Physicochemical and Emulsifying Properties of Melia azedarach Gum

Naturally occurring hydrophilic colloids are versatile excipients in drug delivery systems. They are often used as coating materials, disintegrating agents, binders, emulsion stabilizers, and other applications. This study sought to investigate the physicochemical and emulsifying properties of gum extracted from Melia azedarach (MA). The gum was harvested, authenticated, and purified using ethanol precipitation. Physicochemical, microbial, and proximate analyses were performed on the purified gum. Oil of olive emulsions containing different amounts (5–15%w/v) of the gum as emulsifiers were prepared by homogenization. The zeta potential, creaming index, and average droplet size of products were assessed. The effects of pH changes, temperature, and monovalent and divalent electrolytes on the stability of the emulsions were also investigated. The yield of the gum after purification was 68.3%w/w. The gum has low moisture content and good swelling properties. Lead, copper, cadmium, and mercury were not detected. Emulsions containing 15%w/v of acacia or MA gum had the smallest average (Z-average) droplet size (acacia: 1.837 ± 0.420 μm; MA gum: 2.791 ± 0.694 μm) and the highest zeta potential (acacia: −30.45 mV; MA gum: −32.867 mV). Increasing the concentration of the gums increased the emulsion viscosity with MA gum emulsions being more viscous than corresponding acacia emulsions. MA gum emulsions had higher emulsion capacity and stability but lower creaming index relative to acacia gum emulsions of similar concentrations. Potassium chloride (KCl) reduced zeta potential but increased Z-average for emulsions prepared with either gum. Calcium chloride (CaCl2) produced a similar but more pronounced effect. When the pH was decreased from 10 to 2, the zeta potential of the droplets was reduced, but the droplet size of emulsions prepared from either gum was increased. Increasing temperature from 25 to 90°C produced no significant (p value >0.9999) change in droplet size. These findings suggest that MA gum is a capable emulsifying agent at 15%w/v.


Introduction
Synthetic emulsifying agents are commonly used to stabilize pharmaceutical emulsions.Tough efective stabilizers, they are costly, produce toxic efects through direct or indirect means, and cause environmental problems [1].Most of these synthetic surfactants afect the disposition of encapsulated drugs.Anionic surfactants may interact with proteins and enzymes, altering them and rendering them defective [2].
Natural proteins and polysaccharides used in food emulsions such as milk, dressings, and ice cream are nontoxic, nonirritant, and biocompatible [3].Gums disperse in water to yield highly hydrated particles of colloidal dimensions that interact with each other to form entangled networks and increase the viscosity of the aqueous media.Gums also adsorb at the interface of oil and water in emulsions and generate rupture-resistant multilayers that surround dispersed globules and act as mechanical barriers to impede coalescence [4].Acacia, tragacanth, and guar gums have been efectively used as emulsifying agents [5].Tey, however, remain costly to import, making it imperative to identify and assess cheaper and readily available local gums with similar emulsifying properties.Local gums would reduce the costs of importation and consequently, the cost of pharmaceutical emulsions.It would also represent a readily available and renewable source of emulsifying agents and reduce the time lag required to take receipt of imported emulsifers [6].
Melia azedarach (MA) is a wooden plant that produces copious amounts of tasteless, clear to dark amber-colored gum [7].Te gum is a capable binder and disintegrating agent in tablets.Tis study also revealed that the gum has good swelling and fow properties.Te good swelling property implies that the gum may readily interact with water to form the gel network to stabilize emulsions.However, the potential of this gum as an emulsifying agent has not been investigated.Local availability and the merits of natural polymers make it prudent to assess the emulsifying properties of MA gum.Tis study seeks to purify, characterize, and investigate the suitability of MA gum as an emulsion stabilizer.

Materials and Methods
2.1.General Materials.Food-grade olive oil manufactured by Bell Sons and Co. was purchased from a local pharmacy.Te Department of Pharmaceutics, Kwame Nkrumah University of Science and Technology (KNUST), provided acacia gum, all growth media, and other reagents.

