The influence of sucrose was investigated on the formation, microstructure and rheological behaviour of (1.5 wt%) agar fluid gels, with a focus on both the particulate and continuous phases. Rheology, texture analysis and phase contrast microscopy were used to assess the impact of sucrose concentration (0-60 wt%) and the timing of its addition. Increasing sucrose concentration resulted in a reduction of fluid gel particle size, increase in bulk viscosity, and slowed aggregation rate. At high concentrations of sucrose (>45 wt%) present during gelation, a significant increase in the gel particle stiffness and viscoelastic moduli was also observed. In contrast, sucrose addition after gel formation resulted in weakened rheological properties due to a reduction in effective volume fraction of the gel phase. Dilution studies revealed that unbound agar chains in the continuous phase contribute to maintaining interparticle interactions at reduced gel phase volume fractions. However, sucrose diminished the functional role of the continuous phase, likely due to contracted conformation of agar chains in the solution. These results provide insights into the functional relationship between agar and sucrose and offer practical guidance for the formulation of novel fluid gel-based foods where sucrose is a key component.

Quinoa is a pseudocereal with a complete essential amino acid profile and nutritionally favourable fatty acid composition. Here, cryo-milling was used to disrupt quinoa seeds, promoting the preservation of the native oleosome structure, which was then recovered by centrifugation of the cryo-milled seed suspension. The remaining flour suspension was used to extract quinoa protein isolate; applying alkalinisation followed by precipitation with HCl, acetic acid or citric acid. Microscopy, droplet size and zeta-potential data indicated recovered oleosomes were predominantly in their native state, which was retained after acid treatment. Quinoa protein precipitated with citric acid showed a higher denaturation enthalpy compared to protein precipitated with HCl or acetic acid. The citric acid-based protein gel also had the highest final gel strength and showed a fine stranded microstructure, while the HCl-based protein gel had the lowest final gel strength and displayed a particulate microstructure. Treatment with acetic acid gave a protein gel that demonstrated a mix of both types of microstructures. This study not only introduces quinoa seed oleosomes and quinoa protein isolate with improved and tailored functionality but also demonstrates the potential of cryo-milling as a seed disruption technology that allows recovery of intact oleosomes.

This study was designed to assess whether the functionality of quinoa protein isolate (QPI) precipitated with acetic acid (QPI-A), citric acid (QPI-C) or HCl (QPI-H) could be further improved or modulated by the dispersion conditions. The soluble protein content, protein profile, secondary structure, thermal properties, gelation behaviour and microstructure of the isolates were evaluated. Dispersion in water for 24 h promoted the solubilisation of QPI-H and improved gel strength. Dispersion in 0.1 M NaCl for 1 h resulted in extensive protein aggregation and hindered gel formation in QPI-A and QPI-C. Dialysis before dispersion impaired the gelation properties for all three types of isolates. The demonstrated ability to improve or modulate the functional properties of QPI not only by choice of precipitation acid but also by dispersion conditions provides a handle for product formulators to broaden the application spectrum for QPI across a range of food textures.

The typically low solubility and gelation capacity of plant proteins can impose challenges in the design of high-quality plant-based foods. The acid used during the precipitation step of plant protein isolate extraction can influence protein functionality. Here, acetic acid and citric acid were used to extract quinoa protein isolate (QPI) from quinoa flour, as these acids are more kosmotropic than the commonly used HCl, promoting the stabilisation of the native protein structure. While proximate analysis showed that total protein was similar for the three isolates, precipitation with kosmotropic acids increased soluble protein, which correlated positively with gel strength. Microstructure analysis revealed that these gels contained a less porous protein network with lipid droplet inclusions. This study shows that the choice of precipitation acid offers an opportunity to tailor the properties of quinoa protein isolate for application, a strategy that is likely applicable to other plant protein isolates.

