Accepted Abstracts for Oral Presentations

ASSESSING 3D PRINTABILITY OF MILLET-BASED MATERIAL SUPPLY THROUGH X-RAY DIFFRACTION STUDIES

P. S, R. P, Moses J

3D printing in the production of millet-based food items has been found to positively impact both the nutritional value and consumer perception of the final product. Banana pulp (BP) was

employed as a natural ingredient to enhance the sensory qualities, acting as a natural taste and flavour enhancer of pearl millet flour (PMF). In the process of creating a material supply

formulation based on pearl millet, the PMF was evaluated both in its pure form and with the incorporation of BP at five distinct ratios (PMF:BP; 100:0, 80:20, 60:40, 40:60, 20:80, and 0:100). The water content of material supply was optimized based on the moisture content (>50%) for all the formulations. The X-ray diffraction (XRD) pattern of all the material supply formulations denotes the materials' crystallinity and amorphous nature. The crystallinity majorly influences the printability of the material supply. The results of XRD also correlated with the rheological behavior of the material supply. The printing nature was identified for 100:0, 80:20, and 60:40 composition through the printability studies. Among these, the 60:40 formulation has

good printability with high precision and layer definition, proved by the visual sensory evaluation. This is the first work to explain the printability of food materials based on the crystallinity behavior of the material.

 

Co-extrusion Confusion: the Challenges of Sausage Manufacturing Using Plant-based Gels

Zajac M

Co-extrusion is a well-known food manufacturing technique involving formation of extrudate from multiple raw materials pumped through the same dye. In the last decade it has been gaining popularity in the commercial sausage production due to smaller footprint of required equipment, higher line speeds achievable and fewer staff needed to operate it. Additional to the cost savings it offers, it expands the range of polymers suitable to form edible sausage casings, which can be derived from more sustainable sources. Among these, the most common material is sodium alginate – a polysaccharide sourced from several species of seaweed. However, depending on the extraction method and part of the plant it is derived from, its chemical composition and physical properties can vary significantly. It is, therefore, important to understand the key characteristics of different grades of alginate available on the market that drive their suitability for sausage co-extrusion. This review presents the industrial perspective on the usefulness of Rheology in the quality control of the commercially available sodium alginate grades and their variability. It also discusses how those methods can guide the product development of alginate food gels suitable for sausage co-extrusion process.

 

Effects of Xanthan Gum on Foam Properties and Physical Characteristics of Beetroot Powders Produced by Foam-Mat Freeze-Drying

Bodapati V, Vanchipurackal Sherif S, Farshchi A

Beetroot extract powder, enriched with bioactive compounds such as betaines and antioxidants, can be used as a valuable natural colouring agent in functional food formulations and various food products. This study explores the impact of xanthan gum, a versatile carrier agent, on the foam stability and physical properties of beetroot powders produced through foam-mat freeze-drying techniques. Beetroot extracts were whipped and transformed into foams by adding egg white protein (5 wt%) as the foaming agent, with maltodextrin (5 wt%) and xanthan gum (0.05, 0.1, and 0.2 wt%) added as foam stabilizers.

The addition of maltodextrin and xanthan gum led to a substantial improvement in foam stability, with remarkable enhancements observed upon incorporating 0.2 wt% xanthan gum; no drainage was observed even after 4 hours.

However, xanthan gum was found to decrease the overrun% which was consistent with optical microscopic observations and foam density measurements. These measurements revealed the highest bulk density and fewer occurrences of bubble coalescence at the 2 wt% xanthan concentration.

Furthermore, xanthan gum significantly influenced the functional properties of beetroot powders. Its addition improved powder flowability, achieving the lowest Hausner ratio (HR) with 0.2 wt% xanthan gum. However, the dissolution rate exhibited a remarkable decrease with increasing xanthan concentration. Xanthan gum, also, led to a decrease in the moisture sorption capacity of the beetroot powder.

 

From structure to function: In Situ Analysis of Structural Heterogeneities in Multi-phase Colloidal Systems Utilizing Microfluidics and Chemical Imaging Technologies.

