The use of biostimulant Kelpark for controlling cold-induced sweetening in Mondial potato tubers

Abstract

Potatoes are usually stored at low temperatures to suppress sprouting and diseases, simultaneously maintaining their shelf life and processing quality. However, prolonged exposure to cold storage leads to the accumulation of reducing sugars as a physiological reaction to cold stress, which leads to a phenomenon known as cold-induced sweetening (CIS). Limited studies have investigated postharvest technologies that can be used to reduce cold stress and, consequently, CIS in potato tubers. Therefore, the aim of the present study was to control CIS in potato tubers using Kelpak®, an Ecklonia maxima seaweed extract (SWE), which contains hormones that mitigate against abiotic stress. To evaluate the effectiveness of Kelpak® in reducing sugar accumulation during cold storage, potato tubers (cv. Mondial) were dipped in Kelpak® solutions at 0.5, 1.5, 2.0, 2.5, and 3.0% for five minutes, while control tubers were dipped in distilled water. To determine whether there were statistically significant differences among the treatments, analysis of variance was employed. Furthermore, the TOPSIS-entropy model was employed to determine the optimal Kelpak® concentration for mitigating CIS. The results showed that 3.0% Kelpak® application significantly delayed the accumulation of reducing sugars (glucose and fructose) and sucrose (p<0.05) when compared with the control tubers. During 60-day cold storage, 3.0% Kelpak® maintained significantly (p<0.05) higher starch, dry matter, and amylose contents. Scanning electron microscopy (SEM) revealed that control tubers were dominated by small granules (<30 μm), whereas Kelpak®-treated tubers exhibited predominantly large-sized granules (50–80 μm) after 60 days of cold storage. In addition, the TOPSIS analysis ranked 3.0 % Kelpak® as the most effective concentration for delaying sugar accumulation and preserving tuber quality. The findings suggested that the use of the biostimulant Kelpak® could be a sustainable and eco-friendly postharvest technology for maintaining potato shelf-life and processing quality.