases and meat The level of general contamination reported in the PHI for skin-on goat carcases in 2015 was 1.94 Log cfu/cm 2. This is slightly higher than the level reported on skin-off goat carcases and skin-on pig carcases (Figure 3). Figure 3: APC (Log cfu/cm 2 ) counts on carcases sampled after chilling, reported under the PHI program in In an Australian industry study on hair removal from goat carcases (Anon, 2011), final APC counts of < Log 3 cfu/cm 2 were reported, while Bass et al (2011) reported APC counts of 0.7 Log cfu/cm 2 on skin-on goat carcases and 1.15 Log cfu/cm 2 on skin-off carcases in the Australian state of New South Wales. A study on the microbiological status of goat carcases in Serbia (Ivanovic et al, 2015), found 77% of the carcases to have satisfactory APC levels (<3.5 Log cfu/cm 2 ) and 5% to have unacceptable levels (>5 Log cfu/cm 2 ) when compared to the requirements in EU regulations (European Commission, 2005). Although not clear in the report it is gathered that these results relate to skin-off carcases. In a US study (Kannan et al, 2014), very high APC were obtained from skin-off goat carcases prior to the final wash 7.93 Log cfu/cm 2, although earlier work by this author (Kannan et al, 2007) reported much lower levels (Log 4.0 cfu/cm 2 ). Fisher et al (2007) reported an average APC on skin-on sheep carcases of 2.8 Log cfu/cm 2. Pig carcases are generally produced skin-on. Given that this process is similar to that used for the production of skin-on goat carcases it could be surmised that the counts on carcases produced under both systems would be similar. The APC reported in the PHI for skin-on goat carcases (1.94 Log cfu/cm 2 ) was not that different from the APC reported for skin-on pig carcases (1.56 Log cfu/cm 2, Figure 3). Pearce et al (2004) reported average APC counts on pig carcases prior to chilling of 3.5 Log cfu/cm 2, while Gill et al (2000) reported mean levels of 2.4 Log cfu/cm 2 on pig carcases post-final wash from 8 Canadian establishments. E. coli levels on carcases are also captured under the PHI. The monthly prevalence of E. coli reported for skin-on goat carcases under the PHI range between 2.9% and 23.5%, with a downwards trend observed in 2015 (Figure 4). The E. coli prevalence is similar to that for skin-off goat carcases and pig carcases. 6

7 Figure 4: E. coli prevalence (%) on carcases sampled after chilling, reported under the PHI program in Numbers of E. coli recovered from carcases were very low with an average count of < 1 cfu/cm 2. Bass et al (2011) reported similar levels of E. coli from skin-on goat carcases (<1 cfu/cm 2 ) with a prevalence of 27%. Much higher E. coli levels were reported on pre-washed US goat carcases 2.28 Log cfu/cm 2 (Kannan et al, 2014) and 2.1 Log cfu/cm 2 (Kannan et al, 2007). The microbiological quality of goat meat is also captured under the PHI. Data on APC and coliform levels in carton product is entered into the PHI monthly. There was little difference between the microbiological quality of skin-on goat meat and other product reported under the PHI in 2015 (Figure 5). Figure 5: APC (Log cfu/cm 2 ) counts in carton product sampled prior to carton closure, reported under the PHI program in

8 The mean APC for all goat meat products reported under the PHI was 2.4 Log cfu/g, while the coliform count and prevalence was -0.3 Log cfu/g and 11.3%, respectively. Kim et al (2015) reported an APC of 4.2 Log cfu/g on goat chops from US suppliers with much high count found in ground goat meat (6.1 Log cfu/g). It is important to note that the low counts reported in the current study may reflect that fact that the samples were collected from product still at the abattoir prior to any transportation and retail storage or temperature abuse. Haque et al (2008) reported APC levels of 6.03 Log cfu/g in goat meat at Bangladeshi slaughter establishments. Similar counts (~5.4 Log cfu/g) were found in goat meat sold in Nigerian markets (Eze et al 2012). No data are available for the microbial load in goat meat at point of sale in Australia. Microbiological surveys to date have focused on the major slaughter classes and goat meat has not been included. The APC in goat meat reported in this study is well within the acceptable limits for meat defined in the Meat Standards Committee guidelines (Meat Standards Committee, 2002). Macro Contamination of Goat carcases Visible contamination on carcases is captured by plants using the Meat Hygiene Assessment (MHA) system and reported under the PHI. Carcases are inspected prior to final trimming and washing. Data is verified by MHA measurements collected daily by Department staff. Department verification data for 2015 for skin-on and skin-off goats is shown in Figure 6. Figure 6: Department Meat Hygiene Assessment (MHA) scores for skin-on and skin-off goat carcases slaughtered in Results for the last quarter of 2015 for goat carcases were similar to the average value reported by department staff for skin-on pig carcases (0.3) over the same period. While individual defects are recorded on-plant they are not reported, this makes it difficult to determine the visible contaminant contributing most to the final MHA score. Ford (2015) identified hair as the main visible contaminant on goat carcases, although it is not clear from that reference if carcases were processed skin-on or skin-off. An Australian industry study reported 30-40% contamination rates for hair on carcases (Anon, 2011) under normal processing conditions. Presence of ingesta, faeces or milk (Zero tolerances or ZTs) are also reported under the PHI. In 2015, only 3 ZTs were detected by Department staff on skin-on goat carcases during the year out of 5,456 observations. It is not clear what role visible contaminate plays in relation to the microbiological load on carcases. While Biss and 8

