Ultrasonic-assisted enzymatic extraction and identification of anthocyanin components from mulberry wine residues

Optimization of Ultrasound-Assisted Obtention of Bluish Anthocyanin Extracts from Butterfly Pea (Clitoria ternatea) Petal Powders Using Natural Deep Eutectic Solvents

This study focused on improving the extraction of anthocyanins from medicinal plants using green solvents, which is important for the food, pharmaceuticals, and cosmetics industries. The goal was to optimize the time (15-50 min), temperature (40-80 °C), and petal/solvent ratio (2.5/7%) for the ultrasound-assisted extraction of anthocyanins from Butterfly Pea (Clitoria ternatea), using a natural deep eutectic solvent (choline chloride/glycerol, ChCl:Gly). The extraction was compared with a simple water extraction. To assess stability, we analyzed the anthocyanin content, antioxidant capacity, and color changes over 21 days. The optimal results were achieved using a temperature of 80 °C for 50 min and a 7% petal/solvent ratio. The CHCl:Gly solvent resulted in higher anthocyanin levels (374.65 mg DGE/L) compared to water (211.63 mg DGE/L). After storing the CHCl:Gly extract at 5 °C, only 16% of anthocyanins were lost, while the water extract lost 38%. The CHCl:Gly extract also showed better antioxidant capacity (156.43 µmol/mL). Color changes were less noticeable in the CHCl:Gly extract, especially when refrigerated. These findings demonstrate the method's effectiveness for producing bioactive extracts, with potential for the food, pharmaceutical, and cosmetic industries.

Ultrasound-assisted extraction and antioxidant activity of polysaccharides from Tenebrio molitor

Tenebrio molitor, which is rich in various nutrients, and its polysaccharides, as significant bioactive substances, exhibit strong antioxidant effects. This study utilized defatted T. molitor as raw material and employed an ultrasound-assisted extraction method. The factors considered include extraction temperature, time, ultrasound power, and liquid-to-feed ratio, with the yield of T. molitor polysaccharides as the response value. Based on single-factor experiments and response surface methodology, the optimal extraction parameters for T. molitor polysaccharides were determined. Following purification, protein removal, and dialysis to eliminate impurities, the structure of the extracted polysaccharides was preliminarily investigated using infrared spectroscopy. Their antioxidant activities were explored by measuring their DPPH·, OH·, and ABTS+· radical scavenging abilities and Fe3+ reducing power. The results indicated that the optimal conditions for ultrasound-assisted extraction were an extraction temperature of 75 °C, an extraction time of 150 min, an ultrasound power of 270 W, and a liquid-to-feed ratio of 15:1 mL/g, yielding a polysaccharide extraction rate of 9.513%. Infrared spectroscopy analysis revealed the presence of pyranose sugars with main functional groups including C-O, C=O, and O-H. Antioxidant activity tests showed that within a certain concentration range, the higher the polysaccharide concentration, the stronger its radical scavenging abilities. Compared with Vitamin C(Vc), the polysaccharides had stronger scavenging abilities for DPPH· and OH·, some scavenging ability for ABTS+·, and Fe3+ reduction ability, and corresponding to IC50 values of 0.9625, 9.1909, and 235.69 mg/mL respectively. The Fe3+ reducing power reached a maximum absorbance of 0.38899 at a concentration of 1.6 mg/mL. T. molitor polysaccharides demonstrate promising antioxidant activity and potential as functional ingredients in food, health products, and pharmaceuticals, providing new technical references for the development and utilization of T. molitor resources.

Turning Waste into Wealth: Optimization of Microwave/Ultrasound-Assisted Extraction for Maximum Recovery of Quercetin and Total Flavonoids from Red Onion (Allium cepa L.) Skin Waste

This study optimized the extraction conditions to maximize the recovery yields of quercetin and total flavonoids from red onion skin waste using sequential microwave/ultrasound-assisted extraction. Five effective factors of quercetin extraction yield were investigated using response surface methodology. The method was successfully performed under optimal 60 s microwave irradiation conditions followed by 15 min sonication at 70 °C with 70% (v/v, water) ethanol with a solvent-to-solid ratio of 30 mL/g. The variance analysis of the model for both quercetin (Y1) and total flavonoid (Y2) recovery from DOS demonstrated that ultrasound temperature (X2) was the most highly significant and influential factor, with a p-value of <0.0001 for both responses. Additionally, three key interaction terms—X1X2, X2X4, and X2X5—were identified as highly significant, further underscoring the critical role of ultrasound temperature in optimizing the extraction process for both quercetin and total flavonoids. The maximum recovery yields of quercetin and total flavonoids from red onion skin were 10.32% and 12.52%, respectively. The predicted values for quercetin (10.05%) and total flavonoids (12.72%) were very close to the experimental results. The recovery yields obtained from different extraction methods under the identical experimental conditions mentioned earlier were ultrasound/microwave-assisted extraction (7.66% quercetin and 10.18% total flavonoids), ultrasound-assisted extraction (5.36% quercetin and 8.34% total flavonoids), and microwave-assisted extraction (5.03% quercetin and 7.91% total flavonoids). The ANOVA confirmed highly significant regression models (p-values < 0.0001), with an insignificant lack of fit (p = 0.0515 for quercetin, p = 0.1276 for total flavonoids), demonstrating the robustness and reliability of the optimization. This study provides valuable insights for improving the extraction of bioactive compounds, which is critical for developing effective cancer treatments and advancing medical research. Additionally, the model shows potential for scaling up food processing applications to recover valuable products from red onion skin waste.

