Ozonated Water for Enhancing Quality and Antioxidant Activity in Ready-to-Eat Table Grapes During Cold Storage

Table grapes are widely cultivated worldwide and are highly appreciated by consumers for their sensory characteristics and high nutritional value. Recently, many researchers have focused on applying specific post-harvest preservation strategies, such as the use of ozone, which represents an environmentally and health-friendly approach to sanitizing and preserving fresh fruits. In addition, ozone acts as a stressor, stimulating the defense mechanism of fruits and the synthesis of polyphenols, important antioxidant compounds. This study aimed to investigate the effect of different concentrations of ozonated water (8 ppm and 12 ppm), cold stored for 12 (T1) and 24 (T2) days, on the weight loss, texture and color parameters, phenolic content, and antioxidant activity of ready-to-eat Italian ‘Regal seedless’ grapes. Weight loss increased during cold storage for all treatments; however, the control exhibited higher values at 12 and 24 days (0.30% and 1.06%, respectively). Cold storage clearly affects the color of grapes, resulting in a loss of brightness and saturation, an increase in the yellow component, and a reduction in hue. At T2, ozonated water showed a significant increase in total phenolic content (TPC), antioxidant activity (DPPH, ORAC), and some phenolic compounds, including gallic acid, kaempferol, and resveratrol, compared to the control. The results indicated that using ozonated water on grape berries could be an effective strategy for enhancing their shelf life and nutraceutical value in post-harvest treatment.