Valorization of Coffee Silverskin through Subcritical Water Extraction: An Optimization Based on T-CQA Using Response Surface Methodology

Abstract

Coffee silverskin (CS) is the only byproduct of the roasting process for coffee beans and is rich in phenolic compounds with various bioactivities. This study proposes a valorization option for bioactive compounds (T-CQA) based on a subcritical water extraction (SWE) technique, which is known for its high efficiency and feasibility for use on an industrial scale. The use of water as a sole solvent requires a minimum number of cleaning steps and renders the extract safe for further applications, such as in either the cosmetic or food industry. Response surface methodology with a Box–Behnken design is effectively used to optimize and explain the individual and interactive process variables (i.e., extraction temperature, extraction time, and solid–liquid ratio) on the T-CQA content obtained from coffee silverskin by the SWE technique. The final model exhibits a precise prediction of the experimental data obtained for the maximum T-CQA content. Under the optimum conditions, the CS extract is found to contain a higher content of T-CQA and TPC than that reported previously. For antioxidant activity, up to 26.12 ± 3.27 mg Trolox equivalent/g CS is obtained.

Antioxidant and Sensory Properties of Raw and Cooked Pork Meat Burgers Formulated with Extract from Non-Compliant Green Coffee Beans

“…The addition of plant extracts into the meat matrix can be difficult if their color and flavor are not suitable for meat and if their solubility is insufficient, generating unpleasant spots in the final product [ 29 , 30 ]. Some authors investigated the effectiveness of the subcritical water extraction (SWE) method for the recovery of water-soluble phenolic compounds from medicinal plants and coffee by-products [ 31 , 32 ], as well as the possibility of producing plant extracts that can be used as natural antioxidant ingredients in pharmaceuticals, cosmetics, and food [ 33 , 34 , 35 , 36 ]. During the last decade, some studies have reported increased oxidative stability and improved functional properties of food products prepared with extracts from green coffee beans, which are rich in polyphenols [ 27 , 37 , 38 ], but there are not results on their use as an ingredient in pork meat.…”

Circular valorization of coffee silverskin through supercritical CO2 for the production of functional extracts

“…43 Subcritical water was also employed by Ginting et al , targeting chlorogenic acids, reaching a percentage of 0.27% (w/w dry CS) at 147.8 °C. 44…”

“…43 Subcritical water was also employed by Ginting et al, targeting chlorogenic acids, reaching a percentage of 0.27% (w/w dry CS) at 147.8 °C. 44 The solvent-based extraction was supposed to be exhaustive in chlorogenic acids' complete extraction from both the delipidized biomasses. Aer assessing for consistency the effectiveness of the extraction of chlorogenic acids from GCB and CS with solvents with the literature, data were assumed to represent the reference when studying the recovery of the same phenolics by means of supercritical uids.…”

Application of Response Surface Methodology to Optimize the Extraction Process of Bioactive Compounds Obtained from Coffee Silverskin

“…In recent years, one of the most efficient methods of TPC extraction is subcritical water extraction. With the use of this method, Ginting et al [69] obtained above 51 mg GAE/g CS, which is a significantly higher yield in comparison to conventional methods.…”