Comparison of different drying pretreatment combined with ultrasonic-assisted enzymolysis extraction of anthocyanins from Lycium ruthenicum Murr

Extraction of anthocyanins from Lycium ruthenicum Murr. (L. ruthenicum) is a notable challenge in food production, requiring methods that balance efficiency and safety. In this study, we conducted a comparative analysis the extraction of anthocyanins by natural air drying (NAD), vacuum freeze drying (VFD), hot air drying (HAD), and vacuum microwave drying (MVD) combined with ultrasonic-assisted enzymolysis extraction (UAEE). The results demonstrated that the extraction yield and antioxidant activity of anthocyanins were significantly higher in VFD. This phenomenon can be attributed to the modification of raw material's microstructure, leading to an increased extraction yield of specific anthocyanins such as Cyanidin-3-galactoside, Delphinidin chloride, Cyanidin, and Petunidin. According to the pretreatment results, the extraction process of anthocyanins was further optimized. The highest yield (3.16 g/100 g) was obtained in following conditions: 0.24 % pectinase, 48 °C, solid:liquid = 1:21, and 21 min ultrasonic time. This study improves the commercial value and potential application of L. ruthenicum in food industry.

Metabolomic analysis, extraction, purification and stability of the anthocyanins from colored potatoes

Colored potatoes have many health benefits because they are rich in anthocyanins. However, the constituent and property of anthocyanins in colored potatoes have not been systematically studied yet. Herein, metabolomic analysis was carried out to investigate the chemical composition of anthocyanins in the four different colored potatoes. After that, the extract and purification conditions, and the stability of the anthocyanins were further studied. The results indicated that the four colored potatoes contained abundant of polyphenols, flavonoids, and anthocyanins. Cyanidin, delphinidin, and malvidin were identified as the major anthocyanidins in purple potatoes, whereas red potatoes were mainly consisted of pelargonidin and its derivatives. 84.47 mg C3GE/100 g DW of anthocyanins was obtained at the optimal conditions, which could be effectively purified macroporous resin of D101. Moreover, the anthocyanins were sensitive to pH, temperature, light, redox agents, and divalent or trivalent metal ions, but stable to sugars and univalent metal ions.

Optimization of ultrasonic assisted ethanolic extraction for natural pigments from butterfly pea flower applied in Thai dessert using Box-Behnken approach

Butterfly pea is a natural color source used in food and dessert. This study optimized ultrasound-assisted extraction with ethanol for pigments from butterfly pea flowers (BPF) using a Box-Behnken method. Key factors explored were solid-to-solvent ratio, ultrasound extraction time, and ethanol concentration. The extracted compounds were evaluated for extraction yield (EY), total phenolic content (TPC), total anthocyanin content (TAC), and DPPH antioxidant activity. EY increased significantly with reduced ethanol concentration. Optimal conditions were predicted and experimentally validated. BPF extracts showed distinct absorption wavelengths at different pH levels. BPF extract was used in coconut milk jelly, resulting in the lowest b* value. These findings highlight the value of optimal ultrasonic-assisted extraction for enhancing BPF's natural colorant extraction and promoting sustainable use in food and dessert applications.

Research Progress on the Extraction and Purification of Anthocyanins and Their Interactions with Proteins

Anthocyanins, as the most critical water-soluble pigments in nature, are widely present in roots, stems, leaves, flowers, fruits, and fruit peels. Many studies have indicated that anthocyanins exhibit various biological activities including antioxidant, anti-inflammatory, anti-tumor, hypoglycemic, vision protection, and anti-aging. Hence, anthocyanins are widely used in food, medicine, and cosmetics. The green and efficient extraction and purification of anthocyanins are an important prerequisite for their further development and utilization. However, the poor stability and low bioavailability of anthocyanins limit their application. Protein, one of the three essential nutrients for the human body, has good biocompatibility and biodegradability. Proteins are commonly used in food processing, but their functional properties need to be improved. Notably, anthocyanins can interact with proteins through covalent and non-covalent means during food processing, which can effectively improve the stability of anthocyanins and enhance their bioavailability. Moreover, the interactions between proteins and anthocyanins can also improve the functional characteristics and enhance the nutritional quality of proteins. Hence, this article systematically reviews the extraction and purification methods for anthocyanins. Moreover, this review also systematically summarizes the effect of the interactions between anthocyanins and proteins on the bioavailability of anthocyanins and their impact on protein properties. Furthermore, we also introduce the application of the interaction between anthocyanins and proteins. The findings can provide a theoretical reference for the application of anthocyanins and proteins in food deep processing.

Extraction of flavonoids from black mulberry wine residues and their antioxidant and anticancer activity in vitro

Enhancing the valorization of fruit processing by-products is pivotal for advancing the industry. Black mulberry wine residues, a by-product, contains some bioactive compounds, yet its antioxidant and anticancer potentials remain unverified. In this study, ultrasound-assisted enzymatic extraction was optimized by response surface methodology to obtain the flavonoids extracts from black mulberry wine residues, whose antioxidant capacity and anti-cancer activity in vitro was investigated. The results showed that under the optimal extraction conditions (enzyme ratio at pectinase:cellulose = 2:1, mixed enzyme concentration 0.31 mg/mL, enzymatic hydrolysis temperature 55.35 °C, enzymatic hydrolysis time 79.03 min, and ultrasonic time 22.71 min), the extracts from black mulberry wine residues (BMWR-E) reached 5.672 mg/g. At a concentration of 1.2 mg/mL, BMWR-E exhibited strong DPPH and hydroxyl radical scavenging activities. At a concentration of 2.5 mg/mL, BMWR-E showed a strong superoxide anion radical scavenging capacity, with no significant distinction compared to the positive control group (Vitamin C) (p > 0.05). Cell viability assay results showed that BMWR-E was non-toxic to normal BRL-3A cells when applied at concentrations of 0.1-0.3 mg/mL for an incubation period of 24 h, but BMWR-E exhibited the ability to inhibit the proliferation of HepG2 cells. At concentrations of 0.2 mg/mL and above, BMWR-E could induce late apoptosis of HepG2 cells by increasing the protein expression levels of Bax, caspase-3, and caspase-12, reducing the protein expression levels of Bcl-2, inducing cell cycle arrest at G0/G1 phase, thereby inhibiting the proliferation of HepG2 cells. The bioactive properties make BMWR-E possess potential in developing new antioxidants and anti-cancer agents, which would significantly enhance the economic worth of agricultural by-products in product processing. This research can improve the utilization rate of agricultural product processing by-products and protect the environment.

