Extraction of bioactive compounds from berries
Doctors recommend that we eat more fruit and vegetables to improve our well-being and to reduce the risk of chronic diseases. Unfortunately, during the processing of berries and grapes, much of the dietary fibre and healthy phytochemicals are lost. The MAXFUN project has developed enzymatic extraction techniques in order to extract anthocyanin and other phenolic compounds from grape and berry residue. Researchers used both commercial enzyme mixtures, cutinases, rhamnosidases and rhamnogalacturonan IIases (RG IIases), which were isolated during the project. Researchers found that enzyme activity should be avoided so as to avoid the degradation of anthocyanins. Anthocyanins are water soluble pigments, which belong to the flavonoid group of chemicals and are plant nutrients that benefit the human body. The yield of juice and phenols was increased by selecting those enzymes that break down pectin, a natural gelling agent, and soluble fibre. Scientists also found that the use of ultrasound helped the enzyme mixture to breakdown pectin, thus reducing the amount of enzyme needed. High pressure processing affected the way in which enzymes broke down the cell walls of the substrate. However, it did not improve the extraction of phenols. The yield of polyphenols was increased when Humicola cutinase was applied to blackcurrant residue following processing, which had been treated with pectinase. During the processing of grapes, enhanced cell wall hydrolysis through the use of enzymes for breaking down pectin, did not improve the extraction of polyphenol.