Natural Blue Colorant Research Articles

New Findings Regarding the Effects of Selected Blue Food Colorants (Genipin, Patent Blue V, and Brilliant Blue FCF) on the Hemostatic Properties of Blood Components In Vitro.

Natural and synthetic colorants present in food can modulate hemostasis, which includes the coagulation process and blood platelet activation. Some colorants have cardioprotective activity as well. However, the effect of genipin (a natural blue colorant) and synthetic blue colorants (including patent blue V and brilliant blue FCF) on hemostasis is not clear. In this study, we aimed to investigate the effects of three blue colorants-genipin, patent blue V, and brilliant blue FCF-on selected parameters of hemostasis in vitro. The anti- or pro-coagulant potential was assessed in human plasma by measuring the following coagulation times: thrombin time (TT), prothrombin time (PT), and activated partial thromboplastin time (APTT). Moreover, we used the Total Thrombus formation Analysis System (T-TAS, PL-chip) to evaluate the anti-platelet potential of the colorants in whole blood. We also measured their effect on the adhesion of washed blood platelets to fibrinogen and collagen. Lastly, the cytotoxicity of the colorants against blood platelets was assessed based on the activity of extracellular lactate dehydrogenase (LDH). We observed that genipin (at all concentrations (1-200 µM)) did not have a significant effect on the coagulation times (PT, APTT, and TT). However, genipin at the highest concentration (200 µM) and patent blue V at the concentrations of 1 and 10 µM significantly prolonged the time of occlusion measured using the T-TAS, which demonstrated their anti-platelet activity. We also observed that genipin decreased the adhesion of platelets to fibrinogen and collagen. Only patent blue V and brilliant blue FCF significantly shortened the APTT (at the concentration of 10 µM) and TT (at concentrations of 1 and 10 µM), demonstrating pro-coagulant activity. These synthetic blue colorants also modulated the process of human blood platelet adhesion, stimulating the adhesion to fibrinogen and inhibiting the adhesion to collagen. The results demonstrate that genipin is not toxic. In addition, because of its ability to reduce blood platelet activation, genipin holds promise as a novel and valuable agent that improves the health of the cardiovascular system and reduces the risk of cardiovascular diseases. However, the mechanism of its anti-platelet activity remains unclear and requires further studies. Its in vivo activity and interaction with various anti-coagulant and anti-thrombotic drugs, including aspirin and its derivatives, should be examined as well.

Effect of dietary Arthrospira platensis phycocyanin on broiler chicken growth performance, physiological status, fatty and amino acid profiles.

Natural antioxidants are crucial for preserving and enhancing the health, survival, reproduction, and reproductive function of poultry. Phycocyanin (PC) is a natural blue food colorant with various health benefits. The aim of this study was to extract Arthrospira platensis phycocyanin (ApPC) from A. platensis using simple and economical methods and investigate the impact of phytocyanin supplementation on the performance and fatty and amino acid profiles of broiler chicks. PC was extracted from A. platensis by freezing and thawing, and optimization conditions such as pH and temperature were applied during storage periods. A total of 270 1-week-old Ross breed broiler chicks were randomly assigned to the following three treatment groups: basal diet supplemented with 0 mg of PC/kg diet (control), basal diet supplemented with 1 g PC/kg diet (T1), and basal diet supplemented with 2 g PC/kg (T2). In a completely randomized design, three cage replicates (30 birds each) were assigned to each of the three groups. The dietary effects of ApPC on growth performance (body weight gain [BWG], body weight [BW], feed intake, feed conversion ratio, serum constituents, and antioxidant indices) in broiler chickens, free amino acids, and fatty acids in muscles were evaluated. Total BWG and BW increased without a significant effect on the total feed consumption. Serum levels of total proteins and albumin increased with increasing ApPC supplementation. In addition, globulin levels significantly increased. There was a significant decrease in serum total cholesterol levels among the treatments. The activity of antioxidant enzymes (superoxide dismutase, catalase, glutathione, and total antioxidant capacity) is significantly increased. In contrast, an increase in ApPC caused a significant decrease in malondialdehyde. The content and quantity of fatty acids and amino acids in the meat of broiler chicks supplemented with PC varies. The addition of PC to broiler chicken diets enhances antioxidant activities, BW, BWG, and meets quality requirements.