Collection, Extraction, and Purifcation of the Melia azedarach Gum.
Te crude gum was sourced as exudates from the incised trunks of the Melia azedarach tree found in the forests of Kwahu Asakraka in the Eastern Region of Ghana.Te gum was harvested between March and May of 2022.Te tree was identifed and authenticated by the Herbal Medicine Department, KNUST curator.Extraneous materials were removed and the gum was dried at 50 °C until sufciently brittle.Te light-grade gum was separated from the darker grade and the light-grade gum was pulverized using the miller (SK-1, RETSCH, Germany).Te crude gum (100 g) was mixed with 200 ml of distilled water and left for 24 hours with intermittent stirring.Te formed mucilage was fltered twice using a calico strainer.Ethanol (96%, 350 mL) was then added to precipitate the gum.Te precipitated gum was washed with diethyl ether twice and dried in a hot air oven (Gallenkamp Oven, 300 Plus Series, Germany) at 40 °C for 24 hours.Te dried gum was powdered and sifted through sieve number 80 and stored in airtight packages [8].

Assessment of the Percentage Yield.
Te weight of the dry gum before purifcation, W 0, and the weight of the dry purifed gum, W 1 , were determined using the analytical balance (Sartorius, LE623P, Germany).Te percentage yield was estimated using the following equation: (1) Te MA gum (1 g) was weighed into a 50 ml measuring cylinder and distilled water was added to make a 25 mL dispersion.Te cylinder was covered, its content mixed, and allowed to stand undisturbed for 24 hours.Te fnal volume of the dispersion was measured and recorded [9].Equation ( 2) was used to calculate the swelling index as

Evaluation of the
where V f and V o are the fnal and initial volumes of gum, respectively.

Assessment of the Moisture Content of the Purifed
Melia azedarach Gum.Te MA gum (1 g) was weighed into a previously dried and weighed porcelain crucible.Te two were dried in a hot air oven at 105 °C for 5 hours, allowed to cool, and weighed.Te weight of the dried gum was obtained by deducting the weight of the crucible from the total weight of the gum and the crucible obtained after drying [9], and the moisture content was calculated as indicated in the following equation: where W t B and W t A are the weight of the gum before drying and the weight of the dry gum, respectively.

Mineral Content of the Purifed Melia azedarach Gum.
A quantity of 5 mL of HNO 3 (69%) was added to MA gum (1 g) in a 250 mL beaker.Te sample was heated in a fume chamber at 100 °C and mixed with perchloric acid (70%, 15 mL) and digestion was sustained until the solution was clear.Te solution was cooled, made up to 100 mL with distilled water, and boiled for 10 minutes.Te hot mixture was strained into a 100 mL volumetric fask through flter paper and made up to volume [10].An atomic absorption spectrophotometer (novAA 400P, Analytik Jena GmbH, Germany) was used to determine the concentration of metal ions in the sample, using a regression equation of a linear calibration analysis.Te sample was analyzed in duplicates.

Determination of Protein, Fat, and Carbohydrate
Content.MA and acacia gum compositions were determined using ofcial methods [11].Te Kjeldahl method (Tecator TM Kjeltec System) was used to assess the protein content.Fat content was determined by Soxhlet extraction using petroleum ether as a solvent.Carbohydrate content was calculated by subtracting the sum of the moisture content, total ash, protein, fat, and metal elements from 100%.Determinations were performed in triplicates.
2.5.4.Ash Values.Te gum (2 g) was placed in a crucible of known weight (W1) and heated in a mufe furnace at 550 °C for 4 hours.Te crucible and content were allowed to cool and maintained at a temperature below 200 °C and then maintained at that temperature for 20 minutes.Te crucible with the now ashen sample was cooled to 25 °C and weighed (W3).For acid-insoluble ash, a mixture of 25 ml of HCl and hot distilled water (2 : 5) was used to quantitatively transfer the ash from the total ash experiment into a beaker, stirred with a glass rod, and heated for 5 minutes.Te acid solution was fltered through an ashless flter paper.Te flter was washed with hot water until the washings were acid-free to litmus paper.Te flter paper was left to drain any residual fuid and placed in a crucible of known weight.Te flter paper and crucible were dried and combusted in a furnace at 600 °C.Te crucible was cooled and weighed [11].Te ash content was calculated by using the following equation: Te same equation was used to calculate the percentage of acid-insoluble ash.W 1 is the weight of the empty crucible, W 2 is the weight of the sample, and W 3 is the weight of total ash or acid-insoluble ash and crucible depending on the parameter being estimated.

