DEVELOPMENT OF FUNCTIONAL INGREDIENTS FROM PLEUROTUS OSTREATUS OBTAINABLE FROMAGRI-FOOD WASTE RECYCLING

The Pleurotus genus can use by-products of agri-food industry as substrates to develop its edible fruiting body. Pleurotus ostreatus, which is the most cultivated specie of Pleurotus, has high nutritional and nutraceutical properties; in particular, it is a source of vitamin D2 and fiber named β-glucans. However, food uses of this mushroom are limited because of the lack of value-added applications. The overall aim of this PhD thesis was to develop functional ingredients from P. ostreatus biomass. Specific goals were: a) development of a food application and production of a powdered ingredient with a target amount of vitamin D2; b) encapsulation of an oxidizable target using P. ostreatus β-glucans as antioxidant and emulsifying agent. The results showed that using an adequate concentration of dehydrated and milled P. ostreatus for the development of new food applications could help against the increasing vitamin D2 deficiency among specific groups of populations. To enhance the level of vitamin D2 in P. ostreatus, a combined process of UV irradiation and air-drying was applied, and a new powdered ingredient with a target amount of vitamin D2 was obtained. The kinetics of vitamin D2 degradation in P. ostreatus powder was studied as a function of water activity and temperature to predict its stability during storage. The kinetics data obtained can be used as a starting point to project the best formulation strategy to deliver vitamin D2 with functional foods. Since there is a gap of knowledge about the effect of UV irradiation on mushroom bioactive compounds, the antioxidant and antiglycation activities of Agaricus bisporus and P. ostreatus were investigated and the results pointed out that UV irradiation reduced the antioxidant activity, but not the antiglycation properties. Two different β-glucan-rich extracts were obtained from P. ostreatus; after characterization, they were used to stabilized oil-in-water emulsions. Their stability was checked through variation of oil droplets size distribution over time, in order to find the best formulations suitable for further encapsulation, which was carried out using spray drying technique. After production, the powders were analyzed for the particle morphology and in terms of oil protection against oxidation. Results showed that P. ostreatus extracts provided good emulsifying properties and it allowed excellent protection of α-tocopherol and polyunsaturated fatty acids against oxidation. The effects of the P. ostreatus extracts was tested during in vitro digestion; samples underwent partial aggregation, but the oil droplets were still fairly stable, and α-tocopherol degradation was slower in presence of β-glucans up to the beginning of intestinal phase. The protection against oxidation was also studied during 15 days of accelerated storage; β-glucans improved the oxidative stability of the powders, compared to common emulsifier with no inherent bioactivity. In conclusion, it is evident that P. ostreatus and its compounds can be exploited as sustainable food ingredients to deal with the requirements of populations with endemic nutritional deficiencies and to stabilize oxidizable target during encapsulation process, in vitro digestion and storage.