Identification of the anthocyanin profile from butterfly pea (Clitoria ternatea L.) flowers under varying extraction conditions: Evaluating its potential as a natural blue food colorant and its application as a colorimetric indicator

This study aims to extract anthocyanins from BPF (Butterfly Pea Flower) to determine an effective solvent combination resulting in higher total anthocyanin content. Various solvent combinations were utilized to discern crucial characteristics of the obtained BPFE (Butterfly Pea Flower Extract). The BPFE from the optimal treatment was utilized as a pigment in colorimetric indicators, which were then evaluated for their initial response to seafood spoilage stored at room temperature for 24 h. The color change response of the colorimetric indicators employing BPFE pigment was compared with the pH and TVBN (Total Volatile base Nitrogen) values of the seafood initially and after 24 h. The highest total anthocyanin content was achieved with the combination of 96 % ethanol/1.5 N HCl (85:15, v/v) at 551.06 mg/L, followed by the combination of 96 % ethanol/distilled water (70:30, v/v) with pH adjustment to 1 using 1.5 N HCl at 484.27 mg/L. Subsequent combinations, in decreasing order, were 96 % ethanol/1.5 N HCl (99:1, v/v), 96 % ethanol/distilled water (70:30, v/v), and lastly, 96 % ethanol/distilled water (30:70, v/v), with total anthocyanin content of 275.53 mg/L, 200.39 mg/L, and 125.24 mg/L, respectively. BPFE applied in colorimetric indicators demonstrated responsiveness to seafood spoilage through color changes, with tested spoilage indicators being pH and TVBN. The initial (first hour) pH and TVBN values for each tested seafood were 5.5 and 9.42 mg/100 g (Scylla serrata), 6.4 and 4.23 mg/100 g (Litopenaeus vannamei), 5.4 and 11.29 mg/100 g (Uroteuthis sibogae), and 6.5 and 10.26 mg/100 g (Restrelliger kanagurta). Meanwhile, the pH and TVBN values after 24-h storage at room temperature became 7.9 and 57.01 mg/100 g, 7.4 and 76.65 mg/100 g, 7.5 and 216.44 mg/100 g, and 7.8 and 51.86 mg/100 g, respectively. The conclusion drawn is that the extraction of BPFE is more efficient when utilizing acidified ethanol solvent, and the resulting BPFE holds promise as a reliable pH indicator.

A water-based ultrasound-assisted extraction system to obtain natural blue colorant from Genipap (Genipa americana L.)

This study aimed to optimize the extraction of a blue colorant using ultrasound-assisted technology employing water as the solvent from genipap, an Amazon fruit. Process conditions were optimized by multiresponse analysis through the antioxidant activity by the ferric reducing antioxidant potential (FRAP) assay, the total phenolic content, and the b* and C* color parameters. The optimized conditions of 70 °C, 325 W, solid: solvent ratio of 1:40 (m/v), and time of 10 min were validated externally at a level of 90 % confidence. The composition of aqueous blue extract obtained under the greatest conditions was evaluated by ultra-performance liquid chromatography (UPLC). Besides, in vitro bioactivities such as digestive enzymatic inhibitions assays, and antiproliferative activity through human cells assays were evaluated. Genipin, geniposide, and other ten iridoids were identified in the aqueous blue extract. The natural colorant obtained presented the capacity of inhibiting enzymes involved in lipid and glucose digestion, suggesting a potential control of obesity and glucose levels in blood without showing cytotoxicity. Therefore, this study presented, for the first time, the optimal operational conditions to obtain a natural blue colorant from genipap in a green approach with interesting biological properties for the food and pharmaceutical industries.

Total Synthesis of Azulene Derivative, a Blue Pigment Isolated from Lactarius indigo, and Colorant Application of Its Aqueous Dispersion.

