Background

The reduction of E. coli O157:H7 in both pre- and post-harvest areas continues to be a major goal of the beef industry. It has been demonstrated that cattle hides are the major source of E. coli O157:H7 contamination in processing plants. The reduction of E. coli O157:H7 on cattle hides will go a long way in ensuring the safety of the beef supply.

Researchers and beef packers/processors have addressed beef safety concerns by developing a variety of methods that are now implemented, or are being further developed, to reduce numbers of bacteria on beef and beef products and improve microbiological safety. These microbiological decontamination technologies include:

• Animal cleaning; 
• Chemical dehairing at slaughter;
• Spot-cleaning of carcasses by knife-trimming or steam/hot water vacuuming; and
• Spraying/washing/rinsing of carcasses before evisceration and/or before chilling, with water, chemical solutions and/or steam or hot water.

The most commonly used decontamination strategies involve the use of water and steam at various temperatures and spray pressures. Other decontamination strategies involve the use of FDA-approved chemicals applied through water-based sprays.

The objectives of this study were to measure the impact of SANOVA treatment on the aerobic plate count (APC), total coliform and generic E. coli populations of post-chill beef carcasses and to assess microbial growth during the chilling process.  

Methodology

Twenty post-chill carcasses (sides) were selected before fabrication and tracked. SANOVA was mixed from concentrates and sprayed on the lower half (front quarter section) of each carcass for a total of 16 seconds (0.5 gallons). The entire procedure was repeated over 2 days for a total of 40 sides treated.

Sides were sampled before and after the SANOVA spray treatment. Two types of samples were taken, sponge samples and excision samples. Sponge samples were collected from two sites on the neck and one site on the shank. Different sites were sampled before and after the treatment so as not to sample the same spot twice. Excision samples were taken from the lower neck region by cutting a 50-100g portion of the region. Samples were then shipped for analysis of APC, total coliforms and generic E. coli. Samples were grouped according to treatment group and results were reported as CFU/g.

Findings

Data collected over the two days of testing show significantly higher contamination on the first day of testing with 15 of 20 swab samples having Escherichia coli levels of 10-100 CFU/cm². No E. coli was detected after SANOVA treatment for all 40 swab samples and all 10 excision samples. SANOVA treatment also reduced total coliforms to below detection limit for 38 of 40 swab samples and 7 of 8 excision samples. Aerobic plate count was reduced on average from 203,509 CFU/cm² to 58 CFU/cm² (swabs) and from 601,170 CFU/cm² to 770 CFU/cm² on excision samples (99% reduction for both sampling methods).

Implications

The results of this study showed that SANOVA treatment of post-chill beef carcasses significantly reduces microbial contamination.