Neofytos D, Gregersen S, Andersen U, Corredig M

From structure to function: In Situ Analysis of Structural Heterogeneities in Multi-phase Colloidal Systems Utilizing Microfluidics and Chemical Imaging Technologies.

The interactions between food formulations’ components and the dynamics at molecular and supramolecular levels play a crucial role in shaping the structure and function of complex food products. Most food matrixes consist of proteins, polysaccharides, and lipids, and exhibit structural heterogeneities at micro- and meso-length scales, influencing their bulk properties significantly. Understanding these heterogeneities in spatial resolution is key for unravelling the intricate relation between composition, structure, and function in complex food systems. A holistic, mechanistic approach to these systems' analysis in situ and in spatial resolution, can provide essential information about systems dynamics and provide a description of structure formation in spatial resolution, showing how structural heterogeneities are important for texture formation.

In our research, we leverage advanced microfluidics to create and manipulate colloidal systems of monodispersed oil droplets with diverse interface compositions. Employing cutting-edge imaging techniques such as Confocal Raman Microscopy and Imaging in combination with FT-IR Imaging, we are able to localize, quantify and analyze protein structures and interactions in complex multiphase systems. This approach allows us to explore the composition and dynamics of oil-water interfaces, as well as to evaluate their impact on phenomena like lipid domain crystallization dynamics, in situ and in spatial resolution.

Our work demonstrates the potential of combining advanced microfluidics and spectroscopic imaging techniques to unravel structure formation in complex food matrices. By systematically increasing system complexity and performing single droplet analysis, we have achieved a deeper understanding of structure formation, conducting precise analysis in spatial resolution. The combination of Spectroscopic Imaging and Microfluidics emerges as a potent tool for in situ analysis of complex systems, as depicted in Figure 1. We also delve into the critical steps required for robust data analysis and interpretation, showcasing the potential of these techniques for gaining valuable insights into complex food systems analysis.

 

Origins of polysaccharide conformation and viscoelasticity in miscible heterogeneous solvents

Kumar Borah P, Irani A, Reid J, Wesberry B, Harding S, Nicholson R, Baier S, Williams M, Yakubov G

Polysaccharide polymers constitute the fundamental building blocks of life that display a diverse set of conformational states which results in complex viscoelastic behaviour of their solutions. Utilising a model high molecular weight, high Trouton ratio ‘pectin’ polysaccharide extracted from okra mucilage (Abelmoschus esculentus), we combine computer simulations and experimental data to unveil the underlying microscopic hydrodynamic origins of polysaccharide conformation in miscible heterogenous solvents of water and glycerol. We uncovered that the polysaccharide chain undergoes a conformational transition from swelled-to-collapsed configurations, resulting in marked changes in viscoelastic response. The conformational transition is entropy driven. Molecularly adsorbed water molecules have increased presence within ca. 0.40 nm of the chain surface with increase of glycerol in the solvent composition, thus indicating the emergence of preferential solvation. This preferential solvation elicits an entropically unfavourable dynamic solvent heterogeneity, which is lessened by swelling and collapse of polysaccharide chains. Our results provide an essential missing piece of the puzzle that is inaccessible through mean-field assumptions and offer new fundamental insights applicable in food structure design and, more broadly, in biomedical and bioengineering applications.

 

Particle transfer and bolus transformation during mastication flow

Richards J

Many foods are complex multi-phase materials, as they are chewed and mixed with saliva during mastication particular components may transfer to the saliva. This can be vital to the taste and mouthfeel. A prime example of this is chocolate, which can be viewed as a concentrated suspension of particles, including sugar, in a melted cocoa butter background. In this work, we study a model system of hydrophilic particles in an oil background that mimics the rheological and interfacial properties of chocolate. By using glass particles, confocal microscopy during flow is used to track the movement of particles through the interface, from the oil to aqueous, saliva-like phase. This reveals the key role of stress and deformation in actively driving particles into the saliva, influencing the bolus transformation process.

 

Potential for enhanced infrared spectroscopy of food using metamaterials

Nash G

Infrared spectroscopy is a well-established tool providing a label-free, non-destructive method to identify chemicals. As infrared light is absorbed by unique vibrational and rotational- modes of specific chemical bonds, the chemical components of a sample can be identified by measuring the amount of infrared light absorbed at specific frequencies. In contrast to other techniques, infrared spectroscopy removes the need for complex sample preparation, making the technique ideal for characterisation of food samples. However, although infrared spectroscopy is therefore relatively quick, and portable, techniques such as gas chromatography are still dominant for trace chemical detection due to their higher sensitivity.

