engleski

High hydrostatic pressure extraction of polyphenols from tomato waste

During tomato processing a considerable amount of waste, composed of peel, seed and small amount of pulp is generated. Usually, these by-products are disposed in landfills and only partially reused by-composting or drying for animal feeding. Nevertheless, modern eco-compatible technologies offer more efficient strategies to recycle these wastes in order to use them as a sustainable source for the extraction of different biologically active compounds, such as polyphenols. To the best of our knowledge, no research has been done on the extraction of polyphenols from tomato waste by high hydrostatic pressure (HHP). Therefore, this work reports methodology of polyphenols extraction by HHP from tomato canning industry waste at various experimental conditions, i.e. solvents (water, hydrochloric acid and methanol), solvents ratio, v/v (1 % HCl, 50 and 70 % methanol with and without addition of 1 % HCl), temperatures (25, 35, 45 and 55°C) and holding times (5 and 10 min). The isolated polyphenols were evaluated in terms of total phenols (TP) and total flavonoids (TF) content, determined by a photometric Folin-Ciocalteu and aluminium chloride assays. TP and TF mass fractions were expressed as mg of gallic acid and rutin equivalents per g of dried tomato waste, respectively. The results indicate that at steady pressure of 500 MPa, parameters such as temperature, type of solvent, as well as solvent ratio has a significant effect (p<0.05) on TP and TF contents. The highest mass fractions of these compounds were obtained at temperature of 45 °C with water and 50 % methanol as extracting solvents. Under such conditions, the mass fractions were found to be 49.7 and 43.3 mg/g for TP and 1.66 and 1.43 mg/g for TF, in water and 50 % methanol extracts, respectively. Other extraction parameters such as increases of extraction time from 5 to 10 min or addition of 1 % HCl to the organic solvents (50 and 70 % methanol) had no significant effect (p<0.05) on TP and TF contents. Therefore, this preliminary investigation showed that HPP procedure is suitable for fast extraction of polyphenols from waste derived by tomato canning industry. In addition, the exploitation of these bioorganic residues will not only solve the problems of waste disposal, but also meet the requirements of polyphenols as a food supplement. In further work the use of mixture of water and other organic solvents, such as ethanol, acetone and acetonitrile as environmentally acceptable systems, will be investigated too.

high hydrostatic pressure extraction; polyphenols; tomato waste

nije evidentirano