Extending the Shelf Life of Bolu Kukus with the Utilization of Potassium Sorbate as Mold Inhibitor

Abstract

Bolu kukus is a traditional Indonesian steamed cake which is commonly made from wheat flour. There is limited research on the shelf life of bolu kukus, especially on its microbiological quality. Bakery product spoilage is predominantly caused by mold growth from recontamination in post-baking/ post-steaming processes which limits the shelf life to 3-4 days. To counter mold growth, 0.1% potassium sorbate was utilized as a mold inhibitor in bolu kukus. Total yeast and mold count analysis was conducted on all bolu kukus samples (company, control, and treatment) throughout the 9 days of shelf life testing (day 0, 2, 4, 7, and 9). The total yeast and mold count result suggests that based on SNI 7388-2009 standards (<1x104 CFU/g), the bolu kukus with potassium sorbate (1.24x104 ± 8600 CFU/g) did not have better shelf life in comparison to control bolu kukus (7.2x104 ± 11000 CFU/g) at 4 days. However, based on visual observation of the samples the control samples showed surface mold growth on day 4 while the treatment samples on day 7. Meanwhile, the company samples showed the shortest shelf life of 2 days. The treatment samples exceeding the SNI 7388-2009 standards on day 4 may be caused by a higher contamination rate in comparison to control samples. The effectiveness of preservatives is dependent on the inoculum size where larger inoculum sizes require a high concentration of preservatives. Potassium sorbate was not utilized under optimal conditions in bolu kukus. Further analysis on bolu kukus is required, especially other intrinsic factors affecting mold growth such as, pH and water activity.