Effect of grape pomace powder addition on chemical, nutritional and technological properties of cakes

Aim of the research was to study the influence of grape (Vitis vinifera) pomace powder, a by-product of wine manufacturing, on chemical composition, nutritional properties and physical characteristics of cakes prepared replacing bread wheat flour with 4%, 6%, 8% and 10% grape pomace powder. The addition of growing quantities of grape pomace powder gradually increased ash, lipid, proteins, fibres, free phenolics, anthocyanins and total polyphenol content as well as antioxidant capacity (DPPH, FRAP), while decreased moisture and pH. The main phenolics provided by grape pomace were catechin, gallic acid, quercitin, protocatechuic acid, kaempferol and apigenin. The phenolic acids and flavonoids content increased from 4.1 mg/kg DM (control) to 26.4-60.9 mg/kg DM (cake with 4%-10% grape pomace powder). The colour coordinates L* and a* diminished, while b* augmented. The cake containing 4% grape pomace powder showed the best sensory quality. The addition of grape pomace powder significantly improved the content in free phenolics, highly bioavailable, that are scarce in bread wheat, and thus the nutritional value of cakes without penalising their technological and sensorial attributes. Therefore, grape pomace powder utilisation will give foods with nutritionally enhanced properties; additionally, its utilisation will alleviate the ecological problems connected to its disposal.