Over the last decade, plant-based beverages have gained popularity amongst consumers who are seeking alternative and environmentally sustainable options to traditional dairy drinks. Whilst these days there is a variety of cereal-based beverages in the market, the legume-based beverage segment is dominated by soy milk products. There is an opportunity to broaden and diversify this segment into other legumes which may offer better functionality and nutrition than soy. However, little is known about the processability, functionality, health benefits and associated health risks of legume-based milk substitutes. Therefore, this review provides an overview of the current knowledge on fundamental processing steps to convert legumes into milk-alternative beverages, what are processing challenges for different legume varieties, how to overcome these challenges and potential quality deficiencies, and what are the opportunities to maximise textural, nutritional and sensory aspects of legume-based beverages. Special attention is given to chickpea and faba beans, a legume segment largely untouched by industry so far.

The crystallisation behaviour of milk fat plays an important role in the functionality and sensory properties of fat rich dairy products. In this study, we investigated the impact of tempering to 25 degrees C on the viscoelastic properties, particle size and thermal behaviour of 20% w/w unprocessed and homogenised creams prepared from bovine milk. The crystallisation properties were examined by synchrotron X-ray diffraction (XRD) at small (SAXS) and wide angle (WAXS) and differential scanning calorimetry (DSC). Oscillation rheology was performed to characterise the cream's viscoelastic properties. Homogenisation (35 MPa) reduced the average droplet size from 4.4 to 1.3 mu m. After 24 h storage at 4 degrees C, milk fat structures showed triacylglycerol (TAG) 2L and 3L((001, 002, 003, 005)) lamellar stacking orders associated predominantly with the alpha and beta' polymorphic forms. Tempering to 25 degrees C induced the complete melting of the 3L crystals and led to an irreversible loss in the elastic modulus (G') and a reduction in the viscous modulus (G'') once returned to refrigerated conditions, due to changes in the particle-particle interactions and structure of the reformed milk fat crystals. The results demonstrate that crystallisation behaviour of milk fat is influenced by droplet size and the rearrangement of triacylglycerol (TAG) upon tempering, and lead to changes in the viscoelastic behaviour of dairy products containing a high level of milk fat.

Sodium reduction has been recognised by the meat industry as an important driver for consumers. The objective of this study was to investigate the effects of high pressure processing (HPP, 200 MPa, 10 min) on the sensory quality of sodium-reduced chicken sausages formulated with three anion types of potassium salts (K-salts; potassium chloride, potassium lactate and potassium citrate). Partial replacement of 25% sodium chloride (NaCl) with K-salts did not affect the textural properties. Applying HPP before cooking, sausages were more compact and continuous with a uniform gel-matrix than sausages that had not been HPP. HPP contributed to an increased firmness and decreased cook loss of chicken sausages. Colour parameters (L*, a*, b*) were lower in HPP sausages. Moreover, the textural properties and colour were maintained over a 40-day chilled storage period. Sensory evaluation showed that the use of K-salts at the concentrations used in this study had no negative effects on the sensory properties and that HPP improved the texture of sausages. However, HPP treatment in combination with K-lactate or K-citrate reduced the perceived saltiness of the sausages. We conclude that the HPP in combination with K-salts can increase the textural attributes of sodium-reduced chicken sausages. Therefore, the HPP in combination with K-salts might be used as a strategy to reduce NaCl in emulsion-type meat products without compromising consumer preference in textural properties.

Over the last decade, plant-based beverages have gained popularity amongst consumers who are seeking alternative and environmentally sustainable options to traditional dairy drinks. Whilst these days there is a variety of cereal-based beverages in the market, the legume-based beverage segment is dominated by soy milk products. There is an opportunity to broaden and diversify this segment into other legumes which may offer better functionality and nutrition than soy. However, little is known about the processability, functionality, health benefits and associated health risks of legume-based milk substitutes. Therefore, this review provides an overview of the current knowledge on fundamental processing steps to convert legumes into milk-alternative beverages, what are processing challenges for different legume varieties, how to overcome these challenges and potential quality deficiencies, and what are the opportunities to maximise textural, nutritional and sensory aspects of legume-based beverages. Special attention is given to chickpea and faba beans, a legume segment largely untouched by industry so far.

