Quality of Emulsions Based on Modified Watermelon Seed Oil, Stabilized with Orange Fibres

The aim of the study was to evaluate emulsion systems prepared on the basis of blended fat in different ratios (watermelon seed oil and mutton tallow) stabilised by orange fibres and xanthan gum. Emulsions were subjected to stability testing by Turbiscan and were assessed in terms of mean droplet size, colour, viscosity, texture, skin hydration and sensory properties. The most stable systems were found to be the ones containing a predominance of mutton tallow in a fat phase. For these emulsions the lowest increase in mean particle size during storage was observed. The study also confirmed the synergistic effect of the thickeners used. The presented emulsions despite favourable physicochemical parameters, did not gain acceptance in sensory evaluation.

Molecular characterization of xanthan gum producing Xanthomonas Campestris isolated from dark rot spotted leaves in Keffi, Nasarawa State, Nigeria

Background: Despite the wide application of Xanthan gum, its commercial production remains a global challenge. In recent years, considerable research has been carried out using agro-industrial wastes, which are renewable and abundantly available to produce value-added products. The present study was set out for molecular identification of Xanthomonas campestris from leaves of four different plants with indications of dark rot spots and evaluation of their xanthan gum production capacity. Methods: Twenty-five (25) samples of leaves from four different plants with indications of dark rot spots were collected from the study area and isolated for Xanthomonas campestris following standard microbiological methods. Cultural, morphological and biochemical tests were conducted to confirm the organism. Results: The results revealed that of the total 100 samples taken, 6 leaves (24%) were infected with Xanthomonas species in mint, 3(12%) were infected in mango, 1(4%) were infected in rice and 2(8%) were infected in pepper. Further molecular identification of the isolates was carried out to reveal Xanthomonas campestris pv. vesicatoria strain 85-10 and Xanthomonas perforans strain 91-118. These were further used for the production of xanthan gum using sugar cane molasses substrates extracted from sugar cane, which was used as fermentation medium for the production. Isolates from plants varying ability in Xanthan gum production, with the mint plant having the highest Xanthan gum production (0.10 ± 0.02 to 0.9 ± 0.00 g/l). Conclusion: The present study confirmed the high xanthan gum production capacity of Xanthomonas campestris from dark rot spots containing mint leaves and should be considered during local and industrial production of the xanthan gum

Evidence from Thermal Aging Indicating That the Synergistic Effect of Glyoxal and Sodium Sulfite Improved the Thermal Stability of Conformational Modified Xanthan Gum

Xanthan gum is prone to thermal oxidative degradation, which limits its applications. However, conformational changes in xanthan gum and appropriate stabilizers may improve its thermal stability. Therefore, in this study, we aimed to establish a strategy to maintain the viscosity of xanthan gum during long-term storage at high temperatures. We modified the original strain used for xanthan gum production by genetic engineering and added stabilizers during the production process. The structure and thermal stability of the resulting xanthan gum samples were then determined. Pyruvyl deficiency, combined with the addition of sodium sulfite and glyoxal during the production process, was found to significantly improve the maintenance of viscosity. The apparent viscosity of the new xanthan gum solution remained above 100 mPa·s after being stored at 90 °C for 48 days. Fourier-transform infrared spectra and scanning electron microscopy images showed that pyruvate-free xanthan gum with added stabilizers had more extensive cross-linking than natural xanthan gum. In conclusion, these findings may contribute to the use of xanthan gum in applications that require high temperatures for a long period of time.

Bio-Stabilised Earthen Blocks: A Critical Study on Compression Tests of Immersed Samples

Currently, much consideration is given to earthen building materials regarding their highly sustainable properties. Numerous studies have highlighted their structural ability but their water sensitivity is still limiting a potentially more spread use. To limit this sensitivity several studies have recently brought out the positive effects of bio-stabilisers such as linseed oil or xanthan gum. These recent developments allow bio-stabilized earthen materials to be resistant to immersion in water. Also, a French experimental standard (XP P 13-901) for compressed earth blocks already asks for a minimal compressive strength after a two-hour immersion that is overly severe and is difficult to satisfy without the addition of high contents of hydraulic binders. In this paper, a critical study of this compressive test after immersion is conducted on bio-stabilized (linseed oil and xanthan gum) samples of different Breton earths. Some testing adjustments are suggested and the water-diffusion in the samples is followed and linked to previously obtained capillary absorption coefficients. It is shown that the effect of immersion on the mechanical strength depends on the sample size and that an equivalence between size and immersion time can be made based on an equivalent penetration depth. Linseed oil and xanthan gum help to significantly increase the compressive strength of the earthen materials after immersion and allow to avoid the addition of hydraulic binders in earthen blocks to obtained a strong water resistance. The water diffusion in the sample during the immersion can be linked to capillary absorption behaviour, thus a water content and a compressive strength after a given time of immersion could be easily predicted.

