Browning susceptibility of new hybrids of yam (Dioscorea alata) as related to their total phenolic content and their phenolic profile determined using LC-UV-MS

In the French West Indies, to cope with the yam disease anthracnose, new hybrids were selected for their resistance to this disease. However, some of them have quality flaws. The new hybrids of Dioscorea alata exhibited contrasted susceptibility to browning in relation to their total phenolic content (r = 0.91). The detailed polyphenol profiles of "INRA15", highly susceptible to browning, and of "Kabusah", with moderate susceptibility to this flaw, were achieved by HPLC coupled to UV–Visible and mass spectrometry. For the first time, total procyanidins of yam were finely characterized and quantified using HPLC after phloroglucinolysis, revealing that those compounds are by far the main polyphenols in the two cultivars. Differences in terms of browning susceptibilities of the two cultivars are clearly explained by their contrasted polyphenol profiles: (i) absence versus presence of catechin which is a substrate of polyphenol oxidase (PPO). - (ii) significant differences in procyanidin levels and in their average degree of polymerization potentially involved in PPO inhibition.