THE EFECTS OF MAGNETIC INDUCTION ON PHYSICOCHEMICAL, NUTRITIONAL, GLYCOALKALOIDS, ANTIOXIDANTS, AND POSTHARVEST LOSSES OF STORED POTATOES

Abstract

Worldwide, post-harvest losses (PHLs) of potatoes are predicted to be between 10% and 15% per year. However, losses resulting from inadequate storage techniques may reach 30% in underdeveloped nations. There is, therefore, the need to innovatively identify affordable and sustainable storage mechanisms that can reduce PHLs and prolong the shelf life of potatoes without compromising on their quality. Thus, the aim of this research was to evaluate the effectiveness of magnetic fields (MF) in reducing PHLs in potatoes during their storage. The effects of test variables: sources of magnetic fields (direct current (DC) or alternating current (AC)), magnetic field intensity (1.00 mT, 2.00 mT, and 3.00 mT), and exposure time (20, 40, and 80 seconds) on the physicochemical, nutritional, glycoalkaloids and antioxidants quality of stored potatoes were investigated. Selection of range values for both magnetic field intensities and exposure times were based on prior experimental trials Double Helmholtz coils were used to generate MF. The coils were supplied with either DC or AC. Potatoes were then exposed to MF and stored in either the control or the commercial store for eight weeks. At the end of the storage period, analyses were done following standard methods. In this study, shangi potato variety was used due to its dominance in the Kenyan potato market. The AC MF resulted in significant (ρ < 0.05) higher specific gravity, dry matter, starch, and the number of sprouts per tuber but lower weight reduction, total sugars, reducing sugars, and non-reducing sugars than DC MF. Exposing potatoes to 3.00 mT of both DC and AC MF resulted in significant (ρ < 0.05) lower weight reduction, internal and external greening, sprouting, and the number of sprouts per tuber than in potatoes that were not exposed to MF. Exposing potatoes to 2 mT of DC MF with subsequent storage in the control store resulted in significantly (p < 0.05) higher quantities of potassium, magnesium, copper, manganese, chromium, cobalt, and boron. The use of AC MF with an intensity of 2 mT resulted in a significant (ρ < 0.05) reduction in α-chaconine, α-solanine, and TG. Exposing potatoes to 3 mT of AC MF and storing them in the control store significantly increased the content of ascorbic acid by 37% in comparison to the fresh tubers. Exposing potatoes to 3 mT of DC MF with storage in the control store and 3 mT of AC MF with storage in the commercial store resulted in an 11% and 21% increase in carotenoids, respectively. The antioxidant activities of potatoes that were exposed to DC MF were comparable to that of fresh tubers. Hence, findings from this study reveal that MF can be used to reduce PHLs in potatoes and thus contribute to sustainable potato agrifood systems.