Optimization of physical and enzymatic debittering methods for grapefruit juice

Abstract: The acceptability of grapefruit juice is hindered by its inherent bitterness, primarily attributed to the presence of naringin as the main bitter component. To enhance consumer preference, two distinct methods, physical and enzymatic, were employed to mitigate the bitterness of grapefruit juice. In the physical method, the juice underwent treatment with the adsorbent Amberlite IR 400, utilizing a 3-level factorial design. The enzymatic method involved the application of naringinase enzyme, employing the Box-Behnken experimental design. Notably, the physical method revealed a significant linear and interaction effect of time and temperature on the naringin content, while the enzymatic method exhibited a significant linear effect of enzyme concentration, time and temperature on the same. Both debittering methods were optimized using a numerical multi-response optimization technique to determine the optimum variable levels. This ensured that both independent and dependent variables remained within the experimental range, achieving maximum desirability. For the physical debittering method, the optimized conditions were 96 minutes and 28 °C for time and temperature, respectively. Meanwhile, the enzymatic debittering method optimized conditions included 0.83 g/L enzyme concentration, 35 °C temperature, and 3 hours 50 minutes time. Under these optimized conditions, the enzymatic method demonstrated superior results, achieving a higher naringin reduction of 55.77%, compared to the 33.18% reduction achieved by the physical method using Amberlite IR 400.