Microwave-assisted extraction of pectin from lemon peel powder: Optimization and physicochemical properties

This study employed microwave-assisted extraction to extract pectin from dried lemon peel powder. The extraction was carried out using both continuous and intermittent microwave-assisted methods. The effects of several processing input variables (microwave power 360–900 W, irradiation time 20–80 s and pH 1–3.5 at a fixed loading ratio 1:15 g/mL on the yield of pectin were studied and optimized using the face-centered response surface design. In the intermittent process, the extraction parameters consisted of microwave power ranging from 300 to 900 W, pulse ratio ranging from 0.5 to 1, and pH levels between 1 and 3.5. The desirability function approach was used during the optimization procedure. The yield of pectin extracted exhibited a positive correlation with the microwave power but demonstrated a negative correlation with the extraction time, and pH. A second-order polynomial model was established from the results, which effectively described the variation in the data and accurately depicted the correlation between the independent variables and the response. The highest pectin yield (47.3 %) from lemon peels was obtained under the optimal conditions of 900 W microwave power, 80 s duration, a pulse ratio of 0.5, and a pH of 1 using the intermittent method. On the other hand, the continuous process resulted comparatively lesser pectin content (44.5 %) at 900 W, 20 s extraction time, and a pH of 1. The optimized results were confirmed and a high level of agreement was obtained between the validation experiment and the projected value.