Fatty acids, membrane permeability, and sugars of stored potato tubers.

The relationships of potato (Solanum tuberosum L.) tuber membrane permeability and membrane lipid composition to sugar accumulation were examined. Tubers from four potato cultivars were stored for 40 weeks at 3 degrees C and 9 degrees C. Rates of tuber membrane electrolyte leakage, total fatty acid composition, free fatty acid composition, and sugar content were measured throughout the storage period. Storage of tubers at 3 degrees C caused dramatic increases in total fatty acid unsaturation, membrane permeability, and sugar content compared to tubers stored at 9 degrees C. Cultivars with higher levels of fatty acid unsaturation had lower rates of membrane electrolyte leakage and lower sugar contents. We propose that high initial levels or high induced levels of membrane lipid unsaturation mitigate increases in tuber membrane permeability during storage, thus positively influencing the processing quality of stored potato tubers.