Changes in bacterial diversity of refrigerated mango pulp before and after treatment by high hydrostatic pressure

- Mango pulp inoculated with epiphytic microbiota was treated by High-Hydrostatic Pressure (HHP).
- Control microbiota included Actinobacteria > Firmicutes > Proteobacteria > Bacteroidetes.
- Relative abundance of Proteobacteria increased during storage in controls.
- Relative abundance of Proteobacteria increased upon HHP treatment.
- Firmicutes increased during late storage after HHP treatment.

The purpose of the present study was to determine the effect of high hydrostatic pressure treatment (HHP) on the microbiota of mango pulp. Mango pulp was artificially contaminated with its own epiphytic microbiota to simulate a worst-case scenario of contamination during pulp preparation. Controls and samples treated by HHP (600 MPa, 8 min) were chill stored for 30 days. HHP treatment significantly (P < 0.05) reduced viable cell counts. Pyrosequencing analysis of the bacterial community revealed that the relative abundances found in the starting control samples for Actinobacteria (45.63%), Firmicutes (42.55%), Proteobacteria (10.68%) and Bacteroidetes (1.0%) changed during storage, with a strong increase of Proteobacteria. HHP treatment also induced a strong increase in Proteobacteria, followed by a late recovery of Firmicutes and to a less extent Actinobacteria. Lactobacillus was the main operational taxonomic unit (OTU) detected both in controls during early storage and in HHP-treated samples during late storage. Results from the present study indicate how bacterial populations of both controls and HHP-treated mango pulp samples undergo complex changes during refrigeration storage.