Over the last few years there has been considerable work exploring how new engineered materials, known as metamaterials, can be used to enhance the sensitivity of infrared spectroscopy by producing very intense light fields in specific regions, increasing the interaction with molecules under study. Metamaterials are a new class of artificial material that can be engineered to possess properties that do not exist in natural materials. Optical metamaterials that are chiral themselves can also be designed to enhance the interaction of light with chiral molecules, as they can be used to produce strongly localized circularly polarised light fields, in turn improving the ability to detect and characterize chiral molecules and allowing smaller concentrations be determined and identified more easily. The effective spatial concentration of light in a chiral metamaterial would be particularly important if achieved in the mid-infrared region of the spectrum, as it could improve the sensitivity and resolution of vibrational circular dichroism spectroscopy (VCD), an essential tool for characterizing chiral molecules via their vibrational modes. Preliminary experiments undertaken at Exeter have shown that it is possible to use a single chiral metamaterial to identify the two enantiomers of alanine, an important amino acid, with a clear difference in their measured infrared spectra. Ultimately, metamaterials could be used as the building block of cost-effective analytic tools, allowing VCD measurements to be carried out throughout a production process.

 

Recent advances in optical food microstructure imaging

Clausen M

Microscopy, as a non-invasive tool, has significantly contributed to unravelling the complexities of biological systems. However, its application in the study of food microstructures, a cornerstone in determining food properties and structures, has been relatively understated. This presentation explores the practical application of diverse modern optical microscopy techniques to study microscopic structures within a variety of food products, ranging from protein-dominated gels to high-fat emulsions.

Our focus encompasses the examination of animal- and plant-protein gels, such as egg, dairy, and marine and plant-hydrogels, employing super-resolution fluorescence microscopy (SRM). SRM methods, exhibiting a 5-10-fold spatial resolution improvement over conventional confocal laser-scanning microscopy, allow for a detailed exploration of the protein aggregation and gelation processes unlocking previously inaccessible spatial and temporal regimes.

A further focus is on food emulsions and intact food tissue visualized using label-free optical microscopy methods based on the intrinsic sample signal, e.g., chemical signal, structural signal, and auto-fluorescence. The minimal sample preparation in these techniques ensures that complex food systems can be visualized in their native state while maintaining high spatial resolution and the ability to follow dynamic food processes.

Machine learning software aids in the analysis and quantification, offering a more accurate correlation between microscopic features and rheological properties of food systems.

The broader implications of our research extend to the understanding of food systems as complex materials with diverse soft matter behaviours. By delving into the microscopic intricacies, this work contributes to a deeper comprehension of material properties, quality, nutritional dynamics, and overall behaviour of a range of food products. Our findings emphasize the pivotal role of optical microscopy in connecting knowledge across length scales, providing fundamental insights into food structures essential for designing the functional foods of tomorrow and ensuring a sustainable and enjoyable culinary landscape.

 

Solvent-driven food transformation of jellyfish hydrogel

Pedersen M, Vilgis T, Brewer J, Hansen P, Clausen M

Jellyfish have recently emerged as a promising sustainable food source, yet they present a unique challenge in culinary science primarily attributed to their soft hydrogel structure complicating the attainment of a desirable texture and mouthfeel. Despite novel preparation methods for utilizing jellyfish as food have been proposed, there is a gap in understanding the underlying mechanisms of these innovative approaches. Specifically, one such method involves solvent-driven food preparation, capable of a remarkable transformation of jellyfish into a crispy-like texture [1]. This unconventional cooking process involves soaking jellyfish in high concentrations of ethanol followed by solvent evaporation. In this study, we shed light on the underlying mechanism of the solvent-driven transformation of jellyfish [2].