A Review of Quantitative and Topical Analysis of Anthocyanins in Food

Anthocyanins, a subclass of flavonoids known for their vibrant colors and health-promoting properties, are pivotal in the nutritional science and food industry. This review article delves into the analytical methodologies for anthocyanin detection and quantification in food matrices, comparing quantitative and topical techniques. Quantitative methods, including High-performance Liquid Chromatography (HPLC) and Mass Spectrometry (MS), offer precise quantification and profiling of individual anthocyanins but require sample destruction, limiting their use in continuous quality control. Topical approaches, such as Near-infrared Spectroscopy (NIR) and hyperspectral imaging, provide rapid, in situ analysis without compromising sample integrity, ideal for on-site food quality assessment. The review highlights the advancements in chromatographic techniques, particularly Ultra-high-performance Liquid Chromatography (UHPLC) coupled with modern detectors, enhancing resolution and speed in anthocyanin analysis. It also emphasizes the growing importance of topical techniques in the food industry for their efficiency and minimal sample preparation. By examining the strengths and limitations of both analytical realms, this article aims to shed light on current challenges and prospective advancements, providing insights into future research directions for improving anthocyanin analysis in foods.

A critical review on the stability of natural food pigments and stabilization techniques

This comprehensive review article delves into the complex world of natural edible pigments, with a primary focus on their stability and the factors that influence them. The study primarily explores four classes of pigments: anthocyanins, betalains, chlorophylls and carotenoids by investigating both their intrinsic and extrinsic stability factors. The review examines factors affecting the stability of anthocyanins which act as intrinsic factors like their structure, intermolecular and intramolecular interactions, copigmentation, and self-association as well as extrinsic factors such as temperature, light exposure, metal ions, and enzymatic activities. The scrutiny extends to betalains which are nitrogen-based pigments, and delves into intrinsic factors like chemical composition and glycosylation, as well as extrinsic factors like temperature, light exposure, and oxygen levels affecting for their stability. Carotenoids are analyzed concerning their intrinsic and extrinsic stability factors. The article emphasizes the role of chemical structure, isomerization, and copigmentation as intrinsic factors and discusses how light, temperature, oxygen, and moisture levels influence carotenoid stability. The impacts of food processing methods on carotenoid preservation are explored by offering guidance on maximizing retention and nutritional value. Chlorophyll is examined for its sensitivity to external factors like light, temperature, oxygen exposure, pH, metal ions, enzymatic actions, and the food matrix composition. In conclusion, this review article provides a comprehensive exploration of the stability of natural edible pigments, highlighting the intricate interplay of intrinsic and extrinsic factors. In addition, it is important to note that all the references cited in this review article are within the past five years, ensuring the most up-to-date and relevant sources have been considered in the analysis.

Optimization of ultrasound-assisted extraction of fatty acids from royal jelly and its effect on the structural and antioxidant property

Fatty acids are the key active components in royal jelly (RJ) with various biological activities. In this study, a novel ultrasound-assisted extraction (UAE) method was established to extract fatty acids from RJ and their structural and antioxidant property were further evaluated. The optimum extraction conditions were as follows: liquid-to-solid ratio of 10:1, ultrasonic power of 450 W and ultrasonic duration of 20 min, resulting in a better extraction yield of 16.48 % and 10-hydroxy-2(E)-decenoic acid (10-HDA) content of 4.12 %. Furthermore, compared with the solvent extraction method, the antioxidant activity of extract by ultrasound was enhanced significantly by at least 448 %. GC-MS showed that ultrasound didn't change the chemical composition of fatty acids, while it significantly increased the content of fatty acids. SEM image illustrated that extracts by UAE showed a rougher, looser microstructure compared to the solvent method. Overall, UAE is a promising method to obtain fatty acids in RJ with high efficiency.

Anthocyanin Profiles in Colored Potato Tubers at Different Altitudes by HPLC-MS Analysis with Optimized Ultrasound-Assisted Extraction

The elevated anthocyanin content of colored potatoes produces numerous health benefits in humans. However, there is a paucity of studies exploring the influence of environmental factors on anthocyanin components in colored potatoes. In our work, the Box-Behnken design was adopted to optimize anthocyanin extraction from colored potato tubers with ultrasound assistance. The response surface model was stable and reliable (R2 = 0.9775), and under optimal extraction conditions, namely an ultrasonic power of 299 W, an extraction time of 10 min, and a solid-liquid ratio of 1:30 (g/mL), the yield reached 4.33 mg/g. Furthermore, the anthocyanins of colored potato tubers grown at different altitudes were determined by high-performance liquid chromatography-mass spectrometry with optimized ultrasound-assisted extraction, the results showed that anthocyanin levels were the highest at high altitudes, whereas anthocyanins were almost undetectable at mid-altitude. Moreover, the types of anthocyanin compounds present in colored potatoes varied at different altitudes. The red clones exhibited substantial accumulation of pelargonidin across all three altitudes. In contrast, the main anthocyanins found in purple clones were malvidin, petunidin, and cyanidin. We identified the anthocyanin components with a strong correlation to the environment, thereby establishing a fundamental basis for the breeding of potato clones with high anthocyanin content.