9 Hathaway (1996) reported higher counts on sheep carcases from areas associated with wool than areas that were uncontaminated (5.44 and 3.98 Log cfu/cm 2, respectively) they noted that after washing the level of contamination was similar on both areas. The authors attributed this to removal of contaminating microorganisms rather than re-distribution as a result of washing. It is generally accepted that the presence of faecal contamination leads to higher bacterial loads on carcases although the extent of contamination is determined by the process and the skill of the workers (Barco et al, 2014). Gill (2004) noted that removal of contamination did not necessarily result in a reduced microbial load. Impact of Bristle and Skin Pigmentation on Carcase Hygiene Effect of bristle on carcase hygiene Microbiological counts obtained from areas of high bristle load and areas of low bristle load are given in Appendix 1. The average APC count from areas of high bristle load was not significantly different (p=0.73) from the average count obtained from areas of low bristle load, 0.92 and 0.99 Log cfu/cm 2, respectively. The prevalence of E. coli on both carcase groups was also not significant, 3/20 and 1/20 for high and low bristle loads respectively. There are no published studies on the effect of bristle on the microbiological load on skin-on goat carcases. However, the effect of de-haring has been studied in pigs. Loretz et al (2011) noted that scalding reduced the bacterial load on pig carcases while polishing increased the count. Gill and Bryant (1992) showed that the APC count on pig carcases increased from 3 Log cfu/cm 2 after scalding to 4 Log cfu/cm 2 after polishing. The actual level of reduction achieved by scalding could be as high as 3.5 Log cfu/cm 2 (Pearce et al, 2004). This may explain why there was no association between hair on carcases and the microbiological load in the present study. Presumably bacteria are removed or their numbers decreased during scalding and then carcases are re-contaminated during the later stages of the process. This means that hair in itself is not a good measure of the likely microbiological load on a particular area of the carcase. Effect of skin pigmentation on carcase hygiene Microbiological counts obtained from pigmented and non-pigmented areas on skin-on goat carcases are given in 9

10 Appendix 2. The average APC count from pigmented areas was significantly lower (p=0.002) than the average count obtained from areas without pigmentation, 0.99 and 1.61 Log cfu/cm 2, respectively. The prevalence of E. coli on both carcase groups was not significantly different, 0/20 and 2/20 for pigmented and non-pigmented areas respectively. There are no published studies on the effect of pigmentation on the microbiological load on skin-on goat carcases or for skin-on pigs. The brownish-black pigmentation associated with healthy skin is due to the presence of melanin (Collins, 2015), which in itself is not considered harmful. Pigmented skin is an important adaptation in hot climates and goats with low pigmentation are more adversely affected by climate stress (Darcan, Cankaya and Karakok, 2009). It is unlikely that pigmented areas on carcases have lower microbial counts than non-pigmented areas. The mean APC count on pigmented areas observed in the current study were very similar to the counts obtained from high and low density bristle areas. The observed difference between pigmented and non-pigmented areas in the current study is likely due to variations in carcase processing between the two groups rather than any effect of pigmentation. Traceability Animals are mustered on private properties either as distinct slaughter lots or mixed lots that require sorting at the abattoir prior to processing. Animals arrive at the abattoir accompanied by a vender declaration that details the property of origin (including PIC) and the number of head in the mob. Upon unloading at the abattoir all animals from a particular seller/owner are assigned to specific pens. The details of what lots are in what pens are recorded in the stockyard diary. Prior to entering the knocking box, lots are segregated, counted and presented for ante mortem inspection. The following details are recorded on the small-stock daily kill sheet: pen number (each pen has a unique identifier) number of animals in the lot owner/property of origin lot number (sequential number assigned to each lot) eligibility status National Vender Declaration with-holding periods post sale summary lot accepted or rejected at ante mortem details of any corrective action required At the knocking box the first body in each lot is identified by a lot cut-out ticket which lists the lot number, owner s details, market eligibility and number of head in the lot. This is accompanied by an ante-mortem ticket. At the inspection point these details are captured on computer and any condemnation data recorded against that lot. At the scales the lots are recorded and reconciled against copies of the daily kill sheet and cut-out tickets detailing condemnations. A sequential body number is generated and recorded on the sastec tickets (Figure 7). 10