Jellyfish were systematically soaked in various mixtures of water with either ethanol or acetone, facilitating exploration of the interplay between solvent quality and the jellyfish gel matrix. Employing a combination of rheology measurements, Stimulated Emission Depletion (STED) imaging, and quantitative image analysis, we investigate the solvent effects on the jellyfish hydrogel. The results demonstrates that low polarity of solvents induce deswelling, notable increase in gel hardness and significant microstructural alterations within the jellyfish gel matrix. These changes of the jellyfish matrix properties were identified to be crucial for obtaining crispy jellyfish texture upon solvent evaporation.

The study introduces the novel solvent-based preparation method as a reverse cooking technique that incorporates principles of soft matter physics into gastronomic innovation. By investigating the underlying mechanism of solvent-induced transformation of the jellyfish hydrogel, our results not only advance the scientific understanding of jellyfish food preparations but also contributes to a broader knowledge of hydrogel-based materials in culinary contexts.

 

Reference:

[1] Pedersen et al., On the gastrophysics of jellyfish preparation, Int. J of Gastronomy and Food Science, 9, 34-38, 2017.

[2] Pedersen et al., Structural characterization of solvent-based food preparation of jellyfish, under review.

 

Sugar replacement in foods via physical principles

Van Der Sman R, Renzetti S

Due to increasing concerns about obesitas and cardiovascular diseases food industry is facing the challenge to reduce sugar amounts in their products. As sugars do not only provide sweetness, but also have a multitude of other functions their replacement is a difficult task. The most challenging part of sugar replacement is to reproduce the textural properties of the original product in the reformulated product. In the last years we have investigated the functionality of sugars in sweet bakery products like biscuits and cakes. We have realized that most of their functionality boils down to sugars properties as 1) a plasticizer, and 2) a humectant. Prior to that we had developed physical theories describing the behaviour of sugars and their replacers as plasticizers and humectants. The plasticizing behaviour of carbohydrates can be mapped to the volumetric density of (intermolecular) hydrogen bonds, which can be computed from the glass transition of the dry material. The humectant properties, i.e. water sorption, are described by the Flory-Huggins theory, with the interaction parameter being a function of molecular weight.

Based on the above physical theories we have developed a sugar replacement strategy, for the replication of textural properties in sweet bakery properties [1]. As a first step one needs to calculate two characteristic numbers, 1) the volume averaged density of intermolecular hydrogen bonds of all plasticizers present (including water), and 2) the volume-averaged Flory-Huggins interaction parameter of all humectants (all plasticizers excluding water). In the reformulated product one needs to reproduce exactly these two numbers to have a similar texture as the original product. The strategy has been tested with biscuits, which have been subjected to a trained sensorial panel. The trials have shown that textural properties of biscuits indeed correlate strongly with the two defined characteristic numbers, and that biscuits with similar values of these characteristic numbers have a texture indistinguishable from the original biscuit. Successful reformulations included combinations of small polyols and fructo-oligosaccharides. With our strategy we have even achieved 100% sugar replacement with multiple reformulations. Hence, our strategy even leaves room for further optimization towards sweetness, fiber content or reduced laxative properties. Subsequent study shows that our strategy is also applicable to cake, albeit with a slight adaptation [2]. Hence, we think the strategy is also applicable to other food categories like beverages, dairy desserts, candy and ice cream.

 

References:

[1] van der Sman, R. G. M., et al. "Universal strategy for sugar replacement in foods?." Food Hydrocolloids 133 (2022): 107966.

[2] Renzetti, Stefano, and Ruud GM van der Sman. "Food texture design in sugar reduced cakes: Predicting batters rheology and physical properties of cakes from physicochemical principles." Food Hydrocolloids 131 (2022): 107795.

