Effect of magnetic field strength and exposure time on physicochemical properties, biochemical properties, Mould count and shelf life of arrowroots (colocasia esculenta) during storage

Abstract

Arrowroot, an important food crop, experiences significant post-harvest losses due to physicochemical deterioration, biochemical degradation, and microbiological spoilage resulting to a short shelf life. This study used a 4×3factorial arrangement in a completely randomized design (CRD) taking into account repeated measures on day 1, 7, 14, and 25, to include four levels of magnetic intensity (0, 6, 7, and 8 µT) and three exposure times (30, 60, and 90 minutes). Key physicochemical properties including weight, firmness, and colour were assessed using a weighing scale, penetrometer, and chroma meter, respectively. Biochemical tests included total phenolic content (TPC) measured by the Folin-Ciocalteu method and antioxidant activity assessed using the DPPH assay. Microbial stability was evaluated by mould counts using the Standard Plate Count (SPC) method. Shelf life was determined through the survival method by visually assessing attributes of discoloration, softening, mould growth and odour of the treated samples against the controls. Data was subjected to analysis of variance ANOVA and, Tukey’s post-hoc test with a significance level of α=0.05. The results showed that magnetic field treatment significantly reduced weight loss (P < 0.05), with the 8 µT intensity resulting in the lowest weight loss (45.68% after 25 days) compared to the control. The treatment also preserved firmness (P < 0.001) and, reduced browning (P < 0.01), with intensities of 7 µT and 8 µT maintaining significantly better firmness and better colour preservation throughout storage. TPC and antioxidant activity increased significantly (P < 0.05) in treated samples, with TPC maximum at 286.62 mg GAE/100g after 60 minutes of 7 µT treatment. Mold growth decreased substantially (P < 0.05) in treated samples, resulting in lower mould counts. Shelf life was increased from 7 days in the control to 15 days in treated samples (P < 0.01). These findings suggested that magnetic field treatment could be a viable non-thermal, chemical-free method for enhancing the post-harvest quality of arrowroots. This method could benefit farmers, food processors, and policymakers by improving post-harvest management practices, enhancing food security, and promoting economic sustainability in arrowroot production and consumption.