Pullulan

Pullulan is an a-glucose polymer (a-glucan) with a 1 4, and a few a, 1 6 glyco- 

GeUan Gum/titanium dioxide nanoparticle For the cleaning and disinfection of parchment [35, 36] 

P123/TPGS mixed micelles and geUan gum In situ gel systems For ophthalmic delivery of curcumin [37] 

Hexadecyl gellan amphiphilic Nanoparticles In vivo lipid-lowering potential [38] 

GeUan gum methacrylate and laponite Nanocomposite hydrogel Biomedical applications [39] 

Pullulan is a homopolysaccharide that is elaborated by many species of the fungus Aureobasidiurriy specifically A. pullulans. This fungus has also been called Pullularia pullulans, and sometimes it is called black yeast due to its formation of a black pigment [164]. A. pullulans will form pullulan when cultured on a number of sugars such as sucrose, maltose, D-xylose, and starch. D-glucose and sucrose have been reported to be the preferred carbon sources [165]. Pullulan is produced extracellularly in a fermentation process. 

Pullulan is a highly water-soluble linear polysaccharide of D-glucopyranose residues, containing a-l- 4 and a-1 6 glycosidic linkages in the ratio of 2 1 

Although pullulan is a linear polysaccharide devoid of any branch linkages, the presence of an a-1 - 6 glycosidic linkage on every third D-glucose residue combined with the two a-1 4 glycosidic linkages imparts an enhanced flexibility to 

Pullulan readily dissolves in water to give stable, viscous solutions that do not gel. Pullulan will form fibers and films. It is nontoxic and has low digestibility because human salivary and pancreatic a-amylases will hydrolyze only the a-1 4 glycosidic linkage of the maltotetraose unit the a-1 4 linkages of maltotriose 

Production of Pullulan occurs from starch by the fungus Aureobasidium pullulans. 

Pullulan is used extensively in the food industry to provide bulk and texture. Hydrophobic grades of Pullulan are used for preparation of nanoparticles for targeted delivery. Pullulan can also be used as a replacement for dextran as a plasma expander. 

Pullulan films are strong and are therefore used for decoration of food products, in confectionaries. Pullulan acts as an ideal carrier system for flavors, colors and drugs. 

Pullulan is used in coating for immediate release tablets and it is also used for preparation of capsule shells. An edible, mostly tasteless polymer, its chief commercial use is in the manufacture of edible films that are used in various breath freshener or oral hygiene products such as Listerine Cool Mint by Johnson Johnson (USA). 

33 Safety and Regulatory Status Pullulan is listed in GRAS. 

It is a water-soluble, random coil glucan that serves as a paradigm for the behavior of aqueous polysaccharides [247-249]. This biodegradable polymer has extensive applications in food and pharmaceutical industry [250]. 

It exhibits distinctive physical properties, such as adhesive ability, the capacity to form fibers, and the capacity to form thin and biodegradable film, which is transparent and highly impermeable to oxygen [251]. Other applications of pullulan include blood plasma substitutes, food and cosmetic additives, adhesive additives, flocculants, resins, and environmental remediation agents [246, 252, 253]. 

Pullulan films are used for coating or packaging material of dried foods, including nuts, noodles, confectioneries, vegetables, and meats [258]. Pullulan derivatives are promising as nontoxic conjugates for vaccines [259, 260]. 

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Pullularia pullulans Bhi ctonia solani Bhi pus arrhi s B. nigricans Bosellinia sp. 

Nonionic hydrophilic Polyethylene glycol Soluble starch, methyl cellulose, pullulan Dextran Above samples plus hydroxyethyl cellulose, polyvinyl alcohol, polyacrylamide Distilled water 0.01 N NaOH DMSO Buffer or salt solution (e.g., 0.1— 0.5 M NaNO,)... 

Corn Starch Dextrans Gelatin Lignins Pullulans Potato Starch Polysaccharides Wheat Starch... 

Figure 6.21 shows the calibration curves of the SB-800 HQ series using standard pullulan. Because a high molecular weight standard sample is not available, the calibration curves of 805 and 806 are partly estimates (dotted lines). The difference in the conformation between polyethylene oxide (PEO) and pullulan in the solvent causes a shift of the calibration curves of pullulan slightly higher than those of PEO. The OHpak SB-800HQ series is better suited for the analysis of hydrophilic samples than the Asahipak GS/GE series. 

