Purpose: This research proposes some promising ways to control fungi in juices.
Methods: Fusarium oxysporum, Penicillium italicum and Aspergillus nidulans were studied in relation to their resistance to homogenization (single or multiple pass-treatments up to a 150 MPa pressure) and ultrasound (by modulating the duration of treatment and pulse, and power) both in model systems and in juices (pineapple, orange, and tomato juices). These treatments were also combined with Na-benzoate and citrus extract. The experiments were planned and performed by using the theory of the Design of Experiments.
Results: Homogenization could affect fungal spores only when a multiple-pass treatment was used; moreover, it reduced the number of spores but did not control survivors. Similar results were found for ultrasound, although the managing parameters (power, pulse, duration of the treatment) played a different role. The combination of citrus extract improved the effect of the treatment, reduced the targets below the detection limit, and allowed a reduction of the amount of Na-benzoate.
In addition, homogenization also caused a macroscopic variation on Penicillium, as the colonies turned to white and lost the green pigment.
Significance: The use of alternative approaches to thermal treatment and the reduction of benzoate in food are some primary goals of food technology. This research proposes a critical evaluation of two possibilities by highlighting their limits and benefits.