Handbook of Hydrocolloids (Second edition)
9 - Gellan gum
Abstract:
Gellan gum is an extracellular polysaccharide secreted by the micro-organism Sphingomonas elodea (ATCC 31461) previously referred to as Pseudomonas elodea. Commercially it is manufactured by a fermentation process. It is available in two forms, high acyl (HA) and low acyl (LA). Gellan gum forms gels at low concentrations when hot solutions are cooled in the presence of gel promoting cations. An overview of the manufacturing process and chemical structure of gellan gum is given. The functional differences between the two forms of gellan gum are reviewed in detail with regard to hydration, gelation, stability and texture. Methods for the effective preparation of gellan gum solutions and gels are described for the high and low acyl forms. The effects of food ingredients such as salts, sugars, and acids on gel properties are discussed in relation to the main applications. Finally, the main applications of gellan gum in food are described with example formulations.
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Cited by (65)
Incorporation of snail meat particles in gellan gum fluid gels: Stability against sedimentation and rheological behavior
2024, Food HydrocolloidsSnail meat, despite its nutritional value and popularity in some countries, is still underutilized due to its slimy texture. Snail meat powder could be an alternative way to exploit this source of protein. In the present study, the effect of incorporating snail meat powder without the mucus (SMWM) into the matrix of a fluid gel of gellan gum (GG) was studied in terms of SMWM particles stability against sedimentation and gels rheological features, at pH 4.5 and 7.8. All gels were stable against sedimentation after storage, except those with SMWM at pH 7.8 in the presence of NaCl, attributed to deacetylation of GG during gel formation. Τhe particles were larger at pH 7.8 than those at pH 4.5, whilst the presence of NaCl resulted in smaller particles. The presence of SMWM increased the final viscosity of the GG gel at pH 4.5 upon cooling. The transition temperature at pH 4.5 was higher in that case compared to GG gel. The presence of NaCl had a profound effect on the GG rheological behavior when SMWM particles were present regardless the pH or the concentration. A 3D network was developed according to G′ predominating values over the G″, but the narrow differences indicated its delicate nature. All gels, except that at pH 7.8 with SMWM, demonstrated a typical shear thinning behavior of a non-Newtonian fluid. Overall, the stabilization of SMWM particles in the network of GG fluid gel is promising, especially at pH 4.5 and in the presence of 0.25% NaCl.
Mastering textural control in multi-polysaccharide gels: Effect of κ-carrageenan, konjac glucomannan, locust bean gum, low-acyl gellan gum, and sodium alginate
2024, International Journal of Biological MacromoleculesTo comprehend the intricate interplay of five common food polysaccharides, κ-Carrageenan (KC), konjac glucomannan (KGM), locust bean gum (LBG), low-acyl gellan gum (LAG), and sodium alginate (SA), within composite polysaccharide gels, widely employed for textural modulation and flavor enhancement. This study systematically modulates the quantities of these five polysaccharides to yield six distinct multi-polysaccharide gels. The unique impact of each polysaccharide on the overall quality of composite gels were studied by thermostability, microstructure, water-holding capacity (WHC), texture, and sensory attributes. The findings unequivocally manifest the phenomenon of thermoreversible gelation in all composite gels, except for the KC-devoid sample, which displayed an inability to solidify. Notably, KGM, LBG, and LAG emerged as pivotal enhancers of the network structure in these composite gels, while SA was identified as a promotor of layered structure, resulting in a reduction of surface hardness. Leveraging principal component analysis (PCA) to analyzed 14 critical evaluation parameters of the five multi-polysaccharide gels, revealing the order as follows: KC > KGM > SA > LAG > LBG. These findings would imparts valuable insights into the pragmatic utilization of multi-polysaccharide gels for the development of food products (e.g. Bobo balls in milk tea) with tailored textural and sensory attributes.
