Journal Articles
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Item Heat-set gelation of milk- and fermentation-derived β-lactoglobulin variants(Elsevier Ltd, 2025-08) Pan Z; Kornet R; Hewitt S; Welman A; Hill JP; Wubbolts M; Mitchell S; McNabb WC; Ye A; Acevedo-Fani A; Anema SGMilk-derived β-lactoglobulin (mβ-LG) and fermentation-derived β-lactoglobulin (fβ-LG) may slightly differ in their amino acid sequences. This study aims to investigate the heat-set gelling behaviour of mβ-LG (variants A, B, and C) and fβ-LG A variants. Differential scanning calorimetry indicated similar denaturation temperatures for mβ-LG A and fβ-LG A (∼75 °C), with mβ-LG C highest (∼81 °C) and mβ-LG B intermediate (∼78 °C). All fβ-LG A formed translucent gels with a fine-stranded structure, whereas mβ-LG A, B, and C formed opaque gels with a coarse particulate structure. fβ-LG A exhibited delayed gelation onset and lower gel stiffness compared to mβ-LG A. Among mβ-LG's, mβ-LG A showed the highest gel stiffness, followed by mβ-LG B and then mβ-LG C. Rheological analysis showed that fβ-LG A gels were more elastic and ductile compared to mβ-LG A gels, indicated by smaller tan δ values and delayed increases in energy dissipation ratio at higher strain amplitude; mβ-LG B and mβ-LG C gels were less elastic but more ductile compared to mβ-LG A gels. The more elastic and ductile nature of fβ-LG A gels indicates their potential for applications requiring these specific textural properties. By selecting mβ-LG variants from milk and/or utilizing precision fermentation to engineer additional differences, it is possible to tailor the gelation characteristics of β-LG to meet specific functional requirements.Item Starch-Tannin Interactions: Influence of Grape Tannins on Structure, Texture, and Digestibility of Starches from Different Botanical Sources(Elsevier Ltd, United Kingdom, 2025-05) Kaur H; Mehta A; Kumar LThis study investigated the effect of grape seed (GSd) and grape skin (GSk) tannins on the physicochemical, rheological properties and in-vitro digestibility of starches (corn, pea and wheat) derived from three different botanical sources. Quantification of bound and unbound tannins using MCP and HPLC analysis demonstrated that majority of the tannins were bound to starch molecules. The results of particle size distribution, starch-iodine binding and FTIR studies indicated the development of inclusion complexes through hydrophobic interactions with tannins in pea starch, while other two starches prominently formed non-inclusion complexes via hydrogen bonding. Back extrusion analysis of textural properties indicated that wheat starch-tannin complexes resulted in firmer starch-tannin gels compared to other two starches. Rheological studies revealed an increase in the viscoelastic modulus (G’ and G”) with improved elastic behavior for all starch-tannin gels. Starches complexed with tannins demonstrated strong antioxidant properties and in-vitro starch digestion studies revealed significant reductions in rapidly digestible starch (RDS) and slowly digestible starch (SDS), along with an increase in resistant starch (RS), particularly in pea starch complexed with GSd tannins. This study enhanced our understanding of how GSd and GSk tannins influence the properties of starches from various botanical origins, helping in understanding starch-tannin interactions and enabling the creation of foods with improved texture and digestibility.Item Hybrid Paneer: Influence of mung bean protein isolate (Vigna radiata L.) on the texture, microstructure, and in vitro gastro-small intestinal digestion(Elsevier Ltd, 2024-02-15) Tojan S; Kaur L; Singh JReplacing dairy proteins with legume proteins such as mung bean protein can create hybrid cheese alternatives with superior nutritional and functional properties. The effects of partially replacing (30%) cow milk with mung bean protein isolate (MBPI) on the rheology, texture, microstructure, and digestibility of paneer (acid-heat coagulated cheese) were studied. The developed hybrid cow milk-mung bean paneer (CMMBP) had higher protein and moisture contents, lower fat content, and a darker colour than cow milk paneer (CMP). CMMBP showed a significant reduction in hardness, cohesiveness, chewiness, and springiness compared to the cow milk-based control. Frequency sweeps performed using a dynamic rheometer showed higher storage modulus (G') for CMMBP compared to CMP, indicating greater elastic properties of the hybrid paneer. In vitro digestibility of CMMBP was significantly lower than CMP, as shown by the lower overall ninhydrin-reactive free amino N release and the presence of resistant peptides at the end of digestion.Item Self-assembly and hydrogelation of a potential bioactive peptide derived from quinoa proteins(Elsevier BV, 2024-02) Cheng L; De Leon-Rodriguez L; Gilbert EP; Loo T; Petters L; Yang ZIn this work the identification of peptides derived from quinoa proteins which could potentially self-assemble, and form hydrogels was carried out with TANGO, a statistical mechanical based algorithm that predicts β-aggregate propensity of