Study of polygalacturonase production by an Antarctic yeast and obtention of dragon fruit juice by maceration at mild temperature. (October 2022) - Bezus, Brenda
Abstract: The objectives of the present survey were to study the production and the biochemical characterization of an enzymatic cold-active extract with polygalacturonase activity, to perform a first insight into its possible application in fruit-juice obtention process, and to use this juice for food products preparation. The enzymatic extract was produced by the Antarctic yeast Mrakia sp. LP January 7, 2016 in a bioreactor with citric pectin as substrate. The polygalacturonase activity showed optimum conditions for reaction at 45 °C and pH 5.0. This activity was stable until 40 °C but deactivated at higher temperatures. Inhibition by Hg +2 suggested the presence of a thiol-dependent enzyme. A high-molecular polygalacturonase was detected in an SDS-PAGE and zymography analysis. Reaction-products were observed by thin-layer chromatography and suggested the endo -mode of action. The enzymatic extract had some accessory enzymes, such as pectin methylesterase, β-glucosidase, cellulase and inulinase. As a first insight into the potential use of this enzymatic extract for fruit maceration at mild temperatures, red and white dragon fruits were selected as models. At 23 °C, juice yields of 15%–23% higher than control were obtained after treatments, with a decrease of remanent solid of 25%–35%. The color of red dragon fruit juice increased with enzymatic treatment. Alginate balls that were prepared with the juices demonstrated a hardness of ∼10 N. The compression force of low-calorie sugar gels was 3.8 N. This work provided a complete study of the production, characterization, application and food product production using a new cold-active polygalacturonase extract of Antarctic origin.