Food-grade monoglyceride oil foams: the effect of tempering on foamability, foam stability and rheological properties

Abstract

Foams with a continuous oil phase may be stabilized using crystalline particles. Those systems are compelling because of their potential in edible oil structuring, modifying sensorial properties and creating healthier food products. This study aimed to relate oleogel (unwhipped state) properties to oil foam (whipped state) properties using a monoglyceride-sunflower oil model system. The properties of crystal-oil mixtures were influenced by time and temperature during preparation and storage. Therefore, oleogels were prepared using different tempering protocols and their resulting microstructure was investigated with rheology, differential scanning calorimetry and X-ray diffraction. The corresponding oil foams were characterized in terms of foamability and foam stability. The properties of both systems were studied immediately after preparation as well as after 4 weeks of storage. We demonstrated that there is a large influence of the time-temperature history on the foam properties. Partially crystallized mixtures were shown to form weaker structures which capture more air because of their lower viscosity and as crystallization would preferentially take place at the interface. They were characterized by larger bubbles and were less stable and firm. It is proposed that their rheological properties are mainly dominated by interfacial contributions. Fully crystallized and stored monoglyceride-oil mixtures were seen to form stronger gel networks which included less air, contained smaller air bubbles and were stable during storage. It is hypothesized that these samples also included an important bulk gelation contribution.

Synthesis, physicochemical properties, and health aspects of structured lipids: A review

“…(a) The impact of addition of different concentrations of MAG or DAG on the interfacial tension of stripped soybean oil (SSO) (Chen et al., ); (b) The interfacial tension versus time for the 1 wt% sodium caseinate solution in the presence of peanut oil (PO) or peanut oil‐based diacylglycerol (PO‐DAG) (Long et al., ); (c) Schematic illustration of the effect of oil polarity on adsorption of β ‐lactoglobulin and interfacial film structure at oil–water interface in a model system (Bergfreund et al., ); (d) Microscopy images of oil foams formed by air bubbles dispersed in sunflower oil stabilized by MAGs: (left) cryo‐scanning electron microscopy (SEM) image, (middle) CLSM image, and (right) polarized light image (Heymans et al., )…”

“…For example, Heymans et al. () have endeavored to relate the crystalline structure of oleogels formed by tuning tempering protocols to the foamability and foam stability of the resultant oil foams. Gunes et al.…”

“…Long et al (2015) constructed O/W emulsions stabilized by sodium caseinate with either peanut oil (PO) or peanut oil-based DAG oil (PO-DAG, 95.95% purity) as the oil phase. They observed that PO-DAG/water interface had a lower interfacial tension and almost remained constant, whereas the PO-water interface had a significantly higher initial interfacial tension and then decreased with the evolution F I G U R E 3 (a) The impact of addition of different concentrations of MAG or DAG on the interfacial tension of stripped soybean oil (SSO) (Chen et al, 2014); (b) The interfacial tension versus time for the 1 wt% sodium caseinate solution in the presence of peanut oil (PO) or peanut oil-based diacylglycerol (PO-DAG) (Long et al, 2015); (c) Schematic illustration of the effect of oil polarity on adsorption of -lactoglobulin and interfacial film structure at oil-water interface in a model system (Bergfreund et al, 2018); (d) Microscopy images of oil foams formed by air bubbles dispersed in sunflower oil stabilized by MAGs: (left) cryo-scanning electron microscopy (SEM) image, (middle) CLSM image, and (right) polarized light image (Heymans et al, 2018) of time. When protein adsorption equilibrium was reached, the interfacial tension of PO-water interface was slightly lower than that of the PO-DAG-water interface (Figure 3b).…”

“…Oil foams, also called oleofoams, non-aqueous foams, or whipped oils, refer to a colloidal dispersion where air bubbles are dispersed in oils (Figure 3d; Heymans et al, 2018), which can be used as low-calorie food products (Gunes et al, 2017) and lubricating oil (Binks, Davies, Fletcher, & Sharp, 2010). Crystalline particles including MAGs (Gunes et al, 2017;Heymans et al, 2018), DAGs (Shrestha, Shrestha, Sharma, & Aramaki, 2008;Shrestha, Shrestha, Solans, Gonzalez, & Aramaki, 2010), TAGs (Binks & Marinopoulos, 2017;Mishima, Suzuki, Sato, & Ueno, 2016), fatty acids (Binks, Garvey, & Vieira, 2016), fatty alcohol (Fameau et al, 2015), and a combination of sucrose ester and lecithin (Patel, 2017d), as well as solid particles such as fluorinated particles (Binks, Johnston, Sekine, & Tyowua, 2015), have been reported to be capable of stabilizing air-oil interface in oil foams. Here, we mainly focus on edible oil foams stabilized by crystalline MAGs and DAGs.…”

“…It should be noted that the nature of the crystalline particles (for example, size, shape, and polymorphs) as well as the bulk and interfacial rheological behaviors of the stabilizer-oil systems or the formed oleogels should also be taken into account to understand the formation and stabilization mechanisms of oil foams (Fameau & Saint-Jalmes, 2017;Heymans, Tavernier, Dewettinck, & Meeren, 2017). For example, Heymans et al (2018) have endeavored to relate the crystalline structure of oleogels formed by tuning tempering protocols to the foamability and foam stability of the resultant oil foams. Gunes et al (2017) have studied the interfacial contribution of crystalline particles to the foam stability in a MAG-high oleic sunflower oil system, where the adsorbed MAG crystals were found to form a jammed, closely packed layer that could stabilize the air bubbles against a dilution step.…”