High amylose wheat (HAW) starch has been the focus of a number of nutritional studies, but there is limited information around its effect on the mechanical properties of wheat flour dough. This study investigated the size, shape and packing volume of HAW starch and their effect on the microstructure and rheology of dough. Four flour blends were formulated by adding vital wheat gluten and either HAW or commercial wheat starch to HAW flour to achieve a constant 14% protein content, but varied amounts of HAW starch. A large number of small and irregularly shaped HAW starch granules resulted in a high packing volume per gram of starch. Confocal laser scanning microscopy of optimally mixed doughs correlated the degree of starch granule aggregation with the level of HAW starch in the bi-continuous dough network. Small deformation rheology demonstrated that increased quantities of HAW starch in the dough increased the elastic modulus G′ values. Uniaxial extension measurements highlighted a synergy between HAW starch and sources of gluten proteins resulting in increased strain hardening. The impact of HAW starch on dough rheology was attributed to its irregular shape and large number of small granules leading to greater granule-granule interactions.

Meat loses fluid during cooking, resulting in textural changes and loss in cook yield. To understand the structural basis of cooking losses, this work used 10 bovine semitendinosus muscles and two ageing periods (1 vs 14days) to examine micro- and macro-level dimensional changes in muscle during heating. Muscle blocks, muscle fibre fragments and myofibrils all showed similar maximum shrinkage in cross sectional area (20–24%) but maximum length shrinkage was less in myofibrils (15%) than muscle blocks and fibre fragments (25%). Dimensional changes were dominated by shrinkage in individual muscle fibres and myofibrils, indicating that connective tissue does not play a major role. Transverse shrinkage predominantly occurred over 50–65°C whereas the longitudinal shrinkage predominantly occurred over 70–75°C; we attribute these two separate shrinkage events to denaturation of myosin and actin respectively. Higher cook losses in samples aged for 14days versus 1day suggests that desmin, nebulin and titin denaturation are not major drivers of fluid expulsion as these proteins are degraded during ageing. We postulate that proteolysis during ageing produces protein fragments which are more easily lost from the structure during cooking, along with water.

This study examined the retention of β-carotene in extruded corn-based formulations, as influenced by the delivery format of β-carotene and the die temperature (140, 160 or 170 °C) during twin-screw extrusion. The β-carotene was delivered via the liquid feed as (i) an oil-in-water emulsion stabilized by a heated protein-carbohydrate matrix; (ii) an oil-in-water emulsion stabilized by Tween 80 or (iii) solubilized in oil. Up to 90% of β-carotene was retained during extrusion when β-carotene was delivered as an oil-in-water emulsion stabilized by a heated protein-carbohydrate matrix regardless of the die temperature. When β-carotene was delivered as an oil-in-water emulsion stabilized by Tween 80 or solubilized in oil, the β-carotene retention was 70–85% and 65–80%, respectively, with lower β-carotene retention being obtained as the die temperature was increased. This study has shown that the stabilization of β-carotene within a heated protein-carbohydrate matrix enhanced the retention and stability of β-carotene in the extruded product. A heated protein-carbohydrate matrix may have the potential to protect and enable improved delivery of other oil soluble bioactives into extruded food products.

Buttermilk, a by-product of butter manufacture, was examined for its potential as an encapsulant for omega-3 oil (fish oil) emulsions (35% total solids; 17.5% fish oil) and powders (50% fish oil w/w, dry basis). Whole buttermilk on its own or in combination with glucose syrup improved the oxidative stability of the emulsions and powders. With judicious formulation, pH adjustment and heat treatment, buttermilk exhibited superior encapsulating properties compared to skim milk for fish oils. This research provides the industry with an alternative use of the whole buttermilk as an encapsulant for fish oils for food applications.

