Solventless extraction methods for immature fruits: Evaluation of their antioxidant and cytoprotective activities

In this study, extraction of immature fruits using an environmentally friendly pressurized hot water extraction (PHWE) method was compared with the traditional reflux method. Extracts were tested for their polyphenol content using the Folin–Ciocalteu assay and for their antioxidant activity using the oxygen radical absorbance capacity (ORAC) assay. The highest amount of polyphenol was extracted from grape (stem) using PHWE at 100 °C, or reflux extraction. This was followed by reflux extraction of grape (fruit). The results were similar for the ORAC assay. All samples extracted using PHWE at 100 °C showed cytoprotective activity against H2O2-induced oxidative stress in Crandell–Reese feline kidney (CRFK) cells. This study demonstrated that beneficial compounds can be extracted from immature fruits without the use of organic solvents. The utilization of beneficial compounds present in immature fruits can also contribute to the reduction in agriculture waste generated.