Valorization of black grape pomace by pressurized hot water extraction and hydrolysis: Real-time online and in-line monitoring

The primary aim of this study was to maximize the value of black grape pomace by harnessing innovative and environmentally friendly extraction and hydrolysis technology on the biorefinery concept. This automated system seamlessly integrates pressurized hot water extraction (PHWE) and sequential subcritical water hydrolysis (SubCWH), complemented by inline purification through solid phase extraction (SPE) and online analysis via high-performance liquid chromatography (HPLC) equipped with photodiode array (PDA) and refractive index (RI) detectors. The results of this investigation revealed the presence of twelve anthocyanins, each exceeding a concentration of 3 mgEC3G gDBGP(-1). By summing the concentration of these individual anthocyanins, a total yield of 47.6 mgEC3G gDBGP(-1) was achieved, attributed to the utilization of acidified water as the solvent and adherence to optimal process conditions. The newly developed system demonstrated its efficacy in both PHWE and SubCWH of black grape pomace, coupled with inline SPE purification and real-time HPLC analysis of various natural compounds. The real-time monitoring capability facilitated swift and efficient responses, reducing processing time, minimizing solvent consumption, decreasing labor requirements, conserving energy, and mitigating environmental impact.