Optimization of extraction conditions for flavonoids content from Citrus grandis peels

Abstract

Recently, the development of flavonoids become a hot topic and have received much attention from researcher because of the ability and effectiveness in reducing blood lipid, as an anti-oxidative, in assimilating cholesterol, inhibiting thrombosis and the dilating the coronary artery. In addition, epidemiological studies had proved that increased the consumption of flavonoids abundant diet leads to decrease in mortality from coronary heart disease and certain types of cancer. This implies that the extraction of flavonoids with high biological activity and high content are very important for the medical and food industry. Citrus grandis are recognized to be rich in certain phytonutrient that are vital in both health promotion and disease prevention. However, during the processing of Citrus grandis for juice, peels are the primary byproduct. If not processed, the peels become waste and a possible source of environmental pollution. In fact, phytochemicals such as flavonoids, carotenoids and pectin that contribute to health are abundant in the Citrus grandis peels. In particular, the highest amount of flavonoids (a major group of citrus secondary metabolites) occurs in the peel. In order to optimize the flavonoids content from Citrus grandis peels in this study, the condition for extraction parameters varied by different solvents (methanol and ethanol), extraction time(1-5 hours) and temperature of extraction ( 50°C-80°C ) are essential to investigate under the Design Expert software via response surface methodology (RSM). This is because time and temperature of extraction are the important parameters to be optimized in order to minimize energy cost of the process. Hence, the total content of flavonoids in citrus peels can be determined qualitatively by using coloration methods with chromogenic system of NaNO2–Al (NO3)3–NaOH and quantitatively by using VersaMax Microplate Reader.