Potent Inhibition of Enzymatic Browning of Yam Tubers (Dioscorea cayenensis-rotundata) Cultivar ‘zrèzrou’ using Red Onions (Allium cepa)

Enzymatic browning is a natural phenomenon observed in yam tubers (Dioscorea cayenensis-rotundata) without the addition of exogenous phenolic compounds. The undesirable effects of this physiological process led to the use of sulfites and their derivatives to inhibit enzymatic browning. However, the risks associated with these chemical agents and current regulations concerning their use as food additives have prompted the search for natural substances as food ingredients to replace synthetic compounds. The objective was therefore to prevent this physiological phenomenon in situ using extracts of Allium cepa (red onion, yellow onion) and Allium sativum (garlic). To evaluate the effect of natural inhibitors such as red onion, yellow onion, and garlic on browning, a yam tuber (Dioscorea cayenensis-rotundata) of the 'Zrèzrou' variety, one kilogram (1 kg) of red onion bulb, one kilogram (1 kg) of yellow onion bulb, and one kilogram (1 kg) of garlic cloves were used. This work first involved studying enzymatic browning in different parts (proximal, midline, and distal) of the yam tuber (Dioscorea cayenensis-rotundata) of the 'Zrèzrou' variety. It then aimed to prevent this physiological phenomenon in situ using extracts of Allium cepa and Allium sativum (red onion, yellow onion, and garlic) without the addition of exogenous phenolic compounds. Finally, the optimal concentration of red onion extract was determined to achieve satisfactory inhibition of enzymatic browning. The significant results obtained in this study suggest solutions for inhibiting enzymatic browning of yam tubers (Dioscorea cayenensis-rotundata) of the "Zrèzrou" variety using crude extracts of red onion bulbs, which provide satisfactory inhibition at a concentration of 0.6 g/L.