The current study focused on defining the stability of apple
juice after UHPH processing and aseptic packaging. For that purpose,
UHPH processing treatment of 300 MPa at 4 C (inlet temperature)
was used to preserve apple juice and the samples were
subjected to storage at different temperatures (4–30 C) for
60 days.
UHPH was not able to modify the original PAT content; but storage
at the highest temperature caused a decrease in PAT content.
Addition of AA before the UHPH-treatment could contribute to
the reduction of PAT content. The weak aspects of UHPH regarding
reduction of the PAT contents can be overcome by selecting good
quality fruit. Furthermore, washing and sorting are the most
important factor in the reduction of fungal contamination during
the juice production.
UHPH-treated apple juice was microbiologically stable at any
storage temperature for up to 60 days, despite it not being able
to destroy non-germinated spores. In the aseptically packaged
UHPH-treated apple juice, the presence of enzyme activity was
not observed after processing and during storage. The time–temperature
effect of storage caused degradation of nutritional components
(vitamin C, chlorogenic acid and total polyphenols) as well as
color changes. This effect was confirmed by the HMF accumulation.
Thus, storage temperature of 4 C was the best condition to preserve
the overall characteristics of the aseptically packaged
UHPH-treated juice, by obtaining a shelf-life similar to a commercial
juice. Acceptable commercial shelf-life was obtained when the
juice was stored at room temperature. However, a decrease in their
quality parameters was observed. Changes during storage are only
dependent on the storage conditions and the initial characteristics
of apple juice. As UHPH causes smaller changes to the original
product, the final characteristics would be closer to those of the
raw product that when a thermally treated product were stored
on the same conditions.