11 Figure 7: Carcase identification placed on goat carcases at the time of processing Carcase tags identify the body number, the operator, the slaughter lot and the date of processing. These tags remain with the side until the carcase has entered the boning room and the information recorded. Animals can be traced through the process from the supplying farm to a specific time period in the boning room. Animals cannot be traced to a specific carton. Conclusions The work reported in this study highlights the good microbiological quality of skin-on goat carcases and meat produced in Australia. The studies into the effect of bristle and pigmentation on carcase hygiene have demonstrated that these factors do not contribute significantly to the final microbiological quality of the carcase and should not form the basis for any decision on the acceptability of a carcase on the grounds of microbiological safety. Data collected by the Department of Agriculture and Water Resources under the PHI shows that the microbiological quality of skin-on goat carcases is similar to that reported for skinon pig carcases. This is not surprising given the similar processing conditions for these two classes.. 11

12 References Anon (2003). Revised ESAM Program. Meat 2003/6, Department of Agriculture and Water Resources, Retrieved from: Anon (2011). Automated Skin-on goat meat processing. Meat and Livestock Australia, P.PIP Barco, L., S. Belluco, et al. (2014). Escherichia coli and Enterobacteriaceae counts on pig and ruminant carcases along the slaughter line, factors influencing the counts and relationship between visual faecal contamination of carcases and counts: a review. EFSA Supporting Publication, EFSA. EN-634. Bass, C., P. Crick, et al. (2011). "The use of microbiological surveys to evaluate the coregulation of abattoirs in New South Wales, Australia." Food Control 22(6): Biss, M. E. and S. C. Hathaway (1996). "Microbiological contamination of ovine carcases associated with the presence of wool and faecal material." Journal of Applied Bacteriology 81(6): Collins, D. S. (2015). Gracey s Meat Hygiene, 11 th Edition. Collins. D. S. and Huey, R. J. (Ed). Wiley Blackwell, New Jersey (USA): 208. Darcan, N. K., Cankaya, S. and Karakok, S. G. (2009). The effects of skin pigmentation on physiological factors of thermoregulation and grazing behaviour of dairy goats in a hot humid climate. Asian Australasian Journal of Animal Science, 22(5): European Commission (2005). Microbiological Criteria for Foodstuffs. Commission Regulation (EC) No 2073/2005. Official Journal of the European Union, 22/12/2005. Eze, V. C. and N. Ivuoma (2012). "Evaluation of Microbial Quality of Fresh Goat Meat Sold in Umuahia Market, Abia State, Nigeria " Pakistan Journal of Nutrition 11(9): Fisher, A., C.-A. Wilkin, et al. (2007). The production and microbiological status of skin-on sheep carcases. Meat Science 77(4): Ford, R. (2015). Assessing the effectiveness of a carcase hot water decontamination cabinet in small stock processing. Australian Meat Processor Corporation, 3000/5124. Gallina, S., D. M. Bianchi, et al. (2015). "Microbiological recovery from bovine, swine, equine, and ovine carcases: Comparison of excision, sponge and swab sampling methods." Food Control 50: GICA (2016). Goat Facts and Stats, Goat Industry Council of Australia, Gill, C. O. and J. Bryant (1992). "The contamination of pork with spoilage bacteria during commercial dressing, chilling and cutting of pig carcases." International Journal of Food Microbiology 16(1): Gill, C. O., F. Dussault, et al. (2000). "Evaluation of the hygienic performances of the processes for cleaning, dressing and cooling pig carcases at eight packing plants." International Journal of Food Microbiology 58:

13 Gill, C. O. (2004). "Visible Contamination on Animals and Carcases and the Microbiological Condition of Meat." Journal of Food Protection 67(1): Haque, M. A., M. P. Siddique, et al. (2008). "Evaluation of sanitary quality of goat meat obtained from slaughter yards and meat stalls at late market hours." Bangladesh Journal of Veterinary Medicine 6(1): Ivanovic, S., K. Nesic, et al. (2015). "The Microbiological Status of Carcases of Goats Slaughtered in an Inadequate Facility." Procedia Food Science 5: Kannan, G., A. K. Jenkins, et al. (2007). "Preslaughter spray-washing effects on physiological stress responses and skin and carcass microbial counts in goats." Small Ruminant Research 67(1): Kannan, G., V. R. Gutta, et al. (2014). "Preslaughter diet management in sheep and goats: effects on physiological responses and microbial loads on skin and carcass." Journal of Animal Science and Biotechnology 5(42). Kim, C., R. A. Stein, et al. (2015). "Comparison of the Microbial Quality of Lamb and Goat Meat Acquired from Internet and Local Retail Markets." Journal of Food Protection 78(11): Loretz, M., R. Stephan, et al. (2011). "Antibacterial activity of decontamination treatments for pig carcases." Food Control 22(8): Mathews, R., Ryan, T. and Donlan, M. (2015). Australian goat Industry Summary 2015, Meat and Livestock Australia. Meat Standards Committee (2002). Microbiological testing for process monitoring in the meat industry. Pearce, R. A., D. J. Bolton, et al. (2004). "Studies to determine the critical control points in pork slaughter hazard analysis and critical control point systems." International Journal of Food Microbiology 90:

