Gum Arabic Complex Research Articles

Validity and Breakdown of Superposition Principles in the Viscoelasticity of Chitosan–Gum Arabic Complex Coacervates

Complex coacervates of chitosan and gum arabic, two naturally abundant weak polyelectrolytes, were investigated by oscillatory shear rheology at varying temperatures, salt concentrations, salt types, pH, and polyelectrolyte mass ratios. The complex shear moduli are shown to scale with temperature, salt concentration, and pH, implying that the concepts of time–temperature superposition (TTSP), time–salt superposition (TSSP), and time–pH superposition (TpHSP) are applicable. However, in the case of TSSP and TpHSP, a superposition breakdown occurs in the low-frequency regime toward high salt concentrations (>300 mM) and pH values near the pKa of chitosan (≈6.5). Since the shear moduli G′ and G″ are observed to increase and become less frequency-dependent at high salt concentration and pH, the superposition breakdown is ascribed to gelation, presumably due to the associative interaction of chitosan chains and the formation of a chitosan network.

Addition of gelatin increased the spray drying performance of the Pickering emulsion stabilized by the ovalbumin – gum Arabic electrostatic complex

Gelatin was added to the perilla seed oil (PSO) Pickering emulsion stabilized by the ovalbumin (OVA) – gum Arabic (GA) electrostatic complex to increase its spray drying performance. The results indicated that the addition of gelatin to the primary PSO Pickering emulsion in mass ratio to the OVA – GA complex 1:1 before high-pressure homogenization could increase the total solid concentration of the feed to 20% and decrease the surface oil content of the resultant powder to 9.90% without compromising its total oil content (77.84%) and powder yield (76.08%) compared with that in the absence of gelatin. Characterization of the Pickering emulsions revealed that gelatin adsorbed to the surface of the primary emulsion droplets through electrostatic interaction and the subsequent high-pressure homogenization caused composition and structure rearrangement in the emulsion interface, leading to reduced particle size and viscosity of the secondary emulsion. The optimized PSO powder possessed excellent structural integrity according to scanning electron microscope observation as well as good flowability and water dispersibility. Hence, the addition of gelatin is an effective strategy to improve the economy for producing powders with ultra-high oil contents by spray drying Pickering emulsions stabilized by the OVA – GA electrostatic complex.

Impact of pH on the interaction between soy whey protein and gum arabic at oil–water interface: Structural, emulsifying, and rheological properties

In this study, gum arabic (GA) and pH modulation were used to change the structural and emulsion properties of soy whey protein (SWP). The interaction mode and binding site of SWP and GA were analyzed by structural characterization and molecular modeling techniques. The microscopic morphological, emulsifying, interfacial, and rheological properties of emulsions formed by SWP–GA complexes were characterized. The ζ-potential results showed that pH has a significant effect on the electrostatic interaction between SWP and GA. Fluorescence spectra and surface hydrophobicity (H0) illustrated that the H0 of SWP–GA complexes significantly decreased. Fourier transform infrared spectroscopy (FTIR) showed that GA provided the basis for the formation of ordered structures and that the β-sheet content of SWP–GA complexes reached the maximum value (44.68%) at pH 6.0. Molecular docking results further verified that SWP–GA interaction occurred through hydrogen bond and hydrophobic interaction. Compared with SWP emulsions, droplets of SWP–GA emulsions were uniformly distributed and formed a dense network structure. The emulsifying activity index and emulsifying stability index significantly improved, especially at pH 6.0, which were 902.78 ± 4.44 m2/g and 4648.27 ± 203.59%, respectively. SWP–GA complexes facilitated adsorption at the oil–water interface and reduced the interfacial tension. GA significantly improved the rheological properties of SWP–GA emulsion. Furthermore, statistical analysis indicated that the structural properties of SWP–GA complexes were significantly correlated with the emulsifying and interfacial properties of SWP–GA emulsions. This study would provide theoretical guidance for the preparation of the stable emulsion system of protein–polysaccharide complexes.

Encapsulation of essential oils using hemp protein isolate–gum Arabic complex coacervates and evaluation of the capsules

Complex coacervates of hemp protein isolate and gum Arabic were prepared. These complex coacervates were used to encapsulate essential oils (EOs). The nature of the EO affected the physical properties, structure and bioactives of capsules.

