Abstract
Freshly slaughtered pork carcasses were treated with various concentrations of acetic and propionic acid mixed in 60:40 ratio (w/w). Both inhibition of microbial growth and the effects of the acids on carcass appearance were noted. Results from treatment of 116 pork carcasses in a local processing plant showed significant differences in the number of microorganisms on treated and control sides, the locations of sampling on the carcasses and the concentrations of acids used. No difference was noted in numbers of organisms on control sides examined on the 5 different days on which samples were obtained. The use of propionic acid with acetic acid resulted in a reduction of microorganisms at higher pH than when only acetic acid was used. Treatment with 1.5 M acetic: propionic acid (60:40, w/w) (pH 2.3) resulted in a two log cycle reduction in total numbers with no apparent detrimental effects on the carcass. Salmonellae were isolated and identified. Microbial contamination is the result of the slaughter and dressing processes necessary for the conversion of meat animals into food for humans (Haines, 1931, 1933 a,b; Scott, 1931; Haines and Smith, 1933; Empey, Scott and Vickery, 1934; Empey and Scott, 1939; Ayres, 1955; Shotts, Martin and Galton, 1961). The factors that affect the nature and extent of contamination have been reviewed by several investigators (Empey and Scott, 1939; Jensen and Hess, 1954; Ingram, 1964; Mulcock, 1964; Patterson, 1967; Grau, Brownlie and Roberts, 1968). Washing the animal prior to slaughter with cold water (Empey and Scott, 1939), or with hot water (74 C) (Shotts et al., 1961; Patterson, 1970) and various washing, brushing and drying combinations (Patterson, 1968) have all been reported as effective in reducing microbial numbers on carcasses. The use of chemicals in reducing bacteria, particularly salmonellae, on meat and poultry has been reported by Dixon and Pooley (1961), Nilsson and Regner (1963), Mountney and O'Malley (1965) and Thompson et al. (1967) with varying results. Biemuller, Carpenter and Reynolds (1973), using hydrogen peroxide, stannous chloride, acetic acid and steam, found that these agents were effective in eliminating salmonellae and reducing total bacterial populations but not all treatments were acceptable from the standpoint of carcass appearance. Chung and Goepfert (1970) found acetic and propionic acids to be the most effective of 13 acids tested in inhibiting the growth of salmonellae in tryptic soy broth under optimum laboratory conditions. Solutions of acetic and propionic acids (60:40, w/w) are used as fungicides on cereal grains in storage. The present study was conducted to evaluate the effects of these acids on reduction of total microorganisms and elimination of salmonellae when applied directly on pork carcasses. Information of this type would be particularly useful to the meat industry should restrictions on bacterial levels in meat be established by regulations. Copyright © 1974. American Society of Animal Science . Copyright 1974 by American Society of Animal Science