Validation of a hot water rinse and lactic acid spray in combination with scaling for treating hide-on carcasses to control biotype I strains of Escherichia coli used as surrogates for Shiga toxin-producing E. coli

Authors: HASTY, JOSHUA - Fresno State University; HENSON, JOHN - Fresno State University; ACUFF, GARY - Texas A&M University Health Science Center; BURSON, DENNIS - University Of Nebraska; Luchansky, John; SEVART, NICHOLAS - Kansas State University; PHEBUS, RANDALL - Kansas State University; Porto-Fett, Anna; THIPPAREDDI, HARSHAVARDHAN - University Of Nebraska

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2018
Publication Date: 5/5/2018
Citation: Hasty, J.D., Henson, J.A., Acuff, G.R., Burson, D.E., Luchansky, J.B., Sevart, N.J., Phebus, R.K., Porto Fett, A.C., Thippareddi, H. 2018. Validation of a hot water rinse and lactic acid spray in combination with scaling for treating hide-on carcasses to control biotype I strains of Escherichia coli used as surrogates for Shiga toxin-producing E. coli. Journal of Food Protection. 81:762-768.

Interpretive Summary: About 100 million pounds of veal, that being meat from calves or very young cattle, are consumed annually in the U.S. In recent years, however, there have been several recalls veal products due to contamination with bacterial pathogens such as Shiga toxin-producing Escherichia coli (STEC). The USDA Food Safety and Inspection Service (FSIS) has also reported a higher prevalence of 6 (sero)types of STEC in trimmings from raw veal products compared to trimmings from raw beef products. Although an explanation for why the prevalence of select STEC are higher in veal than in beef and/or why there have been an increased number of recalls over the last 5 years or so attributed to veal has not been fully elaborated, it is clear that interventions must be developed to lower the occurrence and levels of STEC during veal slaughter and further processing. In the present study we evaluated the effect on hide-on and subsequently eviscerated veal carcasses of immersion in a scald tank (60degreeC; with and without harsh chemicals) along with hot water (82.2degreeC) washing and lactic acid (4.5%) spraying on levels of STEC surrogates both before and after overnight chilling. Our results showed that scalding, washing, and/or spraying hide-on veal carcasses with water (with or without chemicals) was effective for lowering levels of STEC surrogates by at least 100,000 colony forming units per centimeter squared of veal. It should be noted that such treatments did not adversely affect the rate/efficiency of chilling and/or the pH decline or color characteristics of the veal. These findings will be particularly useful to small and very small processors of veal for lowering the public health risk associated with STEC on veal.

Technical Abstract: Scalding of hide-on bob veal carcasses with or without standard scalding chemical agents typically used for hogs, followed by an 82.2degreeC hot water wash and lactic acid spray (applied at ambient temperature) prior to chilling, was evaluated to determine its effectiveness in reducing the levels of surrogate strains for Shiga toxin-producing Escherichia coli. A five-strain cocktail of rifampicin resistant, non-pathogenic E. coli (E. coliRif) surrogates was used to inoculate veal carcass hides immediately after exsanguination (target inoculation level of 7.0-log CFU/100 cm2). For carcasses receiving no scalding treatments, spraying with 82.2degreeC water as a final wash resulted in a 4.5-log CFU/100 cm2 surrogate reduction, and an additional 1.2-log CFU/100 cm2 reduction was achieved by spraying with 4.5% lactic acid prior to chilling. Scalding hide-on carcasses in 60degreeC water (no chemicals added) for 4 min resulted in a 2.1-log CFU/100 cm2 reduction in surrogate levels, and a subsequent pre-evisceration 82.2degreeC water rinse provided an additional 2.9-log CFU/100 cm2 reduction. Spraying a 4.5%-solution of lactic acid onto scalded, hide-on carcasses (after 82.2degreeC water rinse) resulted in a minimal additional reduction of 0.4-log CFU/100 cm2. Incorporation of scalding chemicals into the scald water resulted in a 4.1-log CFU/100 cm2 reduction (1.9 log CFU/100 cm2 greater than scalding without chemicals) in the surrogate population, and the first 82.2degreeC wash provided an additional 2.5-log CFU/100 cm2 reduction. Application of antimicrobial interventions did not affect the carcass temperature decline during chilling, pH decline or the color characteristics of the rib-eye or the flank of the bob veal carcasses. The availability of validated antimicrobial interventions will allow bob veal processors to weigh the quality and yield advantages of chilling carcasses with hide-on in relation to their overall food safety objectives.