Hemp protein isolate – gum Arabic complex coacervates as a means for oregano essential oil encapsulation. Comparison with whey protein isolate – gum Arabic system

The potential of hemp protein isolate-gum Arabic complex (HPI-GA) coacervates to encapsulate Origanum vulgare L. subsp. hirtum essential oil (OEO) was evaluated in comparison to the well-studied whey protein isolate-GA encapsulating system. Different biopolymer (1 or 2% w/w) and OEO (0.5 or 1%) concentrations were tested and the formed OEO microcapsules were characterized in terms of encapsulation yield and efficiency, as well as structural, morphological, moisture sorption, antioxidant, and antimicrobial properties. Gas chromatography was applied to determine possible ensuing changes to oil's composition. OEO was successfully encapsulated in both protein-polysaccharide systems as demonstrated by encapsulation yield and efficiency results and confirmed by FTIR spectroscopy, while its major volatile constituents (carvacrol and thymol) were highly preserved. Biopolymer concentration increase and low OEO's addition levels positively affected the encapsulation parameters (e.g., ∼90% encapsulation efficiency for the HPI-GA) due to the more complete droplets' surface coverage and enhancement of proteins-GA interactions at the interface. SEM analysis showed the typical, uneven, irregular morphology of freeze-dried powders, being denser and more aggregated upon OEO content increase. The sorption characteristics of coacervates exhibited the type II isotherm and the GAB model accurately described the obtained curves revealing lower monolayer moisture content in the case of HPI. The implementation of disc diffusion method showed that encapsulation acted protectively on OEO's antimicrobial activity, while DPPH and CUPRAC assays revealed the preservation of EO's antioxidant activity. These features provide evidence that HPI-GA can be used as alternative wall materials to encapsulate EOs by the complex coacervation method.

Preparation of powdered oil by spray drying the Pickering emulsion stabilized by ovalbumin – Gum Arabic polyelectrolyte complex

The suitability of the perilla seed oil Pickering emulsion stabilized by the ovalbumin (OVA) – gum Arabic (GA) polyelectrolyte complex for spray drying was investigated and the resultant powder was characterized. The OVA – GA complex conferred enhanced stability to the emulsion than OVA, GA, and their mixture. The viscosity of the Pickering emulsion was highly sensitive to stabilizer concentration and that fabricated by 2% OVA – GA complex showed acceptable viscosity and powder yield. The Pickering emulsion was more effective in preventing oil leakage during spray drying than the OVA-stabilized emulsion and the resultant powder possessed an oil content of up to 77.7%. Besides, the spray-dried Pickering emulsion powder showed greater rehydration and better flowability than that of the OVA-stabilized emulsion powder. Hence, the Pickering emulsion stabilized by the OVA – GA polyelectrolyte complex is promising as a novel feed for the production of oil powders by spray drying.

Complexation between ovalbumin and gum Arabic in high total biopolymer concentrations and the emulsifying ability of the complexes

To promote the application of Pickering emulsions stabilized by protein – polysaccharide polyelectrolyte complexes in the production of oil powders by spray drying, the complexation between ovalbumin (OVA) and gum Arabic (GA) in high total biopolymer concentrations (TBOCs) was investigated and the emulsifying ability of the resultant OVA – GA complexes was evaluated. The results indicated that electrostatic complexation could occur between the two polyelectrolytes in TBOCs of as high as 6% (w/v), though the reaction was suppressed in TBOCs higher than 3%. The phase separation TBOC greatly affected the composition, viscoelasticity, and aggregation of the OVA – GA complexes as well as the structure of OVA. The ability of the OVA – GA complexes to stabilize the high internal phase Pickering emulsion with oil fraction 75% was closely related to the TBOC, that is, the complexes separated in TBOC 2% failed to stabilize the emulsion, but those separated in 4% and 6% could produce stable emulsions. Raman spectroscopy, contact angle, and interfacial tension analysis confirmed this result and demonstrated that the complex assembled in TBOC 4% possessed stronger emulsifying ability than TBOC 6%. The complexes in the two TBOCs allowed the possibility in the industrial production of powders with ultra-high oil contents and hence are promising as novel Pickering stabilizer in spray drying.

