Optimization of high antioxidant smoothie from a mixture of milk, fruits and vegetables by response surface methodology (RSM)

Introduction: Smoothie which is mainely prepared from fruits and vegetables is a good source of health-promoting bioactive compounds, primarily antioxidants, which actively modulate disease development by inhibiting ROS-mediated reactions in the body. Smoothies represent an excellent and convenient alternative to promote the daily consumption of fruits and vegetables. Methods: The optimum combination of the five factors (carrot, beef, lettuce, pineapple, and banana) used to obtain the highest yield of total phenolic content (TPC), DPPH, and FRAP was analyzed using the central composite design by response surface methodology. These fruits and vegetables used due to their availability and well-known health benefits. The effects of carrot (X1: 25-60g), beef (X2: 25-60g), lettuce (X3: 25-60g), pineapple (X4: 30-70g), and banana (X5: 25-60g), on the three variables (Y1, Y2, and Y3) were tested. Results: RSM generated 50 formulations. The experimental outcomes were adequately fitted into a second-order polynomial model regarding TPC (R2 = 0.9436, p = 0.0001), DPPH (R2 = 0.9292, p = 0.001), and FRAP (R2 = 0.0.9176, p = 0.001). The optimum combination was 25 g of carrot,25 g of beet, 25.55 g of lettuce, 70 g of pineapple, and 30.05 g of banana. The predicted results for TPC, DPPH, and FRAP were 21.87 mg GAE/100 g, 37.17 mmol TE /100g, and 54.12 mmol TE /100g, respectively. The experimental outcomes were close to the predicted results: 21.97±0.99 mg GAE/100 g, 36.86±0.76 mmol TE /100g, and 52.26±1.52 mmol TE /100g, respectively. Conclusion: As a result, RSM successfully optimized the range of variables. Consequently, the optimal combination of fruits and vegetables provided the highest antioxidant content and activities, which can be used as a functional smoothie.