Hydrophobins and air filled emulsions

Suspensions of micron sized air cells, Air Filled Emulsions (AFEs), represent a new colloidal material with outstanding physical properties. They have the potential for technological applications in very different fields such as biomedical, environmental sciences and the food industry. This thesis focuses on the construction of AFEs and their use as ingredients to construct reduced fat and calorie emulsion-based products. These microstructurally complex materials have been termed triphasic A/O/W emulsions. A sonochemical templating process has allowed for the construction of air cells (the majority around 0.5-10 μm) in the size range of oil droplets found in emulsion based foods. Air cells were stabilised with either hydrophobins, obtained from submerged fermentation and extraction, or other cysteine rich but more common proteins such as bovine serum albumin (BSA) and egg albumen (EWP). The air cells were stable against disproportionation and ripening for substantial periods of time. They resisted destabilisation effect of oil droplets and could survive unit operations involving mild vacuum treatment and centrifugal forces, relatively high shear forces, temperatures and pressures. Triphasic A/O/W emulsions were created with up to 60% included phase of air and oil in an aqueous continuous phase. This gave a greater than 50% reduction in lipid content. Comparative rheology and tribology showed that the triphasic A/O/W emulsions could have similar if not better lubrication properties than a full O/W version. The molecular properties of the protein used for the AFEs played a crucial role in the determination of lubrication properties (mouth-feel). Moreover, AFEs and triphasic emulsions offer the potential for new structures and textures for the food industry due to their self interaction to give a weak ge

Engineering microencapsulated PCM slurry with improved performance for cold storage

Cold is essential in many aspects of everyday life ranging from food, drugs and chemicals processing, storage and distribution to control of thermal comfort and superconductors in power electronics. The demand for cooling in all its forms is accelerating with the growing global urban population1. However, existing cooling technologies consume large amounts of energy and can be highly polluting in terms of carbon and other emissions2. One way of reducing the energy required for cooling and increasing cooling technologies efficiency whilst minimising their environmental impact involves the storage of energy efficiently as cold and to deliver cooling whenever needed without worsening peak demand. To this end we have developed a range of microencapsulated low freezing point phase change materials in slurries (MPCMSs) where the PCM core and the carrier fluid are both liquid coolants. Our strategy was to encapsulate LPCM and structured LPCM with thermal conductivity enhancer materials using inorganic-organic composite shell material to achieve improved cold storage performance from -35˚C to -110˚C. Figure 1 shows microencapsulated diethyl benzene based coolant and structured methanol-water dispersed in ethylene glycol-water and silicone based fluid, respectively. Initial results are promising and these MPCMSs now offer new horizon for cold storage and energy management. Please click Additional Files below to see the full abstract

Co-encapsulation of vitamin D and rutin in chitosan-zein microparticles

© 2022 The Authors. Published by Springer. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1007/s11694-022-01340-2There is a growing interest in co-encapsulating multiple species to harness potential synergy between them, enhance their stability and efficacy in various products. The aim of this work was to co-encapsulate vitamin D3 and rutin inside chitosan-zein microparticles using a simple and easily scalable process for food fortification. This was achieved via anti-solvent precipitation coupled with spray-drying. Free-flowing powders of spherical microparticles with wrinkled surface and particle size < 10 μm were obtained. The encapsulation efficiency was 75% for vitamin D3 and 44% for rutin and this could be attributed to their different molecular size and affinity to the aqueous phase. The physicochemical properties were characterized by X-Ray powder diffraction and Fourier transform infrared spectroscopy. The two crystalline bioactive compounds were present in the microparticles in amorphous form, which would allow for better bioavailability when compared to non-encapsulated crystalline solid. Therefore, the obtained microparticles would be suitable for use as food ingredient for vitamin D3 fortification, with the co-encapsulated rutin acting as stability and activity enhancer.This work was supported by Regione Veneto FSE project No. 1695–16-11–2018.Published onlin

Impact of mechanical stimulation on the life cycle of horticultural plant

© 2023 The Authors. Published by Elsevier. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1016/j.hpj.2023.01.003Mechanical stimulation technology is critical in agricultural crop production because it is constantly regarded as a developing green technology to regulate plants to meet people's need for green and healthy agricultural products. Various environmental mechanical stimulation impacts seed germination, seedling growth, flowering date, fruit quantity, and fruit quality throughout the life cycle of a horticultural plant. This study first outlines the basic characteristics of six types of common mechanical stimulation in nature: precipitation, wind, gravity, touch, sound, and vibration. The effects of various mechanical stimulation types on the seed, seedling, flowering, and fruit of horticultural plants throughout their whole life cycle are then presented, as reviewed in the recent 100 years of existing literature. Finally, potential future study directions are discussed. The main challenge in mechanical stimulation technology is to uncover its potential capabilities for regulating and controlling plant development and fruit quality in green agriculture instead of agricultural chemicals.This work was supported by a European Marie Curie International Incoming Fellowship (Grant Nos. 326847 and 912847), a Chinese Universities Scientific Fund (Grant No. 2452018313), a High-End Foreign Expert Recruitment Program (Grant No. G2022172006L), and an Agricultural Science Innovation and Transformation Project of Shaanxi Province [Grant No. NYKJ-2022-YL(XN)12].Published versio

Characterization of textural failure mechanics of strawberry fruit

This is an accepted manuscript of an article published by Elsevier in Journal of Food Engineering on 05/03/2020, available online: https://doi.org/10.1016/j.jfoodeng.2020.110016 The accepted version of the publication may differ from the final published version.Fresh strawberry fruit is highly susceptible to damage during mechanical handlings. To prevent fruit macro-damage from external forces and predict damage evolution in internal tissues, the textural failure mechanics of strawberry fruit and its tissues were characterized by loading-unloading tests at different compression speeds. Strawberry fruit showed expected three stages of deformation during the loading phase, namely elastic, local plastic and structural failure deformation. