Study of benzoate, propionate, and sorbate salts as mould spoilage inhibitors on intermediate moisture bakery products of low pH (4.5-5.5)

A hurdle technology approach has been applied to control common mold species causing spoilage of intermediate moisture bakery products (Eurotium spp., Aspergillus spp., and Penicillium corylophilum), growing on a fermented bakery product analogue (FBPA). The factors studied included a combination of different levels of weak acid preservatives (potassium sorbate, calcium propionate, and sodium benzoate; 0-0.3%), pH (4.5-5.5), and water activity (aw; 0.80-0.90). Potassium sorbate was found to be the most effective in preventing fungal spoilage of this kind of products at the maximum concentration tested (0.3%) regardless of aw. The same concentration of calcium propionate and sodium benzoate was effective only at low aw levels. On the other hand, potassium sorbate activity was slightly reduced at pH 5.5, the 0.3% being only effective at 0.80 aw. These findings indicate that potassium sorbate may be a suitable preserving agent to inhibit deterioration of a FBPA of slightly acidic pH (near 4.5) by xerophilic fungi. Further studies have to be done in order to adjust the minimal inhibitory concentration necessary to obtain a product with the required shelf life.