High pressure inactivation of Escherichia coli and Staphylococcus aureus in
pineapple puree (variety MD2) and preliminary quality evaluation during
chilled storage

The increased demand in the global pineapple market from Malaysia makes the focus on
downstream processing even more important. However, contamination of fruit purees with
foodborne pathogens could take place during processing and post-processing handling. In
this study, the efficiency of high-pressure processing (HPP) was investigated against
aseptically inoculated Escherichia coli ATCC® 25922™ and Staphylococcus aureus
ATCC® 25923™ in pineapple puree. Pineapple (Ananas comosus) variety MD2 was
chosen for HPP treatment due to Malaysia’s competitive advantage in the global pineapple
market. An 8-log reduction of E. coli and S. aureus (p<0.05) in pineapple puree during
HPP (400 MPa for 5 mins at 30oC processing temperature) in this research making HPP
an effective technology. In this study, S. aureus showed a higher inactivation effect than
E. coli in HPP-treated pineapple puree. Untreated pineapple puree samples with
inoculated pathogens were kept as control samples. Knowledge of food safety is necessary
for a reliable HPP process; hence a preliminary storage study was added to compare the
chemical and microbiological quality between HPP-treated pineapple puree and heattreated pineapple puree. Interestingly, HPP-treated samples effectively retained vitamins
A, B1, B2 and C close to fresh samples (control) during 0 months, and vitamin A was
retained after 6 months of storage. The microbiological results also showed that HPPtreated samples were microbiologically safe during chilled storage for a minimum of 6
months based on international microbiological standards. In summary, E. coli and S.
aureus inactivation can be accelerated with pressure higher than 400 MPa at 30oC
processing temperature within 5 mins and HPP successfully maintained the safety of
pineapple puree for a minimum of 6 months.