Functional and structural properties of gum arabic complexes with casein and hydrolyzed casein achieved by Maillard reaction

In this study, casein was extracted from milk and hydrolyzed with pepsin at three different enzyme/substrate ratios (0.1:100, 0.15:100, and 0.2:100). Three molar ratios of casein or hydrolyzed caseing/gum Arabic (GA) (1:1, 1:2, and 2:1) were exposed to Millard reaction using wet heating method at 80 °C, 6 h. The conjugation of biopolymers through Millard reaction was verified by Fourier Transform Infrared (FT-IR), high performance size exclusion chromatography (HPSEC) and fluorescence spectrophotometry methods. Higher molecular weight was observed after the reaction experiment. Moreover, FT-IR spectrum showed changes in amide 1 and 2 bands and fluorescence spectrophotometry showed reduction of intrinsic fluorescence intensity. Maillard reaction got faster by increasing the degree of hydrolyzation and GA/hydrolyzed casein ratio. Conjugates with higher ratios of GA/casein showed more stable particle size distribution against freeze-thawing process. Increasing the degree of hydrolyzation did not affect significantly on particle size distribution of conjugates. Functional properties of conjugated biopolymers including solubility, emulsifying and foaming properties were promoted compared to casein and casein/GA mixture. Also, hydrolyzed casein-GA showed better emulsifying and foaming ability but less foaming stability than non-hydrolyzed samples.

Complex coacervation behavior and the mechanism between rice glutelin and gum arabic at pH 3.0 studied by turbidity, light scattering, fluorescence spectra and molecular docking

Complex coacervation of mixtures of rice glutelin (RG) and gum arabic (GA) at fixed pH 3.0 as affected by mass ratio, NaCl and urea were investigated. The interaction mechanism of RG-GA complex was analyzed using fluorescence spectra and molecular docking. The maximum yield of coacervates occurred at the biopolymer-mixing ratio of 1.0 RG/GA or 1.4 GA/RG. As the NaCl concentration increased from 0 to 100 mmol/L, maximum complex formation occurred at a mass ratio from 1.0 RG/GA to 4.0 RG/GA. The presence of urea possibly induced the formation of RG - GA complex with different structures. The binding constant (Ka) ranged from 2.20 × 105 to 1.67 × 105 L/mol, which indicated that the interaction between RG and GA was exothermic. And the binding process was spontaneous (ΔG < 0). The molecular docking results revealed the major intermolecular forces between RG and GA, and additionally indicated that hydrogen bonding and hydrophobic interaction were also the main force driving the RG-GA complex coacervation, just like electrostatic interaction. This study provides theoretical and methodological information for expanding the use of rice protein as functional components in food products.

Bioaccessibility and antioxidant activity of phenolic acids, flavonoids, and anthocyanins of encapsulated Thai rice bran extracts during in vitro gastrointestinal digestion

Encapsulation technique was applied to improve the stability of bioactive compounds in bran extracts from Thai rice cultivars (Khao Dawk Mali 105, Kiaw Ngu, Hom Nil, and Leum Pua), using three carriers including gelatin, gum Arabic, and the mixture of gelatin and gum Arabic. The microcapsules obtained using gelatin provided a higher production yield of 76.08, 85.63, 85.63 and 85.59%, respectively. A greater encapsulation efficiency was also observed in the extracts encapsulated with gelatin (93.45, 95.91, 91.19 and 95.09%, respectively). After simulated gastric and intestinal digestion, the microcapsules formed by using gelatin exhibited the higher release of bioactive compounds and antioxidant activity than unencapsulated extracts. However, the extracts encapsulated using gelatin and gum Arabic complex yielded the lowest release of bioactive compounds and their antioxidant activity after simulated digestion. The overall results showed that gelatin was an appropriate carrier that could protect bioactive compounds from the digestion conditions.

Formation and Characterization of β-Lactoglobulin and Gum Arabic Complexes: the Role of pH.