Safety concerns in the food industry have increased the demand for natural food colorants. However, the application ranges of natural blue colorants are insufficient because they are scarce in nature, and the currently available natural blue dyes are limited to water-soluble products. In this study, we investigated a fat-soluble azulene derivative isolated from the mushroom Lactarius indigo as a potential candidate for a natural blue colorant. We developed its first total synthesis, where the azulene skeleton was constructed from a pyridine derivative and an ethynyl group was converted into an isopropenyl group using zirconium complexes. Moreover, nanoparticles of the azulene derivative were prepared via reprecipitation method, and their colorant ability was investigated in aqueous solutions. The new candidate food colorant exhibited a deep-blue color in an organic solvent and aqueous dispersion.

Isolation of bluish anthocyanin-derived pigments obtained from blueberry surplus using centrifugal partition chromatography

Replacement of synthetic colorants with natural ones is a current marketing trend. Nevertheless, the naturally occurring blue color is rare compared to other colours. In this work, centrifugal partition chromatography (CPC) process was developed as a more efficient and sustainable alternative to reversed phase column chromatography (RP-CC) for the preparative-scale purification of portisins. The strategy began with the extraction of anthocyanins from blueberry surplus and hemi-synthesis of respective portisins. Then, the CPC method development started with the biphasic solvent system selection followed by the optimization of the operating parameters and ended up with a comparison with RP-CC. Aiming at maximizing the portisin content, process throughput, efficiency, and minimizing the environmental risk factor, the effect of sample load (100–500 mg/100 mL of column volume), mobile phase flow rate (10–20 mL/min), and rotation speed (1000–1600 rpm) was evaluated. The two-phase solvent system consisted of tert‑butyl‑methyl ether, n-butanol, acetonitrile, and water (volume ratio 2:2:1:5) acidified with 0.1 vol.% of HCl was selected. The best conditions were 464 mg of sample/100 mL of column volume, 20 mL/min of mobile phase flow rate, and 1600 rpm of rotation speed at reversed phase mode, allowing the purification of portisins by 5-fold. Compared to the RP-CC, the CPC process efficiency was 2.4 times higher, while the CPC process environmental risk factor was 5.5 times lower. Overall, this study suggests that CPC can be considered an effective, and sustainable alternative process for the preparative isolation of portisins. With this purification approach, the blueberry surplus has been valorized and a naturally derived product has been prepared, allowing its subsequent use as a natural blue colorant.

A natural blue colorant from butterfly pea (Clitoria ternatea) petals for traditional rice cooking.

The online version contains supplementary material available at 10.1007/s13197-023-05752-w.

Carboxylated chitosan improved the stability of phycocyanin under acidified conditions

Phycocyanin, a natural blue colorant, derived from Spirulina platensis, is now widely used in the food industry. However, its main drawbacks are loss of color and denature of structure in an acidic environment. In this study, carboxylated chitosan (0.1 %–1 % w/v) was chosen as an additive in acid-denatured phycocyanin for preserving phycocyanin's blue color and natural structure. Zeta-potential and particle size revealed that the carboxylated chitosan with high negative charge adsorbed on phycocyanin and provided stronger electrostatic repulsion to overcome the protein aggregation. Ultraviolet-visible absorption spectrum and fluorescence spectroscopy showed that the carboxylated chitosan recovered the microenvironment of tetrapyrrole chromophores and β-subunits, which led the secondary structure changed and the trimers depolymerized into the monomers changed by the acidic environment. Furthermore, Fourier transform infrared spectroscopy revealed highly negatively charged carboxylated chitosan with the groups (NH2, COOH and OH) could restored the microenvironment of tetrapyrrole chromophores and β-subunits of phycocyanin, and interact with phycocyanin through hydrogen bonding, NH bonding, ionic bonding and van der Waals, which led to a change in secondary structure and depolymerization of trimers into monomers. Our study demonstrated the carboxylated chitosan played a beneficial role in recovering the structure of acid-denatured phycocyanin and its blue color.