14 Appendix 1 Microbiological counts on areas of high and low bristle density from paired carcases sampled before the final trim. APC Coliforms E coli DATE 1 CODE 2 (CFU/cm2) (CFU/cm2) (CFU/cm2) 18/01/2016 #1B 37.5 < < /01/2016 #2B 7.5 <0.25 < /01/2016 #3B 7.5 <0.25 < /01/2016 #4B 7.5 <0.25 < /01/2016 #5B 2.5 <0.25 < /01/2016 #1B /01/2016 #2B 2.5 <0.25 < /01/2016 #3B /01/2016 #4B < /01/2016 #5B <2.5 <0.25 < /01/2016 #1B 65.3 <0.25 < /01/2016 #2B <2.5 <0.25 < /01/2016 #3B <2.5 <0.25 < /01/2016 #4B 22.5 <0.25 < /01/2016 #5B /01/2016 #1B 35.3 <0.25 < /01/2016 #2B 2.5 <0.25 < /01/2016 #3B <2.5 <0.25 < /01/2016 #4B 5.0 <0.25 < /01/2016 #5B 12.8 <0.25 < /01/2016 # < /01/2016 # <0.25 < /01/2016 #3 <2.5 <0.25 < /01/2016 #4 <2.5 <0.25 < /01/2016 #5 2.5 <0.25 < /01/2016 # < /01/2016 # < /01/2016 # <0.25 < /01/2016 #4 2.5 <0.25 < /01/2016 #5 9.8 <0.25 < /01/2016 # < /01/2016 #2 7.5 <0.25 < /01/2016 #3 2.5 <0.25 < /01/2016 #4 7.5 <0.25 < /01/2016 # /01/2016 # <0.25 < /01/2016 #2 2.5 <0.25 < /01/2016 #3 <2.5 <0.25 < /01/2016 # <0.25 < /01/2016 # < Date carcases sampled; 2 Sample number (B=Bristle) 3 Counts preceded by < are below the limit of detection for that test 14

15 Appendix 2 Microbiological counts on pigmented and non-pigmented areas of carcases. APC Coliforms E coli DATE 1 CODE 2 (CFU/cm2) (CFU/cm2) (CFU/cm2) 18/01/2016 #1P <3.3 3 <0.33 < /01/2016 #2P <3.3 <0.33 < /01/2016 #3P <3.3 <0.33 < /01/2016 #4P <3.3 <3.3 < /01/2016 #5P 37 <0.33 < /01/2016 #1P 270 <0.33 < /01/2016 #2P 77 <0.33 < /01/2016 #3P 200 <0.33 < /01/2016 #4P 100 <0.33 < /01/2016 #5P 4, < /01/2016 #1P <3.3 <0.33 < /01/2016 #2P <3.3 <0.33 < /01/2016 #3P 3.3 <0.33 < /01/2016 #4P 6.7 <0.33 < /01/2016 #5P <3.3 <0.33 < /01/2016 #1P 60 <0.33 < /01/2016 #2P 6.7 <0.33 < /01/2016 #3P 10 <0.33 < /01/2016 #4P 3.3 <0.33 < /01/2016 #5P 3.3 <0.33 < /01/2016 #1 27 <0.33 < /01/2016 #2 73 <0.33 < /01/2016 #3 670 <0.33 < /01/2016 #4 10 <0.33 < /01/2016 #5 13 <0.33 < /01/2016 # /01/2016 #2 8, < /01/2016 #3 2,300 1 < /01/2016 # < /01/2016 #5 1,700 <0.33 < /01/2016 #1 43 <0.33 < /01/2016 #2 43 <0.33 < /01/2016 #3 17 <0.33 < /01/2016 # /01/2016 #5 <3.3 <0.33 < /01/2016 #1 3.3 <0.33 < /01/2016 #2 17 <0.33 < /01/2016 #3 <3.3 <0.33 < /01/2016 #4 <3.3 <0.33 < /01/2016 #5 3.3 <0.33 < Date carcases sampled; 2 Sample number (P=Pigmented) 3 Counts preceded by < are below the limit of detection for that test 15

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