Influence of Enzymatic Pretreatment on the Cell Structure and Oil Recovery from Pumpkin Seeds

Abstract

The pretreatment of pumpkin seeds with proteolytic, cellulolytic and pectolytic enzymes and their effect on cell structure and oil yield was studied. Pumkin seed samples were treated with pepsin, papain, Viscozyme L, cellulase or pectinase. The evaluation of cell integrity by immediate hexane extraction (shaking method) showed that all samples treated with different enzymes had a higher oil yield, ranging from 33.2 to 34.1 % of seed weight, than the control samples (32.1 %). The number of disrupted cells was also higher than the control (64.4%), ranging from 67.6 to 69.5 %. The highest percentage of disrupted cells, 71.0 and 71.1 %, was found in samples treated with pepsin+Viscozyme L+pectinase and pepsin+cellulase+pectinase mixtures, respectively. To study the effect of enzymatic pretreatment on the microstructure of pumkin seeds, ultramicrotome slices of pumpkin seeds were treated with individual enzymes and enzyme mixtures. The highest percentage of cell destruction was observed in samples treated with Viscozyme L and the mixture of pepsin+Viscozyme L+pectinase. The yield of pressed oil from pumpkin seeds pretreated with the pepsin+Viscozyme L+pectinase mixture was 7.0 % higher than that of control samples. The quality parameters, chemical composition and antioxidant activity of pressed oils were investigated and the enzymatic pretreatment did not significantly affect the free fatty acid content, peroxide value, fatty acid composition, or phytosterol profiles. The antioxidant activity expressed as DPPH° radical scavenging effect of the enzymatically pretreated pressed oil was 2.7 % higher than that of the sample not pretreated with enzymes.