Impact of different hyperbaric storage conditions on microbial, physicochemical and enzymatic parameters of watermelon juice

- Hyperbaric storage at room temperature (HS/RT) was compared to refrigeration (RF).
- HS/RT (75/100 MPa) increased shelf-life of watermelon juice compared to RF.
- HS/RT performed better than RF also for inoculated E. coli and L. innocua loads.
- HS had a reduced impact on the majority of the quality attributes of the juice.
- HS/RT evolution of enzymatic activities (PPO, POD, and PME) was comparable to RF.

Hyperbaric storage (HS) of raw watermelon juice, up to 10 days at 50, 75, and 100 MPa at variable/uncontrolled room temperature (18-23 °C, RT) was studied and compared with storage at atmospheric pressure (AP) under refrigeration (4 °C, RF) and RT, being evaluated microbiological (endogenous and inoculated), physicochemical parameters, and enzymatic activities.Ten days of storage at 50 MPa resulted in a microbial growth evolution similar to RF, while at 75/100 MPa were observed microbial load reductions on endogenous and inoculated microorganisms (Escherichia coli and Listeria innocua, whose counts were reduced to below the detection limit of 1.00 log CFU/mL), resulting in a shelf-life extension compared to RF.The physicochemical parameters remained stable at 75 MPa when compared to the initial raw juice, except for browning degree that increased 1.72-fold, whilst at 100 MPa were observed higher colour variations, attributed to a lycopene content decrease (25%), as well as reductions on peroxidase residual activity (16.8%) after 10 days, while both polyphenol oxidase and pectin methylesterase residual activities were similar to RF.These outcomes hint HS as a reliable alternative to RF as a new food preservation methodology, allowing energy savings and shelf-life extension of food products. This is the first paper studying the effect of HS on inoculated microorganisms and on a broad number of physicochemical parameters and on endogenous enzymatic activities, for a preservation length surpassing the shelf-life by RF.

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