Mathematical Modeling and Optimization of the Microwave Assisted Extraction of the Natural Polyphenols and Flavonoids from the Raw Solid Waste of the Orange Juice Industry

Orange pomace is the solid waste of the orange juice industry which accounts for approximately 50% of the quantity of the fruits processed into juice and is a good raw material for production of high added value products with diverse uses. Orange pomace is rich in polyphenols and flavonoids which can substitute the potentially hazardous or less desirable chemical antioxidants/antimicrobials used in agro-food and cosmetics industry. In this work, an eco-friendly aqueous microwave assisted extraction of orange pomace was investigated and optimized in order to produce aqueous bioactive antioxidant/antimicrobial extracts. A three factorial Response Surface Optimization methodology with centered Box & Behnken experimental design was used to obtain optimum values of total polyphenols and total flavonoids and build predictive models for their optimal extraction conditions. The three optimization factors in terms of applied process parameters were (a) water/solid ratio, (b) extraction temperature and (c) extraction time. The effectiveness and statistical soundness of the two corresponding models regarding optimal total polyphenols and flavonoids were verified by Analysis of Variance (ANOVA).