A SUPERIOR ALL-NATURAL ANTIOXIDANT MATERIAL FROM SPENT COFFEE GROUNDS FOR APPLICATION IN ACTIVE PACKAGING AND FOOD SUPPLEMENTATION

Spent coffee grounds (SCG) represent the main by-products of the coffee industry as they are obtained both during instant coffee production and as a result of coffee beverage consumption in restaurants and coffee shops. We report herein the up to 30 times enhancement of the intrinsic antioxidant potency of SCG following overnight treatment with 6 M HCl, at 100 °C [1], leading to a versatile multifunctional material (hydrolyzed spent coffee grounds, HSCG). Spectral and morphological analysis suggested that the remarkable potentiation of the antioxidant activity is due to efficient removal of the hydrolyzable components, mainly carbohydrates, making the polyphenol-rich component available for interaction with free radicals and oxidizing species. Based on these results, the possible exploitation of HSCG as an active component in functional food packaging, e.g. for food lipid preservation and stabilization of polymers, or as a food supplement was then invesitgated. HSCG efficiently delays lipid peroxidation in fish and soybean oils. Moreover, films made of polyethylene/2% HSCG blends display greater stability to thermal and photo-oxidative degradation. Regarding the possible use as a food supplement, in other experiments HSCG was subjected to a simulated digestion-fermentation treatment in vitro [2]. The potentially bioaccessible (soluble) fractions obtained exhibit high chemoprotective activity in human hepatocellular carcinoma (HepG2) cells against oxidative stress. Structural analysis of both the indigestible (insoluble) and soluble material revealed partial hydrolysis and release of the lignin components in the potentially bioaccessible fraction following simulated digestion-fermentation. A high prebiotic activity as determined from the increase in Lactobacillus spp. and Bifidobacterium spp. as well as the production of short chain fatty acids following microbial fermentation of HSCG is also observed. HSCG may thus represent an easily accessible and sustainable alternative to currently available antioxidant materials for biomedical, food and technological applications.