Italian scientists selected optimal processing conditions for 2 weeks shelf-life of fresh-cut melons

Packaging of fresh-cut products are becoming more and more popular because it offers several advantages in terms of convenience. However, fresh-cut fruit and vegetables need unit operations such as peeling, trimming or cutting, portioning, slicing and coring that alter the integrity of tissues and can induce wounding stress. In addition, the high amount of water and sugars available in the product after cutting and the neutral pH constitute are ideal conditions for microbial proliferation.

Microbial load is a serious problem for the melon that is grown on the ground in direct contact with any organic substances and its surface being uneven and porous allows the microorganisms to adhere very well to the pulp at the time of cutting. These reasons make it necessary to study proper technological options to be applied during the entire minimal processing stage, from the washing of the whole melon to the packaging of the fresh-cut fruit.

Italian scientists at University of Foggia, partner within European Project Quafety on safety and quality of fresh-cut produce, have carried out a study on melon (Cucumis melon L.) and have investigated several minimal processing operations to select:

the best washing treatment of the whole melon before cutting;
the optimal dipping treatment to reduce the pH of fresh-cut melon;
the best coating system, in terms of polymeric matrix and its concentration, to preserve quality and safety of fresh-cut fruit;
the best film, in terms of gas transport properties;
the best conditions established in each step were combined to prolong the shelf life.

In each trial, a shelf life test was carried out on fresh-cut melon by monitoring, during the refrigerated storage time, the microbiological quality, the pH, the mass loss and the headspace composition. The sensory properties were assessed by a trained panel that evaluated colour, odour, firmness and overall quality of each melon piece. A score equal to 5 in a scale ranging from 1 to 9 was used as the threshold for product acceptability. To calculate the product shelf life, microbial and sensory thresholds were taken into account. The approach adopted in the study allowed the assessment of the best conditions to prolong the fresh-cut melon shelf life.

Results showed that the washing of a whole melon according to a precise protocol, the dipping of pulp pieces in exanal essential oil, followed by a coating in sodium alginate solution and packaging in oriented polypropylene film (40 micron thickness) assured a shelf life of over two weeks compared to the control sample that remained acceptable for less than one week.

Contacts:
Amalia Conte, Alessandra Danza, Marcella Mastromatteo, Matteo Alessandro Del Nobile - Department of Agricultural Sciences, Food and Environment, University of Foggia - Italy
Email: amalia.conte@unifg.it