Protein–polysaccharide complexes have received increasing attention as delivery systems to improve the stability and bioavailability of multiple bioactive compounds. However, deep and comprehensive understanding of the interactions between proteins and polysaccharides is still required for enhancing their loading efficiency and facilitating targeted delivery. In this study, we fabricated a type of protein–polysaccharide complexes using food-grade materials of β-lactoglobulin (β-Lg) and gum arabic (GA). The formation and characteristics of β-Lg–GA complexes were investigated by determining the influence of pH and other factors on their turbidity, zeta-potential, particle size and rheology. Results demonstrated that the β-Lg and GA suspension experienced four regimes including co-soluble polymers, soluble complexes, insoluble complexes and co-soluble polymers when the pH ranged from 1.2 to 7 and that β-Lg–GA complexes formed in large quantities at pH 4.2. An increased ratio of β-Lg in the mixtures was found to promote the formation of β-Lg and GA complexes, and the optimal β-Lg/GA ratio was found to be 2:1. The electrostatic interactions between the NH3+ group in β-Lg and the COO− group in GA were confirmed to be the main driving forces for the formation of β-Lg/GA complexes. The formed structure also resulted in enhanced thermal stability and viscosity. These findings provide critical implications for the application of β-lactoglobulin and gum arabic complexes in food research and industry.

Effect of cooling–heating rate on sol-gel transformation of fish gelatin–gum arabic complex coacervate phase

The objective of this study was to characterize influence of different cooling and heating rates on gelation of fish gelatin (FG)-gum arabic (GA) complex coacervate phase using rheological measurements. For the coacervate phase prepared at 10°C, the gelling temperature, melting temperature, gel strength, and stress relaxation decreased with increasing cooling or heating rate, however, no gelation was observed at the highest cooling rate of 0.05°C/min. Similar trends were obtained for the coacervates phase prepared at 30°C, but the gelation did not occur at a cooling rate of 0.033 or 0.05°C/min. The results indicated that rheological properties of FG-GA coacervate gels were highly dependent to the cooling process, where more thermos-stable and stronger gels formed at slower cooling. This was probably because of higher degree of molecular rearrangements, more hydrogen bindings, and formation of greater junction zones into the gel network at slower cooling rates. However, all of the FG-GA coacervate gels obtained at different cooling rates were classified as a weak physical gel.

Dynamic rheological and structural characterization of fish gelatin – Gum arabic coacervate gels cross-linked by tannic acid

The propose of this study was to investigate the rheological and structural properties of fish gelatin (FG)–gum arabic (GA) complex coacervate gels treated with oxidized or non-oxidized tannic acid (OX-TA or NO-TA, respectively) at different concentrations ranged from 0.0 to 0.3% (v/v), using compositional, dynamic oscillatory rheological, and Fourier transform infrared (FTIR) analyses. The results revealed that the degree of NO-TA incorporation for cross-linking with FG via hydrogen bindings into the system was more pronounced than affinity of OX-TA for reaction through covalent bindings as evidenced by greater loss in volume fraction, moisture content, and biopolymer content values into the FG–GA coacervate phase. FTIR analysis showed addition of NO-TA led to more molecular disorder into the system, so that higher concentrations (0.2 and 0.3%) of the cross-linker disrupted electrostatic interactions through formation of stronger hydrogen bindings with proteins. Rheological results mentioned that addition and enhancement of (NO- or OX-) TA concentration improved gelling ability and mechanical properties of the FG–GA coacervate gels. However, frequency sweep test results implied that all the gels obtained can be classified as weak gels with shear-thinning behavior. Based on weak gel model, the gels obtained by treated FG–GA coacervates with NO-TA had more developed network structures and stronger intermolecular connectivities than those of obtained by the coacervates modified by OX-TA. The results of the current study provide basic knowledge necessary for the use of reinforced FG–GA complex coacervate gels in many useful applications, such as microencapsulation and hydrogel formation, in food and pharmaceutical industries.