An Exploration of Dynamic Changes in the Mulberry Growth Process Based on UPLC-Q-Orbitrap-MS, HS-SPME-GC-MS, and HS-GC-IMS

This work was designed to investigate the dynamic changes process of non-volatile organic compounds (n-VOCs) and volatile organic compounds (VOCs) in mulberries during different growth periods using UPLC-Q-Orbitrap-MS, HS-SPME-GC-MS, and HS-GC-IMS. A total of 166 compounds were identified, including 68 n-VOCs and 98 VOCs. Furthermore, principal component analysis (PCA), random forest analysis (RFA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to analyze differences in mulberries at different ripening stages. A total of 74 compounds appeared or disappeared at different ripening periods and 24 compounds were presented throughout the growth process. Quantitative analysis and antioxidant experiments revealed that as the mulberries continued to mature, flavonoids and phenolic acids continued to increase, and the best antioxidant activity occurred from stage IV. Conclusively, an effective strategy was established for analyzing the composition change process during different growth periods, which could assist in achieving dynamic change process analysis and quality control.

High-efficiency foam fractionation of anthocyanin from perilla leaves using surfactant-free active Al2O3 nanoparticle as collector and frother: Performance and mechanism

Anthocyanin (ACN) is a natural pigment with significant industrial applications. However, foam fractionation of ACN from perilla leaves extract presents theoretical challenges due to its limited surface activity and foaming capacity. This work developed a surfactant-free active Al₂O₃ nanoparticle (ANP) as a collector and frother, which was modified with adipic acid (AA). The ANP-AA efficiently collected ACN through the electrostatic interaction, condensation reaction, and hydrogen bonding, with a Langmuir maximum capacity of 129.62 mg/g. Moreover, ANP-AA could form a stable foam layer by irreversibly adsorbing on the gas-liquid interface, reducing surface tension, and alleviating liquid drainage. Under the appropriate conditions of ANP-AA 400 mg/L and pH 5.0, we achieved a high ACN recovery of 95.68% with an enrichment ratio of 29.87 after ultrasound-assisted extraction of ACN from perilla leaves. Additionally, the recovered ACN displayed promising antioxidant properties. These findings hold significant importance in the food, colorant, and pharmaceutical industries.

Deep eutectic solvent-ultrasound assisted extraction as a green approach for enhanced extraction of naringenin from Searsia tripartita and retained their bioactivities

Background

Naringenin (NA) is a natural flavonoid used in the formulation of a wide range of pharmaceutical, fragrance, and cosmetic products. In this research, NA was extracted from Searsia tripartita using an environmentally friendly, high efficiency extraction method: an ultrasound-assisted extraction with deep eutectic solvents (UAE-DES).

Methods

Six natural deep eutectic solvent systems were tested. Choline chloride was used as the hydrogen bond acceptor (HBA), and formic acid, ethylene glycol, lactic acid, urea, glycerol, and citric acid were used as hydrogen bond donors (HBD).

Results

Based on the results of single-factor experiments, response surface methodology using a Box-Behnken design was applied to determine the optimal conditions for UAE-DES. According to the results, the optimal NA extraction parameters were as follows: DES-1 consisted of choline chloride (HBA) and formic acid (HBD) in a mole ratio of 2:1, an extraction time of 10 min, an extraction temperature of 50°C, an ultrasonic amplitude of 75 W, and a solid-liquid ratio of 1/60 g/mL. Extracted NA was shown to inhibit the activity of different enzymes in vitro, including α-amylase, acetylcholinesterase, butyrylcholinesterase, tyrosinase, elastase, collagenase, and hyaluronidase.

Conclusion

Thus, the UAE-DES technique produced high-efficiency NA extraction while retaining bioactivity, implying broad application potential, and making it worthy of consideration as a high-throughput green extraction method.

Extraction of anthocyanins from haskap using cold plasma-assisted enzyme

BACKGROUND

Haskap berries (Lonicera caerulea L.) are rich in anthocyanins. Cold plasma-assisted enzyme method (CPEM) is an innovative method for green extraction of anthocyanins, which was optimized by an artificial neural network-genetic algorithm (ANN-GA) to maximize the yield. In this study, seven factors were screened using by Plackett-Burman design based on single-factor experiments and optimized by ANN-GA.

RESULTS

The results showed that the maximum total anthocyanin content (TAC, 42.45 ± 0.25 g cyanidin-3-glucoside equivalent (C3G) kg^-1 dry weight, DW) was obtained under optimal pretreatment power of 192 W, pretreatment time of 29 s and liquid-to-solid ratio of 39 mL g^-1 . Cleavage and porosity appeared on the surface of the treated sample. The active ingredients and antioxidant capacity of the CPEM extracts were identified by ultra-performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Compared with other extraction technologies, CPEM presents the advantages of shortening the extraction time, reducing the solvent volume, and significantly increasing active ingredients and antioxidant activity.

CONCLUSION

The ANN-GA has better predictive and higher accuracy than the response surface methodology (RSM) model and is more suitable for optimizing the CPEM by greatly improving the process yield and the utilization of biomass, thus contributing to the sustainability of the agri-food chain. © 2022 Society of Chemical Industry.

Sono-activation of food enzymes: From principles to practice

Over the last decade, sono-activation of enzymes as an emerging research area has received considerable attention from food researchers. This kind of relatively new application of ultrasound has demonstrated promising potential in facilitating the modern food industry by broadening the application of various food enzymes, improving relevant industrial unit operation and productivity, as well as increasing the yield of target products. This review aims to provide insight into the fundamental principles and possible industrialization strategies of the sono-activation of food enzymes to facilitate its commercialization. This review first provides an overview of ultrasound application in the activation of food protease, carbohydrase, and lipase. Then, the recent development on ultrasound activation of food enzymes is discussed on aspects including mechanisms, influencing factors, modification effects, and its applications in real food systems for free and immobilized enzymes. Despite the far fewer studies on sono-activation of immobilized enzymes compared with those on free enzymes, we endeavored to summarize the relevant aspects in three stages: ultrasound pretreatment of free enzyme/carrier, assistance in immobilization process, and modification of the already immobilized enzyme. Lastly, challenges for the scalability of ultrasound in these target areas are discussed and future research prospects are proposed.

