ULTRASOUND AND PULSED ELECTRIC FIELD FOR IMPROVING FUNCTIONAL PROPERTIES OF GRAPE SEED FLOUR IN EMULGELS DURING IN VITRO DIGESTION

The worldwide consumption and processing of grape has boosted the generation of agro-industrial coproducts, such as grape seeds. These seeds are rich in

macromolecules such as proteins, fibers, and lipids, besides bioactive compounds that may be subjected to valorization. These whole seed flour shows potential as

functional ingredients in food systems, especially in emulsions, although plant-based protein fraction tend to present limited functionality. Because of that, nonconventional technologies such as ultrasound (US) and pulsed-electric-fields (PEF) can be used to enhance technofunctionality of the flours. Complementary,

simulated in vitro digestion assessment has been used to evaluate the lipid encapsulation and bioaccessibility of bioactive compounds throughout the

gastrointestinal tract. In this context, US and/or PEF have been investigated as strategies to modify the functionality of defatted grape seed flour (GSF) in o/wemulsion systems subjected to in vitro digestion. Dried, defatted, ground, and sieved seeds (<400m) constituted the whole flour and, except for the control, the flours were subjected to aqueous treatments in US (400W; 10 min) EF (6 kV/cm; 100 pulses), or their combination (US+PEF) to be subsequently oven-dried. Sunflower oil emulgels (1.5 g oil/g GSF) were prepared by initially emulsifying the oil in aqueous GSF suspensions, followed by gel formation induced by amidated low-methoxyl pectin and calcium. In vitro digestion was conducted according to the INFOGEST protocol, simulating the oral, gastric, and intestinal phases. The soluble fraction obtained after digestion was analyzed regarding the bioaccessibility of total phenolic compounds by Folin-Ciocalteu method. The results showed that emulgels with US- modified GSF resulted in higher bioaccessibility of phenolic compounds (89.86%), followed by the combination US+PEF (73.92%) and PEF alone (66.05%), compared to the untreated sample (54.92%). Furthermore, confocal microscopy analyses revealed better dispersion and greater homogeneity of droplets in the emulgels produced by the modified flours, confirming the previously mentioned results. Thus, the applied treatments, particularly US, were effective in improving emulsion structure and increasing the bioaccessibility of phenolic compounds. These technologies reinforce their potential for valorizing agro-industrial coproducts and for developing more sustainable functional foods.