Anthocyanin pigment stability of Cornus mas-Macrocarpa under treatment with pH and some organic acids

Effect of maltodextrin and Persian gum as wall materials and tannic acid as copigment on some properties of encapsulated sour cherry anthocyanin microcapsules

Due to the instability of anthocyanins, their application as natural colorants is limited. To improve their stability, anthocyanins extracted from sour cherry were copigmented with tannic acid at varying molar ratios. The optimal anthocyanin:copigment molar ratio was determined to be 1:0.25. Subsequently, both non-copigmented and copigmented anthocyanins (using the optimal tannic acid molarity) were spray-dried with either maltodextrin alone (T1 and T2) or a combination of maltodextrin and Persian gum (T3 and T4). The anthocyanin retention in T2 and T4 was approximately 53 % and 38 %, respectively, which were higher than in the non-copigmented samples. All powders demonstrated high encapsulation efficiency (>90.37 %). Stability tests on the anthocyanins conducted over 28 days indicated that light exposure had no effect on the reduction of anthocyanin content when maltodextrin was used. Thus, the copigmentation of anthocyanins with tannic acid, combined with encapsulation in maltodextrin, presents a promising method for producing a stable natural colorant.

Comparison of different green extraction methods used for the extraction of anthocyanin from red onion skin

Green extraction primarily emphasizes developing new extraction techniques that consume less energy. It involves using safe, non-toxic alternative solvents and sustainable natural resources to ensure the production of safe and high-quality extracts. Red onion skin is an important source of anthocyanins, a subgroup of phenolic compounds. Anthocyanins are an important group of natural pigments that have attracted a lot of attention due to their health benefits. However, the instability and high sensitivity of these pigments have limited their use in food and cosmetics. Therefore, in this study, various modern green extraction methods were used, including solvent extraction, ultrasound-assisted extraction, subcritical water extraction, microwave-assisted extraction (MAE), pulsed electric field extraction, supercritical fluid extraction (SFE), and high hydrostatic pressure-assisted (HHPAE) extraction, to specifically extract and purify anthocyanins. The extraction efficiency, specifically targeting anthocyanins, showed the highest efficiency with HHPAE (81.84%) and the lowest with MAE (40.01%). Measurement of total anthocyanin content revealed that HHPAE and SFE methods yielded the highest anthocyanin concentrations, with 248.49 and 244.98 mg/L, respectively. Identification of anthocyanin by LC-MS revealed that the main anthocyanidins in red onion peel are pelargonidin, cyanidin, delphinidin, and petunidin. These results indicate that innovative green extraction methods, particularly HHPAE and SFE, can effectively replace conventional techniques due to their superior efficiency and enhanced preservation of anthocyanin compounds.

Enhancing the accuracy, speed, and efficiency of kafirin-PEO electrospun bio-nanocomposite pH indicators with red beetroot extract using image processing

Intelligent electrospun pH indicators were produced from bio-nanocomposite kafirin-polyethylene oxide (PEO) containing red beetroot extract. The aim was to evaluate the performance and stability of the electrospun pH indicators via image processing. Red beetroot extract was added to a mixture of kafirin and PEO at various concentrations. The mixtures were electrospun, and infrared Fourier transform spectroscopy confirmed the presence of kafirin, PEO, and red beetroot extract in the resulting pH indicator. The results showed that the pH indicators had high stability and reversibility at different temperatures, pHs, and environmental conditions. The results showed that the color of the indicators was significantly reversible after pH changes, with highly desirable reversibility observed at pH values of 1, 3, 4, 5, 7, 9, and 10. The findings proved that the red beetroot extract loaded bio-nanocomposite pH indicator accompanied by evaluation of color characteristics through image processing technique, can serve as a time-efficient, accurate tool for detecting and tracking pH changes caused by food spoilage.

Dye stability of black cherry plum anthocyanins in the interaction with co-pigments and sucrose sweetener

In this research, the co-pigmentation reactions between black cherry plum (Prunus cerasifera Ehrh. cv. Pissardii Nigra) anthocyanins and caffeic, gallic, 4-hydroxybenzoic, malic, and tannic acids with different concentrations (0, 120, 240, 480, and 960 mg L-1) at various temperatures (20, 40, 60, 80, and 100°C) were investigated at pH 3.5. The strongest immediate co-pigmentations resulted at 960 mg L-1, being significantly highest using tannic acid at all temperatures. In addition, the anthocyanin stability and the brown polymeric color formation were investigated in the presence of different concentrations of sucrose sweetener (0, 30, and 60%) and different pHs (2 and 3) in the range of 0-60 h. Also, the amount of furfural was measured in the presence of 0% and 30% sucrose concentrations at pH 2 after 20 h at 90°C by HPLC (high-performance liquid chromatography), and the most polymeric color formation was observed in the concentration of 60% sucrose at pH 2 after 60 h.