Survival, oxidative stability, and surface characteristics of spray dried co-microcapsules containing omega-3 fatty acids and probiotic bacteria

ABSTRACTThe objective of the study was to determine optimum inlet and outlet air temperatures of spray process for producing co-microcapsules containing omega-3 rich tuna oil and probiotic bacteria L. casei. These co-microcapsules were produced using whey protein isolate and gum Arabic complex coacervates as shell materials. Improved bacterial viability and oxidative stability of omega-3 oil were used as two main criteria of this study. Three sets of inlet (130°C, 150°C, and 170°C) and outlet (55°C, 65°C, and 75°C) air temperatures were used in nine combinations to produce powdered co-microcapsule. The viability of L. casei, oxidative stability of omega-3 oil, surface oil, oil microencapsulation efficiency, moisture content, surface elemental composition and morphology of the powdered samples were measured. There is no statistical difference in oxidative stability at two lower inlet air temperatures (130°C and 150°C). However, there was a significant decrease in oxidative stability when higher inlet temperature (170°C) was used. The viability of L. casei decreased with the increase in the inlet and outlet air temperatures. There was no difference in the surface elemental compositions and surface morphology of powdered co-microcapsules produced under these nine inlet/outlet temperature combinations. Of the range of conditions tested the co-microcapsules produced at inlet-outlet temperature 130–65°C showed the highest bacterial viability and oxidative stability of omega-3 and having the moisture content of 4.93 ± 0.05% (w/w). This research shows that powdered co-microcapsules of probiotic bacteria and omega-3 fatty acids with high survival of the former and high stability against oxidation can be produced through spray drying.

Microencapsulation of flaxseed oil by soya proteins–gum arabic complex coacervation

SummaryApplication of soya proteins (SP) in flaxseed oil microencapsulation based on complex coacervation was investigated. The effects of SP/gum arabic (GA) mixing ratio (1:2, 1:1 and 2:1) and pH (2.80, 3.15 and 3.75) on coacervate preparation were studied firstly. The highest coacervate yields (CY) were achieved at SP/GA = 1:1, pH 3.15, and SP/GA = 2:1, pH 3.75, which were 81.2 ± 2.0%, 88.1 ± 0.6%, respectively. Thereafter, the microencapsulation of flaxseed oil was detected in accordance with the results of the coacervation of SP/GA, that is the optimal condition for microencapsulation was corresponded to the condition where CY was the highest. Under the conditions of SP/GA = 1:1, pH 3.15, and SP/GA = 2:1, pH 3.75, the microencapsulation efficiency and total yield reached 81.5 ± 0.1% and 81.7 ± 0.4%, and 77.4 ± 3.7% and 86.7 ± 2.4%, respectively. Microscopic morphology revealed that the formation of a biopolymer shell around the oil droplets was achieved at specific conditions.

Characterization of fish gelatin–gum arabic complex coacervates as influenced by phase separation temperature

The rheological and structural characteristics of fish gelatin (FG)–gum arabic (GA) complex coacervate phase, separated from an aqueous mixture of 1% FG and 1% GA at pH 3.5, were investigated as influenced by phase separation temperature. Decreasing the phase separation temperature from 40 to 10°C lead to: (1) the formation of a coacervate phase with a larger volume fraction and higher biopolymer concentrations, which is more viscous, more structural resistant at low shear rates, more shear-thinning at high shear rates, and more condensed in microstructure, (2) a solid-like elastic behavior of the phase separated at 10°C at a high oscillatory frequency, (3) the increase in gelling and melting temperatures of the coacervate phase (3.7−3.9°C and 6.2−6.9°C, respectively), (4) the formation of a more rigid and thermo-stable coacervate gel. The coacervate phase is regarded as a homogeneously networked biopolymer matrix dispersed with water vacuoles and its gel as a weak physical gel reinforced by FG–GA attractive electrostatic interactions.

Co-encapsulation and characterisation of omega-3 fatty acids and probiotic bacteria in whey protein isolate–gum Arabic complex coacervates

Omega-3 fatty acids and probiotic bacteria were co-encapsulated in a single whey protein isolate (WPI)–gum Arabic (GA) complex coacervate microcapsule. Tuna oil (O) and Lactobacillus casei 431 (P) were used as models of omega-3 and probiotic bacteria, respectively. The co-microcapsules (WPI-P-O-GA) and L. casei containing microcapsules (WPI-P-GA) were converted into powder by using spray and freeze drying. The viability of L. casei was significantly higher in WPI-P-O-GA co-microcapsules than in WPI-P-GA. The oxidative stability of tuna oil was significantly higher in spray dried co-capsules than in freeze dried ones.

