By-Products from Five Grape Varieties Grown in Northwest Mexico Are Sources of Bioaccessible and Bioavailable Phenolic Compounds in a Simulated Digestion

The inclusion of by-products or discarded fruit in a second value chain can be a strategy to contribute to sustainable food production and consumption, with a focus on following a circular economy model, since certain by-products may be a source of nutrients and compounds with biological potential. The objective of this research was to evaluate the content of phenolic compounds and antioxidant capacity of by-products from five non-marketable grape varieties, as well as the bioaccessibility and absorption of their phenolic compounds during a simulated digestion, in order to support their potential use as sources of health-promoting compounds of interest. By-products of five grape varieties grown in northwest Mexico were evaluated. They were manually divided into two fractions, skin and pulp + seed, and subjected to a simulated digestion. Grape skin had the highest concentration of phenolic compounds and antioxidant capacity. Catechin exhibited the highest bioaccessibility and absorption, although 40% of this compound was compromised during simulated digestion. Catechin, quercetin, and protocatechuic acid contained in grape by-products make them attractive for insertion into a second value chain with potential uses, such as applications in the food and pharmaceutical industries. Additional research is required to evaluate potential applications, ensuring that these alternative uses are profitable and sustainable.