Berry Pectins: Microwave-Assisted Extraction and Rheological Properties

Press residues formed during processing of berry fruits are regarded as valuable pectin sources. In this work, pectins were extracted from press residues obtained by processing of various fresh berry fruits: red and black currant, raspberry and elderberry. The extraction was carried out by conventional and microwave-assisted methods. Comparing the two methods, the microwave-assisted process gave significantly better results. The rheological behaviour of the pectins extracted was studied, and we found that the gels of pectins from berry press residues are somewhat weaker than gel of commercial citrus pectin, but stronger than that of commercially available apple pectin. Red currant pectin was found to possess outstanding values regarding gel-forming capacity and thickening effect.