| Coconut water, the clear liquid inside immature green coconuts, is highly valued due to its nutritional and therapeutic properties. It has been successfully used in several parts of the world for oral rehydration, treatment of childhood diarrhea, gastroenteritis and cholera. This juice is mostly consumed locally as fresh in tropical areas since it deteriorates easily once exposed to air. Commercially, it is thermally processed using ultra high temperature (UHT) technology. However, coconut water loses its delicate fresh flavor and some of its nutrients during heating. A non-thermal process is desirable to protect the fresh flavor and nutrient content of coconut water, which would increase marketability of this healthy drink and availability to consumers throughout the world. This study evaluated the effects of dense phase CO2 (DPCD) pasteurization on sensory, physical and chemical quality of a coconut water beverage. The coconut water beverage was formulated by acidification with malic acid to pH around 4.30, sweetened with Splenda (0.7% w/w) and carbonated at 1.82 atm CO2 at 4°C. Microbial reduction was quantified as a function of pressure, temperature and % CO2 level. Optimum DPCD treatment conditions for microbial inactivation were determined to be 13% CO2, 25°C, 34.5 MPa for 6 min. Quality attributes such as pH, oBrix, % titratable acidity (%TA) and color of DPCD treated, fresh and heat pasteurized (74°C for 15 s) coconut water beverages were measured and compared throughout refrigerated storage (4°C for 9 weeks). DPCD treatment did not cause a change in pH or oBrix. The color of coconut water eventually turned pink during storage, independent of treatment. Sensory panels showed that DPCD treated coconut water was liked as much as fresh coconut water; whereas heat pasteurized coconut water was significantly less liked (alpha=0.05) at the beginning of storage. Flavor compounds of immature coconut water were identified. Flavor profiles showed that heat treated coconut water had more aroma active compounds than DPCD treated coconut water.; This study showed that a fresh-like tasting coconut water beverage can be produced by DPCD technology with an extended shelf-life of more than 9 weeks at 4°C. |
