Biochemical and microstructural assessment of minimally processed peaches subjected to high-pressure processing: Implications on the freshness condition

• The viability of tissues is not a necessary condition for freshness in fruit products.
• The anaerobic metabolism of vacuum-packed peaches can be prevented by high pressure.
• The browning of peach pieces can be controlled by high pressure and vacuum packing.
• The microstructure of peach pieces subjected to 600 MPa 5 min remained rather unaltered.

Since the condition of freshness is closely linked to the definition of minimally processed fruits, it is generally assumed that they should be constituted by living tissues. High-pressure processing (HPP) has been proven to be successful in maintaining the freshness of foods, although the integrity of some tissues could be altered. The aim of this work was to assess different biochemical and microstructural changes experimented by the HPP-treated tissues. The following determinations were conducted in control and treated diced peaches: viability assay, microstructure analysis, relative expression of RNAm, and enzyme activities related to browning and anaerobic metabolism. Results showed that although HPP-treated tissues were not viable, changes in the expression of the RNAs of the enzymes evidenced that some metabolic processes were still active. In turn, the microstructure remained rather unaltered, while the enzymes tested were significantly inhibited. Then, although some characteristics of living tissues were modified in the HPP-treated fruits, they could be considered as fresh in appearance.Industrial relevanceIt is well known that conventional thermal treatments applied to preserve fruit products usually cause important changes in flavor, color, texture, and consequently the loss of fresh appearance. However, in the case of novel technologies such as high-pressure processing (HPP), this causality is not straightforward. Interestingly, the claim of “freshness” in foods has become a controversial topic, since some regulations indicate that for a food to be regarded as fresh, it should not have been subjected to any preservation processing. However, a list of exceptions has been considered for processes such as irradiation at low doses, or application of edible coatings. This list of exception is expected to increase, accordingly to the raise in successful experiences with the application of novel technologies such as HPP. This work provides information on the effect of HPP on different biochemical and structural aspects of treated peaches, with the aim to contribute toward the commercial application of HPP to minimally processed fruits.