Bioactive Natural Pigments' Extraction, Isolation, and Stability in Food Applications

Color in food has multiple effects on consumers, since this parameter is related to the quality of a product, its freshness, and even its nutrient content. Each food has a characteristic color; however, this can be affected by the technological treatments that are applied during its manufacturing process, as well as its storage. Therefore, the development of new food products should take into account consumer preferences, the physical properties of a product, food safety standards, the economy, and applications of technology. With all of this, the use of food additives, such as dyes, is increasingly important due to the interest in the natural coloring of foods, strict regulatory pressure, problems with the toxicity of synthetic food colors, and the need for globally approved colors, in addition to current food market trends that focus on the consumption of healthy, organic, and natural products. It is for this reason that there is a growing demand for natural pigments that drives the food industry to seek or improve extraction techniques, as well as to study different stability processes, considering their interactions with the food matrix, in order to meet the needs and expectations of consumers.

Co-Pigmentation Mechanism and Thermal Reaction Kinetics of Mulberry Anthocyanins with Different Phenolic Acids

Applying the intermolecular co-pigmentation to improve the stability of mulberry anthocyanins is an important co-pigment method. Seven co-pigments, ferulic acid (FA), caffeic acid (CA), p-hydroxybenzoic acid (HBA), protocatechuic acid (PA), gallic acid (GA), vanillic acid (VA) and vanillin (VN) were selected to investigate mulberry anthocyanin co-pigmentation thermal reaction kinetics. The strongest co-pigment reactions were observed for FA at a molar ratio of 1:20, pH 3.5 and 20 °C, with the highest hyperchromic effects (52.94%), equilibrium constant (K) values (3.51) and negative values of Gibbs free energy (ΔG°) (-3.06 KJ/mol). Co-pigments that contained more free hydroxyl groups facilitated the co-pigmentation, and methyl contributed more to color enhancement, with respect to the hydrogen group. Ultra Performance Liquid Chromatography-Quadrupole-Time Of Flight-Mass/Mass Spectrometry (UPLC-Q-TOF-MS/MS) results indicated that FA and CA formed different anthocyanin derivatives with mulberry anthocyanin. The Fourier Transform Infrared Spectroscopy (FTIR) and molecular docking confirmed that hydrogen bonding, π-π stacking and hydrophobic interaction were formed between anthocyanins and three prevalent co-pigments (FA, CA and VA). CA and C3G could form four hydrogen bonds and two π-π stackings; this was the most stable system among three phenolic acid-C3G complexes. Due to the functional effect of phenolic acids, the addition of FA and CA not only enhanced the stability and color intensity of mulberry anthocyanins but also the functionality of the processing product.

Optimization of the ultrasonic-assisted extraction process to obtain total phenolic and flavonoid compounds from watermelon (Citrullus lanatus) rind

This context presents the study of ultrasonic-assisted extraction (UAE) to obtain phenolic and flavonoid compounds from watermelon rind powder (WRP). The antioxidant activity of the extracts was investigated using DPPH and ABTS⁺ assays. One-factor experiments were conducted to examine the effect of each factor (solid-to-liquid ratio (SLR), acetone concentration (AC), temperature, and time) on the UAE of WRP. Box-Behnken Design (BDD) model was employed to optimize the UAE conditions based on total phenolic contents (TPC), total flavonoid content (TFC), and their antioxidant activities. The optimal conditions were 1:30.50 SLR, 70.71% AC, 29.78 °C, and 10.65 min extraction time. There were no significant differences between predicted and experimental results (less than 6.0%), recommending a feasible and innovative process of deploying UAE to extract phenolics and flavonoids effectively from watermelon rind.

•

Sonication increases the extraction of total phenolic and flavonoid contents.

•

Sonication increases the antioxidant activity of watermelon rind extracts.

•

Box-Behnken Design model is used to optimize ultrasonic-assisted extraction conditions.

Anthocyanins in Different Food Matrices: Recent Updates on Extraction, Purification and Analysis Techniques

Anthocyanins (ANCs), a kind of natural pigments, are widely present in food substrates. Evidence has shown that ANCs can promote health in terms of anti-oxidation, anti-tumor, and anti-inflammation. However, the oxidative stability of ANCs limits accurate quantitation and analysis. Therefore, faster, more accurate, and highly sensitive extraction and determination methods are necessary for understanding the role of ANCs in medicine and food. This review presents an updated overview of pretreatment and detection techniques for ANCs in various food substrates since 2015. Liquid-liquid extraction and various green solvent extraction methods, such as accelerated solvents extraction, deep eutectic solvents extraction, ionic liquids extraction, and supercritical fluid extraction, are commonly used pretreatment methods for extraction and purification of ANCs. Liquid chromatography coupled with different detectors (tandem mass spectrometry and UV detectors) and spectrophotometry methods are some of the determination methods for ANC. This study has updated, compared, and discussed different pretreatment and analysis methods. Moreover, the advanced methods and development prospects in this field are comprehensively summarized, which can provide references for further utilization of ANCs.

