Pasteurization of pumpkin juice

The aim of this study was to investigate the use of ultrasonication, thermosonication and conventional heat treatment for the pasteurization of pumpkin juice obtained from pumpkin (Cucurbita moschata Butternut) which has recently gained the attention of researchers due to its positive effects on health and nutrition. For this purpose; effects of these treatments on the inactivation of the inoculated target microorganism Escherichia coli K-12 (surrogate of pathogenic E. coli O157:H7) was monitored. Ultrasonication (23 °C, 30 min) could inactivate less than 1 log of E. coli K-12. The maximum inactivation on E. coli K-12 was achieved by thermosonication at 60 °C as 6,62 log and followed by conventional heat treatment at 80 °C that could inactivate 4.06 log E. coli K-12. Effects of these three methods on the physicochemical and bioactive properties of pumpkin juice such as color (L*, a*, b*, ∆E), pH, titratable acidity, non-enzymatic browning, total soluble solids content, turbidity, total phenolics, total flavonoids and total carotenoids content and antioxidant capacity were studied and statistically analyzed. Sensorial analysis showed a non-significant (P<0.05) difference between the fresh (control) and thermosonicated (60 °C) pumpkin juice, with respect to general liking, however, conventional heat-treated samples had the least scores. This study is believed to give idea to the manufacturers on the production of pumpkin juice – a new vegetable juice - emphasizing the type of pasteurization methods and norms.