Study on ultrasonic-assisted extraction of ester substances from pear residues

Ultrasonic-assisted extraction of ester substances using edible ethanol as solvent was carried out from fresh Ya pear's residues in this study.Orthogonal experiment was used based on the single factor results to study the effects of ultrasonic power, ultrasonic time, solid-to-solvent ratio, extraction temperature, and ethanol concentration and vacuum concentration temperature on the extraction of ester substances.The effects of ultrasonic-assisted extraction conditions on the extraction of polyphenols and sugars were also investigated.The results showed that the optimal extraction conditions were ultrasonic power 80 W, ultrasonic time 10 min, solid-to-solvent ratio 1∶ 10, extraction temperature 25 ℃ and ethanol concentration 95%, vacuum concentration temperature 40 ℃.Under the optimal extraction conditions, extraction yields of esters, polyphenols and sugars were 3815.73 μg/g, 603.33μg/g and 53.12 mg/g ( fresh weight) respectively. The extraction solution was vacuum concentrated at 40 ℃ and 0.1MPa.The yield of extract concentrate ( nutrient and flavour agent of pear) was 19.05 g/100 g ( fresh weight) , and it contained16028.34 μg/g esters, 3104.88 μg/g polyphenols and 266.46 mg/g reducing sugars. Using ultrasonic-assisted extraction can effectively extract nutrient and flavour substances such as esters and polyphenols from pear residues.