No abstract

Phenolic compounds in olive leaves have an excellent antioxidant activity and good antimicrobial properties. These bioactive molecules have beneficial properties for health, arousing great scientific and commercial interest. This study reports lyophilized olive leaf extracts (OLE) encapsulated by spray-drying using maltodextrins, maltodextrins–pectin and maltodextrins–gum Arabic as encapsulating agents. Lyophilized OLE were collected from two varieties cultivated in a harsh pedo-climatic conditions of the arid region of Tunisia. The effects of the genetic factor and the different encapsulating agents on the physicochemical properties of microcapsules and their behavior during storage, as well as their antimicrobial activities, were studied. Microcapsules successfully passed heat treatment and storage conditions and their antimicrobial activities were preserved. The encapsulating agent combination improved the encapsulation efficiency and the product yield in Zarrazi variety compared to Dhokar one. In addition, Dhokar variety microparticles showed the best heat stability at 4 and 25 °C after 90 days of storage and the higher inhibition percent against bacteria. The results of the present study evidenced that the best conditions for OLE encapsulation were obtained when the maltodextrins–pectin and maltodextrins–gum Arabic were combined to form a hybrid coating material.

The current study aims to investigate the application of the olive mill wastewater (OMW) extract (100 ppm) as additive to the refined sunflower oil and olive oil to reduce the formation of the oxidation products during deep frying of chicken and potato. The production of polymerized triacylglycerols (pTAG) and aldehydes was lower during frying in olive oil than in enriched refined oil. The highest percentage of polyunsaturated fatty acids in refined oil exhibits a great tendency to form polymeric compounds. The enrichment of sunflower oil with OMW extract reduces the formation of pTAG and aldehydes, whereas the enrichment of olive oil with OMW extract showed an increase in the formation of pTAG and promoted the biosynthesis of aldehydes whose rate remains significantly lower than that observed in enriched sunflower oil. The production of polymerized and aldehydic compounds was more pronounced when chicken was fried compared with potatoes. For the phenolic alcohols, their degradation was reached at the end of the experimentation. Novelty impact statement Olive mill wastewater (OMW) is a source of bioactive molecules that can be extracted and valorized in several industrial sectors. OMW extract reduces the production of p‐TAG and aldehydic products during frying foods in refined sunflower oils Frying of foods in olive oil without any additive is healthier than frying in enriched refined oils.