Competition of rapeseed proteins and oleosomes for the air-water interface and its effect on the foaming properties of protein-oleosome mixtures

Modifying the interfacial dynamics of oleosome (lipid droplet) membrane using curcumin

Cells store energy in lipid droplets, known as oleosomes, which have a neutral lipid core surrounded by a dilatable membrane of phospholipids and proteins. Oleosomes can be loaded with therapeutic lipophilic cargos through their permeable membrane and used as carriers. However, the cargo can also adsorb between the phospholipids and affect the membrane properties. In the present work, we investigated the effect of adsorbed curcumin on the mechanical properties of oleosome membranes using dilatational interfacial rheology (LAOD). The oleosome membrane had a weak-stretchable behavior, while the adsorption of curcumin led to stronger in-plane interactions, which were dependent on curcumin concentration and indicated a glassy-like structure. Our findings showed that adsorbed curcumin molecules can enhance the molecular interactions on the oleosome membrane. This behavior suggests that oleosomes membranes can be modulated by loaded cargo. Understanding cargo and membrane interactions can help to design oleosome-based formulations with tailored mechanical properties for applications.

Biochemical insights into tea foam: A comparative study across six categories

Tea foam properties, crucial indicators of tea quality, have gained renewed interest due to their potential applications in innovative beverages and foods. This study investigated the foaming properties and chemical foundations of six major tea categories through morphological observations and biochemical analyses. White tea exhibited the highest foaming ability at 56.28%, while black tea showed the best foam stability at 84.01%. Conversely, green tea had the lowest foaming ability (10.83%) and foam stability (54.24%). These superior foaming characteristics are attributed to the relatively low lipid content and acidic pH values. Surprisingly, no significant correlation was found between tea saponin content and foaming properties. Instead, specific amino acids (including Tyr, Gaba, Phe, Ile, and Leu) and catechins (GA and CG) were identified as potential contributors. These results deepen our understanding of tea foam formation and offer insights into utilizing tea-derived plant-based foams in food products.

Peanut de-oiling at room temperature by micro-aqueous hydration: Co-destabilization driven by oleosome coalescence and protein aggregation

The peanut de-oiling industry currently lacks efficient processing technologies for de-oiling at low or room temperatures. A novel method, micro-aqueous extraction (MAE), offers over 93 % de-oiling efficiency at room temperature and is also effective for other oilseeds like sesame, camellia, and rapeseed. Despite its effectiveness, the exact mechanism behind oleosomes destabilization at a critical hydration level or oil volume fraction (φ ∼ 0.75) is not fully understood. This study investigates how MAE affects peanut oleosome size, paste stability, and the interfacial properties of surfactant proteins. Results showed that micro-aqueous hydration and agitation caused small droplets (85.6 vol% < 10 μm) to coalesce into larger droplets (90.0 vol% > 30 μm) due to press-induced rupture of the liquid film. Simultaneously, agitation decreased water mobility and protein intrinsic fluorescence, while increasing paste viscosity, leading to protein aggregation. This aggregation further promoted oleosome coalescence. Additionally, hydration and agitation weakened the ability of membrane proteins to stabilize oleosomes by increasing interfacial tension and decreasing dilatational storage modulus. The insights into the peanut oleosome destabilization mechanism for MAE provide a foundation for scaling up the process, with the potential to replace current hot and cold pressing techniques.

Investigating the physicochemical properties and air-water interface adsorption behavior of transglutaminase-crosslinking rapeseed protein isolate

Improving the technical functionality to adapt to the application of complex food systems is an important challenge for the development of plant protein ingredients. Herein, the correlation between the physicochemical properties and interfacial adsorption behavior of rapeseed protein isolate (RPI) at the air-water interface after transglutaminase (TG) treatment was investigated. The results of cross-linking degree, Fourier transform infrared spectroscopy (FTIR) and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the TG enzyme was able to catalyse cross-linking between lysine and glutamine residues of RPI. The foaming capacity of RPI was enhanced from 120 % to 150 % after TG cross-linking 5 h, whereas the average size (210-219 nm) of the RPI determined by dynamic light scattering did not change significantly. Besides, the hydrophobicity tended to increase overall under the enzyme treatment, while the surface electrostatic potential decreased. The former indicates the unfolding of the protein and reduces the kinetic barriers to protein adsorption at the air-water interface, with a consequent increase in disulfide bonding and surface pressure. Furthermore, as the enzyme treatment time increased, a significant increase in protein content of foam by 33.86 %. These findings provide novel insight into the foaming mechanism of TG cross-linking RPI.

Characterisation of the Enzymatically Extracted Oat Protein Concentrate after Defatting and Its Applicability for Wet Extrusion

An oat protein concentrate (OC1) was isolated from oat flour through starch enzymatic hydrolysis, by subsequent defatting by ethanol and supercritical fluid extraction (SFE) reaching protein concentrations of 78% and 77% by weight in dry matter, respectively. The protein characterisation and functional properties of the defatted oat protein concentrates were evaluated, compared and discussed. The solubility of defatted oat protein was minor in all ranges of measured pH (3-9), and foamability reached up to 27%. Further, an oat protein concentrate defatted by ethanol (ODE1) was extruded by a single screw extruder. The obtained extrudate was evaluated by scanning electron microscope (SEM), texture and colour analysers. The extrudate's surface was well formed, smooth, and lacking a tendency to form a fibrillar structure. Textural analysis revealed a non-unform structure (fracturability 8.8-20.9 kg, hardness 26.3-44.1 kg) of the oat protein extrudate.

Mild Fractionation for More Sustainable Food Ingredients

With the rising problems of food shortages, energy costs, and raw materials, the food industry must reduce its environmental impact. We present an overview of more resource-efficient processes to produce food ingredients, describing their environmental impact and the functional properties obtained. Extensive wet processing yields high purities but also has the highest environmental impact, mainly due to heating for protein precipitation and dehydration. Milder wet alternatives exclude, for example, low pH-driven separation and are based on salt precipitation or water only. Drying steps are omitted during dry fractionation using air classification or electrostatic separation. Benefits of milder methods are enhanced functional properties. Therefore, fractionation and formulation should be focused on the desired functionality instead of purity. Environmental impact is also strongly reduced by milder refining. Antinutritional factors and off-flavors remain challenges in more mildly produced ingredients. The benefits of less refining motivate the increasing trend toward mildly refined ingredients.