Ma-khwaen essential oil vapour suppresses potato sprouting under tropical ambient storage via GA3-ABA modulation, oxidative stress and carbohydrate metabolism.

BACKGROUND: Sprouting is a major postharvest challenge in potato storage, accelerating physiological ageing, starch mobilisation and α-solanine accumulation, thereby reducing processing quality and food safety. With the phase-out of hazardous synthetic sprout inhibitors, safe and residue-free alternatives are needed. This study evaluated the vapour-phase efficacy of three essential oils (EOs; lime peel, holy basil and ma-khwaen) applied at a nominal loading of approximately 70 μL L-1 (v/v) as overnight fumigation to 'Spunta' potato tubers stored under ambient conditions (28 ± 4 °C, 65-83% relative humidity).

RESULTS: Ma-khwaen EO (MKEO) was the most effective in reducing postharvest deterioration. After 63 days of storage, MKEO-treated tubers maintained weight loss below 1.0% compared to more than 2.2% in non-treated controls. Sprouting incidence was reduced to less than 50% with sprout lengths ≤ 5 mm compared to more than 90% incidence and sprout length > 10 mm in controls. MKEO delayed the attainment of 50% sprouting beyond 63 days compared to the first week of storage in controls. MKEO reduced α-amylase activity by 25-40% compared to water-treated and non-treated controls, resulting in lower accumulation of reducing sugars during storage. On day 63, MKEO further reduced H2O2 accumulation, antioxidant enzyme (peroxidase and catalase) activities, lowered GA3 levels and decreased α-solanine content by 32% compared to controls at the same time as elevating abscisic acid levels.

CONCLUSION: MKEO effectively suppressed sprouting and delayed potato tuber deterioration by regulating hormonal balance, oxidative status and carbohydrate metabolism. MKEO represents a promising eco-friendly and residue-free sprout suppressant for ambient potato storage in tropical regions. © 2026 Society of Chemical Industry.