Assessment of the Flow Properties of the
2.6.2.Angle of Repose.Te MA gum (10 g) was poured through a funnel clamped at a height that allowed a cone to be formed whose tip was just beneath the orifce of the funnel.Te gum was allowed to fow freely onto a horizontal surface to form the cone.Te diameter of the base of the cone was measured and the radius was taken as half of the diameter.Te angle of repose was determined as θ by using the following equation: where h represents the height of the cone from the horizontal surface and r is the radius of the cone formed [9].

Determination of the Microbial
Quality of the Melia azedarach Gum.MA gum mucilage (1%w/v) was prepared using sterile water.Tis mucilage (1 mL) was inoculated into previously sterilized growth media.Te inoculated agar was allowed to stand for about 30 minutes, inverted, and incubated at 37 °C for 48 hours (25 °C in Sabouraud agar).Controls were also set up by incubating the growth media without the gum under the same conditions.Te selective media used were observed for the presence or absence of characteristic microorganisms.

Phytochemical Screening of the Melia azedarach Gum.
Te presence or absence of phytochemical constituents was determined using the methods described by Shaikh and colleagues [12].Te target phytoconstituents tested include saponins, coumarins, phytosterols, tannins, favonoids, triterpenoids, alkaloids, and glycosides.

FTIR Analysis of the Melia azedarach Gum.
Te FTIR uses the attenuated total refectance (ATR) with a diamond crystal.Te diamond crystal was cleaned with isopropanol and a background scan was quickly taken.Te sample was placed directly on the crystal and the pressure gauge was applied to ensure maximum contact.Te sample was then scanned between wavelengths of 4000 and 400 cm −1 to generate the spectrum.

Preparation of Emulsions.
Amounts of MA and acacia gum required to prepare emulsions containing 2.5%, 5%, 7.5%, 10%, 12.5%, and 15%w/v of gum were weighed and distilled water was added to make a 35 mL dispersion.Tis was mixed with a magnetic stirrer for about 2 hours at room temperature and stored at 4 °C for 18 hours to ensure complete hydration [13].A quantity of 15 mL of olive oil was measured and added dropwise to the dispersions while mixing with a magnetic stirrer.Te mixture was then homogenized with the ULTRA-TURRAX homogenizer (T25, IKA, Germany) at 22000 rpm for 3 minutes to obtain the fnal emulsion.Tis procedure was used for the other gum dispersions [14].

Determination of Emulsion Type.
Te emulsion type was determined using the dilution test.Two 5 mL samples of each emulsion prepared with both gums were measured and Scientifca transferred into a test tube.Excess water was added to each sample and observed for miscibility or otherwise [15].

Analysis of Average Droplet Size, Zeta Potential, and
Polydispersity Index.Te samples were analyzed using Zetasizer (Nano ZS, Malvern Instruments, UK).Deionized water was used to perform 1 in 100 dilution of the emulsion.Te diluted sample was placed in a cuvette and analyzed at 25 °C.To determine the zeta potential, a cuvette ftted with electrodes was used.Te tests were performed in triplicates.
Te refractive index values used for the dispersed and continuous phases were 1.47 and 1.33, respectively [13].

Viscosity of Emulsions.
Te viscosity of emulsions was determined using the viscometer (Brookfeld LVT, SN: 8401183, USA) at room temperature.Te determination was performed at a rotation speed of 3, 6, and 12 rpm using spindle number 1. Te viscosities were measured triplicate in cP.