Cream liqueur formulations are limited to ethanol concentrations below 20wt% due to clumping of the lipid phase at higher levels. However, it is not generally understood whether the properties of the dispersed phase, containing surface-active and crystallising lipids, or the detrimental impact of ethanol on the emulsifying properties of protein are responsible for this limitation. Here, model cream liqueurs were processed, containing solely ethanol (0, 15 or 50wt%), water, sodium caseinate (3wt%) and one of three lipid phases (10wt%): sunflower oil stripped off surface-active molecules, native sunflower oil, or clarified butterfat. Ethanol was added either before or immediately after emulsion processing in a microfluidizer, and final emulsions were stored at 5 °C. At 0 and 15wt% ethanol, independent of point of ethanol addition, native oil and butterfat resulted in up to three times smaller emulsion droplets than treated oil, remained stable for at least nine months. The presence of ethanol (15wt%) suppressed butterfat crystallisation at the selected storage temperature. At 50wt% ethanol, the presence of a crystallising lipid fraction negatively affected emulsion stability, as such butterfat emulsions showed immediate clustering and creaming. Native oil-based emulsions were stable against creaming and coalescence at this ethanol level. The study concludes that the interplay of ethanol-compromised emulsifying properties of the protein and the crystallisation characteristics of the lipid inhibits the formulation of a commercially viable cream liqueur at elevated ethanol concentrations. For non-crystallising lipid phases however, the novel findings reported in this study are encouraging in view to formulating alternative product ranges.

Lignin is the second most abundant natural polymer after cellulose, and valorisation of lignin-rich streams has attracted increasing attention recently. This paper presents a novel and sustainable method to recover lignin from Cocoa Bean Shells (CBS) using Deep Eutectic Solvents (DES) and microwaves. A DES containing p-toluenesulfonic acid, choline chloride and glycerol (2:1:1 M ratio) was selected based on its dielectric properties. Under 200 W microwave power, the optimum yield of 95.5 % lignin was achieved at 130 degrees C and 30 min. DES-extracted lignin exhibited unique structural characteristics including larger particle sizes (242.5 mu m D50 size), structural diversity (410.4 mu m D90-D10 size) and H/G sub-unit ratio (71.9 %) compared with commercial Kraft lignin (77.2 mu m, 157.9 mu m and 0.1 % respectively), indicating the potential of DES in the modification and upgrading of lignin for novel value-added products.

Chloroplasts are abundant organelles in a diverse range of plant materials; they are predominantly composed of multicomponent thylakoid membranes which are lipid and protein rich. Intact or unravelled thylakoid membranes should, in principle, have interfacial activity, but little has been published on their activity in oil-in-water systems, and nothing on their performance on an oil continuous system. In this work different physical methods were used to produce a range of chloroplast/thylakoid suspensions with varying degrees of membrane integrity. Transmission electron microscopy revealed that pressure homogenisation led to the greatest extent of membrane and organelle disruption compared to less energy intensive preparation methods The ability of the derived materials to modulate the flow behaviour of a chocolate model system (65% (w/w) sugar/ sunflower oil (natural amphiphiles removed) suspension) was investigated by acquiring rheological parameters. All chloroplast/ thylakoid preparations reduced yield stress, apparent viscosity, tangent flow point and cross over point in a concentration-dependent fashion, although not as significantly as polyglycerol polyricinoleate applied at a commercially relevant concentration in the same chocolate model system. Confocal laser scanning microscopy confirmed presence of the alternative flow enhancer material at the sugar surfaces. This research reveals that low-energy processing methods that do not extensively disrupt thylakoid membranes are applicable to generating materials with marked capacity to affect the flow behaviour of a chocolate model system. In conclusion, chloroplast/thylakoid materials hold strong potential as natural alternatives to synthetic rheology modifiers for lipid-based systems such as PGPR.

Sucrose oleate was assessed as alternative lipophilic emulsifier to polyglycerol polyricinoleate (PGPR) for the stabilisation of the internal aqueous phase of a water-in-oil-in-water emulsion formulation designed for salt release from the internal aqueous phase during oral processing. The study was motivated by the fact that PGPR is generally regarded as not label friendly. A water-in-oil emulsion (30 g water/100 g oil), containing an internalised salt solution (1.5 g salt/100 g), was successfully incorporated as droplets into a salt containing external aqueous phase (0.5 g salt/100 g) with in-situ gelatinised waxy rice starch (WRS) stabilising the oil droplet interface. The droplets of the sucrose ester stabilised water-in-oil emulsion were aggregated, and this microstructure carried over into the water-in-oil-in-water emulsion. The PGPR stabilised water-in-oil emulsion showed no evidence of aggregation, and the primary droplet size was smaller. Mean oil droplet size was comparable, slightly increasing for the sucrose ester containing formulation over a 3-months observation period. Nevertheless, salt encapsulation efficiency, reducing by around 10% over 3-months, as well as in vitro salt release, reducing by 20%, were comparable. This study demonstrated that sucrose ester SE O-170 is a viable replacement for PGPR in w/o/w emulsions designed for salt release during oral processing.