Quality and sensorial evaluation of beef burgers added with Sicilian sumac (Rhus coriaria L)

The Sicilian sumac (Rhus coriaria L.) is considered an excellent source of natural polyphenols whose antioxidant activity is able to affect specific technological functions. The effect of the Rhus coriaria addition on the quality of beef burgers before and after cooking was evaluated, by pH, colour, protein (-SH) and lipid oxidation, total phenol content and antioxidant activity (ABTS assay). The sumac in burgers (THs) resulted in a significant increase in all dry matter components (P < 0.05), while water content and pH value decreased. Furthermore, THs, compared with control burgers (CHs), were characterised by lower L* and peroxidation values and higher a* and b* values (p < 0.05). The Rhus added in the burgers positively influenced the total phenolic content and antioxidant activity values. Cooking reduced content of phenols, -SH groups and antioxidant activity. However, in THs the reduction of -SH, phenols and antioxidant activity was more limited than in CHs (p < 0.05). Sensory analysis showed a higher appreciation for THs by consumers for all the considered attributes. The ground meat incorporated with sumac could be a valid strategy to improve its quality and sensorial evaluation.

Lemon juice improved color acceptance of aronia (Aronia melanocarpa) pound cake by copigmentation

Anthocyanins can be changed into dark purplish color during pound cake preparation due to high temperature and alkaline baking soda, which lowers color acceptance by consumers. To stabilize a red color of anthocyanins in pound cake enriched with aronia (Aronia melanocarpa) powder, lemon juice was added to contain final concentrations of 0, 1, 2, and 3% (w/w) in the pound cake, which were assigned as control, PL1%, PL2%, and PL3%, respectively. As lemon juice amount increased, redness (a*) and sensory color perception as well as overall acceptance were enhanced, whereas hardness, gumminess, and chewiness decreased in texture profile analysis. In a model system, the addition of lemon juice to aronia solution caused bathochromic shift and hyperchromic effect in UV-Vis absorption spectrum, which are typical phenomena of copigmentation derived from interactions between anthocyanins and copigments. The results indicate that lemon juice improved color acceptance for aronia pound cake by copigmentation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01286-1.

Preparation and characterization of a novel intelligent starch/gelatin binary film containing purple sweet potato anthocyanins for Flammulina velutipes mushroom freshness monitoring

In this study, intelligent food package was developed and characterized by loading purple sweet potato polyphenolic extract (SPS) into starch/gelatin film. The application of this film in indicating the freshness of Flammulina velutipes was also determined. The color of SPS buffer changed from red to blue and final yellow when pH increasing from 3 to 10. The blending film with starch/gelatin ratio of 1:1 wt showed a minimum water vapor permeability of 6.26 × 10-11 gs-1 m-1 Pa-1. The value of elongation at break and tensile strength of the starch/gelatin film with starch/gelatin ratio of 1:1 wt increased to 78.89 % and 11.70 MPa. Upon its application to monitor of F. velutipes freshness level, SG11 film color changed from initially green to purplish gray and finally to yellow as F. velutipes deteriorated post storage. Our results suggested that SG11 films could be used as an intelligent packaging material in the future for other food products.

Optimization of the Extraction Conditions of Antioxidant Phenolic Compounds from Strawberry Fruits (Fragaria x ananassa Duch.) Using Response Surface Methodology

The subject of this study is to determine the best solvent and optimum extraction conditions for the extraction of maximum antioxidant phenolic compounds and antioxidant activity from strawberry fruits (Fragaria x ananassa Duch.). Extractions were carried out using solvents with different polarities (water, methanol, ethanol, acetonitrile, and acetone). Box-Behnken Design was used to optimize extraction conditions, including extraction time (t), temperature (°C), and liquid/solid (L/S) ratio. In the study, extracts obtained with acetone indicated the highest total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity. The optimal extraction conditions for both responses were determined to be time of 17.5 min, temperature 52.5 °C, and liquid/solid ratio of 30:1. The maximum TPC and TFC values were found as 18.78 ± 0.22 mg of gallic acid equivalent (GAE/g) and 10.52 ± 0.35 mg of catechin equivalents (CE/g) under optimum extraction conditions. The results indicated that optimizing extraction conditions is critical for quantifying antioxidant phenolic compounds. The present model can contribute to finding a cheap way of delivering natural antioxidants in the food, cosmeceutical, and pharmaceutical industries. Furthermore, these results indicate that strawberry fruits (Fragaria x ananassa Duch.) can be a natural food colorant in dietary applications with potential health benefits.

