Fungal composition, quantification of mycotoxins, and enzyme activity in processed Solanum tuberosum Linn (potato) products stored at different relative humidity

Abstract

Aim Postharvest loss of potatoes at the peak of harvest is of global concern. This study aimed to determine the quality of stored processed potato products based on fungal composition, mycotoxin contamination and fungal enzyme activity. Materials and Methods Potato products from three cultivars (Caruso, Marabel and Nicola) were grouped as peeled or unpeeled, oven- or sun-dried and all samples were in flour form. Samples were incubated separately for six weeks at 25%, 74% and 87% relative humidities (RH) at 25 °C. The pH, moisture content, visible deterioration, mycotoxin, fungal identity by DNA sequencing, and enzyme activity were determined. Results Results of grouped products (based on variety, drying and peeling method) revealed that moisture content increased in the oven-dried samples and the pH value reduced after incubation. About 26% of the products at 87% RH showed visible deterioration, low amounts of fumonisin were detected in fermented potato product and nine fungal genera were identified across the three RH levels. Enzyme activities by Aspergillus niger, Fusarium circinatum and Rhizopus stolonifer isolates were confirmed. Conclusion RH influenced deterioration and fungal activities in some stored processed potato products. Low levels of fumonisin were detected.