Abstract
Wickerhamomyces anomalus is pectinolytic yeast isolated from citrus fruits peels in the province of Misiones, Argentine. In the present work, enzymes produced by this yeast strain were characterized, and polygalacturonase physicochemical properties were determined in order to evaluate the application of the supernatant in the maceration of potato tissues. W. anomalus was able to produce PG in liquid medium containing glucose and citrus pectin, whose mode of action was mainly of endo type. The supernatant did not exhibit esterase or lyase activity. No others enzymes, capable of hydrolyzing cell wall polymers, such as cellulases and xylanases, were detected. PG showed maximal activity at pH 4.5 and at temperature range between 40°C and 50°C. It was stable in the pH range from 3.0 to 6.0 and up to 50°C at optimum pH. The enzymatic extract macerated potato tissues efficiently. Volume of single cells increased with the agitation speed. The results observed make the enzymatic extract produced by W. anomalus appropriate for future application in food industry, mainly for the production of fruit nectars or mashed of vegetables such as potato or cassava, of regional interest in the province of Misiones, Argentine.
Highlights
Enzymes hydrolyzing pectic substances, which contribute to the firmness and structure of plant cells, are known as pectinolytic enzymes or pectinases
Capable of hydrolyzing cell wall polymers, such as cellulases and xylanases, were detected. These results are in agreement with the observation of several authors who reported that the most common enzyme found to be secreted by pectinolytic yeasts is PG [17, 18]
Schwan et al [16] reported that four yeast strains isolated from cocoa fermentations (Kluyveromyces marxianus, K. thermotolerans, and Saccharomyces cerevisiae var. chevalieri) showed extracellular PG activity, and neither PE nor lyases were detected in culture filtrates
Summary
Enzymes hydrolyzing pectic substances, which contribute to the firmness and structure of plant cells, are known as pectinolytic enzymes or pectinases. Maceration is a process by which organized tissue is transformed into a suspension of intact cells, resulting in pulpy products used in the food industry for the production of fruit nectars as pears, peaches, apricots, strawberries, and vegetables mashed such as potatoes, carrots, red pepper, and others that are used in babies and seniors foods [4] For such purposes, only the intercellular cementing material that holds together cells and some portion of primary plant cell walls should be removed without damage to adjacent secondary cell walls, to help avoid cell lysis, keeping nutritional properties of food [5]. Enzymes produced by this wild yeast strain were characterized, and physicochemical properties of polygalacturonase were determined by the study of the effect of temperature and pH on its activity and stability, in order to evaluate the application of the supernatant in the maceration of potato tissues
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