Phase separation behavior and structural analysis of ovalbumin–gum arabic complex coacervation

Phase separation behavior and structure between ovalbumin (OVA) and gum arabic (GA) were investigated at pH 1.5–6.5; 2:1 OVA:GA mixing ratio, total biopolymer concentration 0.05 wt%. Soluble and insoluble complexes were observed as a function of pH. The biopolymers particles had a tiny diameter (d ≤ 500 nm) at pH above 4.0 or below 2.5, and increased sharply at pH 4.0 together with the turbidity under the same conditions. As the biopolymers mixing ratios increased from 1:3 to 24:1, critical pHs shifted towards higher pH. However, monovalent ions had a same influence on OVA–GA complex formation; the divalent cations reduced the formation of complex compared with same concentration monovalent ions. Second-derivative UV spectra and intrinsic fluorescence results indicated that the unfolding of the tertiary conformation was induced by GA, and more tryptophan residues were buried inside the OVA protein after complexation.

Nanoencapsulation of EPA/DHA with sodium caseinate–gum arabic complex and its usage in the enrichment of fruit juice

In this study, encapsulating fish oil, as a source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), with multi-layered interfacial membranes using electrostatic attraction between sodium caseinate and gum arabic and its usage in the enrichment of fruit juice was investigated. Initially, optimum conditions for forming a stable complex between sodium caseinate and gum arabic were determined at pH 4 and at a concentration of 0.1 g/100 ml sodium caseinate-0.2 g/100 ml gum arabic. This complex was utilized for nanoencapsulation of fish oil. Encapsulation efficiency and particle size were obtained as 78.88 ± 2.89%, 232.3 nm, respectively. Fish oil nanocomplex containing 40–50–60 mg EPA + DHA were used in the enrichment of 100 ml fruit juice. After in vitro digestion, the bioaccessibility of EPA, DHA and EPA + DHA were found as 56.16 ± 6.39, 36.25 ± 5.38 and 47.37 ± 10.65 percent, respectively (p < 0.05). This study indicates that stable protein–polysaccharide complexes can be used for nanoencapsulating hydrophobic compounds such EPA and DHA, useful for enrichment of non- or low-fat beverages.

Antimicrobial delivery systems based on electrostatic complexes of cationic ɛ-polylysine and anionic gum arabic

ɛ-Polylysine (ɛ-PL) is a potent food-grade cationic antimicrobial but its application within foods and beverages is currently limited because of its tendency to associate with anionic substances, thereby increasing product turbidity or forming sediments. In this study, we examined a potential means of overcoming these problems by forming electrostatic complexes between cationic ɛ-PL and anionic gum arabic (GA). The nature of the complexes formed depended on the mass ratio of gum arabic-to-ɛ-PL (RGA–PL), since this determined their electrical charge, aggregation stability, and antimicrobial efficacy. The electrical charge on the complexes went from positive to negative with increasing RGA–PL, with the point of zero charge being around RGA–PL ∼15. Soluble complexes were formed at low and high RGA–PL levels, but insoluble complexes were formed at intermediate levels (i.e. 5 < RGA–PL < 25). The antimicrobial activities of the ɛ-PL–GA complexes were investigated in a model beverage system against two acid resistant spoilage yeasts: Zygosaccharomyces bailii (ZB) and Saccharomyces cerevisiae (SC). In general, the antimicrobial efficacy of ɛ-PL decreased with increasing amount of GA, and this effect also depended on microorganism type, with SC being less sensitive to increased levels of gum arabic than ZB. Finally, we showed that certain ɛ-PL–GA complexes (15 μg/mL ɛ-PL; RGA–PL ≥ 20) could be incorporated into model beverages without adversely affecting their appearance or physical stability. This work has shown that the function of a cationic antimicrobial (ɛ-polylysine) can be improved by incorporating it within electrostatic complexes using a food-grade anionic biopolymer (gum arabic).