Ultrasonic-assisted Extraction of Bioactive Chlorogenic Acid from Heilong48 Soybean Variety: Parametric Optimization and Evaluation of Physicochemical and Bioactive Properties

This study aims to assess the physicochemical and bioactive features of the heilong48 soybean (HS) variety and improve ultrasonic-assisted extraction parameters for chlorogenic acid extraction. Soybean is a major source of plant protein and oil. Soybean breeding has benefited from advances in functional genomics. In particular, the release of soybean reference genomes has advanced our understanding of soybean adaptation to soil nutrient deficiencies, the molecular mechanism of symbiotic nitrogen (N) fixation, biotic and abiotic stress tolerance, and the roles of flowering time in regional adaptation, plant architecture, and seed yield and quality. Despite being a highly bioactive chemical, chlorogenic acid (CA), particularly that found in soybeans, has garnered very little attention in research settings during the past few decades. An effective way to boost the release of chlorogenic acid from soybeans is using ultrasonic-assisted extraction (UAE). Optimization of ultrasound parameters with Box-Behnken design (BBD) found a frequency of 20.0 kHz, a power density of 30.0 W/L, a temperature of 37.9 oC, and a time of 28.0 min to be the best conditions, which gave a chlorogenic acid yield of 5.007 ± 0.033 mg/g and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of 93.197 ± 0.213
mol AA eq/g dry sample; these were higher than those of a non-ultrasound-treated (raw) heilong48 soybean sample (chlorogenic acid yield of 1.627 ± 0.528 mg/g, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of 10.760 ± 0.207
mol AA eq/g dry sample). A satisfactory model was obtained. Scanning electron microscopy results confirmed the structural alterations of the heilong48 soybean variety caused by the optimized ultrasonic-assisted extraction parameters. High total polyphenol contents (TPCs; 4.726 ± 0.002 mg GAE/g), total phenolic acids (1.883 ± 0.005 mg GAE/g), and low total flavonoid contents (0.040 ± 0.008 mg RE/g) were obtained. A positive linear correlation between antioxidant activity and total polyphenol content was established. A protein–phenolic interaction in the heilong48 soybean variety was observed. The results established that polyphenols should be considered a significant component of the heilong48 soybean variety. Likewise, the heilong48 soybean variety could be used for chlorogenic acid extraction.