Effect of Sulphite and UHT Sterilization Parameters in the Coconut Water Quality

Abstract

Coconut water (Cocus nucifera L.) has been widely exploited in recent years, with the UHT sterilization process (Ultra High Temperature) as the greatest economic impact for this sector. In a long period of storage, the color and quality of the product may change, impacting the visual aspect and influencing consumer acceptance.The aim of this study was to optimize the processing conditions, including temperature, retention time and sulphite content added. A central composite design (CCD) was performed, with temperature (128 °C to 142 °C), retention time (4 to 14 seconds) and sulphite addition (up to 50 mg.L-1) as independent variables, and the chemical and physical analysis as dependent variables. Hunter color, enzyme activity and turbidity were performed in 24 h and after 45 days storage at 25 °C. The results after one day storage, showed residual sulphite correlated only with the initial amount added, lowering around 20 %, allowing generate a response surface model. After 45 days it was found that the b* value and sulphite showed a significant effect with respect to the temperature level and added sulphite, respectively. Coconut water before processing presented polyphenoloxidase activity and no peroxidase activity, being inactivated in the UHT processing trials. In conclusion, all the levels used allow evaluate the processing effects in coconut water quality parameters, being effective in the polyphenoloxidase inactivation during storage.