Chemical, Microbial, and Sensory Effects of Natural Preservatives as Sulfur Dioxide Replacers in Boerewors

This study determined whether natural preservatives, when used as substitutes for sulfur dioxide (SO₂) in Boerewors, influenced water activity (a_w), pH, and moisture content; microbial and sensory quality; and the lipid oxidative and color stability in Boerewors models. The inclusion of sulfur dioxide at 0.035% (positive control), formulation without preservatives (negative control); protective cultures (PrC1 and PrC2), containing lactic acid bacteria; and plant extract blends (KD1 and KD2), containing rosemary and acerola extracts and buffered vinegar, were evaluated. The use of KD2 increased pH on Days 0 and 6, but the increased pH did not affect the microbial preservative effect. The a_w of the treatments was stable over 6 days and therefore also did not have an influence on the microbial preservative effect of the natural preservatives. Both plant extract preservatives (KD1 and KD2) increased the oxidative stability of lipids more than any other treatment, including the positive control. The microbial stability results were inconclusive because of the protective cultures, which increased the total bacteria count. The counts of coliform and Enterobacteriaceae, Escherichia coli, and Staphylococcus aureus were analyzed, but significant differences between the treatments were not observed. KD1, which contained rosemary plant extract, maintained the lowest TBC at the same level as the positive control but had a slightly lower redness score. Treatments had no effect on sensory evaluation. The use of KD1 and KD2 plant preservatives proofed to be worthy as replacers of SO₂ in Boerewors. This manuscript contains research data that formed part of an M.Sc. thesis. This manuscript also contains materials and methods that were used in a Ph.D. thesis where salt reduction in South African meat products was evaluated.