Protein intake is essential for growth and repair of body cells, the normal functioning of muscles, and health related immune functions. Most food proteins are consumed after undergoing various degrees of processing. Changes in protein structure and assembly as a result of processing impact the digestibility of proteins. Research in understanding to what extent the protein structure impacts the rate of proteolysis under human physiological conditions has gained considerable interest. In this work, four whey protein gels were prepared using heat processing at two different pH values, 6.8 and 4.6, with and without applied shear. The gels showed different protein network microstructures due to heat induced unfolding (at pH 6.8) or lack of unfolding, thus resulting in fine stranded protein networks. When shear was applied during heating, particulate protein networks were formed. The differences in the gel microstructures resulted in considerable differences in their rheological properties. An in vitro gastric and intestinal model was used to investigate the resulting effects of these different gel structures on whey protein digestion. In addition, the rate of digestion was monitored by taking samples at various time points throughout the in vitro digestion process. The peptides in the digesta were profiled using SDS-polyacrylamide gel electrophoresis, reversed-phase-HPLC and LC-MS. Under simulated gastric conditions, whey proteins in structured gels were hydrolysed faster than native proteins in solution. The rate of peptides released during in vitro digestion differed depending on the structure of the gels and extent of protein aggregation. The outcomes of this work highlighted that changes in the network structure of the protein can influence the rate and pattern of its proteolysis under gastrointestinal conditions. Such knowledge could assist the food industry in designing novel food formulations to control the digestion kinetics and the release of biologically active peptides for desired health outcome.

The deliberate design of food structures that impact on lipid digestion has received increasing attention because of the need for solutions to combat nutrition related concerns such as obesity and metabolic syndrome. In this study we examined how the hierarchical structure of foods can impact lipid digestion by incorporating gastric structuring emulsions in different biopolymer networks, namely i) a thermally reversible gelatine network, ii) a colloidal casein network, and iii) a concentrated starch particulate dispersion. The digestive breakdown of these emulsion filled biopolymer gels was followed by fat digestion kinetics in vitro and human clinical study (in vivo), rheological measurements and confocal laser scanning microscopy. The parent caseinate/monoglyceride (CasMag) stabilised emulsion underwent extensive partial coalescence upon exposure to gastric juice and as a result had very slow lipolysis (in vitro and in vivo). When the emulsion was incorporated within the biopolymer networks the rates of lipolysis were strongly correlated with the extent of partial coalescence of the CasMag emulsion, which was directly influenced by the structure and breakdown properties of each different biopolymer network. The way that biopolymer networks alter the digestion of the parent CasMag emulsion is likely affected by; i) how well the digestive juices mixed with the network/emulsion and, ii) the frequency and speed of droplet encounters, both of which have a direct impact on the ability of emulsions to undergo flocculation and (partial) coalescence. This knowledge may have important implications for the design and testing of real foods to understand and control the digestive behaviour of food nutrients. Crown Copyright (c) 2013 Published by Elsevier Ltd. All rights reserved.

The colour, water-holding capacity (WHC) and tenderness of meat are primary determinants of visual and sensory appeal. Although there are many factors which influence these quality traits, the end-results of their influence is often through key changes to the structure of muscle proteins and their spatial arrangement. Water acts as a plasticiser of muscle proteins and water is lost from the myofibrillar lattice structure as a result of protein denaturation and consequent reductions in the muscle fibre volume with increasing cooking temperature. Changes in the myofilament lattice arrangement also impact the light scattering properties and the perceived paleness of the meat. Causes of variation in the quality traits of raw meat do not generally correspond to variations in cooked meat and the differences observed between the raw muscle and cooked or further processed meat are discussed. The review will also identify the gaps in our knowledge and where further investigation would beneficial.