Emulsion Capacity and Emulsion Stability.
Te prepared emulsions were transferred into falcon tubes and the initial height of the emulsion was noted.Emulsions were centrifuged at 1200 g for 5 minutes immediately after preparation to determine the emulsion capacity.For emulsion stability, the emulsions were initially heated at 80 °C for 30 minutes before centrifugation.Te emulsions were centrifuged at 1200 g for 5 minutes using the centrifuge (Heraeus Biofuge Primo, Termo Fischer Scientifc, USA) and then the fnal height of the emulsion after centrifugation was noted [9,16] Te pH of the MA and acacia emulsions was also adjusted to 2, 5, 7, and 10 using either 0.1 M hydrochloric acid or 0.1 M sodium hydroxide solutions as required.Te efect of these factors on the particle size, zeta potential, and creaming index was determined using the previously described methods [13].
2.11.7.Statistical Analysis.Te results of the tests that were carried out on the MA gum and acacia gum emulsions were compared by one-way analysis of variance (one-way ANOVA) followed by the Brown-Forsythe test using the GraphPad Prism (version 9).A p value <0.05 indicates signifcant statistical diferences.

Results and Discussion
3.1.Percentage Yield.Te percentage yield from gum extraction may depend on factors such as season, geographical location, solvent choice, and extraction procedure [7].Te extraction process employed for this gum resulted in a percentage yield of 68.3% ± 0.2500, a value comparable to that obtained by Owusu and colleagues [7] for the same gum.Tis value is, however, higher than that obtained for other 4 Scientifca gums including Albizia with a yield of 39.38% [17], Tamarindus indica with a yield of 29.83% [18], and T. cordifolia gum with a yield of 54.96 ± 2.15% (w/w) [19].Te relatively high yield suggests that the extraction process and the solvents used were ideal for the MA gum.  1. Commercially, the color of the gum is of a particular essence, and light colors are most desired.After purifcation, the crude MA gum had a yellowish-brown color and light grade (Figure 1).

Physicochemical
Te light-colored nature of the gum suggests that it might contain low levels of impurities.Gums are often expected to be tasteless and odorless or nearly so even though a few gums have been found to possess distinctive taste.
Te purifed MA gum was tasteless and odorless.Tis lack of a distinctive taste implies it may not interfere with such properties if used as an ingredient in pharmaceutical products.
Te moisture content, total ash, water-soluble ash, and water-insoluble ash were based on the triplicate determination with the standard deviations as shown in Table 1.

Swelling Index of the Purifed Melia azedarach Gum.
In emulsions, a gel network presence within the continuous phase limits instabilities induced by gravity or Brownian motion [20].Higher swelling indices imply higher entrapment of water and improved formation of gel networks [18].Te swelling index of MA gum was 82.9% ± 0.46.Te value although lower than that of Albizia (611.29 ± 4.07) gum [17] is considerably better than that of tamarind seed mucilage (7.6-21.196)[21].Te recorded value suggests that the gum is capable of interacting strongly with water molecules to form a gel network.Consequently, it implies that the gum may possess properties that aid in the stabilization of oil-inwater emulsions.

Moisture Content in the Melia azedarach Gum.
Moisture in a natural product usually afects chemical and fow properties and may enhance the growth of microorganisms.Economically, high moisture content is undesirable as determined weights may not be entirely attributable to the product itself and may be accounted for by moisture [17].Te moisture content of the gum was determined to be 9.28% ± 2.40.Tis is lower than the value (11.95%) reported [22] for acacia gum, the most established gum used as an emulsifer.Te moisture content of the gum thus complies with this standard.Tis relatively low moisture content suggests a reduced susceptibility to chemical changes or decomposition by microbes and a reduced likelihood of clumping of dry gum powder.Economically, this is favorable as any determined weight of gum is highly attributable to the gum itself rather than any associated moisture.

Mineral Content.
Te atomic absorption spectrophotometer was used to quantify elements in the gum.Lead, copper, cadmium, sodium, and mercury were either absent or were below the detection limits.Zinc (0.3736 ± 0.0018 mg/L), calcium (4.419 ± 0.2761 mg/l), iron (0.4475 ± 0.0255 mg/l), magnesium (11.24 ± 0.0335 mg/l), manganese (0.6387 ± 0.0226 mg/l), and potassium (0.2535 ± 0.0080 mg/L) were detected in quantities indicated in brackets.Te elemental content values detected in this report are lower than those reported in other plant materials [23,24].Te absence of heavy metals makes MA gum a promising candidate excipient in pharmaceutical and food products.