Preparation of anthocyanin-rich mulberry juice by microwave-ultrasonic combined pretreatment

The work aims to study the process of microwave-ultrasonic combined treatment to obtain anthocyanin-rich mulberry juice. A Box-Behnken design was employed to analyze the effects of microwave time and citric acid content on the total phenol content, total anthocyanin content, hue, color intensity, DPPH and ABTS radical scavenging activities. Under the optimum conditions (microwave time of 46 s, citric acid addition of 273 mg/kg), the total phenol content, total anthocyanin content, the DPPH and ABTS radical scavenging activities reached 4.24 mg GAE/mL, 3.29 mg C3G/mL, 4.59 mg TE/mL and 11.90 mg TE/mL, respectively. Subsequently, the mulberry juice was processed with ultrasound of different frequencies. It was found that low-frequency ultrasonic treatment (25 kHz) could significantly reduce the loss of total phenolic and anthocyanin monomers and improve the antioxidant capacity of mulberry juice during storage for five weeks. Overall, mulberry juice with microwave-ultrasonic pretreatment is a natural antioxidant.

Extracting Total Anthocyanin from Purple Sweet Potato Using an Effective Ultrasound-Assisted Compound Enzymatic Extraction Technology

This study aimed to develop an effective technique for extracting total anthocyanins from purple sweet potato (Mianzishu 9) (PSP9) by ultrasound-assisted compound enzymatic extraction (UAEE). Single-factor experiments, Plackett-Burman experimental design, and response surface methodology were utilized for optimizing extraction conditions, and the antioxidant activities were evaluated. Anthocyanins were also measured using an ultra-performance liquid chromatograph linked to a mass spectrometer (UPLC-MS). The maximum yield of total anthocyanins was 2.27 mg/g under the following conditions: the ethanol concentration was 78%, the material-to-liquid ratio was 1:15 g/mL, the enzyme ratio (cellulase: pectinase: papain) was 2:2:1 and its hydrolysis was at 41 °C, pH = 4.5, 1.5 h, the ultrasonication was at 48 °C and conducted twice for 20 min each time. In addition to higher yield, anthocyanins extracted from purple sweet potato by UAEE showed great ability to scavenge DPPH (IC₅₀ of 0.089 μg/mL) and hydroxyl radicals (IC₅₀ of 100.229 μg/mL). Five anthocyanins were found in the purple sweet potato extract from UAEE. Taken together, the ultrasound-assisted compound enzymatic method can rapidly and effectively extract anthocyanins with greater antioxidant capacity from purple sweet potato.

Ultrasound-Assisted Extraction of Anthocyanins from Malus ‘Royalty’ Fruits: Optimization, Separation, and Antitumor Activity

Red Malus ‘Royalty’ fruits are rich in anthocyanins. This study aimed to obtain the optimal parameters for the extraction and separation of anthocyanins from Malus ‘Royalty’ fruits and to evaluate the inhibitory effect of the enriched anthocyanin fraction on gastric cancer cells. Ultrasonic-assisted extraction was used for the extraction of the anthocyanins of Malus ‘Royalty’ fruit, and the extraction results showed that the optimum parameters were an extraction temperature of 20 °C, a solid–liquid ratio of 1:6 (g/mL), ethanol and formic acid contents of 70% and 0.4%, respectively, an extraction time of 40 min, and an ultrasonic power of 300 W. The optimum extraction parameters to achieve the highest anthocyanin yield by a single-factor experiment coupled with response surface methodology were identified. The separation results showed that the AB-8 macroporous resin was a better purifying material, with 60% ethanol as an adsorbent, and the adsorption–desorption equilibrium times were 6 h and 1 h, respectively. Cyanidin-3-galactoside was the main body composition separation of anthocyanins by a high-performance liquid chromatography-diode array detector. The antitumor activity results showed that the anthocyanins of Malus ‘Royalty’ fruits have a significant inhibitory effect on the gastric cancer cell line BGC-803. The in vitro cell viability test of CCK-8 showed that the inhibitory effect on tumor cells was more significant with the increased anthocyanin concentration, with a half maximal inhibitory concentration (IC₅₀) value of 105.5 μg/mL. The cell morphology was observed by an inverted microscope, and it was found that the backbone of BGC-803 treated with a high concentration of anthocyanins was disintegrated and the nucleoplasm was concentrated. The mechanism of apoptosis was analyzed by Western blotting, and the results showed that with increasing anthocyanin concentration in the medium, the expression levels of the proapoptotic proteins Bax and Bak increased, and the expression levels of the antiapoptotic proteins Bcl-2 and Bcl-xL decreased, which coordinated the regulation of cell apoptosis. This research suggests that the enriched anthocyanin fraction from Malus ‘Royalty’ fruits have potential antitumor and adjuvant therapeutic effects on gastric cancer.

Ultrasound-Assisted Extraction of Natural Pigments From Food Processing By-Products: A Review

Ultrasound is an emerging technology, which has been highly explored in the food area to improve processes and products. When ultrasound is applied to a product with solid or fluid characteristics, the passage of acoustic waves and acoustic cavitation generates different mechanisms responsible for modifications in the original matrix of the sample. These effects of ultrasound can also be used to take advantage of by-products, for example by extracting compounds of interest, including natural pigments. Natural pigments or colorants are being highly demanded by different industries not only for color purposes but also due to their healthy properties, the greater demands in regulations and new consumer preferences. This review presents an updated critical analysis of the application of ultrasound-assisted extraction (UAE) to obtain natural pigments from food processing by-products. Initially, the ultrasound effects and mechanisms that improve the extraction of natural pigments in a fluid medium, as well as the factors that influence the extraction and the energy consumption of UAE are analyzed and described. Subsequently, the UAE application to obtain pigments belonging to the groups of carotenoids, chlorophyll, anthocyanins and betalains is evaluated. These sections detail the processing conditions, positive and negative effects, as well as possible applications of the extracted pigments. This review presents relevant information that may be useful to expand and explore new applications of ultrasound technology as well as promote the revaluation of by-products to obtain pigments that can be used in food, pharmaceutical or cosmetic industries.

