A sustainable and efficient preparation process of anthocyanins from blue honeysuckle fruit and comprehensive bioactivity assessment

Ultrasound-assisted natural deep eutectic solvent extraction of anthocyanin from Vitis davidii Foex. pomace: Optimization, identification, antioxidant activity and stability

An efficient and environmentally friendly extraction method utilizing an ultrasonic-assisted natural deep eutectic solvent (UAE-NADES) was developed for the extraction of anthocyanins from Vitis davidii Foex. A screening process was conducted to evaluate seven different NADESs, resulting in the selection of a high-efficiency NADES (choline chloride-glycerol (ChGly)). To analyze the influence of significant factors and their interactive effects on the total anthocyanin content (TAC), response surface methodology (RSM) was employed. Furthermore, the conditions of extraction were optimized to attain the most productive yield of total anthocyanin content. The theoretical optimal conditions were determined to be a liquid‒solid ratio of 34.46 mL/g, an extraction temperature of 322.79 K and an ultrasonic power of 431.67 W, under which the verification TAC value (3.682 ± 0.051 mg/g) was highly consistent with the theoretical value (3.690 mg/g). Seventeen anthocyanins were identified by UPLC‒MS/MS. The contents of the main anthocyanins peonidin-3,5-O-diglucoside, malvidin-3,5-O-diglucoside, malvidin-3-O-5-O-(6-O-coumaroyl)-diglucoside, and malvidin-3-O-(6-O-p-coumaroyl)-glucoside in the ChGly extracts were significantly higher than those in the acid‒alcohol extract. Stability assays showed that the stability of anthocyanins in ChGly is higher than that in acidified alcohol at higher temperature, pH and stronger illumination. In vitro antioxidant results showed that the antioxidant capacities of the compounds extracted through the use of UAE-NADES were higher than those extracted using acidified alcohol. Additionally, the thermal behavior of anthocyanin extracts was further characterized through DSC analysis, highlighting the influence of ChGly or acidic ethanol. The results indicate that UAE-NADES exhibits a significant effect on the extraction of anthocyanins from plant byproducts, suggesting that its potential for use in the food sector is considerable.

C3G quantified method verification and quantified in blue honeysuckle (Lonicera caerulea L.) using HPLC–DAD

Blue honeysuckle is a source of anthocyanins with great potential as a food colorant, and a healthy and functional food material, and contains much cyanidin 3-glucoside (C3G), which has many benefits for human health. A rapid, reliable, accurate quantification method of anthocyanin content in different varieties of blue honeysuckle is critical to help in breeding and selecting excellent varieties which are used in the food processing industry and healthcare industry. Our objective was to verify the modified quantification method of C3G and quantified C3G content in three blue honeysuckle varieties of 'Berel', 'Lanjingling' and 'Wulan' using the modified HPLC method by Agilent 1200 system and CAPCELL PAK C18 column (150 mmⅹ4.6 mm, I. D., 5 μm, Japan), with detection at 530 nm, the solvent flow rate was 1 mL/min, the temperature of the column chamber is 35 °C. The results indicated that the modified method was validated in terms of linearity (R2 = 0.999), precision (RSD = 0.61%), stability (RSD = 5.23%), and recovery with a good level, and C3G can be quickly quantified in blue honeysuckle. In addition, 'Wulan' contains the highest C3G level compared with 'Lanjingling' and 'Berel'.

Alternative Extraction and Downstream Purification Processes for Anthocyanins

Anthocyanins are natural pigments displaying different attractive colors ranging from red, violet, to blue. These pigments present health benefits that increased their use in food, nutraceuticals, and the cosmetic industry. However, anthocyanins are mainly extracted through conventional methods that are time-consuming and involve the use of organic solvents. Moreover, the chemical diversity of the obtained complex extracts make the downstream purification step challenging. Therefore, the growing demand of these high-value pigments has stimulated the interest in designing new, safe, cost-effective, and tunable strategies for their extraction and purification. The current review focuses on the potential application of compressed fluid-based (such as subcritical and supercritical fluid extraction and pressurized liquid extraction) and deep eutectic solvents-based extraction methods for the recovery of anthocyanins. In addition, an updated review of the application of counter-current chromatography for anthocyanins purification is provided as a faster and cost-effective alternative to preparative-scale HPLC.