Abalone is a highly regarded food in many cultures. It is consumed as a luxury food, valued for its unique sensory properties, which include both flavor and texture. The aim of this research was to understand the texture of abalone and to link textural attributes to the microstructure of the muscle tissue. Two different sources, and species, of abalone-wild (Haliotis rubra) and farmed (Haliotis laevigata)-were characterized structurally using light microscopy and confocal laser scanning microscopy. The structure at different length scales of the abalone foot muscle tissues was related to perceived texture by a trained sensory panel. The results of the microscopy work showed isotropic assemblies of interwoven muscle bundles with a diameter of approximately 20-40 mu m. The muscle fibers consisted of bundles of aligned muscle fibrils, 2-4 mu m in diameter, that were interconnected with anisotropic collagen. During steaming, the muscle fibers were observed to separate as a result of configurational changes of the protein. The sample from wild abalone was found by the sensory panel to be the most chewy, firm and springy. The size of the collagen-rich areas was linked to the texture perception, with the toughest pieces of meat displaying the largest collagenrich areas. The size of the muscle fiber bundles also contributed to the perceived texture, in which samples containing larger bundles were perceived as more chewy than samples with fewer fibers per bundle.

The visualization of hydrogels and other forms of hydrated, soft matter pose a significant challenge for studies by electron microscopy. The main challenges can be subdivided into: (1) accurate preservation of structure, (2) ensuring a sufficiently high signal-to-noise ratio, and (3) acquisition of comprehensive datasets. A shortcoming in any of these areas will lead to measurement uncertainty. We demonstrate the characteristic differences between the polymer networks formed by the potassium and sodium forms of kappa-carrageenan, in 3D and at a resolution sufficient to resolve fiber bundles. Finally, we discuss the uncertainties involved in quantitative measurements obtainable with current methodologies as well as prospects for improvement.

Plant cell walls are the major structural component of fruits and vegetables, which break down to cell wall particles during ingestion (oral mastication) or food processing. The major health-promoting effect of cell walls occurs when they reach the colon and are fermented by the gut microbiota. In this study, the fermentation kinetics of carrot cell wall particle dispersions with different particle size and microstructure were investigated in vitro using porcine feces. The cumulative gas production and short-chain fatty acids (SCFAs) produced were measured at time intervals up to 48 h. The results show that larger cell clusters with an average particle size (d0.5) of 298 and 137 μm were more rapidly fermented and produced more SCFAs and gas than smaller single cells (75 μm) or cell fragments (50 μm), particularly between 8 and 20 h. Confocal microscopy suggests that the junctions between cells provides an environment that promotes bacterial growth, outweighing the greater specific surface area of smaller particles as a driver for more rapid fermentation. The study demonstrates that it may be possible, by controlling the size of cell wall particles, to design plant-based foods for fiber delivery and promotion of colon fermentation to maximize the potential for human health.

The use of ultrasound pre-processing treatment, compared to blanching, to enhance mechanical properties of non-starchy cell wall materials was investigated using carrot as an example. The mechanical properties of carrot tissues were measured by compression and tensile testing after the pre-processing treatment prior to and after retorting. Carrot samples ultrasound treated for 10 min at 60 °C provided a higher mechanical strength (P<0.05) to the cell wall structure than blanching for the same time period. With the addition of 0.5% CaCl(2) in the pre-treatment solution, both blanching and ultrasound treatment showed synergistic effect on enhancing the mechanical properties of retorted carrot pieces. At a relatively short treatment time (10 min at 60 °C) with the use of 0.5% CaCl(2), ultrasound treatment achieved similar enhancement to the mechanical strength of retorted carrots to blanching for a much longer time period (i.e. 40 min). The mechanism involved appears to be related to the stress responses present in all living plant matter. However, there is a need to clarify the relative importance of the potential stress mechanisms in order to get a better understanding of the processing conditions likely to be most effective. The amount of ultrasound treatment required is likely to involve low treatment intensities and there are indications from the structural characterisation and mechanical property analyses that the plant cell wall tissues were more elastic than that accomplished using low temperature long time blanching.