Impact of thermosonication processing on the phytochemicals, fatty acid composition and volatile organic compounds of almond-based beverage

Consumers are demanding not animal-derived food products produced by clean technologies. An almond-based functional beverage enriched with coconut oil, xylooligosaccharides, and natural blue colorant was processed by low-frequency ultrasound combined with mild heat treatment. This study aimed to evaluate the effects of thermosonication treatments on the phytochemicals, antioxidant capacity, fatty acids stability, volatile organic compounds, and color attributes of the plant-based beverage. Thermosonication treatments were carried out at 50 °C using three levels of acoustic power (4.6, 8.5, and 14.5 W) and holding time (5, 10, and 15 min). The acoustic energy increased the working temperature up to 25 °C beyond that provided by the external heat source. However, thermosonication treatments did not affect the antioxidant capacity of the beverage. These promoted the release of some bioactive compounds that were bound. Likewise, the degradation of others that were free. Higher acoustic powers and longer holding times degraded stearic and palmitic fatty acids. The thermosonication treatment at 14.5 W for 15 min degraded ethyl esters of the samples modifying the natural flavor of the beverage. Additionally, all thermosonication treatments intensified the blue color of the almond-based beverage maintaining its sensory appeal concerning color attributes.

An efficient protein isolation process for use in Limnospira maxima: A biorefinery approach

With an increasing global population, the demand for protein will place unprecedented pressure on protein production worldwide. The full utilization of microalgae biomass as a nutrient source based on the biorefinery concept remains challenging, especially with regard to protein isolation and extraction. Herein, we report a strategy combining sodium hydroxide and urea to extract nearly 85.4 % of the total proteins from the defatted fraction of pellets in a single step, recovering approximately 76.8 % (weight yield) of the total Limnospira maxima biomass through the process. The content of essential amino acids and of total amino acids was 32.1 % and 39.2 %, respectively. Both of them showed high water solubility. When the pH was 7.0, the water solubility of PE-SA and PE-DPA was 88.4 % and 86.2 %, respectively. Moreover, the two end products (PE-SA and PE-DPA) have different characteristics, which might be used in different food formulations. For instance, the PE-SA fraction contains a pigment protein (C-phycocyanin) that may be exploited as a natural blue colorant in functional beverages. Meanwhile, the PE-DPA fraction has a higher protein content, making it a potential protein resource in nutritional supplements or other plant protein-based foods.

Identification of Anthocyanin Compounds in Butterfly Pea Flowers (Clitoria ternatea L.) by Ultra Performance Liquid Chromatography/Ultraviolet Coupled to Mass Spectrometry.

Butterfly pea flower have great sensory attraction, but they have not yet been used widely in Vietnam. Extracts of butterfly pea flowers can be used conveniently as a natural blue colorant for food products. In this study, the identification of anthocyanin compounds in butterfly pea flowers was performed by UPLC coupled with a UV and Mass spectrometer instrument. Positive and negative ion electrospray MS/MS chromatograms and spectra of the anthocyanin compounds were determined. By analyzing the chromatograms and spectra for each ion, five anthocyanins were identified in the butterfly pea flower extract; these were delphinidin-3-(6″-p-coumaroyl)-rutinoside, cyanidin 3-(6″-p-coumaroyl)-rutinoside, delphinidin-3-(p-coumaroyl) glucose in both cis- and trans- isomers, cyanidin-3-(p-coumaroyl-glucoside) and delphinidin-3-pyranoside. Additionally, based on their intensity, it was determined that cyanidin-3-(p-coumaroyl-glucoside) was the most abundant anthocyanin, followed by cyanidin 3-(6″-p-coumaroyl)-rutinoside, delphinidin-3-(p-coumaroyl-glucoside), delphinidin-3-(6″-p-coumaroyl)-rutinoside and delphinidin-3-pyranoside. In this study, cyanidin derivatives were discovered in butterfly pea flower extract, where these compounds had not been detected in previous studies.

