Final Report for GS04-042
The microbiological quality of whole rabbit carcasses were determined at pre and post-evisceration and pre and post chilling during processing of whole rabbit carcasses from a regional rabbit processing facility. Data indicated Salmonella, Staphylococci and total viable plates counts were significantly reduced for pre and post-chilled whole rabbit carcasses compared to samples tested at pre and post-evisceration.
Worldwide rabbit meat consumption is estimated to be 1,000,000 tons annually. Consumption of this meat is increasing in the United States as evidenced by the recent awarding of a contract to Tri-state Rabbit Growers (Alabama, Tennessee and Mississippi) to provide quality whole rabbit meat to a major cruise line and Sysco foods, Inc. However, most of this meat is produced by small processors that may not have resources to conduct investigations on the quality and safety of their product. Studies have been performed to evaluate the overall microbial quality of rabbit meat carcasses, but no attention has been given to investigate the incidence of specific foodborne pathogens on rabbit meat and the feasibility of adapting HACCP plans in small farmer rabbit producers. Rabbit carcasses may allow survival of microorganisms because of its relative high pH (5.9 to 6.2) after dressing.
1: To determine incidence of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on whole carcass rabbit meat.
2: Determine the feasibility of incorporating HACCP plans into small farm rabbit producers.
Baseline levels of microorganisms on vacuum packaged whole rabbit carcasses was determined by laboratory investigation. Microbiological testing included total viable counts at 4°C and 25°C, for Escherichia coli, coliforms, Salmonellae, E. coli O157:H7, Staphylococcus aureus, Campylobacter jejuni, and Listeria monocytogenes. The aim of this investigation will be to identify which potentially pathogenic organisms may be present on the rabbit products, so that barriers can be put in place in the processing line to minimize the likelihood of such organisms surviving or multiplying to levels which may limit product acceptability.
Rabbit carcass sampling
Rabbit carcasses (weighing less than 2 kg and 12 to 14 weeks of age) was sampled according to FSIS/USDSDA standards for non-traditional and exotic meats (FSIS/USDA, 1996). The employed protocols will prove to be the most effective method of sampling as the whole carcass area was sampled. Carcasses will be massaged with 500 ml buffered peptone water (BPW) in sterile ‘stomacher bags’ and the resultant wash retained for testing. The carcasses was sampled and tested over an 8 day storage period aerobically and under vacuum packaging.
Development of HACCP Plans
The process for rabbit processing will be examined individually. The HACCP plans developed will contain:
1. Description of the food borne pathogens
2. Product description
3. Flow diagram of the process
4. Critical control point (CCP) determination
5. HACCP audit table
A HACCP plan for each rabbit processing line was developed generically to allow application, with minor modification, to other processing plants. Shelf life trials was conducted on vacuum packaged whole rabbit carcasses. These products was used as these will be the usual way such meat is presented to the respective customers. Product was collected from processing plants and stored at 4°C and tested periodically for TVC, E.coli, coliforms, Pseudomonas spp., Lactobacillus spp. and Brochothrix thermosphacta until microbiological spoilage was evident. Rabbit vacuum packs was tested weekly while rabbit carcasses were tested every 2-days, for a period of one week.
Pre and post food safety questionnaires
A student pre/post-food safety survey was conducted during the planning period (January – March) and at the conclusion (May) of the project. The purpose of the questionnaire will be to determine current food safety knowledge of our students before and after the food safety campaign on the campus of AAMU. All surveys was developed in collaboration with project investigators and the Educational Testing and Information Systems Office (ETIS) on the campus of Alabama A&M. All surveys was computer generated, sent to all students, faculty and staff via email two months before (Jan and Feb.) and after (May) the food safety marketing campaign. All responses was recorded and tabulated by ETIS, analyzed by project directors and make available at the conclusion of the project for food safety data comparison.
A complete randomized block arrangement was used as the experimental design. Data was collected in triplicate and replicated three times. Analysis of variance (ANOVA) using general linear model (SAS, 2000) was used to analyze the data. If means significant differences are found at a confidence level of p≤ 0.05, the mean separation test (Tukey’s studentized range tests) was used to determine where the differences occur.