Carbohydrate, Fat, and Protein
Content.Te protein content (1.02 ± 0.1556%) of the gum is higher than that of Persian gum (0.69%) and ammoniacum gum (0.3%) reported by Golkar and others [13] and Ebrahimi and colleagues [14], respectively.Tis value is, however, lower than what was observed for acacia gum (1.97 ± 0.3110%).Te presence of proteins in polysaccharides may improve their ability to adsorb at oil-water interfaces, and that contributed to the enhancement of their emulsion-stabilizing properties [4].Te presence of protein in the MA gum thus projects its likelihood of being a stabilizer.Te gum had a carbohydrate content of 87.561% compared to 87.453% for acacia.Golkar and colleagues [13] again reported that a high carbohydrate content confrms the purity of gums.As such, the high carbohydrate content recorded for the acacia and MA gum indicates that they are of good quality.

Ash
Values.Ash value is useful for identifying lowgrade products.Total ash detects if plant products are mixed with materials such as soil and inorganic salts such as calcium oxalate.Te acceptable range of total ash varies within wide limits and cannot be relied upon solely.Te total ash for the gum is 1.2% ± 0.05.Tis value is relatively low in comparison to that detected for other gums such as ammoniacum gum (3.6%) by Ebrahimi et al. [14] and

Scientifca
Persian gum (2.59%) by Golkar et al. [13].Te results indicate that the gum contains low amounts of inorganic materials, sand, and other soil components.Te results, however, cannot be relied on completely in light of the previously stated demerit.Te acid-insoluble ash evaluates the amount of ash that is insoluble in hydrochloric acid.It provides useful information regarding the quantity of inorganic material detected using total ash represented by material other than calcium oxalate.Te acid-insoluble ash was determined to be 0.28% ± 0.0173.Tis represents a relatively small fraction of the total ash.

Flow Properties.
Many industrial processes involve the movement of powder from one location to another using diferent methods.In all of these methods, the fow rate of the powder depends on the process design and signifcantly, the powder fow properties [25].Te angle of repose, Hausner's ratio, and Carr's index were determined to ascertain the fow properties of MA gum.A powder with excellent properties must possess an angle of repose, Hausner ratio, and Carr's index between 25 and 30 °, 1.00 and 1.11, and 1 and 10%, respectively [25].Te results from this study returned values of 1.08 ± 0.02, 7.29 ± 1.83, and 30.35 ± 0.56 for Hausner's ratio, Carr's index, and angle of repose, respectively.Tese fgures are consistent with excipients in some pharmaceutical industry activities including tableting and capsule-flling that require uniform fow of ingredients during the processes.
3.5.Microbial Quality.Fungi, bacteria, and viruses are ubiquitous in our environment.Some of these organisms produce malignant efects, whereas others remain relatively benign.Due to the former, materials included in foods and medicines should comply with set standards [26].Food and pharmaceutical products should not contain Salmonella spp.and E. coli and the total aerobic count should be at most 10 5 cfu/g and combined yeast and mold count be not more than 10 3 cfu/g.In addition, bile-tolerant Gram-negative bacteria count should not exceed 10 3 cfu/g [27].Te results returned a negative test for Staphylococcus aureus, Salmonella spp., Pseudomonas spp.and Escherichia coli.
Viable aerobic fungi counts were 250 cfu/g and 40 cfu/g, respectively.Tis result shows that the gum complies with the standards set by the USP.Tis could be attributed to hygienic harvesting practices, efcient purifcation procedures, and storage conditions.MA gum may be incorporated into products with confdence that it will not compromise safety by introducing excessive amounts of potentially pathogenic organisms.
3.6.Phytochemical Screening.Te phytochemical constituents present include favonoids, tannins, glycosides, and saponins.Except for favonoids, these are the same as those found in earlier research [7].Te diferences observed may be attributed to the diferences in the age of the plants, the season of harvests, and environmental conditions [28].
Tannins and glycosides possess antioxidant properties; in addition, glycosides have some antimicrobial activity [29].
Te gum may have the capacity to confer preservation on products that may be incorporated.Te amphiphilic saponins present confer surface activity on the gum [30] and make it a potential emulsion stabilizer.

