Abstract:

Water was used to extract total flavonoids from sweet orange residue left after squeezing juice under ultrasonic assistance instead of organic solvents. On the basis of single factor experiments, quadratic rotational combination design combined with response surface analysis was used to optimize total flavonoids yield as a function of ultrasonic power and treatment time, temperature and material/water ratio. Results showed that the developed mathematical model for total flavonoids yield exhibited tremendous significance and excellent goodness of fit and a significant effect on total flavonoids yield was observed in linear and quadratic terms. The interactions among the above parameters had a significant effect on total flavonoids yield. Material/water ratio had the most significant effect, temperature took second place and ultrasonic power and treatment time had a little effect. The optimal values of these parameters were determined as follows: ultrasonic treatment time 41 min, ultrasonic power 1410 W, temperature 57 ℃ and material/water ratio 1:16. The total flavonoids yield obtained under such conditions was 1.061%.

Key words: sweet orange, total flavonoids, extraction, response surface methodology (RSM)