Origin of the effects of optical spectrum and flow behaviour in determining the quality of dry fig, jujube, pomegranate, date palm and concentrated grape vinegars

In this study, we focused on physical characterization and quality control of dry fig, jujube, pomegranate, date palm and concentrated grape vinegars using UV spectroscopy method and rheology technique. The optical spectra and flow behaviour of the vinegars were analysed in detail in the selected specific wavelength, shear rate and frequency ranges, respectively. It was determined that the peak values seen in the UV spectra of the vinegars were caused by the organic acid and phenolic compound concentration. The peak values in the UV spectra of the vinegars wavelength range of 190 nm to 240 nm and 250 nm to 300 nm were caused by the organic acid and phenolic compound concentration, respectively. In this context, it was predicted that concentrated grape vinegar, which has the highest absorbance value, has higher organic acid content and more antibacterial/antioxidant properties compared to the others. It is thought that the optical energy gaps of vinegars are related to the organic acid concentration and the release time. Flow properties of the vinegars were non-Newtonian thickening fluids (dilatant fluids) and compatible with the Power law model. The stable flow of the vinegars in the high shear rate region was interpreted as having a successful production process and being of good quality.

Effects and mechanism of natural phenolic acids/fatty acids on copigmentation of purple sweet potato anthocyanins

Anthocyanins are attractive alternatives to colorants; however, their low color stability hinders practical application. Copigmentation can enhance both the color intensity and color stability of complexes. Herein, we report an investigation of copigmentation reactions between purple sweet potato anthocyanins (PSA1) and phenolic acids (tannic, ferulic, and caffeic acids) or fatty acids (tartaric and malic acids) at pH 3.5. The effects of the mole ratios of the copigment and the reaction temperature were examined. In addition, quantum mechanical computations were performed to investigate molecular interactions. The optimum PSA:copigment molar ratio was found to be 1:100. The strongest bathochromic and hyperchromic effects were observed for copigmentation with tannic acid (Tan), which might be attributable to the fact that its HOMO-LUMO energy gap was the smallest among the investigated copigments, and because it has a greater number of phenolic aromatic and groups to form more van der Waals and hydrogen bond interactions. However, the formation of the PSA-caffeic acid (Caf) complex was accompanied by the greatest drop in enthalpy (−33.18 kJ/mol) and entropy (−74.55 kJ/mol), and this was the most stable complex at 90 °C. Quantum mechanical calculations indicated that hydrogen bonds and van der Waals force interactions contributed to the color intensification effect of copigmentation. These findings represent an advancement in our understanding of the properties of PSA, expanding the application scope of this natural product.

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Anthocyanin-phenolic/fatty acid copigmentation interactions were investigated.

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Copigment HOMO-LUMO gaps served as a copigmentation capability guide.

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Color changes in the presence of the acids were associated with structural effects.

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Copigmentation was mainly driven by hydrogen bonding and van der Waals interactions.

Cyanidin-3-glucoside Regulates Osteoblast Differentiation via the ERK1/2 Signaling Pathway

Osteoporosis, characterized by a gradual decrease in the number of osteoblasts and a gradual increase in bone resorption of osteoclasts in bone tissue, is a global chronic disease, which severely impairs the quality of life of the elderly. Therefore, it is extremely urgent to study the prevention and treatment of osteoporosis. It has been reported that anthocyanins can regulate bone metabolism and prevent osteoporosis. Cyanidin-3-O-glucoside (C3G), the most common type of anthocyanin in nature, widely exists in a variety of vegetables and fruits. Although it has been shown that C3G has multiple effects on osteoclasts, its impact(s) and underlying mechanism(s) on osteoblasts are still not clear. Here, we evaluated the effect of C3G on cell proliferation and differentiation of osteoblasts (extracted from the hip joint of patients with osteoporosis) and MC3T3-E1 (a kind of osteoblast cell line from mice). We also test the ability of osteoblasts to mineralize after C3G treatment. To find the underlying mechanism of the above effects, we further evaluated the role of the ERK signaling pathway in C3G regulation of osteoblasts. The results showed that C3G treatment enhanced osteoblast proliferation rate, osteoblast mineralization points, the mRNA levels and protein expression levels of OC (osteocalcin), and the level of ERK phosphorylation, which could be blocked by pretreatment with ERK signaling pathway inhibitor. The above results not only indicate that the ERK pathway was involved in C3G regulation of osteoblast differentiation but also provide strong suggestive evidence that osteoblasts may be promising targets in preventive and therapeutic strategies for osteoporosis.