FTIR Analysis of the Melia azedarach Gum.
Te Fouriertransform infrared (FTIR) spectroscopy is a good tool for identifying functional groups present in materials [31].It has helped in the identifcation of materials and the detection of adulterations.FTIR analysis was performed to provide a fngerprint for MA gum as shown in Figure 2. Te spectrum showed a medium stretch at 3287.60 cm −1 , which indicated the presence of an O--H.In addition, at 2924.46 cm −1 , an alkane C--H stretch was observed, highlighted by the occurrence of a medium C--H bend at 1370.27 cm −1 and a medium C--C stretch at 1412.93 cm −1 .
Equally, an aromatic C--C stretch was observed in the 1600 cm −1 region.Tis data can be used to aid the easy identifcation of the gum.

Evaluation of Formulated Emulsions
3.8.1.Appearance, pH, and Type of Emulsions.All emulsions (Figure 3) were creamy and appeared stable except for the ones containing 2.5%w/v gum, which began to cream minutes after formulation.Te pH was assessed to predict the stability of the emulsions and how they may afect mucosae.Te pH of the emulsions was in the acidic range (5.2−4.2).It is reported that the prescribed pH for formulations designed for oral administration ranges from 5 to 8 [6].Te acidic nature of the emulsions suggests that they may irritate the oral mucosa.Tus, the pH will have to be  6 Scientifca adjusted to near-neutral to reduce the tendency of mucosal irritation.All emulsions were of the oil-in-water (o/w) type.Tis is in line with the fact that hydrophilic gums favor the formation of oil-in-water emulsions.All the emulsions were creamy and homogenous.

Viscosity of Emulsions.
During storage, viscosity is an important factor in the stability of emulsions.High viscosity reduces the coalescence of oil droplets and improves stability [13].Increasing gum concentration increased the viscosity of the emulsion, which is consistent with previous reports [32].Te viscosities of the MA gum emulsions were higher than those of acacia gum at all concentrations.Tis implies that the MA gum forms a relatively higher proportion of gel networks making it more efcient at slowing down droplet aggregation.Te viscosity of the emulsions decreased with increasing shear speed, which depicts shear-thinning behavior.Applying sufcient force then will reduce the viscosity of these emulsions, making them easier to pour from containers and to apply to the skin if used in topical creams.

Emulsion Capacity (EMC), Emulsion Stability (EMS),
and Creaming Index.Te emulsifying capacity assesses if an agent is capable of forming emulsions.Te emulsion stability characterizes the destabilization process as a function of time [18].Te emulsion capacity and stability were enhanced, whereas creaming was reduced when the concentration of the gums was increased.Te stability of emulsions containing the MA gum was higher than those containing the acacia gum.Tis is attributable to the higher viscosity that reduces the tendency for the droplets to collide.Higher emulsion capacity and stability do not prove that MA gum possesses a higher surface activity than acacia since the particle size of emulsions produced with MA gum increased as concentration was increased.Huang et al. [33] made similar observations for emulsions prepared with various gums that did not contain an emulsifying agent.Te observation in this work may be attributed to a relatively lower protein quality in the MA gum.Proteins improve the surface activity of gums such as acacia, guar, and fenugreek [34].Jafar and colleagues also reported the surface tension reduction by gum from Ferula gummosa [35].Tus, it may be reasonable to assume that MA gum may not possess similar surface activity as acacia gum and other gums [35] but contributes to the stability of the emulsion by forming a gel network that traps oil droplets.Creaming reduced as the concentration of gums increased.As the days went by, creaming increased progressively in the emulsions with lower concentrations (5 and 7.5%).For the emulsions with concentrations of 10%, 12.5%, and 15%, no creaming was experienced after 7 days of storage.Tese observations are consistent with those of Koocheki and coworkers [36], where increased gum concentration was found to retard creaming.Te acacia emulsions creamed earlier than their MA gum counterparts of similar concentration.