The funding from USDA-SARE has allowed us to travel to rabbit processing plant in Hattiesburg, MS (Rabbit Man Rabbitry) to conduct research and strengthen this objective. A total of two trips have been made to collect samples and determine the most effective ways to ensure the processing of wholesome and pathogen free rabbit meat. While at the processing plants, our research team (Dr. Williams and Mr. Howard) had the opportunity to talk with plant managers and staff to gain a better understanding of our role and how AAMU may continue to play an important part helping the rabbit industry continue to grow. Currently, our research has focused on determining critical control points for the rabbit processing and determining specific pathogens (E. coli O157:H7; Salmonella spp.; Staphylococcus aureus; Listeria monocytogenes and total viable counts) from four sampling points (pre-evisceration, pre-chill, post-evisceration and post chill) during processing. The total viable counts represent the total populations of microorganisms in/ on the surfaces of the rabbit carcasses. There were no significant differences (p ≥ 0.05) in the numbers of microorganisms recovered from the whole rabbit carcasses at each sampling points. The total viable counts ranged from mean log10 cfu/carcass 4.69 to 4.91 for post evis and post chill, respectively. Slightly higher numbers were recovered from post chilled carcasses compared to pre chilled carcasses. Although slightly higher, the increase was not significant (p≥0.05).
Salmonellae counts on the whole rabbit carcasses were significantly (p ≤ 0.05) higher for counts of Salmonellae isolated from the pre-evis and pre chill samples compared to post evis and post chilled carcasses. The dipping of rabbit carcasses into tempered (~12°C) water and chilled tank (~2°C) significantly reduced the Salmonella counts from average of log10 4.60 and 4.23 cfu/carcass for pre evis and prechill to average of log10 3.98 and 3.25 cfu/carcass for post evis and post chilled carcasses. These numbers remained low after chilling suggesting that the storage of carcasses in chilled water can reduce Salmonella by approximately 2 logs when properly stored.
Staphylococcus aureus were also significantly (p≤ 0.05) reduced after dipping in chilled holding tanks. There were significant reductions in S. aureus counts were reduced from an average of log10 4.10 to 3.34 cfu/carcass for pre-evis and postevis, respectively. Similar numbers of log10 3.96 and 2.93 cfu/carcass were recovered for prechill and post chill, respectively.
The number of E. coli recovered from whole rabbit carcasses followed a similar trend. Sample collected from post-evis resulted in significantly (p≤ 0.05) lower number compared to pre-evis samples. An average of log10 4.10 and 3.40 cfu/carcass were recovered for pre-evis and post-evis, respectively. This trend suggested that pre-evisceration steps (before removal of viscera, hair, etc.) may have a significant impact on the recovery and survival of E. coli from rabbit carcasses before they are fully dressed and dipped into continuous water holding tank. There was no significant reductions found among the carcasses sampled from both pre (log10 4.58 and 4.58 cfu/carcass), respectively.
Educational & Outreach Activities
Several research presentations have been made at international and national scientific meetings by Dr. Williams and several of his graduate students. Recently, a total of three scientific presentations were presented at food safety conferences, receiving positive responses from numerous attendees. Brandee Dowdy-Hunter, a former graduate student in Dr. Williams’ food microbiology laboratory conducted her thesis research titled “Reduction of Citrobacter freundii, Pseudomonas fluorescens and Hapnia alvei during storage on lean ground rabbit meat sanitized with organic acids”. Her work is currently in the process of being prepared for publication. Overall 4 manuscripts are in pipeline for submission to journals such as Journal of Food Protection and Journal of Food Safety.
In addition to presentations, this SARE project results were dessiminated through regional states (KY, MS, GA, AL,and TN) in Co-op newsletters, AALGA Report and Tri-State Rabbit Growers Assoc. monthly newsletter.
At the conclusion of funding period, the general consensus is that important parts of the goals and objectives were met. Several changes to rabbit husbandry and processing practices are currently being implemented and adopted by several rabbit producers and processors as a result of the findings from this study funded by SARE. Dr. Leonard Williams met with numerous rabbit growers at local and regional meetings to disseminate our findings as they became available. Because of this research funded by SARE, a closer partnership with Auburn and Tuskegee University has been fostered. In particular, several proposals to continue this work has begun between Auburn and Tuskegee Universities.