**6. Discussions**

#### *6.1. Study Limitations & Recommendations for Future Research*

The project aimed to valorize some materials destined for zootechnical use, investigating whether hull and pre-distillation marc, correctly processed, could be valorized in a food market production. Post-distillation marc has lower organoleptic characteristics comparing to winemaking by-products, thus its use in the food market is not advisable. Indeed, to create a production process for the food sector, distillation should be avoided, and pomace should be processed as soon as possible, after pressing and winemaking. The fundamental process to be done immediately after pressing should be the stabilization (dehydration/drying) of the byproduct, to stabilize and process it over time.

During the project, an economic analysis was carried out by the Department of Management and Production of Politecnico di Torino based on data provided by partners through a survey. It highlighted the creation of value in the various processes on the material, which suggests that using the by-product in the food sector is of immediate technical and economic feasibility and could be considered a viable way that deserves further experimentation. In this regard, the project investigates also obtaining high added value molecules from marc flour by performing extraction with supercritical CO2 to obtain polyphenols, anthocyanins, and resveratrol. However, the flour turned out not to be as rich in these molecules as it was forecasted. This mismatch could be attributed to the grape variety. More likely, it can be attributed to the volatility and sensitivity of these compounds that degrade in contact with light or heat. The extracts, therefore, prove to be even more deficient in these components compared to literature. Anthocyanins, polyphenols and trans-resveratrol are, in any case, present in the flour, which can be used as it is, and without prior extraction, for the preparation of food. On the other hand, as far as hull flour is concerned, it has also been successfully tested to obtain rice oil/rice butter, rich in gamma-oryzanol, a molecule with antioxidant properties. In particular, 20 g of butter is extracted from 1 kg of rice flour. The concentration of gamma-oryzanol is 0.6% of the extracted oil component according to the analysis carried out by the Department of Applied Science and Technology of Politecnico di Torino. The presence of gamma-oryzanol inside the rice butter gives unique properties to the final product, compared to typical milk-derived butter. Several experimental studies demonstrated that gamma-oryzanol, introduced in the diet, even if in minimal quantities, has powerful antioxidant and anti-inflammatory e ffects and has a positive e ffect on lipid metabolism and cholesterol levels regulation. Butter derived from rice hull was used in all three final products. In the final composition of 'taralli', crackers and cream produced, gamma-oryzanol content varies between 336 and 360 mg every 500 g of product. There are no real exact recommended doses at the time of writing, but the daily amounts vary in the wide range between 50 mg per day and 800 mg because experimental studies on these molecules are still in progress. The final products fit perfectly within this range, making them excellent allies for health. However, the project would require further analysis to understand how to optimize the supercritical CO2 extraction process to reduce costs and make it economically feasible in the food sector. There are no real impediments for its use except its cost: the final rice butter price is about 250 €/kg, already considering an industrial process at full production capacity. At this stage, the use of rice butter in pharmaceuticals could be investigated in more detail, given the relatively high gamma-oryzanol concentration.