Phytochemicals, Pharmacological Effects and Molecular Mechanisms of Mulberry

There are numerous varieties of mulberry, and each has high medicinal value and is regarded as a promising source of traditional medicines and functional foods. Nevertheless, the nutrients and uses of mulberry differ from species (Morus alba L., Morus nigra L. and Morus rubra L.). Phenolic compounds are prominent among the biologically active ingredients in mulberry, especially flavonoids, anthocyanins and phenolic acids. Epidemiologic studies suggest that mulberry contains a rich, effective chemical composition and a wide range of biological activity, such as antioxidant, anti-inflammatory, anti-tumor and so on. However, compared with other berries, there has been a lack of systematic research on mulberry, and this hinders its further expansion as a functional fruit. The main purpose of this review is to provide the latest data regarding the effective chemical constituents and pharmacological effects of mulberry to support its further therapeutic potential and health functions.

A comparison study between ultrasound-assisted and enzyme-assisted extraction of anthocyanins from blackcurrant (Ribes nigrum L.)

•

2 anthocyanin extraction methods have been developed in blackcurrant by EAE and UAE.

•

The 7 major anthocyanins have been separated in less than 7 min.

•

The composition of the extraction solvent has been the most influential variable.

•

Optimal extraction times have been 5 min for UAE and 10 min for EAE.

•

No differences have been observed in anthocyanin extraction with both methods.

Blackcurrant (Ribes nigrum L.) is a fruit rich in vitamins, fatty acids, minerals, essential oils and phenolic compounds, including anthocyanins. In the present work, two anthocyanin extraction methods from blackcurrant samples based on Ultrasound-Assisted Extraction (UAE) and Enzyme-Assisted Extraction (EAE) have been developed. A Plackett–Burman design with seven variables has been preliminary used for both UAE and EAE in order to determine the most influential variables in each methodology. After that, a Box-Behnken design was employed to optimize the extraction methods. The composition of the extraction solvent (% EtOH in water) has been the most influential variable for both UAE and EAE. The optimal extraction times have been 5 min for UAE and 10 min for EAE. No differences have been observed in anthocyanin extraction with both methodologies. Both methods have been applied to blackcurrant-derived products and proven their suitability for quality control analysis.

Interaction characterization of zein with cyanidin-3-O-glucoside and its effect on the stability of mulberry anthocyanins and protein digestion

Ingredient interactions usually occur in food matrix, which may affect their functions and properties. This study aimed to investigate the interactive effects of mulberry and corn protein on pigment stability and zein digestibility. The interaction of main compounds in both ingredients, that is, cyanidin-3-O-glucoside (C3G) and zein, was characterized via their structural, morphological, thermal stability, and digestible properties using multi-spectroscopic techniques, scanning electron microscopy, high performance liquid chromatography, and in vitro digestion models. Results showed that zein exhibited a strong binding affinity for C3G via van der Waals forces and hydrogen bonds determined in fluorescence assays. The secondary structure of zein changed due to C3G binding, with a decrease in α-helix and an increase in β-sheet. The particle size of zein decreased after interacting with C3G. The zein complexation with mulberry anthocyanin-rich extracts in a simulative food system did not affect the digestibility of zein significantly but enhanced the thermal stability of pigments slightly. Specifically, anthocyanins did not change the susceptibility of zein to pepsin proteolysis, suggesting that binding sites of C3G might not be the cleavage sites of pepsins. These results provide important insight into the binding mechanism of zein and anthocyanins and might help guide the design of anthocyanin-based functional food. PRACTICAL APPLICATION: Zein, as a storage protein widely distributed in corn flour, was commonly co-existing with anthocyanins in starchy food. This study provides insights into the molecular interactions between zein and cyanidin-3-O-glucoside. However, the interaction might not impact the zein digestion but enhance anthocyanin thermal stability. The findings of this work could throw light on the selection of ingredients rich in zein and anthocyanins in the food industry.

Robust and recyclable magnetic nanobiocatalysts for extraction of anthocyanin from black rice

Anthocyanins, which are natural pigments and nutraceuticals, can be extracted from plant materials using enzyme-assisted methods. However, the enzymes used are often expensive, fragile, and hard to recover/reuse. In this study, cellulase and α-amylase were immobilized on amino-functionalized magnetic nanoparticles to prepare a magnetic nanobiocatalyst. The enzymes in this nanobiocatalyst exhibited higher stability and greater catalytic activity than free enzymes, including good thermal stability (50 to 70℃) and pH stability (pH 4.5-7.5). Nanobiocatalyst efficacy was demonstrated by extracting anthocyanins from black rice, with a maximum yield of 266 mg anthocyanin/100 g black rice obtained. After six reuse cycles, cellulase and α-amylase retained around 70% and 64% of their activity, respectively. Immobilization also increased their reusability. In summary, a novel magnetic nanobiocatalyst was developed for extracting anthocyanins from black rice, which may also have other applications within the food industry.

Value-added application of Platycodon grandiflorus (Jacq.) A.DC. roots (PGR) by ultrasound-assisted extraction (UAE) process to improve physicochemical quality, structural characteristics and functional properties

Platycodon grandiflorus (Jacq.) A.DC. roots (PGR), a Chinese herb with medicinal and edible value, was powdered by freeze drying (FD) and spray drying (SD) after maceration extraction (ME) or ultrasound-assisted extraction (UAE) to develop a new functional food product. Four PGR powders were obtained namely ME-FD, ME-SD, UAE-FD, and UAE-SD and their powder quality, structural properties, and functionalities were evaluated. UAE-FD powder had the highest powder recovery (85.3 ± 5.79%) and also presented better hydration properties due to the larger particle size compared with other three PGR powders. Four PGR powders exhibited similar thermal decomposition process, molecular structure, amorphous characteristics, amino acids composition, and taste profiles. Furthermore, the UAE-FD PGR powders presented the highest Platycodin D (3.68 ± 0.04 mg/g), total phenolic (2.84 ± 0.11 mg GAE/g), and total flavonoids content (2.11 ± 0.14 mg RE/g), resulting in best antioxidant activity (58.67 ± 2.42 μmol Trolox/g). Therefore UAE-FD is an environment-friendly technique for the production of functional PGR powder with improved nutritional and redispersion properties.

