Making ordinary food extraordinary

Preserving the goodness of vegetable juices

Cold pasteurised juices are gaining popularity, but most juices in the market are more commonly preserved by thermal pasteurisation. Chew Ding Xiang's final-year project examines the effect of High-Pressure Processing (HPP), which is an industrial non-thermal process involving the application of high pressure to inactivate microorganisms in food, on the nutrient preservation of vegetable .

"Vegetable juices are popular as a low-sugar alternative to fruit juices and for their reputation as 'detox drinks'," said Ding Xiang, as he explained the context of his project.

Based on his research, Ding Xiang found that the bok choy juice he prepared using HPP not only preserved nutrients well, it also retained the ideal sensorial properties of the juice. The colour of the juice was a fresh-looking green, compared to the dark, less appealing green of the thermally processed version.

"This means that HPP could be a viable option to produce and distribute vegetable juices on a large scale, and consumers can enjoy greater convenience and accessibility. Furthermore, as vegetables are susceptible to spoilage, juicing is one way to help reduce wastage," said Ding Xiang.

Final-year FST student Chew Ding Xiang holding a bottle of high-pressure processed bok choy juice. This improved version preserves nutrients well, and retains the flavour of the vegetables. Credit: National University of Singapore

Bok choy juice that has been high-pressure processed retains nutrients and freshness well. Credit: National University of Singapore

Apple slices being dipped into the probiotic coating solutions. Credit: National University of Singapore