Extensional rheology of condensed milk treated with glucosyl transferases
2024, Food HydrocolloidsThis study proposes a constant velocity scheme for filament stretching rheometry as a valuable and differentiating tool in food science. The methodology is developed to overcome challenges with constant rate filament stretching rheology regarding strains and strain rates accessible in lower viscosity fluids relevant to foods. It also maintains the accuracy and versatility of filament stretching rheometry, and range of material properties that can be investigated. We demonstrate this technique on a condensed milk system thickened by a mixture of two specific glucosyl transferases (GTFs), which allow tuning of the stringiness of food systems. The qualitative concept of stringiness often assessed by a spoon drip method is replaced by a stringiness parameter directly obtained from the extensional kinematics and mapped against the capillary number. The latter allowed to demonstrate that the filament stabilization is not a shear viscosity but rather an elastic effect. This allows further discussion of the colloidal structures and interactions that may cause the specific dependence of stringiness of enzyme treatment. Accurate stress data is obtained up to higher Hencky strains by data graduation, enabling the observation of highly nonlinear effects that provide valuable insights into the structural rearrangements of the colloidal and polymeric components of the system. Enabled by these improvements, the study highlights the strength of extensional rheology in its ability to detect subtle differences in the colloidal structure of GTF thickened foods that are not measurable in shear.
Reducing starch digestibility of white rice by structuring with hydrocolloids
2023, Food Research InternationalControlling starch digestion in high glycaemic index staple foods such as white rice is of interest as it has been associated with reduced risk for conditions such as obesity and type-2 diabetes mellitus. Addition of hydrocolloids has been proposed to reduce the rate of post-prandial glucose by controlling the rate of starch hydrolysis. In this work, the potential of a range of hydrocolloids to modify starch digestibility when added (at 1 % maximum concentration) during cooking of white rice was first investigated. Low acyl gellan gum (LAG) showed the highest potential (in-vitro estimated Glycaemic Index reduced by about 20 %, from 94 in the control to 78 in the LAG rice) and was investigated further. While the grains of rice control and rice with LAG appeared similar, SEM images revealed a gel-like layer (a few micrometers in thickness) on the surface of the treated samples. Addition of LAG appeared to also have an effect on the breakdown of a simulated cm-sized bolus. During gastric digestion, bolus breakdown of the rice control was completed after 30 min, while the rice LAG bolus appeared intact after 1 h of observation. This was attributed to strengthening of the LAG gel in the acidic environment of the stomach. During intestinal digestion, rice samples containing 1 % LAG appeared to be less susceptible to breakdown when seen under a microscope and in environmental SEM, while they showed larger rice particle aggregates, compared to rice control. Overall, LAG showed potential to control starch digestion kinetics of white rice with a mechanism that may involve formation of a protective layer on the rice grains (um) that reduces bolus break down (cm) and enzymatic hydrolysis (nm). Outcomes of this work will be used to identify conditions for further relevant in-vitro and in-vivo investigations.
Fluidized bed granulation of gellan gum: Investigations of binder effect on physical, structural and rheological properties
2023, Powder TechnologyMultiple binders such as maltodextrin, glucose and lactose at different concentrations were screened for the granulation of gellan gum (GG) in fluidized bed granulator to avoid limitations of powder GG such as dustiness, low dispersibility, wettability etc. Granulation was confirmed by analyzing physical, structural and rheological properties against commercial GG powder. Granulation significantly improved the particle size, flowability, dispersibility and wettability of GG without changing the native chemistry. Among the binders, lactose (10% w/v) gave granules with highest particle size (D0.9 = 828 μ) and porosity (64%). The process retained the color and stability by decreasing water activity (aw < 0.30). However, binder type and concentration altered the flow and dynamic rheological properties of granular GG compared to non-granulated. Concisely, fluidized bed granulation seems to be a potential technique to improve processability of GG by overcoming existing limitations without altering the chemistry and functional properties at lower binder concentration.
In situ gel based on gellan gum
2023, Polysaccharide Hydrogels for Drug Delivery and Regenerative MedicineGellan gum has a broad application in the field of food, drug, and cosmetic industries as a thickening agent, a gelling agent, and a formulation stabilizer, due to its unique properties including biodegradability and biocompatibility, low toxicity, excellent thermal stability, high aqueous solubility, and good water-holding capacity. In this review, it summarizes the mechanisms of gellan gum to form in situ gels and its applications in different delivery systems (both aqueous-based and lipid-based formulations) and different delivery routes (through ophthalmic, intranasal, oral, injectable, virginal, topical, and intracanal pathways). The formation of in situ gels by gellan gum not only provides a good option for regenerative medicine but also serves as a potent drug delivery system to reduce the drug irritability, increase the drug retention time at target sites, control the drug release rate, and eventually improve the bioavailability and therapeutic effects of drugs.