Stability of Foams in Vacuum Drying Processes. Effects of Interactions between Sugars, Proteins, and Surfactants on Foam Stability and Dried Foam Properties

Abstract

The hypothesis was that saccharides mediate interactions between surface-active components and that this will have an impact on foam decay during the drying process. Static light scattering was performed to determine changes in interactions between the foam stabilizer on a molecular level. Furthermore, pendant drop and oscillating drop measurements were performed to examine the surface tension and surface rheology. Foams were dried in conventional dryers as well as microwave-supported vacuum dryers. Final foam properties were determined. It was shown that the addition of sugars, often added as protective substances for sensitive organic molecules, resulted in lower repulsion between different types of surface-active components, namely polysorbate 80 and β-lactoglobulin (β-lg). Differences in impact of the types of sugars and between different types of surfactant, protein, and small molecules were observed influencing the foam decay behavior. The interfacial properties of polysorbate 80 and β-lg were influenced by the type of the used sugars. The surface elasticity of protein stabilized surfaces was higher compared to that of polysorbate stabilized systems. Protein stabilized systems remained more stable compared to polysorbate systems, which was also affected by the used saccharide. Overall, a correlation between molecular interactions and foam decay behavior was found.

Recent development in foam‐mat drying process: Influence of foaming agents and foam properties on powder properties

“…The convective hot air + microwave‐assisted foam mat drying of powders has a superior property in bulk density which is important for packaging, storage, and transportation (Çalışkan Koç & Yüksel, 2020). In another study, it is reported that microwaved supported vacuum dried samples showed more indications for foam decay compared to conventional vacuum dried samples (Kubbutat et al, 2021). It has been determined that the microwave drying method is more efficient in terms of the drying time of the foams compared to the hot air drying method (Varhan et al, 2019).…”

“…Foam mat drying has been hybridized by replacing hot air drying with other drying methods to minimize the negative effects of hot air drying on product quality and drying characteristics. Several studies are highlighted that drying samples by hybridizing foam mat drying with advanced dehydration techniques such as freeze drying, microwave drying and vacuum drying has a positive effect on drying kinetics and quality parameters (Qadri et al, 2019; Kubbutat et al, 2021). Various research groups have looked at the drying kinetics of foam mats using thin‐layer modeling to determine which model best suits the drying process.…”

“…Gao et al (2022) used three different foaming agents (egg albumin, maltodextrin, and carboxymethyl cellulose) in their study and found that for all foaming agent types, increasing concentration increased the solubility and porosity of the powders. In another study, which aimed to reveal the effects of interactions between sugars, proteins, and surfactants on foam stability, the addition of saccharides to β‐lactoglobulin solutions caused an improvement in the surface properties (Kubbutat et al, 2021). In the literature, several studies are using different types and concentrations of foaming agents.…”

“…In order to the functional, economical, and commercial considerations of the food powders, the powder properties, such as particle properties (particle size, shape, distribution and density and morphological properties), bulk properties (bulk and tapped density, flowability, stickiness), and reconstitution properties (sinkability, dispersibility, wettability, and solubility) have to be determined (Figure 3) (Çalıs¸kan Koç & Dirim, 2018;Ermis¸, 2021). Particle properties refer to Kubbutat et al (2021) the properties of a single particle such as size, shape, surface structure, density, and hardness. Particle distribution refers to the distribution of the particle's size, while morphology is defined as the evaluation of properties by the form of an object (Ermis¸, 2021).…”

“…In the literature, egg white (albumin) is mostly used as a foaming agent, and methylcellulose is used as a foam stabilizer (Djaeni et al, 2015; Tekgül, 2021; Varhan et al, 2019). The final drying process of the foam layer can be accomplished by several drying methods, such as hot air drying (Çalışkan Koç, 2020; Osama et al, 2022; Tekgül, 2021; Varhan et al, 2019; Watharkar et al, 2021), microwave drying (Çalışkan Koç et al, 2020; Gao et al, 2022; Qadri & Srivastava, 2017; Varhan et al, 2019; Yüksel, 2021), freeze‐drying (Muthukumaran et al, 2008a, 2008b), microwave‐supported vacuum drying (Kubbutat et al, 2021), combined drying techniques (convective hot air drying + microwave drying (Çalışkan Koç et al, 2020), etc.…”