Co-pigmentation of anthocyanins extracted from sour cherry (Prunus cerasus L.) with some organic acids: Color intensity, thermal stability, and thermodynamic parameters

The co-pigmentation reactions involving anthocyanins of sour cherry (Prunus cerasusL.) were investigated with tannic, caffeic, 4-hydroxybenzoic, gallic, and malic acids at pH 3.5. The influence of the co-pigments with different concentrations (120, 240, 480, and 960 mg/L), and temperatures (20, 40, 60, 80 and 100 ℃), on the co-pigmentation effects, stoichiometric ratio (n), the equilibrium constant (K) and thermodynamic parameters (ΔG°, ΔH°, and ΔS°) were determined.The strongest immediate co-pigmentation reactions were observed at 960 mg/L, being significantly highest using tannic acid; also,the greatest bathochromic and hyperchromic effects were reasonable for itsn,K, and ΔG° values of 0.64, 56.55, and -10.00 kJ/mol, respectively. Furthermore, tannic and caffeic acids, with the highest negative values ofΔH°(-11.74 kJ/mol) andΔS°(-8.08 J/K.mol) led to the most excellent stability at 100 ℃.The presence of anthocyanins in the sour cherry extract was confirmed with the Fourier-transform infrared spectroscopy technique.

Anthocyanins: From the Field to the Antioxidants in the Body

Anthocyanins are biologically active water-soluble plant pigments that are responsible for blue, purple, and red colors in various plant parts-especially in fruits and blooms. Anthocyanins have attracted attention as natural food colorants to be used in yogurts, juices, marmalades, and bakery products. Numerous studies have also indicated the beneficial health effects of anthocyanins and their metabolites on human or animal organisms, including free-radical scavenging and antioxidant activity. Thus, our aim was to review the current knowledge about anthocyanin occurrence in plants, their stability during processing, and also the bioavailability and protective effects related to the antioxidant activity of anthocyanins in human and animal brains, hearts, livers, and kidneys.

The Synergistic Behavior of Antioxidant Phenolic Compounds Obtained from Winemaking Waste's Valorization, Increased the Efficacy of a Sunscreen System

Grape pomace retains polyphenols in the peels and in the seeds after winemaking, which is indicative of the high valorization potential of this industrial waste. There is strong evidence that phenolics are robust antioxidants and confer photoprotection; thus, it is rational to apply these active compounds from winemaking waste to sunscreens, in order to increase UV protection. Despite the importance of this class of cosmetics to public health, more efficacious strategies are still needed to overcome the problems caused by the photoinstability of some UV filters. The hydroethanolic extract of Vitis vinifera L. grapes was obtained by percolation and then lyophilized. Six formulations were developed: Type I—cosmetic base and UV filters; Type II—cosmetic base and extract; and Type III—cosmetic base, extract and UV filters. Each formulation was prepared in the pHs 5 and 7. The antioxidant activities of the samples were measured by DPPH• and expressed in Trolox^® equivalents (TE), and their photostability and in vitro sun protection factor (SPF) were analyzed by diffuse reflectance spectrophotometry. The anti-radical efficiencies observed in the formulations with grape extract were: (II) 590.12 ± 0.01 μmol TE g⁻¹ at pH 5 and 424.51 ± 0.32 μmol TE g⁻¹ at pH 7; (III) 550.88 ± 0.00 μmol TE g⁻¹ at pH 5 and 429.66 ± 0.10 μmol TE g^−1, at pH 7, demonstrating that the UV filters, butylmethoxydibenzoyl methane, ethylhexyl methoxycinnamate and ethylhexyl dimethyl 4-aminobenzoic acid had no influence on this effect. The photoprotective efficacy and the photostability of formulation III containing the extract and UV filters at pH 5 suggested that a synergism between the active molecules provided an 81% increase in SPF. Additionally, this was the only sample that maintained a broad spectrum of protection after irradiation. These results confirmed that the grape pomace extract has multifunctional potential for cosmetic use, mainly in sunscreens, granting them superior performance.