Efect of the Concentration of Gum on the Zeta Potential and Average
Droplet Size of Emulsions.Smaller droplets improve the stability of emulsions.In the acacia gum emulsions, there was a signifcant (p value <0.0001) decrease in droplet size as the concentration of the gum increased from 5 to 15%, with the smallest droplet size (1.837 ± 0.420 μm) being observed at 15%w/v (Figure 4).Te determinations were performed in triplicates.Te MA gum emulsion seems to have a relatively larger average droplet size compared to that of the acacia gum.
Previous studies have reported that 14% of acacia gum is sufcient for covering the total area of the interfacial region of an oil-in-water emulsion [37].For the MA gum, the particle size increased when the concentration of gum was increased from 5% to 10% w/v.However, emulsions containing more than 10% MA gum had smaller particle sizes (4.520-2.791μm) with the 15% MA emulsion having the least droplet size (2.791 ± 0.694 μm).Gums stabilize emulsions by increasing viscosity and inducing steric stabilization [34,36], which could account for the observed results.
A modest increase (65-161.25 cP) in viscosity was observed for emulsions containing an increasing amount (5-10%) of MA gum.However, high increments (161.25-483.75 cP) are seen as the concentration rises from 10-15%.Larger particles at lower concentrations could be observed because the relatively low viscosities are insufcient to hinder aggregation.However, as the viscosity increases signifcantly, the movement of particles is sufciently slowed, preventing them from aggregating into larger particles.
Te efciency of MA gum at reducing droplet size compared to acacia gum was determined by assessing Zaverage.Steric stabilization tends to occur when a high enough amount of gum is available to cover the surface of oil droplets [34].Te gum may induce steric repulsion between droplets close to one another and prevent them from aggregating.Tis phenomenon probably occurs at concentrations greater than 10% for MA gum.It was determined that both gums resulted in negative zeta potentials which increased as the concentration of the gums increased (Figure 5).Te highest (acacia: −30.45 mV; MA gum: −32.867 mV) zeta potential for both gums was observed at 15%w/v.
Te zeta average of the emulsion droplets appeared to reduce when the gum concentration was increased.
Te absolute value of zeta potential at 15% for both gums is higher than 30 mV (−30.45 mV for acacia and −32.867 mV for MA gum) and the limit for signifcant droplet stabilization by electrostatic repulsion [38].Te low particle size and sufcient zeta potential produced at 15% gum concentration suggest that the gum may have emulsionstabilizing properties.Acacia, however, produced smaller droplets as compared to MA gum at 15% concentration where both gums had the highest zeta potential.Te presence of some protein and the reduction of particle size by MA gum confrmed that it may be a promising candidate for the stabilization of emulsions [39].

Efect of Electrolytes on the Formulated Emulsions.
Electrolytes may afect zeta potential and produce a system where attractive forces exceed repulsive forces depending on the nature of the electrolytes.Tis phenomenon promotes the aggregation of dispersed phase particles to form larger droplets [40].Te efects of KCl and CaCl 2 on the particle size and zeta potential of emulsions were examined.It was observed (Figure 6) that for both gums, an increase in KCl concentration caused a signifcant (acacia, p value <0.0001; MA, p value −0.4342) increase in particle size.

