IInfluence of grape seeds powder on preservation of fats in confectionary glaze

Abstract

The polyphenol composition of grape seeds powder (GSP) and defatted grape seeds flour (DGSF) in water-alcohol (ethanol, isopro- panol) extracts was studied by the chromatographic method. There was established the content of antioxidants, which are present in the form of phenolic acids (gallic, ellagic), stilbenes (resveratrol) and flavonoids, first of all, flavanols (catechin, epicatechin) and flavonols (kaemferol, myricetin, quercetin and its derivative glycosides). It was shown that the total content of polyphenols reaches a maximum size of about 4.5 % in gallic equivalent of the powder weight at the extraction of water-ethanol mixture with ethanol content of 50 % (w/w). The effect of phenolic antioxidants on peroxide (PV) and acid (AV) values of confectionery fats of lauric and non-lauric types in the model systems was studied as the markers of the rancidity formation process. It was proved that thanks to a high content of antioxidants in grape powders, the introduction of these powders in the composition of samples significantly slows down the process of auto-oxidation of fats. It was shown that grape powders as vegetable raw material are more stable in terms of catalyzing the process of fats hydrolysis in confectionery glaze. This is evidenced by the data on the activity of lipase enzyme, the magnitude of which is lower in the samples of grape seeds powders – 1.03 and 1.12 сm3/g for GSP and DGSF, respectively, compared with that of different samples of cocoa powder – 0.84 and 1.87 сm3/g. The study into changes in acid value of the samples also showed that the addition of GSP and DGSF as the source of antioxidants significantly inhibits the process of hydrolysis of fats to free fatty acids. The obtained results have a practical significance for the improvement of the process of confectionary glaze production in the direction of partial substitu- tion of cocoa powder with grape seeds powders. This contributes to the creation of a product with a high nutritional value and which is more resistant to damage as a result of the process of oxidation and hydrolysis of fats.