Formulation and Physical Stability of High Total Solids Lentil Protein-Stabilised Emulsions for Use in Plant Protein-Based Young Child Formulae

Abstract

The demand for high-quality plant protein products is increasing and the aim of this work was to evaluate the impact of increasing the total solids content on the formation and stability of lentil protein stabilised oil-in-water emulsions. A series of emulsions were formulated using different proportions of total solids: 23, 26, 29, 32, and 35% (w/v). The emulsions were formulated using three ingredients—lentil protein, sunflower oil, and maltodextrin—which made up 15.85, 27.43, and 56.72% (w/w) of the total solids, respectively. The changes in apparent viscosity, particle size distribution, and colour during thermal processing were evaluated, with the physical stability investigated using an analytical centrifuge. The apparent viscosity of the solutions increased with total solids content (25.6 to 130 mPa.s−1), as did redness colour intensity (a* value increased from 5.82 ± 0.12 to 7.70 ± 0.09). Thermal processing resulted in greater destabilisation for higher total solids samples, as evidenced by greater changes in particle size, along with decreased redness colour. These results bring a better understanding of high total solids plant protein emulsions and factors affecting their stability, which could be used for the development of cost-effective and sustainable processing solutions in the production of plant protein young child formulae.

Enhancing the Techno-Functional Properties of Lentil Protein Isolate Dispersions Using In-Line High-Shear Rotor-Stator Mixing

“…The particle size distribution (PSD) parameter, volume-weighted mean particle diameter (D [4,3]) of the lentil powders, control sample and that processed through the in-line high-shear mixer are shown in Table 1. The red lentil protein isolate powder ingredient displayed a D [4,3] value of 30.7 ± 0.06 µm in line with the literature [34,40,41]. The control red lentil protein dispersion and the sample processed through the in-line high-shear mixer for 0 min displayed similar (p > 0.05) D [4,3] values, of 5.13 ± 0.58 µm and 5.00 ± 0.04 µm, respectively, indicating that the pumping through the semi-continuous system and application of back pressure did not affect the particle size distribution.…”

“…The lentil protein dispersions were prepared by rehydrating red lentil protein isolate powder (72.15% protein, w/w), provided by Döhler GmbH (Darmstadt, Germany), at a concentration of 5% powder (w/v) (corresponding to 3.61% protein (w/v)) in pre-heated deionised water (70 • C), stirred magnetically at 300 rpm for 1 h at 20 • C. While the protein content of the lentil protein isolate powder was not as high as existing protein isolates generally used in the formulation of infant nutritional products, it is in line with previous studies on plant-based nutritional products [21,33,34]. The main non-protein constituents of such ingredients are typically fat, starch and fibre, with the starch and fibre components, in particular, having the potential to contribute to functional properties (see Section 3.2 for further details).…”

“…After loading the sample (20 mL) into the cylinder and preheating it to 20 • C, the shear rate was increased to 100 s −1 over 30 s and maintained for 30 s. A constant temperature of 20 • C was applied throughout the measurement, and viscosity was continuously recorded. The Ostwald-de Waele model (Equation (1)) was used to describe the rheological properties of the protein dispersions while ensuring that R 2 ≥ 0.95. τ = generally used in the formulation of infant nutritional products, it is in line with previous studies on plant-based nutritional products [21,33,34]. The main non-protein constituents of such ingredients are typically fat, starch and fibre, with the starch and fibre components, in particular, having the potential to contribute to functional properties (see Section 3.2 for further details).…”

“…Microstructural analysis of the dispersions was performed using an OLYMPUS FV1000 confocal laser scanning biological microscope (Olympus Corporation, Tokyo, Japan). The dispersions were prepared as described by Malterre et al (2023) [34] with the following modifications, whereby 1 mL of the dispersion was mixed in 4 mL of low gelling temperature agarose (Sigma-Aldrich, St. Louis, MO, USA) solution (1.5%, w/v) at 37 • C to fix the dispersion and allow for higher quality imaging. As described by Grasso et al (2021) [36], 20 µL of Fast Green FCF aqueous solution (200 µL of 0.1 g/L) was added to 1 mL of the dispersion-agarose sample, which was then incubated at 20 • C until gelation.…”