Extraction of phenolic compounds from edible flowers (Phlogacanthus thyrsiflorus) using ultrasound‐microwave‐assisted extraction and its screening by HPLC

Abstract Phlogacanthus thyrsiflorus flowers have been consumed as a traditional delicacy in the north‐eastern region of India. The present investigation utilized the microwave‐assisted extraction (MAE) technique in conjunction with an ultrasound pretreatment (at 250 W for 15 min) to extract phenolic compounds from Phlogacanthus thyrsiflorus flowers. Here, independent factors for optimization of MAE were microwave power (300, 500, and 700 W) and extraction time (2, 4, and 6 min), and responses were total phenolic content (TPC), total flavonoid content (TFC) and DPPH (2,2‐dipheny‐1‐picrylhydrazyl) activity. For the experimental design, a Response surface methodology and a central composite design were followed. The optimum MAE condition was found at microwave power 700 W for 5 min resulting 30.204 mg GAE/g TPC, 81.26% DPPH and 22.50 mg QAE/g of TFC. The extraction of phenolic compounds was significantly impacted by both the microwave power and the extraction time. The high‐performance liquid chromatography (HPLC) analysis detected various phenolic compounds in both conventional and MAE extracts. However, compared to conventional extract, the majority of the identified phenolic compounds were found to be higher in quantities in MAE extract. These results highlighted that MAE‐optimized flower extract could be beneficial as a functional ingredient for food product development. Practical applications Phlogacanthus thyrsiflorus is a highly nutritious flower with medicinal properties. Though traditionally edible flowers have been consumed in the northeastern part of India but people are still neophobic and there is scanty awareness available regarding the benefits of consuming edible flowers. This scientific justification regarding the advantages of edible flowers makes them appealing for future novel use in food technology and also for further scientific study. High perishability of flowers makes them limited for market viability and extraction of its phenolic compounds is one of the novel solutions to utilize the flowers before spoilage. Also, using ultrasound as a pretreatment could enhance the efficiency of microwave‐assisted extraction techniques for a higher yield of phenolic compounds. Microwave‐assisted extraction technique as its novel and was proven an easy successful extraction technique on this flower. Also, the study of phenolic compounds through HPLC provides important information regarding the presence of various phenolic compounds in the Phlogacanthus thyrsiflorus flower. This research can be supportive of both food technology and the medicinal industry.