Do novel technologies lead to the redefinition of freshness in minimally processed fruits?

DENOYA GABRIELA; NANNI MARIANA ; APOSTOLO NANCY; VAUDAGNA SERGIO R.; POLENTA GUSTAVO

Columbus, Ohio

Workshop; 2014 International Nonthermal Food Processing Workshop; 2014

Ohio State University

Fresh-cut fruits are defined as fruits that have been minimally processed for the convenient use by consumers or retailers. Since products under this category implicitly require a freshness condition, some definitions consider that these products should be constituted by living tissues. In the case of conventional thermal processing applied for preservation, treatments usually cause significant changes in flavor, color, texture, and consequently, the loss of fresh appearance. However, in novel technologies such as High Pressure Processing (HPP), this causality is not straightforward. Considering the demonstrated success of novel technologies to preserve the freshness of foods, the aim of this work was to study if the condition of ?freshness? depends on the viability of tissues and other metabolic aspects. For this purpose, the following determinations were conducted in minimally processed peaches untreated (control) or subjected to HPP: Viability assay with Fluorescein Diacetate, relative expression of RNA (by Real-Time RT-PCR) of enzymes related to browning (phenylalanine-amonio-lyase, polyphenoloxidase-PPO) and to anaerobic metabolism (alcohol dehydrogenase-ADH, piruvate decarboxilase), and activity of PPO and ADH. Results show that although pressurized tissues were not viable in terms of the viability assay, changes found in treated samples in the relative expression of RNA associated to all the enzymes analyzed, evidence that metabolic processes are still active in tissues after treatment application. Although the PPO activity was significantly (p<0.05) reduced because of the HPP, it was not totally inhibited. In turn, ADH was completely inactivated by HPP, which evidences that the induction of anaerobic metabolism was prevented, even though the fruit was vacuum-packed. We conclude that although this technology modifies some characteristics of living tissues, pressurized products can still be considered as ?fresh?. Therefore, novel technologies make necessary the revision of some definitions, especially those linking physiological aspects of tissues with parameters associated to consumers? perception, as would the case with the ?freshness? of minimally processed fruits and vegetables.