A Novel Approach to Structure Plant-Based Yogurts Using High Pressure Processing

Abstract

Current plant-based yogurts are made by the fermentation of plant-based milks. Although this imparts fermented flavors and probiotic cultures, the process is relatively longer and often leads to textural issues. The protein content of these plant-based yogurts is also lower than their dairy counterparts. To overcome these challenges, this paper explores the high pressure processing (HPP) of plant protein ingredients as an alternative structuring strategy for plant-based yogurts. Using mung bean (MB), chickpea (CP), pea (PP), lentil (LP), and faba bean (FB) proteins as examples, this work compared the viscosity and viscoelastic properties of high pressure-structured (600 MPa, 5 min, 5 °C) 12% (w/w) plant protein gels without, and with 5% (w/w) sunflower oil (SO) to commercial plain skim and whole milk Greek yogurts and discussed the feasibility of using HPP to develop plant-based yogurts. HPP formed viscoelastic gels (G' > G'') for all plant protein samples with comparable gel strength (G'~10²-10³ Pa; tan δ~0.2-0.3) to commercial dairy yogurts. The plant protein gel strength decreased in the order: CP~CPSO~LP~LPSO > MBSO~PPSO~FB~FBSO > PP >> MB. Modest addition of sunflower oil led to little change in viscoelastic properties for all plant protein samples except for MB and PP, where gel strength increased with incorporated oil. The emulsion gels were also more viscous than the hydrogels. Nonetheless, the viscosity of the plant protein gels was similar to the dairy yogurts. Finally, a process involving separate biotransformation for optimized flavor production and high pressure processing for consistent texture generation was proposed. This could lead to high protein plant-based yogurt products with desirable texture, flavor, and nutrition.

Keywords: emulsion gels; high pressure processing; hydrogels; plant proteins; plant-based yogurts.

Figure 1

Amplitude sweeps of high pressure-treated 12% (w/w) mung bean (MB), chickpea (CP), pea (PP), lentil (LP) and faba bean (FB) protein samples without and with 5% (w/w) sunflower oil (SO) as compared to commercial plain skim and whole milk Greek yogurt. Storage modulus, G’ (closed symbol) and loss modulus, G’’ (open symbol). Each curve is the average of two treatments.

Figure 1

Amplitude sweeps of high pressure-treated 12% (w/w) mung bean (MB), chickpea (CP), pea (PP), lentil (LP) and faba bean (FB) protein samples without and with 5% (w/w) sunflower oil (SO) as compared to commercial plain skim and whole milk Greek yogurt. Storage modulus, G’ (closed symbol) and loss modulus, G’’ (open symbol). Each curve is the average of two treatments.

Figure 2

Rheological parameters obtained from amplitude sweeps of high pressure-treated 12% (w/w) mung bean (MB), chickpea (CP), pea (PP), lentil (LP), and faba bean (FB) protein samples without and with 5% (w/w) sunflower oil (SO) as compared to commercial plain skim and whole milk Greek yogurt. (a) Storage modulus (G’) at 0.1% strain; (b) loss tangent (tan δ) at 0.1% strain; (c) crossover strain (γ_co) when G’ = G’’. The average of two treatments is presented with the error bar extremes showing the data for each treatment.

Figure 2

Rheological parameters obtained from amplitude sweeps of high pressure-treated 12% (w/w) mung bean (MB), chickpea (CP), pea (PP), lentil (LP), and faba bean (FB) protein samples without and with 5% (w/w) sunflower oil (SO) as compared to commercial plain skim and whole milk Greek yogurt. (a) Storage modulus (G’) at 0.1% strain; (b) loss tangent (tan δ) at 0.1% strain; (c) crossover strain (γ_co) when G’ = G’’. The average of two treatments is presented with the error bar extremes showing the data for each treatment.

Figure 3

Flow curves (a,b) and viscosity at 1 s⁻¹ (c,d) of high pressure-treated 12% (w/w) mung bean (MB), chickpea (CP), pea (PP), lentil (LP), and faba bean (FB) protein samples without and with 5% (w/w) sunflower oil (SO) as compared to commercial plain skim and whole milk Greek yogurt. Each curve is the average of two treatments. The average of two treatments is presented with the error bar extremes showing the data for each treatment.

Figure 4

A proposed plant-based yogurt-making process using biotransformation for optimized flavor production and high pressure processing (HPP) for consistent texture generation. The bracketed ingredients are optional depending on formulation. The image shows HPP-structured mung bean yogurt (MBSO) in a cup.