Effect of blanching, freezing and microwave-assisted pretreatment methods on chlorophyll extraction from Sauropus androgynus leaves

Sauropus androgynus is grown commonly in Vietnam, which has a high content of bioactive substances including chlorophyll, polyphenols, and antioxidant activity. Sauropus androgynus is used as food or a colorant for traditional Vietnamese cakes. Green pigments are employed in various industrial sectors, such as food, drinks, soap, and drug. Chlorophyll can be replaced synthetic green pigments that might be unhealthy. In this study, the effect of chlorophyll extraction efficiency and perceptional green color by extraction condition combinined with physical pretreatment methods was investigated using Sauropus androgynus leave as a model. Fresh raw materials were pre-treated by blanching, freezing and microwave treatment at 55w/g for 3 min and then extracted with 40% (v/v) ethanol solvent. The best chlorophyll recovery efficiency (CRE) from Sauropus androgynus by heat pretreatment methods with and without microwave assistance was 32.035% and 25.784% of chlorophyll content in material; or 1.081 mg/g d. w and 0.862 mg/g d. w of fresh leaves, respectively. The chlorophyll extract is then spray-dried to form a water-dispersible powder. Chlorophyll extracted with microwave-assisted pretreatment having high CRE that has potential applications in food production, but green color is not much more favorable than the non-microwave assisted sample. [Display omitted] •Physical pretreatment improved chlorophyll recovery efficiency (CRE) and the green color of Sauropus androgynus extracts.•The CRE of the MAE method (32.035%) was higher than that of the non-MAE method (25.784%).•Chlorophyll powder by non-MAE method had favorable green color.