 

The elastic properties of soft solids characterised by acoustics and rheology and exemplified in anhydrous milk fat (AMF)

Povey M, Hefft D

Foods vary in their elastic properties over a wide range of behaviours. In the case of mastication, textures vary from hard solid through brittle (chocolate bar) and crispy/crunchy (biscuits) to viscous and extensional flow (syrup) and finally very low viscosity fluid (water). Here we deploy an elastic description of soft solids which embraces all these behaviours to quantify the elastic behaviour of food, in particular through the use of sound. We illustrate the use of this mathematical description in the quantitative characterisation of the elastic and flow properties of food through orthodox measurement techniques and novel ultrasound methods. Measurement is complicated by human sensory capabilities that span the entire range from solid to fluid to gas in an integrated manner, during the appreciation of food. We use acoustic and rheological measurement techniques for the determination of the mechanical properties of soft solids, comparing oscillatory rheometry with acoustic parameters as exemplified by acoustic and oscillatory rheometry measurements in crystallising anhydrous milk fat (AMF). We conclude that acoustic and rheological measurements complement each other with acoustic techniques offering the possibility of inline, in process determination of mechanical and flow properties such as viscosity, rigidity, compressibility and bulk modulus.

 

The oral cavity as a micro-rheometer

Wandersman E

The oral cavity is extremely sensitive for detecting and discriminating the texture of a food product. One hypothesis to explain this extreme sensitivity is the presence of filliform papillae on the surface of the tongue, which are elongated structures with a large aspect ratio, not involved in the sense of taste.  We have therefore developed artificial tongues decorated with analogues of filiform papillae. The tongue is then filled with model liquids and we measure using rheomicroscopy tools the deflections of the apex of these papillae when the liquid is sheared. Our results showed that the average deflection of the papillae was proportional to the local shear stress and allows to determine the viscosity of the liquid probed, up to viscosities as low as that of water. Then, we showed that when a diluted granular suspension is sheared (as a textured liquid food analogue), each individual passage of a particle induces a fluctuation in deflection of the papilla. This behaves like a particle detector. Measuring the deflection gives access to the particle concentrations and sizes.

 

 

Time-of-flight spin-echo SANS (SESANS) measurements of food hydrocolloids

Smith G

Neutrons have found extensive use in the study of food materials, due to their ability to probe a wide range of length scales and crucially due to their sensitivity for light elements, particularly hydrogen. This is especially true for food hydrocolloids, which can contain highly hydrated polymers where the neutron's sensitivity for the difference isotopes of hydrogen (1H or protium, 2H or deuterium) can be exploited. This presentation will discuss an example of how a neutron scattering technique (spin-echo small-angle neutron scattering or SESANS) has been used to study colloidal structures in an example food hydrocolloid (casein micelles in D2O).

The SESANS technique uses the spin of a neutron to quantify scattering at very small angles or equivalently long length scales, which is beneficial for the study of colloidal particles. Furthermore, it does so by obtaining data in real space giving correlation functions, rather than in reciprocal space as for most scattering or diffraction techniques, providing data that are readily comparable to other measurement techniques. The particular variant of SESANS (time-of-flight) used on the LARMOR instrument at the ISIS Neutron and Muon Source measures neutrons with a distribution of wavelengths simultaneously, and the sensitivity for scattering in SESANS depends on the square of the wavelength, making it an ideal technique for studying systems that scatter weakly.

This was found to be the case for time-of-flight SESANS measurements on deuterated milk, milk powder in D2O, making this technique dramatically more sensitive than comparable measurements from other instruments. This makes time-of-flight SESANS able to produce data of equivalent quality with significantly less material. While deuterated milk is not a scarce product, the measurements that I will discuss could be extended straightforwardly to studying other food hydrocolloids where only limited amounts could be obtained. In my presentation, I will discuss the SESANS technique generally, the time-of-flight variant specifically, measurements of deuterated milk using SESANS, and the prospects for using the technique more widely.

 

Understanding the relationship between instrumental, sensory and consumer testing of dairy vs non-dairy yoghurt to predict 'creaminess'

Voong A

A demand for plant-based products has continuously grown and development of plant-based yoghurts has been challenging, to mimic the textural properties experienced during oral processing of dairy yoghurts. Five varying plant protein yoghurts were explored against dairy yoghurts. Tribology, rheology, microscopy and particle size analysis has been used to characterise the physical properties of each yoghurt. Sensory profiling and consumer testing was carried out to identify differences in sensory attributes and liking.

Correlation PCA shows traction coefficient and viscosity to correlate highly with: oily, creaminess, thickness/body. These attributes were selected for statistical modelling as they are considered as important attributes for product quality and acceptance. Partial least square regression was compared to Multiple Linear Regression and have both been explored as a statistical tool to predict 'creaminess' and 'oily' from instrumental parameters.  The use of both instrumental and sensory testing provides a fuller understanding of oral processing of yoghurts, and drivers of liking towards plant-based and dairy yoghurts.

