EFFECT OF PECTINASE ENZYME TREATMENT ON THE RHEOLOGICAL, PHYSICAL AND CHEMICAL PROPERTIES OF PLUM, BANANA AND GUAVA JUICES.
 
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Pol. J. Food Nutr. Sci. 2002;52(3):13–19
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ABSTRACT:
Viscometric characteristics of untreated and pectinase enzyme treated plum, banana and guava juices were studied at a temperature range of 30 to 70oC and at various spindle speed (0.6-60 rpm), using a Cannon-rotary viscometer. Viscosity decreased with increasing of spindle speed and temperature. The power-low model was used to determine the viscometric constants. Consistency coefficient values (k) were higher for pectinase treated plum juice than that of pectinase treated banana and guava juices, but were higher for untreated guava juice than that for untreated plum and banana juices. No appreciable effect on the values of flow behaviour index (n) was found due to change of temperature for all untreated and pectinase treated juices, while the values of consistency coefficient decreased with increasing of temperature. It was found that the activation energy for viscous was increased in pectinase treated juices than in untreated juices. The results showed that the effect of temperature on the Newtonian viscosity and consistency coefficient of these juices could be described by an Arrhenius-Type equation. It is concluded that the technique of pectinase enzyme treatment used produced good results; the pectinase enzyme treated juice showed good quality with respect to physical and chemical properties. Also, pectinase enzyme treatment improved juice yield, colour, total soluble solids, acidity and clarity of juices.