Physicochemical control of foam properties

Denkov, Nikolai; Politova-Brinkova, Nadya

doi:10.1016/j.cocis.2020.08.001

Cited by 73 publications

(41 citation statements)

References 103 publications

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“…Therefore, while maintaining a constant shear rate in the planetary mixer, the bubble size (and shape) distribution does not change significantly with the SFC%, or the prolonged aeration time, as reported also for aqueous foams. 38 The effect of sample viscosity, which depends on the SFC%, is visible in the different air incorporation profiles: higher viscosity samples (30F) are characterized by a slower air incorporation and eventually a low final overrun, whereas low-viscosity samples (15S) present higher overruns, obtained during the first stages of aeration. Air incorporation is accompanied by the depletion of the oleogel domains, which are used as a source of fat crystals for stabilizing newly entrained air bubbles.…”

Section: Resultsmentioning

confidence: 99%

“…It is hypothesized that the presence in the samples of air cavities larger than or of comparable size to the total volume analyzed with XCT (about 1 mm 3 ) led to the underestimation of the overrun, as these could not be included in the tomography analysis. Additionally, the occurrence of air bubbles with comparable size to the VOI might have caused the large standard deviation in the XCT overrun (Metilli et al 38 ). Figure 3 b displays the variation of oleogel thickness as the ratio between the intensity of the peak at 35 μm (i.e., the unwhipped oleogel domains) and the peak at 10 μm (i.e., the oleogel surrounding the air bubbles).…”

Section: Resultsmentioning

confidence: 99%

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Application of X-ray Microcomputed Tomography for the Static and Dynamic Characterization of the Microstructure of Oleofoams

et al. 2022

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Oleofoams are a novel, versatile, and biocompatible soft material that finds application in drug, cosmetic or nutraceuticals delivery. However, due to their temperature-sensitive and opaque nature, the characterization of oleofoams’ microstructure is challenging. Here, synchrotron X-ray microcomputed tomography and radiography are applied to study the microstructure of a triglyceride-based oleofoam. These techniques enable non-destructive, quantitative, 3D measurements of native samples to determine the thermodynamic and kinetic behavior of oleofoams at different stages of their life cycle. During processing, a constant bubble size distribution is reached after few minutes of shearing, while the number of bubbles incorporated keeps increasing until saturation of the continuous phase. Low amounts of solid triglycerides in oleofoams allow faster aeration and a more homogeneous microstructure but lower thermodynamic stability, with bubble disproportionation and shape relaxation over time. Radiography shows that heating causes Ostwald ripening and coalescence of bubbles, with an increase of their diameter and sphericity.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Application of X-ray Microcomputed Tomography for the Static and Dynamic Characterization of the Microstructure of Oleofoams

et al. 2022

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“…All these have an impact on bubble size, stability, and foam microstructure. The best-known foaming techniques can be classified according to physical, chemical or biological processes used to generate the foam [23].…”

Section: Methods Of Foam Generationmentioning

confidence: 99%

“…From molecular point of view, the surfactant's characteristics like chemical repeating unit, end functional groups, molecular weight and molecular weight distribution have distinct effects on a foam's parameters [23].…”

Section: Foamsmentioning

confidence: 99%

Spectral Properties of Foams and Emulsions

2021

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The optical and spectral properties of foams and emulsions provide information about their micro-/nanostructures, chemical and time stability and molecular data of their components. Foams and emulsions are collections of different kinds of bubbles or drops with particular properties. A summary of various surfactant and emulsifier types is performed here, as well as an overview of methods for producing foams and emulsions. Absorption, reflectance, and vibrational spectroscopy (Fourier Transform Infrared spectroscopy-FTIR, Raman spectroscopy) studies are detailed in connection with the spectral characterization techniques of colloidal systems. Diffusing Wave Spectroscopy (DWS) data for foams and emulsions are likewise introduced. The utility of spectroscopic approaches has grown as processing power and analysis capabilities have improved. In addition, lasers offer advantages due to the specific properties of the emitted beams which allow focusing on very small volumes and enable accurate, fast, and high spatial resolution sample characterization. Emulsions and foams provide exceptional sensitive bases for measuring low concentrations of molecules down to the level of traces using spectroscopy techniques, thus opening new horizons in microfluidics.

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“…Foaming is considered a "general nuisance" in industrial fermentation because the fermentation process provides the essential conditions for foam formation [20]. There are two essential conditions for foam formation and stability: the external force and the property of solution [21]. Many factors affect the stability and formation of foams: the air entrapment in solution (e.g., gas flow rate and stirring frequency), the compositions and viscosity of media (e.g., pH, concentration of proteins and sugars, as well as presence of surfactant), the growth state of microbial cells (e.g., logarithmic phase, stable phase, and death phase), and the concentration of metabolites and surface-active substances (e.g., cresotic acid, rhamnolipid, and saponin) [19,[22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Controlling the Formation of Foams in Broth to Promote the Co-Production of Microbial Oil and Exopolysaccharide in Fed-Batch Fermentation

Guo

Wang

et al. 2022

Fermentation

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A large amount of foam is generated in the production of microbial oil and exopolysaccharide (EPS) by Sporidiobolus pararoseus JD-2, which causes low efficiency in fermentation. In this study, we aimed to reduce the negative effects of foams on the co-production of oil and EPS by controlling the formation of foams in broth. As we have found, the formation of foams is positively associated with cell growth state, air entrapment, and properties of broth. The efficient foam-control method of adding 0.03% (v/v) of the emulsified polyoxyethylene polyoxypropylene pentaerythritol ether (PPE) and feeding corn steep liquor (CSL) at 8–24 h with speed of 0.02 L/h considerably improved the fermentation performance of S. pararoseus JD-2, and significantly increased the oil and EPS concentrations by 8.7% and 12.9%, respectively. The biomass, oil, and EPS concentrations were further increased using a foam backflow device combined with adding 0.03% (v/v) of the emulsified PPE and feeding CSL at 8–24 h, which reached to 62.3 ± 1.8 g/L, 31.2 ± 0.8 g/L, and 10.9 ± 0.4 g/L, respectively. The effective strategy for controlling the formation of foams in fermentation broth reported here could be used as a technical reference for producing frothing products in fed-batch fermentation.

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Physicochemical control of foam properties

Cited by 73 publications

References 103 publications

Application of X-ray Microcomputed Tomography for the Static and Dynamic Characterization of the Microstructure of Oleofoams

Application of X-ray Microcomputed Tomography for the Static and Dynamic Characterization of the Microstructure of Oleofoams

Spectral Properties of Foams and Emulsions

Controlling the Formation of Foams in Broth to Promote the Co-Production of Microbial Oil and Exopolysaccharide in Fed-Batch Fermentation

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