Production of ellagitannins concentrate by UF-NF from tropical highland blackberries

Abstract

Tropical highland blackberries are produced in Costa Rica and other tropical countries. Since weather conditions in tropical regions are more stressful than in temperate ones, polyphenol content in blackberries is hypothetically higher for tropically grown fruits. Ellagitannins are hydrolysable tannins – polyphenols – that have been studied lately due to their health beneficial properties, such as antioxidants, cancer treatment agents and cardiovascular health improvers. The concentration of such components by low-ultrafiltration/nanofiltration technologies is of great interest since low processing temperatures are used. Therefore, thermal labile components are not lost due to heat. CITA and CIRAD have issued a patent for using membrane technologies for the production of fruit juices and concentrate by using mostly membrane technology. The results show that it is possible to concentrate ellagitannins in blackberry up to a concentration 5-times higher than the one in the initial clarified juice with a ceramic membrane at 30ºC, with a VRF of 11. Retentions of up to 99 % were obtained for anthocyanins and ellagitannins. The initial estimate of production cost per kilogram of product is of 34 U$S/kg and assuming a sales price of 72 U$S/kg of product the payback time for an investment of nearly 165,000 U$S and a consumption of 2000 kg/day of blackberries is of two and a half months. The preliminary stability study showed that there is a need for further stabilization steps in order to assure the quality of concentrate, since polyphenol content decreased by 28%, anthocyanins by 52% and the ellagitannin estimate reduction percentage was of 22%, for a storage at 37ºC for a 5-week period. All in all, it was possible to study the concentration of ellagitannins from blackberry clarified juice in a pilot scale.