Plant cell wall structure integrity and associated tissue mechanical properties is one of key determinants for the perceived texture of plant-based foods. Carrots (Daucus carota) were used to investigate the effect of mineral supply of boron (B) and/or calcium (Ca), during plant growth, on the plant cell wall structure and mechanical properties of matured root tissues. Five commercial cultivars of carrots, Kuroda (orange), Dragon Purple, Kuttiger White, Yellow, and Nutri-Red, were cultivated under controlled glasshouse conditions over two seasons. Significant increases in the accumulation of B and Ca were found for all cultivars of carrots when additional B and Ca were included in the nutrient feeding solutions throughout the plant growth period. Elevated levels of B in carrot root tissue reduced the uptake of Ca and other mineral nutrients and enhanced plant cell wall structural integrity, its resistance to fracture, and the weight and size (both diameter and length) of carrots. Although higher amounts of Ca were accumulated in the plant materials, the additional supply of Ca did not have a significant effect on the mechanical properties of mature plant tissues or on the uptake of B by the plant. The results suggest that B cross-linking of pectin (rhamnogalacturonan II) has a greater influence on mature tissue mechanical properties than Ca cross-linking of pectin (homogalacturonan) when supplied during plant growth.

A range of thermal and mechanical processes were used to create dispersions with different particle morphologies, i.e., systems that contain primarily plant cell wall clusters with an average particle size (d(0.5)) of ∼200 µm, single cells ((d(0.5) = ∼70 µm) or cell fragments (d(0.5) = ∼40 µm). The small and large deformation rheology (viscoelastic properties and flow properties) of these dispersions, with a range of total solid contents covering textures varying from a fluid to a paste, were determined. The particle dispersions showed weak gel-like behaviour. Their elastic modulus (G′) as a function of total solid content exhibited three regions of different rheological behaviours. The particles formed particulate colloidal networks at relatively low solid content. The interaction of particles contributed to the sharp increase in the elastic modulus of the dispersion in the concentrated region. Further packing of particles beyond the critical packing volume fraction, caused the G′ for the ‘cluster-cell’ and the ‘single-cell’ dispersions to reach a plateau value. This is due to particle deformation resulting in changes in their microstructure and their ability to pack closely. Plant particle dispersions displayed abrupt yielding at the critical stress with a 3–4 order decrease in viscosity and high yield stress at low solids due to the formation of particulate colloidal network.

The rheological behaviour of plant cell-wall particle dispersions was investigated using dynamic oscillatory measurements. Two starting plant materials, broccoli stem and carrot were used and two types of particles were obtained by mechanically shearing blanched (80°C, 10 min) or cooked (100°C, 15 min) plant tissues. Blanching resulted in cell-wall particles made up of a collection of clusters of cells with an average particles size of ∼200 μm, while cooking generated nearly all single-cell particles with an average particle size of ∼80 μm. The rheological measurements showed that in the range of weight concentrations considered (∼0.5% to ∼8%) the dispersions behaved as elastic materials with the elastic modulus G' higher than G″ within the frequency range (0.01-10 Hz). This study shows that the behaviour of the complex modulus G* as a function of the effective volume fraction ϕ can be modelled using different theoretical equations. To do so, it is assumed that below a critical volume fraction ϕc a network of plant cell-wall particles was formed and G* as a function of ϕ obeys a power-law relationship. However above ϕc, where the particles were highly packed, G* could be modelled using theoretical equations developed for concentrated emulsions and elastic particle dispersions.

Radio-frequency glow-discharge plasma polymer thin films of allylamine (AA) and hexamethyldisiloxane (HMDSO) were prepared on silicon wafers and analyzed by a combination of X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), X-ray reflectometry (XRR), and neutron reflectometry (NR). AFM and XRR measurements revealed uniform, smooth, defect-free films of 20-30 nm thickness. XPS measurements gave compositional data on all elements in the films with the exception of hydrogen. In combination with XRR and NR, the film composition and mass densities (1.46 and 1.09 g cm(-)(3) for AA and HMDSO, respectively) were estimated. Further NR measurements were conducted with the AA and HMDSO films in contact with water at neutral pH. Three different H(2)O/D(2)O mixtures were used to vary the contrast between the aqueous phase and the polymer. The amount of water penetrating the film, as well as the number of labile protons present, was determined. The AA film in contact with water was found to swell by approximately 5%, contain approximately 3% water, and have approximately 24% labile protons. The HDMSO polymer was found to have approximately 6% labile protons, no thickness increase when in contact with water, and essentially no solvent penetration into the film. The difference in the degree of proton exchange within the films was attributed to the substantially different surface and bulk chemistries of the two films.