Effect of ozone and ultrasound treatments on polyphenol content, browning enzyme activities, and shelf life of tender coconut water.

The sweet, clear, aqueous part inside the immature green coconut is referred as
tender coconut water (TCW). Although several processing techniques have been
attempted, preserving the TCW with its wholesome natural property is yet to be
achieved. In the present investigation, the nonthermal treatments (ozone and ultrasound) in combination with nisin were used to extend the shelf life of TCW, and the
results were compared with heat-treated TCW. The reduction in microbial counts,
retention of phenolics (64%) and flavonoids (70%), and inactivation of polyphenol
oxidase and peroxidase enzymes of the fresh TCW by ozone with nisin treatment
indicated its superiority over other treatments for preservation. The heat-treated
and ozone with nisin-treated TCW were sensorily acceptable for 3 weeks, whereas,
ultrasound with nisin-treated TCW was unacceptable after 2 weeks of refrigerated
storage. Hence, ozone with nisin can be used for the preservation of TCW under
refrigerated conditions.
Practical applications
The work described here shows that the preservation of highly perishable TCW is
possible by the use of nonthermal processing methods. The currently used thermal
processing of TCW alters its sensory quality; however, use of ozone in combination
with nisin was not only able to preserve its nutritional and sensory quality but was
also extended its shelf life at refrigerated temperature. Ozone can be easily used at
the industrial level to preserve the quality of TCW.