Search Results (3)

The concept of using ‘acid-adapted’ challenge cultures in the microbial validation of food processes that incorporate an acidic treatment is that they would be more resistant to acid and require a robust process to obtain targeted log reductions. The recent confirmation that acid-adapted Salmonella challenge cultures for droëwors and biltong processes are more sensitive to those processes than non-adapted cultures changes that preference for the use of non-adapted cultures for validation studies with these specific processes. However, it is difficult to achieve > 5-log reductions with non-adapted cultures, one of two USDA-FSIS parameters available for validation of processes that are not aligned with traditional process conditions for dried beef products in the USA (i.e., beef jerky). A natural multipurpose (flavor, antimicrobial) commercial product, described as a refined liquid smoke flavorant, provided >7-log reductions with droëwors when challenged with non-adapted cultures of Salmonella (5-serovar mixture), Shiga toxigenic Escherichia coli (STEC, four-strain mixture), and Listeria monocytogenes (four-strain mixture) as well as a >7-log reduction with biltong processing (vs Salmonella). Comparisons between standard droëwors and biltong processes (all <5-log reductions) using non-adapted challenge cultures vs. the same formulation plus 0.75% pyrolyzed liquid smoke extracts (Flavoset) showed greater and significant (p < 0.05) reductions in duplicate trials with triplicate samples at each sampling point in each trial (total n = 6) when analyzed by repeated measures analysis of variance (RM-ANOVA). Although sold as a flavorant, this study examines the antimicrobial properties of Flavoset 5400L to improve the safety of droëwors and biltong by achieving a >5-log reduction with non-adapted pathogenic challenge cultures. Validation processes for droëwors and biltong established with these parameters should result in greater safety of marinaded, non-thermally processed meats from traditional foodborne pathogens commonly associated with meats or meat processing environments. Full article

US food regulatory agencies have adopted a preference for researchers and testing labs to use ‘acid-adapted challenge cultures’ when performing inoculated validation studies of food processes that involve acidic treatments to accustom the cultures to acidic pH so that they will not be easily affected during processing. We evaluated acid adaptation in regard to the processing of South African style air-dried beef, notably biltong and droëwors, using a mixture of five serovars of Salmonella as well as a unique serovar isolated from dried beef (Salmonella Typhimurium 1,4,[5],12:i:-). Acid adaptation was obtained by growing cultures in tryptic soy (TS) broth containing 1% glucose. Non-adapted cultures were obtained by growth in TS broth without glucose or in TS broth with 1% glucose but buffered with 0.2 M phosphate buffer. Processes included biltong (dried solid beef) and droëwors (ground, sausage-style). Each trial was performed twice and triplicate samples were examined at each sampling point (i.e., n = 6). Statistical analysis was applied using analysis of variance (ANOVA) or one-way repeated measures (RM-ANOVA) and the Holm–Sidak test for pairwise multiple comparisons to determine significant differences (p < 0.05). We observed that in all processes examined (eight trials), treatments using acid-adapted cultures were more sensitive to the biltong and droëwors processes, giving greater reductions (5.3-log reduction) than when non-adapted cultures were used (3.8-log reduction). Acid adaptation leads to stressed conditions in Salmonella resulting in sensitization to the multiple hurdles found in biltong and droëwors processing (acid/vinegar, salt, desiccation). Based on our data, the use of non-adapted Salmonella cultures to achieve desired challenge culture process lethality could result in more robust processing conditions and a greater level of safety in these products as intended by US regulatory guidance. Full article

The physico-chemical properties (proximate, salt content, water activity (a_w), pH) and lipid oxidation of droëwors (dried salted/spiced meat sausages) produced with zebra meat and different sheep fat levels (10, 15, and 20% by weight) measured at day 0 (before drying), day 2 (after drying at 30 °C and 40% relative humidity), and over a 90 day storage (day 17, 32, 47, 62, 77, and 92) under vacuum at 25 °C were investigated. The use of lower fat levels (10 and 15%) in the formulation resulted in higher weight loss during drying and droëwors with higher protein, ash, and salt content and lower a_w and pH compared to the droëwors made with 20% fat. The pH increased (p < 0.001) during storage for all the fat levels, while the moisture content and the a_w were stable as expected. TBARS values were the highest in droëwors made with 20% of fat after drying (day 2), but droëwors made with 10% of fat reached similar maximal values on day 17. Formulations containing 15% sheep fat displayed the lowest TBARS values after drying and along storage, and thus had the best characteristics in relation to oxidative stability. Full article