In Vitro Digestion of Betalainic Foods. Stability and Bioaccessibility of Betaxanthins and Betacyanins and Antioxidative Potential of Food Digesta.

Betalains are considered to be bioactive dietary phytochemicals. The stability of betacyanins andbetaxanthins from either fresh foods or manufactured products of cactus pear fruit (Opuntia ficusindica L. Mill. cv. Gialla and Rossa) and red beet (Beta vulgaris L. ssp. vulgaris) was assessed in asimulated oral, gastric, and small intestinal digestion and compared with the digestive stability ofpurified pigments. A minor loss of indicaxanthin, at the gastric-like environment only, and a decreaseof vulgaxanthin I through all digestion steps were observed, which was not affected by food matrix.In contrast, food matrix prevented decay of betanin and isobetanin at the gastric-like environment.Loss of betacyanins, either purified or food-derived, was observed during the small intestinal phaseof digestion. Betalamic acid accumulated after digestive degradation of purified pigments, but not offood betalains. Betaxanthins were wholly soluble in the aqueous (bioaccessible) fraction afterultracentrifugation of the postintestinal (PI) digesta, whereas release of betacyanins from the matrixwas incomplete. PI digesta inhibited dose-dependently the oxidation of methyl linoleate in methanol,an effect not correlated with the betalain content. The data suggest that digestive stability controlsbioaccessibility of dietary betaxanthins, whereas additional factors, relevant to the food matrix andstyle of processing, affect betacyanin bioaccessibility.