Electrolytes Cause an Increase in Droplet
Size due to a Drop in Zeta Potential.Increasing electrolyte concentration shrinks the electrical double layer that surrounds the dispersed globules, thus decreasing the zeta potential.Attractive forces exceed repulsive forces and particles aggregate through focculation [34].Tis accounts for the increase in droplet size seen.Tese results are in line with what has been found by other researchers [13,14].Calcium chloride (CaCl 2 ) produced a more pronounced efect compared to that of KCl, which could be a result of its comparatively higher ionic strength.Creaming increased when the concentration of electrolytes was increased.Emulsions containing acacia creamed at a faster rate than those with MA gum.Te rate and extent of creaming are directly proportional to particle size but indirectly proportional to the viscosity of the emulsion.Te increase in creaming index can thus be attributed to the increased particle size resulting from increasing electrolyte 8 Scientifca concentration.However, the slow rate of creaming associated with MA gum emulsions may be because they are more viscous than acacia emulsions.
3.9.1.Efect of Temperature on Emulsions.Emulsions are exposed to various temperatures during production, sterilization, and storage.Te heating of emulsions enhances hydrophobic interactions and may usually lead to aggregation of droplets.Te stability of MA and acacia gum emulsions to droplet aggregation after heating (25 to 90 °C) was assessed.It was determined that the temperature had no signifcant efect on the droplet size of acacia (p value � 0.0774) and MA gum (p value >0.9999) emulsions, an observation similar to that reported by Golkar et al. [13].
Tese results suggest that the gum will be stable when the emulsion is heated.Emulsions that are stabilized with hydrocolloids are not afected by denaturation at high temperatures [41], and this may have accounted for the reason why droplet aggregation caused by heating had little impact on oil droplet size.Similar results [42] were reported where orange oil-in-water emulsions remained stable to droplet aggregation after heat treatment.
3.9.2.Efect of pH on Emulsions.Te pH of gum solutions was adjusted to 2, 5, 7, and 10 to determine the efect of varying pH on emulsion properties.It was observed that the droplet size of emulsions stabilized by both gums increased (acacia: 2.792-6.080μm, MA gum: 3.159-9.068μm) significantly (acacia, p value 0.0006; Melia gum, p value -0.0356) as pH varied from 10 to 2. Te zeta potential was again found to be negative for emulsions stabilized by both gums and increased from −20.3 mV to −31.5 mV and −22.3 mV to-31.83mV for acacia and Melia gum emulsions, respectively, within the pH range of 2-10.As pH decreases from 10 to 2, the negative charges are shielded by the positive charges of the medium to produce acidic pH [42].Tis leads to a decrease in electrostatic repulsion, which results in the reduction of zeta potential.Droplet aggregation increases and leads to the formation of larger globules.Te increase in particle size may negatively impact the stability of the emulsions because smaller sizes may be relatively more stable than those with larger droplets.Te stability of emulsions may be afected by pH.From the results obtained, manufacturers must consider the efect of diferent ingredients on the pH of the MA gum emulsions.

Conclusion
Tis study assessed the physicochemical properties of the Melia azedarach gum and compared its emulsifying properties with those of acacia.A yield of 68.3% was obtained and the gum had low ash values, good fow properties, and desirable microbial content.Emulsions containing the acacia gum had lower droplets than those of the MA gum.MA gum, however, produced emulsions that were less susceptible to creaming and had better emulsion capacity.Both gums produced similar efects when emulsions were exposed to environmental stresses.Te fndings in this study show that the MA gum may be used to stabilize emulsions with low viscosity either alone or in combination with other emulsifers.Te authors are currently investigating this gum for other potential pharmaceutical applications.

Figure 1 :
Figure 1: Crude (a) and purifed (b) MA gum.Te crude gum has a darker-brown color compared to the purifed gum.

Figure 2 :
Figure 2: FTIR spectrum of the MA gum.

Figure 3 :
Figure 3: Sample of emulsions formulated with the Melia azedarach gum.
. Te equation is as follows: [16].5.Creaming Stability of Emulsions.Emulsions (10 mL each) were transferred into test tubes, capped and stored at room temperature, and observed for instabilities such as creaming and cracking.Te emulsions' initial height was recorded to assess the creaming index.Creaming in the emulsions was assessed immediately after preparation and then on days 3, 7, and 14.Te emulsion was separated into two layers one of which was creamy and another was strawcolored (serum).Te stability of the emulsions on storage was determined by calculating the creaming index via the following formula[16]: Properties of the Melia azedarach Gum 3.2.1.Macroscopic Properties of the Melia azedarach Gum.Physical and organoleptic properties such as color, taste, odor, shape, size, and hardness are infuenced by environmental conditions, age of exudate, and treatment of gum after collection.Te macroscopic characteristics of the crude gum are presented in Table

Table 1 :
Macroscopic and physicochemical properties of the MA gum (R � 3, where applicable).