Extraction and microencapsulation of anthocyanins from alfalfa flowers

Alfalfa flowers are rich in anthocyanins, which can be used as food coloring agents. In this study, ultrasonic-assisted extraction was used to extract anthocyanins from alfalfa, and response surface methodology (RSM) was used to improve the extraction rate of these anthocyanins. These anthocyanins were then microencapsulated to improve their stability. Our results showed that the optimal extraction conditions for these compounds were as follows: 61% ethanol as extraction agent, liquid to solid ratio was 30 ꞉ 1, extraction temperature of 65 ℃, extraction time of 25 min, and ultrasonic power of 250 W. The use of these conditions produced a maximum anthocyanins content of 1.581 mg·g⁻¹. Microcapsules wereprepared using maltodextrin, xanthan gum, and acacia gum as wall materials. The optimal wall material ratio was maltodextrin ꞉ xanthan gum = 30 ꞉ 1 (w : w), and the encapsulation rate was well. The microencapsulated anthocyanins were stable.