Cryoconcentration procedure for aqueous extracts of maqui fruits prepared by centrifugation and filtration from fruits harvested in different years from the same localities

BACKGROUND: At the present time, the food industry is increasingly interested in the development of formulations with maqui-berry extracts as a rich source of bioactive compounds. Maqui, native to Chile, is a relatively new food raw material that is often called a "superfruit", The berries of this plant are rich in anthocyanins, phenolic acids, and tannins; compounds that play an important role as sources of bioactive compounds in the health of consumers. Cryoconcentration, a technology that preserves thermolabile bioactive compounds by combining techniques of freezing-centrifugation, makes it possible to obtain concentrates with a greater content of bioactive compounds than traditional methods of concentration. In this study, maqui fruits were pulped to obtain juice (J) and chaff. The chaff was subjected to aqueous extraction with distilled water in a ratio of 1 : 1 p/v to obtain maqui extract (E). Combined J and E were homogenized, and vacuum filtered to obtain the final extract (A), which was cryoconcentrated at -30 degrees C and then subjected to 3 continuous cycles of freezing-centrifugation and filtration. OBJECTIVE: To assess the process parameters and polyphenol-anthocyanin content of cryoconcentrates obtained from maqui-berry (Aristotelia chilensis (Mol.) Stuntz). MATERIAL AND METHODS: Three continuous centrifugation-filtration cycles were used. The polyphenol content was determined by the Folin-Ciocalteu method with gallic acid as a standard. Anthocyanins were identified by high-performance liquid chromatography (HPLC) and total anthocyanin content was determined by the pH differential method the anthocyaninds present were identified by high performance liquid chromatography (HPLC). RESULTS: After application of the cryoconcentration cycles assisted by centrifugation-filtration, the separation efficiency of solute was found to be maintained over 90%. The content of soluble solids significantly increased in the concentrated fractions and reached 54.2 degrees Brix at the end of the third cycle. Finally, the ratio of the concentration of total polyphenol and anthocyanin increased 2.8 and 6.7 times, with respect to the initial content in the maqui-berry extract. CONCLUSIONS: The maqui cryoconcentrate is a product with a large content of antioxidants and bioactive compounds commonly considered as functional characteristics. This concentration method also conserved the profile of anthocyanins present in maqui fruit extract. The efficient separation solutes and bioactive compounds achieved will permit scaling these process conditions to the industrial level.