Polyglycerol polyricinoleate (PGPR) is a food emulsifier with a unique yield stress reducing efficacy in fat-based suspensions. There are many commercially available PGPRs, and the different products vary in their impact on the yield stress. Choosing the right PGPR for a specific formulation is often based on empirical data and the experience of the formulator. Lack of fundamental understanding of why these differences exist hampers reformulation efforts to replace PGPR. Therefore, this study aimed to link the yield stress reducing efficacy of PGPR to its molecular properties. Five commercial PGPR samples were studied (3 g/kg) in a concentrated sus-pension of icing sugar (650 g/kg, asymptotic to 530 mL/L) in sunflower oil (with naturally-occurring surface-active mole-cules removed). Rheological analysis revealed Herschel-Bulkley yield stress variations of between 0.90 +/- 0.06 Pa and 1.90 +/- 0.18 Pa, compared to 57.6 +/- 15.8 Pa in the absence of PGPR. Yield stress was correlated to critical micelle concentration, obtained from oil-water interfacial tension data. Applying molecular characterisation techniques revealed that the presence of a hydroxyl group on the fatty acid at the end of the polyricinoleate estolide chain could be linked to inferior yield stress reducing efficacy.

Consumers are increasingly looking for new plant-based alternatives to substitute animal proteins in their diets but for some applications it can be difficult to achieve the desired product microstructure using only plant proteins. One approach to facilitate structuring is to mix these plant-based ingredients with a polysaccharide. Here, the phase behaviour and microstructure of quinoa protein isolate (QPI) in mixture with maltodextrin (MD) of two dextrose equivalents (DE 7 and 2) were investigated. The binodals of both QPI-MD phase diagrams showed an atypical shape, where the concentration of MD in the QPI-rich phase and of QPI in the MD-rich phase increased with overall biopolymer concentration. Molecular weight distribution and microstructure analyses revealed that both maltodextrins fractionated between the phases and were probably entrapped within the volume-spanning protein network in the QPI-rich phase, indicating a depletion flocculation mechanism of phase separation. The pre-heating of QPI and the removal of salt from the systems resulted in similarly atypical phase diagrams. The approach presented contributes to our understanding of the phase behaviour of mixtures between plant proteins and polysaccharides, while the results suggest that the formulation of plant-based products of predictable properties may be more challenging than anticipated.

This chapter introduces the perception of food flavour, mainly aroma and taste, across the disciplines of biology and physics. Biology explains how the basic biological receptors in the nose or on the tongue, when in contact with aroma compounds or tastants, provide sensory stimuli for the brain. Olfaction and gustation are the main sensations with respect to aroma and taste perception, although olfactory–gustatory interactions, vision and the oral somatosensory system also contribute. Physics explains the transport of aromas and tastants to the receptors on the surface of the pharynx or tongue, which are affected by both thermodynamics and kinetics. Thermodynamics defines the partition coefficients of aroma compounds and their interactions with the food components that modify aroma partitioning. Kinetics are important in the function of saliva during eating and the impact of food form, which link to the modification of the flow properties of a food in the mouth, affecting aroma or tastant transport. This chapter emphasizes the biophysics of aroma and taste perception in relation to human oral processing and food structure.

Xanthan gum and scleroglucan, two rod-like polysaccharide hydrocolloids, are compared using a wide range of instrumental techniques and methods: steady shear flow, small amplitude oscillatory shear, first normal stress difference, capillary break-up and soft-contact tribology. The aqueous solutions of these two hydrocolloids with similar flow and viscoelastic profile show marked differences in capillary break-up time and apparent extensional viscosity. This result correlates with differences in first normal stress difference and, to a lesser extent, Stribeck curve behaviour. Formulating the hydrocolloids in concentrated sucrose solution (40 wt%) shifts relaxation profiles to longer times which greatly diminishes differences in rheological and lubrication behaviour. With exception of capillary break-up tests, no other methods showed statistically significant differences between the polysaccharides dissolved in the viscosified matrix. The toolbox of techniques is also applied to probe interactions of xanthan gum and scleroglucan with human whole saliva and bovine submaxillary mucin. We report no specific interactions between either hydrocolloid and salivary proteins and suggest that any cumulative effects must stem from specific sets of linear and non-linear rheological properties of saliva/hydrocolloid mixtures.

