There is a growing interest in exploring strategies to obtain plant-based dairy alternatives with desirable technofunctionalities. This study aimed to examine how conventional heating and microbial transglutaminase (MTGase) influence the gelation characteristics of lentil protein isolate (LPI) when combined with whey protein isolate (WPI) or casein micelles (CM). Gel electrophoresis analysis revealed that, during heat treatment, certain fractions in LPI (such as legumin acidic and basic subunits) and nearly all fractions in WPI (including (3-lactoglobulin and alpha-lactalbumin) underwent disulfide-mediated polymerization, contributing to the heat-induced gel formation, while the gelation of CM was hindered during this process. Conversely, some fractions in LPI (specifically the 11S acidic subunit and 7S vicilins), as well as nearly all CM fractions, were involved in MTGaseinduced cross-linking, while this cross-linking reaction was hindered in WPI. Heat-treated LPI-WPI mixtures resulted in self-standing gels with better gel performance than LPI, whereas heated LPI-CM mixtures exhibited liquid viscosity. Additionally, MTGase-induced LPI-CM samples showed better gel performance than LPI alone, whereas no self-standing gels formed for MTGase-induced LPI-WPI samples. The power-law model analysis showed that MTGase treated LPI-CM showed lower K ' than heat-treated LPI-WPI with a similar trend observed for n ' values. Overall, under neutral conditions, heating can enhance the gelation performance of LPI-WPI mixtures, while MTGase treatment is beneficial for promoting gelation in LPI-CM mixtures. This study provides valuable insights into effective strategies for substituting dairy proteins with plant proteins to attain the desired gelation performance.

Protein-rich foods tailored to older adult's dietary needs, textures and digestive capabilities are essential to help mitigate sarcopenia and malnutrition. This study developed two high protein dulce de leche type of desserts that were enriched with whey protein isolate (WPI-DD) alone or in combination with whey protein hydrolysate (WPI + WPH-DD). Their texture, rheology and tribology were characterized against a conventional dulce de leche (control). Protein digestibility was assessed using INFOGEST's in vitro static digestions simulating the adult and older adult gastrointestinal tract (G.I.T). Amino acid profiling revealed an expected increase in total amino acid content 68.4 mg/g (control) to 183.9 and 188.11 mg/g product, with leucine increasing from 5.5 to 19.7 and 20.37 mg/g product, for WPI-DD and WPI + WPH-DD respectively. Both protein-enriched products had a lower firmness and viscoelastic moduli than the control. In the presence of saliva, WPI + WPH-DD showed higher friction coefficients in the boundary and mixed regimes than WPI-DD and the control, indicating reduced lubrication. Size-exclusion chromatography revealed lower gastric proteolysis in the older adult model, with whey proteins resisting pepsin hydrolysis in both age models. Small intestine proteolysis was highly efficient for the enriched desserts, with less pronounced age-related differences. The hydrolysate-containing formulation showed faster leucine release. Both whey-based formulations achieved >95 % protein digestibility, with digestible indispensable amino acid ratios (DIAAR%) ≥100 %, even under older adult conditions. Coupling INFOGEST's age-specific in vitro digestion models with texture, rheology and tribology profiling provides insights into designing food for older adults that meet both nutritional and textural needs.

Background: As concern regarding human health, environmental increases, and the need for sustainable food supplies rises, plant proteins are gaining increasingly popularity as alternatives to dairy proteins. The substantial disparity in structural properties and gelation mechanisms between plant proteins and dairy proteins, along with a lack of comprehensive and systematic understanding of their underlying mechanisms under various modification strategies, pose challenges in unlocking the potential substitution of dairy proteins with different plant proteins. Scope and approach: The review offers insights into the structure, gelation mechanisms of heat and cold-induced gels of dairy proteins and plant proteins. Furthermore, diverse modification techniques for tailoring the structure of these proteins have been discussed, including chemical, physical, and biological modifications, as well as modifying mechanisms and their advantages and disadvantages. Key findings and conclusions: As with whey globular proteins, plant globular proteins usually have compact globular structures and are more prone to heat, making the denaturation of their globular proteins a prerequisite step for gelation. Contrary to globular proteins, casein micelles exhibit flexible random coil structures and good conformational stability to heat in neutral or higher pH but lose stability in acidic conditions. Different modification strategies exhibit diverse mechanisms and peculiarities. Complex coacervation is highly system dependent, while the enzymatic hydrolysis should be controlled in limited degree. Transglutaminase treated gels behave differently when the amount and accessibility of target lysine and glutamine residues differs. Moreover, exploring effective modification strategies for binary plant and dairy proteins to improve their gelation performance can be done in the future.

Concerns about health, the environment, and sustainable food supply have inspired researchers into searching new alternative plant proteins to dairy proteins. This study investigated thermal treatment coupled with pH manipulation (3.0, 5.0, 7.0, and 9.0) on the structural and gelation performance of pea, chickpea protein, and casein. Gel electrophoresis suggested that only specific fractions contributed to disulfide bond-mediated aggregates formation: bovine κ-casein and αs2-casein in casein micelles, acidic and basic legumin subunits in pea and chickpea protein. No protein formed self-standing gels but precipitated in macroscopic flocs at pH 5.0. Casein displayed optimum gel performance at pH 3.0 (storage modulus (G′) of 2596.00 Pa, hardness of 603.47 g, water holding capacity of 94.92%), and transitioned into fluid-like viscous state (G′ < 1, loss tangent >1) under neutral or higher pH conditions. Pea protein did not form self-holding gels but aggregates with globular particles over all test pH. Nevertheless, chickpea protein formed self-standing gels regardless of pH (except 5.0) and peaked gel performance at pH 9.0. Hence, this study indicated considerable potential of casein in acidic thermal gel-based food products and confirmed the promising applications of chickpea protein as an alternative to pea protein across diverse pH conditions, and to casein in neutral and alkaline food gel formulations. In addition to providing scientific insight understanding the effects of thermal treatment coupled with pH manipulation on the performance of plant-based protein and dairy protein, this research sheds light on the promising prospects of incorporating chickpea protein into gel-based food formulations.