peptides. Peptides with the highest aggregate propensity were subjected to gelling screening experiments from which the most promising bioactive peptide with sequence KIVLDSDDPLFGGF was selected. The self-assembling and hydrogelation properties of the C-terminal amidated peptide (KIVLDSDDPLFGGF-NH2) were studied. The effect of concentration, pH, and temperature on the secondary structure of the peptide were probed by circular dichroism (CD), while its nanostructure was studied by transmission electron microscopy (TEM) and small-angle neutron scattering (SANS). Results revealed the existence of random coil, α-helix, twisted β-sheet, and well-defined β-sheet secondary structures, with a range of nanostructures including elongated fibrils and bundles, whose proportion was dependant on the peptide concentration, pH, or temperature. The self-assembly of the peptide is demonstrated to follow established models of amyloid formation, which describe the unfolded peptide transiting from an α-helix-containing intermediate into β-sheet-rich protofibrils. The self-assembly is promoted at high concentrations, elevated temperatures, and pH values close to the peptide isoelectric point, and presumably mediated by hydrogen bond, hydrophobic and electrostatic interactions, and π-π interactions (from the F residue). At 15 mg/mL and pH 3.5, the peptide self-assembled and formed a self-supporting hydrogel exhibiting viscoelastic behaviour with G' (1 Hz) ~2300 Pa as determined by oscillatory rheology measurements. The study describes a straightforward method to monitor the self-assembly of plant protein derived peptides; further studies are needed to demonstrate the potential application of the formed hydrogels in food and biomedicine.Item Formation and properties of highly concentrated oil-in-water emulsions stabilized by emulsion droplets(Elsevier Ltd, 2023-12) Cheng L; Ye A; Yang Z; Hemar Y; Singh H70% (v/v) concentrated emulsion has been prepared using Ca2+-cross-linked sodium caseinate particles (Ca-CAS) or Ca-CAS coated nano-sized primary emulsion droplets as emulsifiers. The primary droplet-stabilised emulsion (DSE) was compared with the conventional Ca-CAS stabilised-emulsion (PSE) in terms of viscoelasticity as affected by aging (30 days) and heating (80 °C, 30 min) at pH 5.8 and 7.0. DSE at pH 5.8 showed the highest complex modulus (G* = 1174 ± 39 Pa), approximately was six-times higher than other emulsions (G* ≤ ∼250 Pa) due to the thick emulsifier layer consisting of primary droplet increasing the effective volume faction of core droplets by a factor of ∼1.21. After aging, G* of DSE at pH 5.8 increased to 1685 ± 68 Pa, while G* of other three emulsions were ∼400 Pa. After heating, G* of DSE reached 1801 ± 69 Pa and 1312 ± 205 Pa at pH 5.8 and pH 7.0, respectively, while G* of PSE were ∼600 Pa at both pHs. The possible mechanism for aging-induced gelation was the gravity-driven microphase separation, in which the droplets flocculate together with the entrapped aqueous phase increasing the effective volume fraction. The heat-induced gelation was attributed to the increase in droplet interactions through protein aggregates and/or primary droplets forming three-dimensional networks at elevated temperature. This study suggests that the mechanical strength of food-grade concentrated emulsions can be effectively improved using nano-sized primary emulsions as emulsifying agent and can be further modulated by aging orItem Acid and rennet gelation properties of sheep, goat, and cow milks: Effects of processing and seasonal variation(Elsevier Inc on behalf of the American Dairy Science Association, 2023-03) Li S; Delger M; Dave A; Singh H; Ye AGelation is an important functional property of milk that enables the manufacture of various dairy products. This study investigated the acid (with glucono-δ-lactone) and rennet gelation properties of differently processed sheep, goat, and cow milks using small-amplitude oscillatory rheological tests. The impacts of ruminant species, milk processing (homogenization and heat treatments), seasonality, and their interactions were studied. Acid gelation properties were improved (higher gelation pH, shorter gelation time, and higher storage modulus (G') by intense heat treatment (95°C for 5 min) to comparable extents for sheep and cow milks, both better than those for goat milk. Goat milk produced weak acid gels with low G' (<100 Pa) despite improvements induced by heat treatments. Seasonality had a marked impact on the acid gelation properties of sheep milk. The acid gels of late-season sheep milk had a lower gelation pH, no maximum in tan δ following gel formation, and 70% lower G' values than those from other seasons. We propose the potential key role of a critical acid gelation pH that induces structural rearrangements in determining the viscoelastic properties of the final gels. For rennet-induced gelation, compared with cow milk, the processing treatments of the goat and sheep milks had much smaller impacts on their gelation properties. Intense heat treatment (95°C for 5 min) prolonged the rennet gelation time of homogenized cow