Recovery and application of natural food colorants and phenolic antioxidants from grape pomace

Due to the consumer demand for natural and healthy food, synthetic dyes are increasingly replaced by natural food colorants. For this reason and considering that color of food is one of the most important factors deciding over consumer preference, the recovery of natural food colorants and coloring foodstuffs from various plant matrices is becoming increasingly important. From an industrial viewpoint, especially by-products originating from fruit and vegetable processing, e. g. grape pomace, are an attractive and rich source of phenolic compounds and natural pigments, which are available in great amounts and at low costs. These sources provide the opportunity to recover natural food colorants in order to reduce production costs by valorizing waste streams in terms of sustainable food production. The by-products of plant food processing, such as grape pomace, are usually also rich in non-anthocyanin phenolics, which increase pigment stability by intermolecular copigmentation also facilitating the application of the extracts as functional food ingredients or dietary supplements. Winery byproducts are particularly rich in polyphenols, especially anthocyanins, due to their poor extraction in the course of vinification. Therefore, the recovery of natural pigments and noncolored phenolics from grape pomace and the evaluation of their stability in various foods, as well as the isolation of individual compounds from the pomace crude extracts were investigated in the present study.