| http://www.w3.org/ns/prov#value | - When fruits such as raspberries are put in contact with metallic tin, no modification appear, but when Sn2+ ions are deposited on crushed raspberries, a purple, turning to black, colour appears, because the complex of anthocyanins with Sn2+ ions shifts a peak in the absorption spectrum toward shorter wavelengths (This, 1995a,b; Belitz & Grosch, 1999).
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