10 Proteins are commonly used as emulsifying agent in food applications, although they are highly 11 affected by their environment, with the presence of ethanol being just one parameter known to 12 influence their properties. An increasing level of ethanol is expected to result in a reduced 13 emulsification efficiency of the protein and, therefore, emulsion processing in the absence of this 14 solvent should lead to more stable oil-in-water emulsions. Sodium caseinate was either dispersed in 15 the presence or absence of heat and/or ethanol and multiple physicochemical properties of the 16 resulting protein aggregates were determined. Further, oil-in-water emulsions were created in a 17 microfluidizer at varying levels of ethanol in the aqueous phase and two different points of its addition 18 in the processing route. The resulting emulsion properties were investigated. Stable oil-in-water 19 emulsions could be prepared at each applied ethanol level (≤ 50 wt.%) and for both examined 20 processing routes. The point of ethanol addition only had an impact if the concentration of this solvent 21 was higher than 25 wt.% - with a processing in absence of ethanol being beneficial. This concentration 22 was also found to be a threshold for the interactions between ethanol and dispersed sodium caseinate 23 as higher ethanol levels resulted in significantly changed protein properties. 24

Equal parts of sugar beet pectin and sodium caseinate were interacted through electrostatic attraction, enzymatic crosslinking, and the Maillard reaction to prepare three oil-in-water emulsifier systems. Oil-in-water emulsions (10%) were processed via high shear overhead mixing at the natural pH of the emulsifier systems, followed by pH adjustment to pH 4.5 and pH 7. The emulsions were stable against coalescence, except for a slight increase in the mean droplet size for the enzymatic cross-liked emulsion at pH 4.5 over a 14-day storage period. This emulsion also showed the lowest absolute zeta (ζ)-potential value of near 30 mV. The Maillard interaction emulsifier system resulted in larger droplet sizes compared to the other two emulsifier systems. Small deformation oscillatory shear rheology assessment of the emulsion cream phases revealed an impact of the emulsifier system design at pH 4.5.

Proteins are commonly used as emulsifying agent in food applications, although they are highly affected by their environment, with the presence of ethanol being just one parameter known to influence their properties. An increasing level of ethanol is expected to result in a reduced emulsification efficiency of the protein and, therefore, emulsion processing in the absence of this solvent should lead to more stable oil-in-water emulsions. Sodium caseinate was either dispersed in the presence or absence of heat and/or ethanol and multiple physicochemical properties of the resulting protein aggregates were determined. Further, oil-in-water emulsions were created in a microfluidizer at varying levels of ethanol in the aqueous phase and two different points of its addition in the processing route. The resulting emulsion properties were investigated. Stable oil-in-water emulsions could be prepared at each applied ethanol level (<= 50 wt%) and for both examined processing routes. The point of ethanol addition only had an impact if the concentration of this solvent was higher than 25 wt% - with a processing in absence of ethanol being beneficial. This concentration was also found to be a threshold for the interactions between ethanol and dispersed sodium caseinate as higher ethanol levels resulted in significantly changed protein properties.

This study concerns the preparation and functionality testing of a new class of Pickering particles for food emulsion stabilization: colloidal lignin-rich particles (CLRPs) derived from ethanol-soluble extract of cocoa shell. A further goal was to achieve Pickering functionality without the need to add co-emulsifying surfactants during emulsion processing. Cocoa shell is a co-product of the food manufacturing industry. As such it is anticipated that the particles would be accepted as a natural food ingredient, provided no harmful solvents are used in any step of their processing. The cocoa shell particles were milled, dispersed in water and exposed to 250 °C for 1 h in a stainless-steel tubular reactor followed by ethanol extraction to obtain a lignin-rich extract (46% (w/w) lignin with the remainder predominantly lipids). CLRPs were then fabricated by the precipitation of ethanol-dissolved extract into water (antisolvent). By employing an agitated process and droplet dosing into a non-agitated process, four particle suspensions of a range of submicron diameters were obtained. All particle suspensions contained the same mass fraction of extract and were surface active, with surface tension decreasing with increasing particle size. The smallest particles were obtained when lipids were removed from the extract prior to particle processing. In contrast to the other four particle suspensions, this one failed to stabilize a 10% (w/w) sunflower oil-in-water emulsion. We hypothesize that the phospholipids indigenously present in these CLRP formulations are a critical component for Pickering functionality. It can be concluded that we have successfully introduced a new class of Pickering particles, fabricated from an industry co-product and anticipated to be food grade.

