Compuestos bioactivos y capacidad antioxidante en zumos y extractos de residuos, obtenidos por ultrasonidos, de mandarinas híbridas

Citrus are the most important crop worldwide. The production of juice generates large amounts of easily degraded waste, but with a high content of bioactive compounds. Ultrasound assisted extraction is one of the non-conventional extraction methods with favorable results. During the extraction, clean-up processes are necessary that favor the purification of the extracts for their best use. In addition, the bibliography indicates that there is a high number of studies with the best-known citrus fruits, however, few investigations show results in hybrid mandarins. For all these reasons, the objective of this work is the study of hybrid mandarins for the determination of the physical-chemical and functional characteristics of the juice, and of skin extracts obtained by ultrasound, as well as the characterization of the phenolic profile of the extracts, and the study for the determination of carotenoids in citrus extracts. The results obtained in the present work show that hybrid mandarin juices (Clemenvilla, Nadorcott and Ortanique) have adequate physicochemical characteristics to guarantee their quality. The variety and harvest season significantly influence the content of bioactive compounds and antioxidant capacity of juices. Thus, Clemenvilla mandarin juices show the highest content of total phenolic compounds and ascorbic acid, with high antioxidant capacity according to the methods used. The Nadorcott variety juices have the highest concentrations of total flavonoids while the Ortanique variety from the second harvest season has the highest content of total carotenoids. The antioxidant capacity of juices is significantly correlated with the content of bioactive compounds. Ultrasonically assisted extraction has a positive effect on the content of bioactive compounds and antioxidant capacity. A significant influence of the variety and the treatment time on the physical-chemical characteristics is not determined, however the content of bioactive compounds is influenced by these factors. Clemenvilla variety samples have higher concentration of total flavonoids and ascorbic acid. The Ortanique extracts contain a higher amount of phenolic compounds, while the Nadorcott variety samples have the highest content of total carotenoids. During the evaluation of the antioxidant capacity, it was determined that the content of flavonoids and ascorbic acid significantly influences the results, with the Clemenvilla variety samples being the ones with the highest activity. The analysis of the extraction index shows that short treatment times favor the obtaining of bioactive compounds such as flavonoids, with high antioxidant capacity. The application of different purification methods on mandarin extracts obtained by ultrasound is also studied. It is observed that with solid phase extraction using C18 cartridges as a clean-up method, satisfactory results are obtained for the separation and characterization of polyphenols by HPLC-UV. The compounds with the highest concentration, identified by UPLC-qTOF-MS/MS, are hesperidin and narirutin, being the skin of Nadorcott and Ortanique tangerines the ones with the highest concentration, respectively. Likewise, a study is carried out on various liquid-liquid extraction and saponification procedures for the characterization of carotenoids by HPLC-UV, in tangerine peel extracts obtained by ultrasound. A better carotenoid profile is observed after extraction with diethyl ether in three phases and subsequent saponification.