Effects of various processing techniques and interventions on beef safety and shelf-life

2017 Spring.Includes bibliographical references.Two experiments were conducted; the first evaluated decrease in log survival of pathogenic bacterial populations using three antimicrobial interventions (Peroxyacetic acid – PAA; Lactic Acid – LA; lactic/citric acid blend – LCA) applied at a spray cabinet used just before carcass chilling. Efficacy was evaluated using a Shiga-toxin producing Eschericia coli (STEC) inoculation cocktail that incorporated two strains of E. coli O157:H7 and 12 non-O157 STEC strains. In addition, this study was intended to validate the use of non pathogenic E. coli to serve as surrogates for the aforementioned STEC cocktail in plant operations. Influence of the carcass interventions on color stability of beef subprimals over a 30-day storage period was included to simulate effects on storage and display life. Each day, for three sampling days, 90 hot tissue samples from the plate subprimal were obtained immediately following slaughter. The tissue samples were evenly split into two inoculation groups (n = 45 samples/group): 1) STEC, or 2) surrogate. Within each inoculation group, samples were assigned randomly to one of nine treatments: i) 200 ppm PAA; ii) 1% LCA; iii) 1.5% LCA; iv) 2.5% LCA; v) 5% LA; vi) 8% LA; vii) 10% LA; viii) potable water; or ix) untreated control. Samples assigned to the surrogate inoculation group were further portioned into two equal sections for evaluation of the treatment influence on microbiological decrease in log survival and color. Samples were subjected to treatment using a custom-built, laboratory-scale spray cabinet to apply the intervention. Lightness (L*), redness (a*), and yellowness (b*) was evaluated before and immediately following spray application using a portable spectrophotometer. Following assessment of color immediately post-treatment application, the sample was further divided into three subsections that were vacuum packaged and stored for color evaluation at 10, 20, and 30 d. Among samples inoculated with STEC, log survival means with potable water and control were greater (P 0.05) were observed among PAA, 1.5 and 2.5% LCA. Pairwise comparisons of surviving populations of STEC and surrogates revealed that the non-pathogenic strains could be effectively used as surrogates for the STEC cocktail. Color measures of L* values for samples spray treated with 8 or 10% LA were lower (P 0.05) or increased (P < 0.05) with retail case storage time