Optimization of Ohmic Heating Conditions for Enhancement of Quality Characteristics of Sonicated Jamun Juice

Jamun juice is a delicious fruit beverage enriched with antioxidants such as flavonoids, phenolics, carotenoids, and vitamins. Traditional thermal processing methods widely used for preservation, often lead to flavor loss and degradation of nutritional value,particularly in heat-sensitive jamun juice. This study aimed to evaluate the impact of ohmic heating conditions on the quality attributes of sonicated jamun juice. The ohmic heating process was applied to the sonicated jamun juice samples under various voltage gradients (20-40 V cm-1), treatment temperatures (40°C -75°C), and treatment duration (2-4 min). Response surface methodology, utilizing the Box-Behnken design, was employed to optimize response parameters, including pH, total soluble solids (TSS), anthocyanin content, and total phenolic content. The results indicated that the quadratic and interaction effects of temperature and time were significant and positively influenced the pH. Conversely, the linear terms showed insignificance. Increasing the voltage gradient resulted in an elevated TSS. The rate of TSS increase was gradual at lower voltage gradients (20-30 V cm-1) and accelerated at higher voltage gradients (30-40 V cm-1). The degradation of anthocyanins remained slow until the voltage gradient reached 30 V cm-1, after which further increase in voltage gradient substantially reduced anthocyanin content in the juice. The linear effects of voltage gradient, temperature, and treatment duration  demonstrated a positive correlation with the total phenolic content. Both temperature and voltage gradient contributed to an increase in the total phenolic content. The optimalprocessing conditions for ohmic heating of sonicated jamun juice were determined at a voltage gradient of 30 V cm-1, temperature of 75°C, and treatment duration of 4 min. These findings contribute to enhancing the quality attributes of jamun juice throughoptimized ohmic heating conditions, thereby benefitting the juice processing industry.