Sugar, salt, and fat are health-sensitive nutrients widely added to processed foods. This may be as processing aide, for preservation, for flavour enhancement, or to develop the product-specific structure. While the reasons for their application are frequently interlinked, the primary focus of this chapter is on food structure. What is the structure functionality of sugar, salt, and fat? What are the healthy alternatives to these nutrients, and what is the impact on food structure? Are there food structure approaches for the reduction of sugar, salt, and fat? There are, and some of the approaches discussed in this chapter include particles with designed morphology (size, shape, internal microstructure), emulsion droplets with encapsulated water (fat reduction), or salt/sugar solution (salt/sugar reduction), bubbles as zero calorie as tastant-excluding fillers, and water-in-water emulsions mimicking the mouthfeel of water-in-oil emulsions (fat reduction). It is concluded that replacement strategies for health-compromising tastants have been exhausted, and levels of reduction are limited by their technological functions. Progress has been made with the food structure approach, ensuring an acceptable flavour profile; future efforts to achieve further reductions of sugar, salt, and fat need to consider the manufacturing paradigm as a variable.

In this study the possibility of replacing current surfactants in chocolate formulations with natural lipids extracted from spinach leaf (SPLIP) or spinach chloroplast (CH.SPLIP) was evaluated. SPLIP and CH.SPLIP were extracted with chloroform/methanol following enzyme deactivation with hot isopropanol. Results showed a higher extraction yield for SPLIP while glycolipids were more concentrated in CH.SPLIP. Sugar/oil suspensions with dispersed volume fractions of 0.28, 0.33 and 0.37 containing 0.1% to 0.7% (w/w) surfactant (SPLIP, CH.SPLIP, lecithin and PGPR as commercial references) based on oil phase were prepared and analyzed in shear rheology. Apparent viscosity at 40 s(-1) was significantly lower for the natural surfactants compared to lecithin at 0.5-0.7% (w/w) addition. With regard to yield stress, taken as the shear stress at 5 s(-1), both natural surfactants showed comparable performance to PGPR at 0.3% to 0.7% addition. As SPLIP and CH.SPLIP behaved similar (p > 0.05), SPLIP, due to higher extraction yield, would be the preferred choice for application in chocolate matrices.

Polysaccharides and proteins are frequently conjugated through electrostatic attraction, enzymatic cross-linking, and heat treatment (Maillard reaction) to obtain food structuring ingredients, mostly for their application as emulsifiers. The conjugate partners and their interaction type affect performance at acidic or neutral pH and during thermal processing, thus requiring careful selection. Here, the aggregate properties (particle size, conjugate charge, shear viscosity) of three types of sugar beet pectin (SBP)-sodium caseinate (SC) 1:1 conjugates, at acidic and neutral pH (4.5; 7), as well as their thermal processing stability (80 °C), were investigated. The enzymatically cross-linked SBP:SC was more acid tolerant than the electrostatically interacting conjugates. Maillard cross-linked conjugates aggregated at pH 4.5, suggesting poor emulsifier performance in acidic conditions. At pH 7, the three conjugate types showed similar aggregate properties. The results are discussed in terms of structural re-arrangement.

Water-in-oil-in-water emulsions containing an internalised salt solution were stabilised with non-chemically modified waxy rice starch (WRS), and octinyl succinic anhydride (OSA) as reference, to release salt during oral processing due to amylase-induced destabilisation. Salt levels were 1.5 g salt and 0.47 g salt per 100 g external and internal aqueous phases, respectively. Variables were the starch content (2, 3, 4 g per 100 g emulsion; 20 g oil per 100 g emulsion), level of polyglycerol polyricinoleate (PGPR) as a lipophilic emulsifier (0.29, 0.57 g per 100 g emulsion) and ambient-pressure processing temperature for WRS gelatinisation, the non-chemical modification process, (75 ± 3, 88 ± 5 °C). OSA starch was used under previously applied conditions (2, 3, 4 g starch, 0.57 g PGPR per 100 g emulsion, 25 ± 5 °C). Emulsions were stable for three months, except OSA and lower level PGPR low temperature processed WRS emulsions lost salt into the external emulsion phase. One day after processing, encapsulation efficiency (EE) was as predicted from the composition for OSA emulsions, while at the same PGPR content an external aqueous phase was incorporated into the oil droplets of the WRS emulsion increasing EE. Salt release was assessed in vitro and through sensory evaluation using paired comparison testing. The results revealed that the efficacy of this salt reduction approach was enhanced for gelatinised WRS compared to OSA starch stabilised emulsions. Consumer tests on a tomato soup, to validate this salt reduction approach for a real food, revealed a possible 25% salt reduction, compared to current UK products.