Anthocyanins Recovered from Agri-Food By-Products Using Innovative Processes: Trends, Challenges, and Perspectives for Their Application in Food Systems

Anthocyanins are naturally occurring phytochemicals that have attracted growing interest from consumers and the food industry due to their multiple biological properties and technological applications. Nevertheless, conventional extraction techniques based on thermal technologies can compromise both the recovery and stability of anthocyanins, reducing their global yield and/or limiting their application in food systems. The current review provides an overview of the main innovative processes (e.g., pulsed electric field, microwave, and ultrasound) used to recover anthocyanins from agri-food waste/by-products and the mechanisms involved in anthocyanin extraction and their impacts on the stability of these compounds. Moreover, trends and perspectives of anthocyanins' applications in food systems, such as antioxidants, natural colorants, preservatives, and active and smart packaging components, are addressed. Challenges behind anthocyanin implementation in food systems are displayed and potential solutions to overcome these drawbacks are proposed.

Ultrasound-assisted enzymatic extraction of anthocyanins from grape skins: optimization, identification, and antitumor activity

Grape skins produced during the grape juice production and processing contain abundant anthocyanins and other active compounds. Consequently, this study optimized the extraction conditions for ultrasound-assisted enzymatic extraction (UAEE) of anthocyanins from grape skins via response surface methodology coupled with genetic algorithm. The optimum extraction parameters to achieve the highest anthocyanins yield (3.01 ± 0.04) mg/g from grape skins by UAEE were obtained under an extraction temperature of 50 °C, ultrasonic power of 400 W, pectinase dosage of 0.16%, and extraction time of 28 min. The AB-8 macroporous resin combined Sephadex LH-20 techniques were further employed to purify the anthocyanins extracts obtained under optimum extraction conditions (AEOEC), and the main anthocyanins were identified using high-performance liquid chromatography tandem mass spectrometry. The purified anthocyanins contained two anthocyanins in terms of delphinidin-3,5-O-diglucoside and cyanidin-3-O-rutinoside with purity of 91.35% and 92.64%, respectively. Ultimately, we further evaluated the antitumor activity of AEOEC and two purified anthocyanins on breast cancer. The results indicated that the antitumor effect of AEOEC on breast cancer MCF-7 cells was better than that of two purified anthocyanins. In addition, AEOEC could memorably increase intracellular reactive oxygen species levels and apoptosis of MCF-7 cells, and arrest MCF-7 cells in the G2/M phases. The findings provide an effective and feasible method for anthocyanins extraction and reduce the environmental burden of this waste.

Optimization Ultrasound-Assisted Deep Eutectic Solvent Extraction of Anthocyanins from Raspberry Using Response Surface Methodology Coupled with Genetic Algorithm

Raspberries have been reported to contain abundant anthocyanins and other active compounds. To extract anthocyanins from raspberries more efficiently, a novel procedure of ultrasound-assisted deep eutectic solvent extraction (UADESE) was proposed in this paper. The extraction process was optimized by response surface methodology coupled with a genetic algorithm. The optimum extraction parameters to achieve the highest yield of anthocyanins 1.378 ± 0.009 mg/g from raspberry powder via UADESE were obtained at a water content of 29%, ultrasonic power of 210 W, extraction temperature of 51 °C and extraction time of 32 min. The AB-8 macroporous resin combined with the high-speed counter current chromatography (HSCCC) method were further used to isolate and purify the anthocyanins extracts obtained under optimum extraction conditions, and the structure of purified anthocyanins components were identified by UV-Visible spectrophotometer (UV-Vis), high-performance liquid chromatography (HPLC), high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS/MS), ¹H nuclear magnetic resonance (NMR) and ¹³C-NMR spectra. The two anthocyanins (cyanidin-3-glucoside with a purity of 92.25% and cyanidin-3-rutinoside with a purity of 93.07%) identified were consistent with those present in raspberries. These findings provided an effective and feasible method for extraction, isolation and purification of anthocyanins from natural plant resources.

Effects of simulated digestion on black chokeberry (Aronia melanocarpa (Michx.) Elliot) anthocyanins and intestinal flora

In this study, the changes of anthocyanin content, total phenols, antioxidant capacity, microbiota composition before and after digestion and intestine fermentation in stomach and intestine were studied. The results indicated that after simulated gastrointestinal digestion, compared with the original sample, the total phenol content and anthocyanin content of intestinal digestion group for 2 h (ID 2 group) decreased by 53.64% and 70.45%, respectively, DPPH inhibition rate was 32.75% and T-AOC values of the extracts decreased to 62.89U/mg. The anthocyanins were identified to be composed of cyanidin-3-arabinoside, cyanidin-3-galactoside, cyanidin-3-xyloside, and cyanidin-3-glucoside. Black Chokeberry (Aronia melanocarpa (Michx.) Elliot) anthocyanins significantly increased the relative richness of Bacteroides, promoted the growth of Bifidobacterium, Blautia, Faecalibacterium, and inhibited the growth of Prevotella, Megamonas, Escherichia/Shigella, etc. Anthocyanins have a positive regulatory effect on intestinal flora. These studies also provide essential information for the development of anthocyanin related health care products and drug products.