LAUSR

The use of natural dyes in foods enhances the product quality and they are also associated with anti-inflammatory and anti-cancer effects. Therefore, they play significant role in human health. Chlorophyll is used as a natural pigment in a variety of foods. This study aims to prepare the extract and chlorophyll from Persian clover ( Trifolium resupinatum L.), using enzymatic and ultrasound methods and evaluation of their antioxidant and physicochemical properties. In the present study, the chlorophyll stability was evaluated in different conditions including temperature (− 18, 4 and 10 °C), time (15, 30 and 45 days), pH (4.5 and 5.5) and NaCl concentration (50, 100 and 150 mM). The results showed the chlorophyll a concentration was approximately as twice as the chlorophyll b concentration. In all of the experiments, the enzymatic method has shown better efficiency than the ultrasound one. Also, with the increment of extract concentration, the DPPH free radical scavenging and ferric reducing antioxidant power (FRAP) as well as total phenolic compounds, anthocyanin, and flavonoids were increased dramatically. Due to the higher efficiency of enzymatic extraction, the stability assessments were performed based on this method. The result demonstrated that 50 mM of NaCl, temperature − 18 °C, pH 4.5 and time 15 days were associated with the highest chlorophyll a and b values. According to the results the enzymatic method to prepare clover extract and its chlorophyll can be used as an efficient method for indicator pigment production in food and pharmaceutical industries. However, further testing is needed to achieve more information.