Efficient extraction of food grade natural blue colorant from dry biomass of Spirulina platensis using eco-friendly methods

Eco-friendly methods for extraction of phycocyanins (C-PC and A-PC) from dry biomass of Spirulina platensis were carried out employing nanoparticles (NP), polyethylene glycol (PEG) and salts. There are practically no reports on such methods of extraction of phycocyanins from S. platensis. Standardization of process parameters such as concentration of NP/salt/PEG, extraction time, temperature and solvent was carried out for all the methods employed to achieve maximum productivity (yield and purity). The standardized conditions for NP, salt and PEG based extractions were observed to be 10 μg/mL, 3 mg/mL and 10% w/w concentration, respectively, phosphate buffer as an extraction solvent, 160 min of extraction time and 35 °C of extraction temperature. Silver nanoparticles based extraction resulted in the highest yield (47.68 and 34.18 mg/g db) and purity (0.98 and 0.33) of C-PC and A-PC, respectively. These results are among the highest reported in the primary extraction (itself) without any additional field intervention or process aids.

Xylooligosaccharides as an innovative carrier matrix of spray-dried natural blue colorant

Xylooligosaccharides (XOS) are emerging prebiotic carbohydrates with a high potential to promote health and wellness due to their ability to modulate gut microbiota. Their use as a carrier of milk proteins-crosslinked genipin, an innovative natural blue colorant, was examined in this study. Fructooligosaccharides (FOS), a standard prebiotic carbohydrate, and maltodextrin (MD), a standard carrier material, were compared to XOS as wall materials. The effect of the carrier system on the powdered blue colorants was assessed regarding their size, morphology, free-genipin content, blue color intensity, moisture content, water activity, hygroscopicity, water adsorption, and physical structure. Their technological properties as food colorants were evaluated by incorporating in foodstuffs: beijinho, Chantilly, and muffin. XOS exhibited positive effects compared to other carriers evaluated. XOS-based microparticles presented higher free-genipin retention; smaller particle diameter equal to 6.5 ± 0.4 μm, and higher blue color intensity. The microparticles produced with XOS were more hygroscopic compared to other carrier matrices. However, similar to FOS and MD, the blue colorant carried with XOS presented an amorphous structure. XOS was the best carrier in food applications due to the less interference on the blue color in the powder colorant. The XOS microparticles could be easily incorporated into some food matrices. Therefore, spray-dried blue colorant using XOS presented significant innovative potential in many food products, acting as a functional ingredient, replacing artificial blue colors, and incorporating prebiotic properties.

Manufacturing natural blue colorant from genipin-crosslinked milk proteins: Does the heat treatment applied to raw milk influence the production of blue compounds?

The production of an innovative food ingredient obtained from unripe Genipa americana L. pulp and milk was studied in this paper. Natural blue compounds were produced from the crosslinking between genipin and milk proteins. They are a promising ingredient for the natural food colorant sector. In this regard, this paper aimed to evaluate the impact of heat treatments applied to raw milk on the production of blue compounds. Thermal treatments could change the milk protein conformation and the exposition of their amine groups affecting the crosslinking with genipin. For this, raw milk was subjected to different thermal treatments such as low-temperature and long-time (LTLT; 60 °C/30 min), high-temperature and short-time (HTST; 72 °C/15 s), ultra-high temperature (UHT; 145 °C/2 s), and spray drying (SD; inlet and outlet temperature: 165 and 79 °C, respectively). Thermally treated milk samples were used as solvents for the genipin extraction from unripe genipap pulp and suppliers of proteins to produce blue compounds. Blue colorants milk-based were compared concerning their FTIR spectra, free-genipin content, and color attributes. High temperatures impacted protein conformation, reducing the number of primary amines available for crosslinking. Free-genipin content after the reaction step was a good crosslinking indicator. The HTST-treated milk produced the bluest colorant due to its higher number of primary amines available to react with genipin. Our findings demonstrated that the heat treatment applied to raw milk could influence the production of blue compounds. These results are useful for the enhancement of the manufacturing process of natural blue food colorants.