A growing global concern about human health, environment, and sustainable food supplies has motivated researchers to find new alternatives to dairy proteins. To investigate the effects of pH and protein varieties on the thermal gelation behaviors, plant protein (soy and lentil) and dairy protein (whey) were subjected to a variety of pH treatments. SDS-PAGE showed that only partial subunits of soy and lentil protein were involved in disulphide bonded aggregate formation regardless of pH, and that of whey protein was inhibited at acidic conditions and facilitated at higher pH. Both soy and lentil protein did not form self-standing gels at pH 5.0, while whey protein did, and all proteins displayed different morphologies as pH moved away from 5.0, from white, opaque, and heterogeneous to relatively transparent and homogeneous. Soy protein exhibited its optimal gel performance at pH 9.0 (storage modulus of 946.05 Pa) with the highest content of alpha-helix, intramolecular beta-sheet, and intermolecular/aggregated beta-sheet, while whey protein demonstrated its peak gel performance at pH 7.0 (storage modulus of 26271.90 Pa). Lentil protein displayed the best gel performance at pH 3.0 and was comparable to that of whey protein (storage modulus of 5366.00 and 4965.00 Pa, respectively). These findings confirmed that lentil protein has the potential to substitute whey and soy protein in formulations of diversified food products in some specific pH systems. This work highlighted the importance of pH control to achieve desired gelation performance and offered valuable insights for selecting suitable protein alternatives in formulating plant-based food products.

Proteins derived from plants, an important source of high-quality protein in the human diet, have recently attracted scientific and industrial interest. The market for plant-based protein has grown exponentially in recent years due to consumer demands and the sustainability of food supply. Proteins from plants are successfully applied in food processing principally because of their functional properties, which are in turn influenced by protein extraction methods and drying procedures. Moreover, the food sector prefers proteins in powder forms because of their chemical and microbiological stability, ease of handling, reduced packaging requirements and lower weight and transportation costs. This chapter discusses the effects of different extraction methods and drying technologies on the production of plant protein powders and their functional properties, as well as the application of plant-based proteins.

Plant proteins are constantly gaining attention as potential substitutes for dairy proteins, due to their suitable functionality and nutritional value. This study was designed to compare the structural and functional responses of different plant protein isolates (soy, pea, lentil, and chickpea) with two commonly used dairy protein (whey protein isolates and sodium caseinate) under different pH treatments (pH 3.0, 5.0, 7.0, and 9.0). The results showed that pH had a different alteration on the structural, surface properties and functional properties of plant and dairy proteins. Plant protein generally possessed a darker color, lower solubility, emulsifying properties, and foaming capacity, whereas their foaming stability and water holding capacity were higher than those of dairy proteins. Soy protein isolates were characterized by its comparable proportion of β-turn and random coils, zeta-potential, emulsifying (30.37 m2/g), and water-holding capacity (9.03 g/g) at alkaline conditions and chickpea protein isolates showed good oil-holding capacity (3.33 g/g at pH 9) among plant proteins. Further analysis confirmed that pH had a greater influence on the structural and functional properties of proteins as compared to protein sources, particularly at acidic conditions. Overall, this study might help processors select the appropriate plant protein as dairy alternatives for their target application in plant-based food products.

In recent years, various strategies have been introduced to partially substitute animal proteins with plant pro-teins. This study applied microbial transglutaminase (MTGase) to crosslink lentil protein isolate (LPI) and casein. The gel mixtures prepared using different LPI-casein ratios (4:0, 3:1, 2:2, 1:3, 0:4), and the structural, gelation characteristics of these hetero-mixtures were investigated. SDS-PAGE showed the bands of vicilins (-50 kDa), and 11S acidic subunit (-40 kDa) almost disappeared and partly 11S basic subunit (20 kDa) involved in the polymerization, whereas almost all the bonds of casein were involved in the MTGase-induced gelation process. With the increasing concentration of casein, LPI-casein binary gels presented enhanced mechanical textural properties (increased from 284.83 to 1128.33g of hardness), rheological properties (increased from 105.8 to 4405 Pa of storage modulus), water holding capacity (increased from 63.86 to 98.82%) and more homogeneous and compact microstructural properties (CLSM, SEM) as a result of homologous and heterologous crosslinking mediated by MTGase. Interestingly, gels prepared by partial casein replacement (by 25% LPI) had similar textural, water holding capacity, and microstructural properties to those prepared by casein-alone gels, demonstrating the possibility of successfully replacing casein with 25% LPI in MTGase induced system. This study presents a new interaction strategy mediated by MTGase for LPI and casein binary system to greatly enhance their gelation performance, as well as the potential of LPI in substitute dairy to formulate diversified food products.