The re-use potential of espresso spent coffee grounds: Optimization of microwave-assisted extraction of polyphenols by use of response surface methodology and their effects on platelet function - pilot study

Abstract

A huge amount of espresso spent coffee grounds (SCG) are obtained as a waste product during the preparation of coffee beverages (cialdes, K-cups and in metallic filters). Although considered a waste and an ecological threat, SCGs could be an excellent source of bioactive components (mainly polyphenols) with outstanding antioxidative activity and potential to be used as raw material in fortified food production. The antiplatelet action of dietary polyphenols represents an important part of their pleiotropic action, and underlying mechanisms of their shown beneficial effects on cardiovascular health. Accordingly, a reduction in platelet aggregation was accepted by EFSA as a beneficial effect of food and dietary constituents, in the context of maintaining cardiovascular health enabling claims related to foods or substances affecting disturbed platelet function. Thus, platelets are considered an emerging target for the prophylactic effects of food bioactives in cardiovascular disease (CVD), with promising scientific evidence of their efficacy. The overall objective of this study was to examine an optimal range of extraction conditions for the extraction of polyphenols from espresso SCGs by using response surface methodology and to investigate the in vitro effects of obtained polyphenol-rich extracts on platelet activation and their aggregation with monocytes and neutrophiles. The obtained results indicated that espresso SCG extracts induce dose dependent inhibition of platelet activation, shown by the decrease in expression of P-selectin (8.7%) and GPIIb/IIIa (5.6%) and their aggregation with monocytes and neutrophiles (up to 20%). The sustainability of the coffee processing system can be substantially improved through the use of by-products by the adoption of new technologies that maximize process profitability. Shown antiplatelet effects of polyphenols, present in espresso coffee SCGs, indicate a favorable profile of bioactive compounds toward platelet function and thereby rationalize their use as functional food ingredients and nutraceuticals aiming to promote cardiovascular health.