Encapsulation of hazelnut skin extract and use of obtained microcapsules as antioxidant in mayonnaise

In this thesis, it is aimed to encapsulate the extract obtained from the hazelnut skin, which is formed as a by-product during the hazelnut roasting process, and to investigate its use as an antioxidant in mayonnaise. For this purpose, traditional and ultrasound assisted extraction conditions were optimized according to total phenolic compound amount and antioxidant capacity of the hazelnut skin, obtained from a hazelnut roasting firm in Ordu, water extracts. For the encapsulation of the extract obtained under optimum conditions by spray drying method, the optimization of spray drying conditions according to the coating material ratio and drying temperature was performed by using the microencapsulation efficiency as a response, also bulk density, tapped bulk density, flowability, particle size and particle imaging analyzes were performed in microcapsules produced under optimum conditions. The obtained microencapsules, freeze-dried hazelnut skin extract and mayonnaises produced by adding synthetic antioxidants (EDTA and TBHQ) were stored at 3 different temperatures (4, 25 and 45°C) for 30 days and the peroxide and p-anisidine values of the samples were analyzed during storage period. In addition, the stability of the microcapsules were determined by performing the accelerated oxidation test at 140°C with ransimat. The acceptability of the hazelnut skin added mayonnaise by the consumers was also determined as a result of the sensory analysis. Optimum conditions for the extraction of hazelnut skin with the traditional method; extraction temperature was 90°C, extraction time was 46.5 min and feeding rate was 15%; Optimum conditions in ultrasound assisted extraction were found to be 50°C, extraction time, 27 minutes, 5% feeding rate and 50% amplitude. Optimum spray-drying conditions to achieve microencapsulation efficiency were for pea protein, maltodextrin and arabic gum; 20% coating material ratio-140°C inlet temperature, 50% coating material ratio-154°C inlet temperature, 50% coating material ratio-180°C inlet temperature, respectively. It was found that the best (97%) microencapsulation efficiency was obtained by using arabic gum as the coating material, and the encapsulation efficiency of the microcapsules obtained by using maltodextrin and pea protein was 90% and 72%. Average particle diameters (45.36 µm) of hazelnut membrane powders obtained by freeze-drying method were found to be considerably higher than microcapsules obtained by spray-drying method. In addition, it was observed that the shapes of the powders obtained by the freeze drying method were irregular, porous, spongy and broken layered compared to the microcapsules produced by the spray drying method. It has been determined that the primary oxidation products in mayonnaises added microencapsulated powders are generally formed more slowly than both freeze-dried hazelnut skin extract and control mayonnaises for 3 storage temperature. It was concluded that the p-anisidine values of mayonnaises did not change at 4 and 25°C storage temperatures, but increased at 45°C at the end of the 30th day. According to the results of the accelerated oxidation test performed in mayonnaises, it was observed that the best result after synthetic antioxidants was obtained with microcapsules obtained by using arabic gum, and it was observed that the emulsified structure rapidly deteriorated in mayonnaises to which microcapsules obtained using maltodextrin were added. Mayonnaises with freeze-dried hazelnut skin added and microcapsules produced using arabic gum were accepted by consumers with a score above 7.