Determining the viability and stability of Bacillus in baked products

Bacillus spores have emerged as a promising alternative to traditional probiotics, such as Lactobacillus, due to their reported resistance to harsh processing conditions. This study evaluates the impact of five variables—water activity, fat content, salt content, baking time, and baking temperature—on the viability of four probiotic strains: Lactobacillus acidophilus, Bacillus subtilis 1, Bacillus subtilis Novonesis ProSilience™ HU58™, and Bacillus coagulans GBI-30, 6086, all with claimed probiotic properties. Results demonstrated that both B. subtilis strains exhibited the highest resistance across all conditions tested, with average viability reductions of less than 1 log. The highest log reductions came from baking these probiotics at 235 °C, averaging 1.5 log reductions. In contrast, L. acidophilus showed the greatest susceptibility to processing factors, experiencing an average of 2.5 log reductions and upwards of 5 log reductions (during baking) in viability. B. coagulans, while remaining above the threshold for human consumption (10⁶ cfu/g), experienced significant viability loss—averaging 2.39 log reductions—due to salt content (average 3 log reductions), baking time, and baking temperature. The high stability of the B. subtilis strains under these conditions highlights their potential for use in food products that undergo harsh processing, providing valuable insights for food and probiotic producers seeking to develop functional foods with consistent health benefits. These findings suggest that Bacillus probiotics, particularly B. subtilis, may be better suited for incorporation into processed food products compared to traditional Lactobacillus strains.