Extracts of White and Red Grape Skin and Rosehip Fruit: Phenolic Compounds and their Antioxidative Activity

The current work concerns solid liquid extraction from red and white grapes skin and the rosehip (Rosa canina) to obtain extracts with a high phenolic content. Extracts have been acquired using conventional extraction techniques and extraction with supercritical fluids (SCFs). The effect of extraction method and experimental parameters (time, pressure, temperature and solvent mixture) mostly believed to affect the extraction process was undertaken. The quantitative parameters studied are: total phenolic compounds, proanthocyanin content, and the phenolic constituent profile. The qualitative parameter analyzed is antioxidant capacity. The results demonstrate that the contents of the major constituents significantly varied among the different types of materials. The highest content of total phenolics was determined in the extract from the white grape skin, macerated with MeOH (26.7 mg GA/g extract), and similar, 25.6 mg GA/g extract in the MeOH extract attained by Soxhlet. Ellagic acid (0.650 mg/100 g extract), catechin (0.164 mg/100 g extract), gallic acid (0.133 mg/100 g extract) as well as caffeic acid (0.038 mg/100 g extract) are the major compounds present in the rosehip extracts attained by maceration using MeOH as solvent. The presence of epictechin, hesperidin/neohesperidin, rutin, and chlorogenic acid was also confirmed. Aspects of each type of processing were correlated with the chemistry of the material. The obtained extracts could be used as natural bioactive compounds in several industrial applications.