Goji berries, known for their health-promoting properties, are increasingly consumed around the world, often in the form of naturally- or freeze-dried fruits, further unprocessed. The aim of the study was to obtain dried goji berries extracts, characterized by high bioactivity and safety in terms of microbial contamination for the consumer. In the study, various solvents (water, ethanol, acetone, ethyl lactate, sunflower oil) and green extraction methods (heating and ultrasound-assisted extraction (UAE)) were used. In goji extracts, antioxidant activity and carotenoids content as bioactivity indicators, as well as total number of microorganisms were determined. Boiling of powdered dried goji fruits in water resulted in extracts with the best features, i.e., with high antioxidant properties (2.75−4.06 μmol of Trolox equivalent (TE)/mL), moderate to high content of carotenoids (0.67−1.86 mg/mL), and a reduced number of microorganisms compared with fruits. Extracts in 50% ethanol and 50% acetone were characterized primarily by very high antioxidant activity (3.09−4.90 μmol TE/mL). The high content of carotenoids (0.98−3.79 mg/mL) and high microbial quality (<10 CFU/g) were obtained by extraction in ethyl lactate by the UAE method. The results could be useful in the development of functional food based on goji berry ingredients.
Keywords: antioxidant activity; bioactivity; carotenoids; goji; green extraction; microbial safety.