Light-induced glycoalkaloid accumulation of potato tubers (Solanum tuberosum L)

Percival, G.

Light-induced glycoalkaloid accumulation of potato tubers (Solanum tuberosum L)

1999

Percival, G.

The total glycoalkaloid concentration of non-sprouted potato tubers, cvs Marfona, Fianna, Maris Piper, Kestrel and Golden Wonder, was measured following 15 days of continuous illumination (250 micromol m(-2) s(-1) photosynthetically active radiation) using high-performance liquid chromatography. Comparisons were made of the influence of four sources of illumination: fluorescent tube-type warm white, high-pressure sodium, high-pressure mercury types MB/U and MBFR/U. Irrespective of cultivar, glycoalkaloid concentrations of tubers placed in the dark remained relatively constant from day 0 to day 15 and did not exceed food safety values of 200 mg kg(-1) FW. A highly significant cultivar, light and cultivar x light (P < 0.01) interaction was recorded. Cultivar Kestrel was shown to be light-sensitive with high rates of glycoalkaloid accumulation irrespective of light source, and cv Maris Piper was demonstrated to be light-insensitive. In the majority of cultivars tested, maximal rates of glycoalkaloid accumulation were recorded following exposure of tubers to sodium or fluorescent light, and minimal rates of accumulation were recorded following exposure of tubers to mercury (MB/U and MBFR/U) illumination. In virtually all cases glycoalkaloid concentrations steadily increased with time during light exposure with no indication of cessation. In some instances the alpha-chaconine/alpha-solanine ratio decreased over 15 days of illumination (P < 0.05), indicating enhanced alpha-solanine synthesis over that of alpha-chaconine. The implications of these results in terms of consumer safety are discussed.

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