Encapsulation of polyphenols from grape marc extract using different natural carriers

winesense - 1Spain has over 1.2 million hectares of planted vines, making it the most widely planted wine producing nation (over 15% of the world total) and the third largest producer of wine in the world, following France and Italy. The winemaking process generates large amounts of by-products such as grape seeds and skins which are rich in polyphenols with strong antioxidant properties that are interesting from a chemical, pharmaceutical and biological viewpoint. These compounds have been proved to have numerous health benefits as antioxidants, i.e. reducing the incidence of cardiovascular diseases, improving the cognition and neuronal function with aging and neurodegenerative diseases, antitumor, anti-inflammation, and anti-microbial. The incorporation of these natural substances into cosmetics, food, or pharmaceutical products represents an interesting market opportunity for wine producers that could lead to sustainable growth and development of the sector. Part of the WineSense project is to study the most suitable formulation techniques that can be applied to grape polyphenols in order to increase their bioavailability and resistance to degradation. A simple yet efficient method is spray drying, widely used in industry for this type of compounds. In this work, a grape marc extract obtained by traditional solid-liquid extraction was spray dried under different operational conditions and using three different natural carriers (maltodextrin, MD; whey protein, WP; and pea protein, PP).

The best results in terms of total phenolic, flavonoid and anthocyanin content expressed per gram of product were obtained with WP, while the results obtained with the other carriers were slightly lower but very similar and following the same trend. In all cases, the highest concentration of bioactive compounds was obtained with a carrier-to-solids ratio of 0.1:1, i.e. 10% carrier with respect to the solids contained in the original aqueous extract. Drying in the absence of carrier produced 72% recovery of the total phenolic content, that is, 28% of the total phenolic content suffered degradation and was lost during the drying process. Addition of 10% carrier rises this recovery to 81, 88 and 91% for PP, MD and WP, respectively.

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Fig. 1: Antioxidant activity (Oxygen Radical Absorbance Capacity) for different natural carriers

These results indicate that either MD or WP are suitable carriers that provide good encapsulation with only 10% carrier. However, Fig.1 points to a clear advantage of using WP over the other carriers: the oxygen radical absorbance capacity of the 10% WP product is far superior than any other. The antioxidant activity when using MD in any ratio is very similar to that obtained in the absence of carrier.

SEM images of the products (Fig. 2) show relatively spherical particles with a certain wrinkly or crushed appearance, especially for MD. Average particle size is similar in all cases, but the distribution is more homogeneous for WP and PP. MD powders showed a higher degree of agglomeration due to the hygroscopic nature of MD.

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Fig. 2: Particle morphology: SEM images for different carriers


Iván Navarro and Teresa MorenoProject Winesense (FP7-PEOPLE- 2013-IAPP- 612208)

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