Microbial safety evaluation of drum dried pregelatinized sweet potato flour during storage
Widya Dwi Rukmi Putri *, Arsy Aulia Putri Wibisono, Dian Widya Ningtyas

Faculty of Agricultural Technology, Department of Food Science and Biotechnology, Brawijaya University, Indonesia
*Email: widya2putri[at]ub.ac.id

Abstract

Sweet potato (Ipomoea batatas L.) is widely cultivated in Indonesia and serves as an important carbohydrate source. However, its high moisture content limits shelf life, leading to rapid deterioration. Processing sweet potatoes into instant flour through pregelatinization followed by drum drying can extend shelf life and broaden utilization. Nevertheless, the high carbohydrate content makes the flour susceptible to microbial contamination. This study evaluated microbial quality by measuring Total Plate Count (TPC) and detecting Escherichia coli using the Most Probable Number (MPN) method in pregelatinized sweet potato flour immediately after production and after six months of storage. The varieties examined were Beta 1, Ase, Cilembu, TW, and IR Kalipare. A Randomized Block Design (RBD) was applied, and data were analyzed using Analysis of Variance (ANOVA), followed by the Least Significant Difference (LSD) test at a 95% confidence level when significant effects were observed. TPC values in all varieties exceeded 3 x 10^9 CFU/g both before and after storage, indicating non compliance with the Indonesian National Standard (SNI). In contrast, all samples tested negative for E. coli, fulfilling SNI requirements. The findings highlight that although pregelatinization followed by drum drying effectively produces instant sweet potato flour free from E. coli contamination, additional interventions are required to control total bacterial counts and meet food safety standards during storage.

Keywords: Drum drying-Microbial analysis-Pre gelatinization-Sweet potato flour-Total plate count

Topic: Food science and biotechnology