Effect of CO2 Preservation Treatments on the Sensory Quality of Pomegranate Juice

Abstract

Due to the interest in identifying cost-effective techniques that can guarantee the microbiological, nutritional, and sensorial aspects of food products, this study investigates the effect of CO₂ preservation treatment on the sensory quality of pomegranate juice at t₀ and after a conservation period of four weeks at 4 °C (t₂₈). The same initial batch of freshly squeezed non-treated (NT) juice was subjected to non-thermal preservation treatments with supercritical carbon dioxide (CO₂), and with a combination of supercritical carbon dioxide and ultrasound (CO₂-US). As control samples, two other juices were produced from the same NT batch: A juice stabilized with high pressure treatment (HPP) and a juice pasteurized at high temperature (HT), which represent an already established non-thermal preservation technique and the conventional thermal treatment. Projective mapping and check-all-that-apply methodologies were performed to determine the sensory qualitative differences between the juices. The volatile profile of the juices was characterized by gas chromatography-mass spectrometry. The results showed that juices treated with supercritical CO₂ could be differentiated from NT, mainly by the perceived odor and volatile compound concentration, with a depletion of alcohols, esters, ketones, and terpenes and an increase in aldehydes. For example, in relation to the NT juice, limonene decreased by 95% and 90%, 1-hexanol decreased by 9% and 17%, and camphene decreased by 94% and 85% in the CO₂ and CO₂-US treated juices, respectively. Regarding perceived flavor, the CO₂-treated juice was not clearly differentiated from NT. Changes in the volatile profile induced by storage at 4 °C led to perceivable differences in the odor quality of all juices, especially the juice treated with CO₂-US, which underwent a significant depletion of all major volatile compounds during storage. The results suggest that the supercritical CO₂ process conditions need to be optimized to minimize impacts on sensory quality and the volatile profile.

Keywords: check-all-that-apply; pasteurization; pomegranate; projective mapping; supercritical carbon dioxide; volatile profile.