 

Using Multiphase CFD to Capture and Understand Retort Process Physics

Brown E, Elson T

The retort process is used for the sterilization, pasteurization or cooking of a product, to extend the shelf life of the food substance. Using Multiphase Computrational Fluid Dynamics (CFD) modelling, we can gain insight to the retort process that can drive process improvement.

The retort process may utilize several methods of heating, this study considered hot water immersion, hot water spray and steam in air heating methods.

Modelling of the retort process requires complex computational models utilizing conjugate heat transfer and Multiphase flow physics. A combination of several multiphase methods is used for both the heating fluid physics and the physics of the food product undergoing the retort process.

The food product is modeled using the Volume of Fluids (VoF) approach, which considers two distinct phases within the food container - air and food product - which are considered immiscible, as such having a distinct interface, and which share common velocity fields.

Hot water immersion is considered using a single phase for the heating fluid, with only water present during the heating process.

The hot water spray process is modeled using the Eulerian Multiphase Mixture Model (MMP), a lightweight and computationally efficient alternative to VoF for the jets and air.

The steam-in-air process is modeled using a multi-component gas model, which is possible due to the similarities between dry steam and air.

The implemented physics was , the model can be used to understand and predict key metrics to determine the performance of the retort process. The metrics include: time to required temperature, energy consumption of the process and excess temperature above the critical value.

The influence of the flow physics on microbial kinetics can also be understood, allowing for the tracking of retort process performance against sterilization or pasteurization requirements.

Thus, the understanding gained from these models can be used to improve the process, reducing time and energy costs while ensuring the process remains effective at sterilization, pasteurization and cooking of food product.

 

What impact does saliva have on the physical characteristics of the food bolus as it undergoes oral processing?

Avila-sierra A, Decerle N, Ramaioli M, Peyron M

Developing novel foods tailored for specific groups requires further understanding of the intricacies involved in food oral processing, particularly the crucial role played by saliva. Saliva facilitates food oral processing, bolus formation, swallowing, and sensory perception, in addition to contributing to oral health and phonation. Ageing, health affections and polymedication are among many causes of altering salivary production, modifying the food impregnation ratio, and in turn altering the characteristics of the bolus, swallowing, and quite possibly digestion.

In this in vitro work, using the AM2 masticator apparatus, we investigated the effect of salivary fluid characteristics, i.e., composition, quantity (from absence to hypersalivation), temperature, and enzymatic action, on the physical characteristics (i.e., particle size distribution (PSD), bolus mass, salivary fluid content) of in vitro boluses of Traditional French baguette.

According to previous in vivo data, a ready-to-swallow bolus of French baguette displays on average a d50 value (sieve size through which 50% of the bolus weight can pass) of 4.1 ± 0.7 mm, with saliva constituting 33% of the final bolus weight. Our in vitro results, performed under normal mastication, suggest that the saliva quantity in mouth is a key factor in determining both PSD and hydration of bread boluses during oral processing. Indeed, the absence of saliva in mouth led to deficient oral processing, forming bread boluses constituted by extremely big particles (~80% particles >7.1 mm) that likely cannot be swallowed safely, while on the contrary, an excess of saliva favoured an excessive breaking down of bread, leading to boluses constituted by smaller particles than those formed under healthy salivary conditions (d50 = 3.1 mm), having a higher salivary fluid content (+10%). On the other hand, the salivary fluid temperature (37°C) did not affect PSD, d50, weight, or fluid content of bread boluses, however, the addition of human salivary α-amylase did, favouring particle size reduction (d50 decreased to 2.6 mm).

Therefore, beyond the correlation between bolus hydration by saliva and food properties such as hardness and moisture content, our findings indicate that the quantity of salivary fluid present in the oral cavity and the enzymatic activity of salivary α-amylase during bread mastication significantly influence both the particle size distribution and the fluid content of bread boluses, ultimately determining the physical properties of the bolus.

 

https://doi.org/10.1016/j.foodres.2023.113753