Deionized water can be used as an eluent for the analysis of nonionic polymers such as pullulan and polyethylene glycol. However, in most cases, salt solutions or buffer solutions are used to decrease ionic or other interactions between samples and the stationary phase or to prevent sample association (Eigs. 6.22 and 6.23, pages 196 and 197). 

Coiumn type Column size (mm) Theoretical plate number Flow rate (ml/min) Exclusion limit Pullulan Usable pH range Particle size (ftm) Maximum pressure (kgf/cm ) Maximum temperature (°C)... 

FIGURE 6.40 Calibration curves of Shodex PROTEiN KW-800 series. Column Shodex PROTEiN KW-802.S, KW-803, KW-804, 8.0 mm i.d. X 300 mm. Eiuent Pullulan, PEG PEO Purified water, Protein SO mM Sodium phosphate buffer + 0.3 M NaCI (pH 7.0). Flow rate 1.0 mL/min. Detector Pullulan. PEG PEO Shodex Rl Protein Shodex UV (220 nm). Column temp. Ambient. 

Nonionic Polyethylene oxide Polyethylene glycol Polysaccharides Pullulans Dextrans Cellulosics Polyvinyl alcohol Polyacrylamide 0.1 M NaNOj... 

The GBR resin works well for nonionic and certain ionic polymers such as various native and derivatized starches, including sodium carboxymethylcel-lulose, methylcellulose, dextrans, carrageenans, hydroxypropyl methylcellu-lose, cellulose sulfate, and pullulans. GBR columns can be used in virtually any solvent or mixture of solvents from hexane to 1 M NaOH as long as they are miscible. Using sulfonated PDVB gels, mixtures of methanol and 0.1 M Na acetate will run many polar ionic-type polymers such as poly-2-acrylamido-2-methyl-l-propanesulfonic acid, polystyrene sulfonic acids, and poly aniline/ polystyrene sulfonic acid. Sulfonated columns can also be used with water glacial acetic acid mixtures, typically 90/10 (v/v). Polyacrylic acids run well on sulfonated gels in 0.2 M NaAc, pH 7.75. 

Absolute system calibration with a set of narrow distributed nb glucans (pullulans) by means of dual detection of mass and scattering intensity applying a mixed peak position/ broad standard calibration... 

FIGURE 16.10 Intial dextran calibration ( ) and resultingnb/Icbglucan calibration ( )forthe Sepha-cryl S-SOO/S-1000 (60 + 9S X 1.6 cm) system achieved from broad standard calibration with Dextran T-SOO and universal calibration, respectively Staudinger/Mark/Houwink constants (dextran Ksu = 0.0978 ml Mg . Osw = O.SO nb/lcb amylose = pullulan K pi. = 0.0268 ml M g . = 0.6S). 

The selective separation range of P-6/S-200 was determined with Blue Dextran (Vexdi exclusion limit) and fructose (V,o total permeation limit). Molecular weight (degree of polymerization) calibration (Fig. 16.22) was established with dextran standards and low dp pullulans (dp 3, 6, 9, 12, 15, 18) formed by the controlled hydrolysis of high dp pullulan. 

The strongest known producer of j8-poly(L-malic acid) has been identified as Aureobasidium sp. providing 61 g of polymer from 1 liter of culture medium [5,6]. 8-Poly(L-malate, Ca -salt) of the culture broth was first separated from accompanying bulk pullulan by methanol precipitation. The water-redisolved precipitate was converted to the polymer acid by passage over Amberlite IR-120B (H -form). Thus, the best to-day producers of... 

Most frequently, SEC with dextran-, pullulan-, or polystyrene calibration standards has been used to characterize the molecular properties of xylans. However, as for viscometric studies [108], a sufficient solvent ionic strength is a prerequisite for useful SEC measurements of charged polysaccharides, including glucuronoxylans [111-113]. An advantage of the SEC technique is that the presence of protein and phenolic components or oxidative changes can be detected by simultaneous ultraviolet (UV) detection. 

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