milk by 8.6 min (74% increase) and reduced the G' of the rennet gels by 81 Pa (85% decrease). For sheep and goat milks, the same treatment altered the rennet gelation time by only less than 3 min and the G' of the rennet gels by less than 14 Pa. This difference may have been caused by the different physicochemical properties of the milks, such as differences in their colloidal stability, proportion of serum-phase caseins, and ionic calcium concentration. The seasonal variations in the gelation properties (both acid and rennet induced) of goat milk could be explained by the minor variation in its protein and fat contents. This study provides new perspectives and understandings of milk gelation by demonstrating the interactive effects among ruminant species, processing, and seasonality.Item Kinetics of pepsin-induced hydrolysis and the coagulation of milk proteins(Elsevier Inc and the Federation of Animal Science Societies on behalf of the American Dairy Science Association, 2022-02) Yang M; Ye A; Yang Z; Everett DW; Gilbert EP; Singh HHydrolysis-induced coagulation of casein micelles by pepsin occurs during the digestion of milk. In this study, the effect of pH (6.7–5.3) and pepsin concentration (0.110–2.75 U/mL) on the hydrolysis of κ-casein and the coagulation of the casein micelles in bovine skim milk was investigated at 37°C using reverse-phase HPLC, oscillatory rheology, and confocal laser scanning microscopy. The hydrolysis of κ-casein followed a combined kinetic model of first-order hydrolysis and putative pepsin denaturation. The hydrolysis rate increased with increasing pepsin concentration at a given pH, was pH dependent, and reached a maximum at pH ~6.0. Both the increase in pepsin concentration and decrease in pH resulted in a shorter coagulation time. The extent of κ-casein hydrolysis required for coagulation was independent of the pepsin concentration at a given pH and, because of the lower electrostatic repulsion between para-casein micelles at lower pH, decreased markedly from ~73% to ~33% when pH decreased from 6.3 to 5.3. In addition, the rheological properties and the microstructures of the coagulum were markedly affected by the pH and the pepsin concentration. The knowledge obtained from this study provides further understanding on the mechanism of milk coagulation, occurring at the initial stage of transiting into gastric conditions with high pH and low pepsin concentration.Item Effect of Process and Formulation Variables on the Structural and Physical Properties in Cream Cheese using GDL Acidulant(Springer Science+Business Media, LLC, 2022-06) Kim J; Watkinson P; Lad M; Matia-Merino L; Smith JR; Golding MWe report on the properties of analogue cream cheeses prepared using glucono delta-lactone (GDL) acidulant, notably the impact of particular processing and formulation variables, (homogenisation pressure, coagulation pH and temperature, and stabiliser level) on cream cheese physical, material and microstructural properties. Protein–protein and protein-fat interactions were seen to be the primary structural contributors to the physical properties of cream cheese. Cream cheese microstructure and its properties demonstrated well-defined correlations to specific and controllable processing elements within the manufacturing process, showing significance in interactions between parameters in multivariable linear regression analysis (P < 0.05). Summarising the effect of processing variables on key cheese properties, we observed that a progressive reduction in fat particle size of cheese milk arising from increasing homogenisation pressures was seen to increase the total surface area of fat that could be incorporated into the curd during coagulation. The greater extent of fat-fat and fat-proteins interactions during coagulation provided a reinforcing effect on the microstructure of the final cream cheese, with a corresponding increase in compressive fracture stress, shear storage modulus (G′) and shear loss modulus (G″). In terms of other processing variables, cream cheese firmness was also observed to progressively increase through lowering of coagulation pH from 5.13 to 4.33. Increasing coagulation temperature from 58 °C to 78 °C similarly caused an increase in cheese firmness. Finally, increasing the levels of added stabiliser were shown to correlate with increasing cheese firmness. Similar correlations could be observed in relation to physical properties, notably forced expressible serum separation. This model cream cheese preparation method has provided a useful model system for relating food structure to material and functional properties. In addition, it has the advantage of being able to rapidly screen many formulation and process variables because it is faster than the traditional cheesemaking. This study showed that the adjustment of process and formulation variables, either in isolation or in combination, in the manufacture of cream cheese can significantly influence the final material and textural properties of the product, thereby enabling controllable functional attributes capable of meeting different customer needs.