Comparisons of carbohydrate-utilizing enzymes inhibitory effects and chemical profiles of five deeply colored food extracts

Deeply colored food has attracted great interest of researchers as they can be loaded with health-promoting compound. Extracts from five deeply colored food (Black currant, Wild rice 1, Black bean hull, Wild rice 2, and Mulberry) were chosen and carried to evaluate the carbohydrate-utilizing enzymes inhibitory effects and compare the chemical compound profiles to lock the candidate compound for the enzymes. Although the contents of total phenolics in five extracts were at comparable levels, the anthocyanins and flavonoids contents varied widely. Especially for the extracts from Black bean hull, the compositions of phenolics and anthocyanins characterized by UPLC-QTOF-MS/MS were significantly different from other samples. In addition, the inhibitory effects of Black bean hull on α-amylase demonstrated approximately half of that of acarbose at the same concentration while its inhibitory effect on α-glucosidase was doubled of that of acarbose. The inhibition kinetics illustrated that Black bean hull had reversible and uncompetitive inhibitory effect on α-glucosidase with the IC₅₀ value being 11.37 μg/ml. Pearson's correlation analysis showed that the contents of total flavonoids and α-glucosidase inhibition were more relevant, and the B-type proanthocyanins was presumably the main active substance. PRACTICAL APPLICATIONS: Carbohydrate-utilizing enzymes are potential therapeutic targets of diabetes since they could balance the postprandial blood glucose. Anthocyanins, the natural pigments with flavonoid structures, are being attracted by citizens and researchers because of their high antioxidant effect. Anthocyanin extracts from Black bean hull among other four deeply colored food could be an alternative anti-hyperglycemic agent and copigments in anthocyanin extracts are the candidate for α-glucosidase inhibition.

Production of a natural color through microwave-assisted extraction of saffron tepal's anthocyanins

The extraction of anthocyanins from saffron (Crocus sativus) flower's tepal by microwave-assisted extraction (MAE) was studied. The independent factors were solvent to sample ratio (10:1‒100:1), extraction temperature (35‒75°C), and time (5‒15 min). Maximum irradiation power in all experiments was 360 W. We applied response surface methodology (RSM) in order to determine optimum processing conditions which give maximum extraction efficiency (mg cyanidin-3-glucoside/g dried tepals). It was found that the influence of solvent ratio was more important for extraction yield than two other variables. Extraction conditions which maximized the extracted anthocyanins content were ratio of solvent to sample 77.5 ml/g, temperature 48°C, and extraction time of 9.3 min that resulted in 101 mg anthocyanins/g. In addition, MAE was a rapid and efficient technique for saffron anthocyanins due to disruption of cell walls under microwave irradiation, which was observed by microstructural analysis.

Anthocyanin pigment stability of Cornus mas-Macrocarpa under treatment with pH and some organic acids

The use of colors in food industry is essential for the creation of new products or their improvement. As an important pigment group, anthocyanin could be used as a natural coloring pigment in foods. This study aims at exploring strategies that result in color stability of anthocyanin in pear‐shaped variety of blueberry (Cornus mas–Macrocarpa). In this study, the effects of different pH values (1, 2, 3, 4) as well as various concentrations (0, 120, 240, 480, 960 mg/L) of five copigments, including tannic, caffeic, benzoic, and coumaric acids, on anthocyanin copigment complexes (ratio 1:1) were investigated. The studied copigments were tannic, caffeic, benzoic, and coumaric acids. Anthocyanin was influenced by the highest concentration of 960 mg/L copigment in the presence of different pHs. Five groups were considered, one of which contained anthocyanin without copigment and the rest consisted of copigments. To evaluate the response of copigmentation through spectrophotometer, absorbance from samples was measured after 30 min of adding copigment to anthocyanin in the range of 450–600 nm wavelengths. The results showed that caffeic acid possessed the greatest anthocyanin stability compared to other copigments and it was the best copigment. An increase in the concentrations of copigments led to a higher level of anthocyanin stability and changes in hyperchromic and bathochromic. Moreover, the results revealed that the strongest hyperchromic effect for all organic acids was observed in pH 2, and the strongest bathochromic changes were observed in pH 4.