Linseed Oil and Xanthan Gum: Promising Stabilisers for Earthen Building Materials

In the current context, the development of new bio-based and local building materials is becoming mandatory. Among them, earthen materials have a strong potential to be used as sustainable structural materials but their variability and their water sensitivity impact their mechanical properties that are difficult to guaranty. Recent developments have emphasised the ability of some bio-based additions to help to ensure these properties: linseed oil and xanthan gum are part of them. In this paper three different Breton earths, representative of a certain local variability, are studied. The impact of the selected bio-based additions on earths’ rheological behaviour is followed in order to adapt it to different forming processes. Then, the mechanical properties of different earth-addition combinations at the dry state, exposed to hygric variations and immersion are investigated for different forming processes. The findings highlight the fact that xanthan gum and linseed oil have a relevant ability to stabilise earthen blocks, that can be processed using different promising forming methods.

Erosion Behaviour of Bio-Stabilised Earthen Materials

Development of earthen building materials is one of the answers that the construction sector can provide to tackle the accelerated climate change issue. However, these materials present a wide variability, even at the local scale, and their water durability can be difficult to ensure. In order to improve their durability regarding water and avoid its prejudicial effect on earthen material’s properties, the stabilisation with bio-polymers is an increasingly studied solution. In this paper a ten-minute erosion drip test is developed and performed for various combinations of Breton earths and bio-based additions or surface treatments (linseed oil, xanthan gum, casein, alginate, vegetal varnish and tannins). The final pitting depths and eroded volumes are compared and the evolution of erosion during the test is monitored. These results are also linked to previously obtained water capillary absorption coefficients. The obtained results enable to highlight the impact of bio-based additions on erodibility of earthen materials: linseed oil and xanthan gum help to protect the earth-based samples from erosion. Other original parameters characterizing the erosion of the samples during the drip test are suggested. Limitations of this type of erosion tests are also brought out.

High Internal-Phase Pickering Emulsions Stabilized by Xanthan Gum/Lysozyme Nanoparticles: Rheological and Microstructural Perspective

Food-grade high internal-phase Pickering emulsions (HIPPEs) stabilized by solid or colloidal particles with different advantages have attracted extensive attention nowadays. However, looking for new appropriate particle stabilizers is the common practice for HIPPEs preparation. It is crucial to find a new strategy for the development of functional HIPPEs with controllable properties. In this study, a high concentration of xanthan gum/lysozyme nanoparticles (XG/Ly NPs) was used for the preparation of HIPPEs for the first time. Visual observations, creaming index (CI), microstructure, and rheology tests were carried out to investigate the potential of XG/Ly NPs as HIPPEs stabilizers. Results indicated that XG/Ly NPs could stabilize oil droplets in the concentration range of 0.5–4% (w/v). The HIPPEs with a minimal particle concentration of 1% exhibited remarkable physical stability. Rheological measurements showed that a high stability of solid-like HIPPEs was successfully obtained with a higher concentration of XG/Ly NPs. Overall, the HIPPEs stabilized by different concentrations of XG/Ly NPs exhibited excellent rheological and structural properties, which might provide a feasible strategy for the development of functional emulsion systems with controllable structures.

3D Bioprinting of Gelatin–Xanthan Gum Composite Hydrogels for Growth of Human Skin Cells

In recent years, bioprinting has attracted much attention as a potential tool for generating complex 3D biological constructs capable of mimicking the native tissue microenvironment and promoting physiologically relevant cell–cell and cell–matrix interactions. The aim of the present study was to develop a crosslinked 3D printable hydrogel based on biocompatible natural polymers, gelatin and xanthan gum at different percentages to be used both as a scaffold for cell growth and as a wound dressing. The CellInk Inkredible 3D printer was used for the 3D printing of hydrogels, and a glutaraldehyde solution was tested for the crosslinking process. We were able to obtain two kinds of printable hydrogels with different porosity, swelling and degradation time. Subsequently, the printed hydrogels were characterized from the point of view of biocompatibility. Our results showed that gelatin/xanthan-gum bioprinted hydrogels were biocompatible materials, as they allowed both human keratinocyte and fibroblast in vitro growth for 14 days. These two bioprintable hydrogels could be also used as a helpful dressing material.

Effect of hydrocolloids on physicochemical properties, stability, and digestibility of Pickering emulsions stabilized by nanofibrillated cellulose

In this study, effect of hydrocolloids with different electrostatic characteristics, i.e. negatively charged xanthan gum (XG), positively charged chitosan (CH), and non-ionic guar gum (GG) on physicochemical properties, stability, and...