Effect of light and preservatives on the stability of the phycocyanin from the extremophilic red microalgae Cyanidioschyzon merolae

Synthetic dyes are replaced more and more in food products by natural pigments. A growing number of consumers are concerned with the potential health risk and behavior problems related to synthetic dyes. The phycocyanin of the cyanobacterium Arthospira platensis is the only natural blue pigment commercially available. The thermoacidophilic red microalgae Cuanidioschyzon merolae could provide an alternative phycocyanin source. As C. merolae grows at relatively high temperatures (45 to 56°C), the phycocyanin has a high thermostability even at relatively low pH. The stability of the C. merolae phycocyanin was determined for several products of relevant parameters. Average daylight (300-500 Lux) did not significantly affect the stability, while intense light (20,000 Lux) reduced the half-life to 35 hours. The preservatives such as glucose, sucrose, fructose, and sorbitol improved the stability of C. merolae phycocyanin considerably, with 20% glucose resulting in no loss of color at all. The results show that C. merolae phycocyanin can be used in various food products as a natural blue colorant.

Impact of thermosonication pretreatment on the production of plant protein-based natural blue colorants

The increase in the consumption of natural and non-dairy products has boosted the worldwide food colorant industry. Thus, the use of non-animal protein sources to produce natural blue compounds from the cross-linking between primary amines and genipin extracted from unripe Genipa americana L. pulp was evaluated in this study. Plant extracts obtained from white rice, oat, peanut, and almond were examined as amine suppliers, extraction media, and carrier systems for the blue compounds. The four plant extracts were thermosonicated at 70 °C and 400 W for 3 min and then subjected to ultrasound-assisted extraction of genipin from unripe genipap pulp at 300 W for 6 min. Thus, this study aimed to evaluate the effects of thermosonication pretreatment and plant material on natural blue colorant production. Four new blue plant-based colorants were produced. Protein availability was the most significant limiting factor in the blue color formation reaction. The acoustic cavitation associated with moderate heat treatment during the thermosonication promoted the rupture of fat globules and starch gelatinization. Furthermore, thermosonication pretreatment showed promising to improve the kinetic stability of the natural blue colorants.

Genipap (Genipa americana L.) fruit extract as a source of antioxidant and antiproliferative iridoids

Iridoid blue-based pigments can be found in fruits of genipap (Genipa americana L.). Besides being a potential source of natural blue colorant in the food industry, they have also been associated with pharmacological effects. Therefore, the recovery of iridoids by ultrasound-assisted extraction from both unripe and ripe fruits was analysed by UPLC-DAD-ESI-(-)-QTOF-MS/MS. Nine iridoids were identified from their exact masses and fragmentation pattern, namely geniposidic acid, gardenoside, genipin-1-β-gentiobioside, geniposide, 6′'-O-p-coumaroyl-1-β-gentiobioside geniposidic acid, 6′′-O-p-coumaroylgenipin-gentiobioside, genipin, 6′-O-p-coumaroyl-geniposidic acid and 6′-O-feruloyl-geniposidic acid. Among them, genipin (60.77 mg/g fdw) was found to be the most abundant iridoid in unripe genipap extract, while the ripe genipap extract mainly contained geniposide and geniposidic acid (89.48 and 25.04 mg/g fdw, respectively). It was also observed that the iridoids of the unripe genipap extract are able to scavenger DPPH, ABTS and peroxyl radicals as well as exerting a cytostatic effect against both glioma and breast cancer cell lines. This study provided information about the properties of unripe and ripe genipap extracts which can be used as a reference for further studies focusing on the potential application of G. americana L. in commercial products containing natural blue colorant with functional claims.

