Enrichment of sunflower oil with tomato carotenoids and its encapsulation in Ca-alginate beads: Preparation, characterization and chemical stability upon in vitro digestion

Carotenoids from tomatoes are not only responsible for the vibrant red color of the fruits but, being powerful antioxidants, they also play a crucial role in enhancing the nutritional value and the health benefits of the raw fruits and products derived therefrom. The extraction of tomato carotenoids with the aid of ultrasounds and sunflower oil as a solvent medium, was explored in this work. Extraction parameters such as duration of sonication (min) and solvent:solid ratio (v/w) were optimized using response surface methodology (RSM). In a subsequent step, the obtained tomato carotenoids-enriched sunflower oil was encapsulated in Ca-alginate beads (three-dimensional cross-linked microgel particles) using ionotropic gelation. The fabricated alginate beads loaded with tomato carotenoids were characterized with a variety of analytical techniques, i.e., optical and confocal laser scanning microscopy (CLSM), chromatometry, Fourier Transform Infrared spectroscopy (FT-IR) and Raman spectroscopy, in order to obtain information regarding their size, shape, chroma as well as the molecular interactions among constituents present in the alginate beads. The encapsulation yield (%) and encapsulation efficiency (%) were found to be satisfactory. Moreover, the swelling behaviour as well as the chemical stability of tomato carotenoids in the oil phase under simulated in vitro gastrointestinal digestion conditions were evaluated. The developed processing approach offers an alternative route for the design of biodegradable and biocompatible carriers of tomato carotenoids-enriched sunflower oil preparations that could be used in food, pharmaceutical and cosmeceutical applications for protection and delivery of such non-polar bioactives derived from agricultural commodities and/or their by-products and wastes.