VALORIZZAZIONE DEI RIFIUTI DI CANTINA: ESTRAZIONE DEGLI ANTOCIANI E APPLICAZIONE COME COLORANTE ALIMENTARE

The current global health and ecological crises anticipate profound changes in the functioning of our society and economy; so, the EU Waste Directive encourages Member States to develop «waste prevention programmes, concentrating on the key environmental impacts and taking into account the whole life-cycle of products and materials». In 2018, Directive 2018/851 of the European Parliament and of the Council, of May 30, 2018, is approved, which modifies Directive 2008/98/EC on waste. This directive reviews some articles of the Waste Framework Directive with the aim of advancing in the circular economy, harmonizing, improving information and traceability of waste and reinforcing governance in this area. This study proposes the food waste hierarchy as a framework to identify and prioritize the options for the minimization and management of food surplus and waste throughout the food supply chain (Papargyropoulou et al., 2014). So, the most important concepts are re-use, recycling, recovery, and the difference between product, production residue and by-product are also important at the legislative level. Anthocyanins are polyphenolic pigments that belong to the flavonoid group and are responsible for many of red-orange to blue-violet colours present in plant. The colour stability of anthocyanins is principally influenced by pH, solvents, temperature, anthocyanin concentration and structure, oxygen, light. Use anthocyanins as a dye can be an opportunity to create a product with added value and health benefits, trying to satisfy the consumer. The purpose of the work was the valorization of a waste of the vinification and subsequent use of the extract in yogurt as a food colourant and antioxidant. After a bibliography search the first part of the work was done by comparing different solvents and two extraction techniques: solid-liquid extraction and ultrasound technique. Afterwards deciding on the best way of extraction, the formic acid of the solvent has been replaced with acids suitable for use in food matrices, such as citric acid, tartaric acid, lactic acid, and malic acid. The extracts have been subjected to the following analyses: HPLC-DAD, spectrophotometry, colour. After a concentration phase of the extracts, tests were done on the colouring effect of the liquid and powdered extract on yogurt and visually see the evolution of colour during 4 weeks. The analyses carried out the solvent S6 has data that make it the best solvent for an extraction process of anthocyanins, with 965.64 mg/L extracted. For the colour analysis also in this case the second extraction phase has better values obtained, the best result is solvent S8 with Chroma 92.48, L* 41.30, a* 73.11, b* 56.63. However, for total polyphenols the best absorbance is that of solvent S1 with 2.40, but for the selection among the second types of solvents, S6 is again the best (2.18). From the preliminary test on yogurt does not prove to be the most performing, stable during storage, while visually the solvent S7 is the most persistent. Further analyses are needed to analyze the colour stability, antioxidant properties conferred, pH, panel test to verify consumer satisfaction, storage temperatures (Turker et al., 2004) to see how it affects the stability of anthocyanins.