Milk colloidal system as a reaction medium and carrier for the natural blue colorant obtained from the cross-linking between genipin and milk proteins

A promising natural blue colorant was obtained from the cross-linking between genipin and milk proteins. Milk was simultaneously used to extract genipin from the unripe genipap (Genipa americana L.) and evaluated as a reaction medium and carrier for the novel blue colorant. The effects of the milk composition (skimmed, semi-skimmed, and whole) on the kinetic of blue color formation in the colorant-loaded milk samples during their cold storage time for 96 h were evaluated using their color parameters and free-genipin content. The reaction between milk proteins and genipin were evaluated by FTIR spectroscopy. In addition, the blue colorant-loaded milk samples were characterized according to their droplet size distribution, microstructure, and phase separation kinetics. The milk fat content influenced the genipin recovery while the milk with higher protein content contributed to obtaining a more intense blue color. Using whole milk with 3.0 g/100 g fat content favored the light scattering and, thus, a blue colorant with a more intense −b∗ and L∗ values was obtained. On the other hand, the use of skimmed milk with 0.5 g/100 g fat content resulted in more consumption of genipin due to its more protein content for the reaction of blue color compounds formation. Thus, a more intense and darker blue coloration was observed with lower light scattering. The milk composition did not modify the phase separation kinetics of the blue colorant-loaded milk. Therefore, our results have demonstrated that the milk was a suitable medium for the reaction of blue color formation and also a good blue compounds carrier. Industrial relevanceConsumer demands for natural colorants have increased in the last years.Thus, the new food industry challenge is to develop novel healthy, safe and high-quality food products based on natural colorants. Currently, the colorant market does not have still available a natural blue colorant. Therefore, the development of a novel natural blue colorant from plant material could meet this worldwide demand increasing the added value of many products such as ice cream, dairy beverages, and candies.

Low-frequency and high-power ultrasound-assisted production of natural blue colorant from the milk and unripe Genipa americana L.

This study presents the production of a novel natural blue colorant obtained from the cross-linking between milk proteins and genipin assisted by low-frequency and high-power ultrasound technology. Genipin was extracted from unripe Genipa americana L. using milk as a solvent. Also, milk colloidal system was used as a reaction medium and carrier for the blue color compounds. The effects of ultrasound nominal power (100, 200, 300, and 400W) on the blue color formation kinetics in milk samples were evaluated at 2, 24, and 48h of cold storage in relation to their free-genipin content and color parameters. In addition, Fourier transform infrared (FTIR) spectrum, droplet size distribution, microstructure, and kinetic stability of the blue colorant-loaded milk samples were assessed. Our results have demonstrated that the ultrasound technology was a promising and efficient technique to obtain blue colorant-loaded milk samples. One-step acoustic cavitation assisted the genipin extraction and its diffusion into the milk colloidal system favoring its cross-linking with milk proteins. Ultrasound process intensification by increasing the nominal power promoted higher genipin recovery resulting in bluer milk samples. However, the application of high temperatures associated with intensified acoustic cavitation processing favored the occurrence of non-enzymatic browning due to the formation of complex melanin substances from the Maillard reaction. Also, the blue milk samples were chemically stable since their functional groups were not modified after ultrasound processing. Likewise, all blue colorant-loaded milk samples were kinetically stable during their cold storage. Therefore, a novel natural blue colorant with high-potential application in food products like ice creams, dairy beverages, bakery products, and candies was produced.

Improvement of the colloidal stability of phycocyanin in acidified conditions using whey protein-phycocyanin interactions

Phycocyanin, a natural blue colorant from Spirulina, can form aggregate and precipitate in acidified beverages. In order to solve the aggregation problem of phycocyanin at low pH, we used whey protein to improve the stability of phycocyanin in acidified conditions. Our results showed that whey protein is much more effective compared to pea and egg white proteins in preventing the aggregation of phycocyanin at pH 3.0, in which a minimum 10% of whey protein solution is required to completely prevent the aggregation. In addition, undenatured whey protein is more effective compared to denatured and hydrolyzed forms. We found that α-lactalbumin, β-lactoglobulin, BSA, immunoglobulins, and glycomacropeptides may all participate in the encapsulation of the phycocyanin molecule. The Fourier transform infrared spectroscopy, native-polyacrylamide gel electrophoresis, and zeta-sizer results also proved that the complete whey protein provides better protection for phycocyanin compared to BSA or whey protein without the glycomacropeptides. The study provides a natural way to stabilize phycocyanin at acidified conditions, making it possible to use phycocyanin as a blue colorant in acidified beverages.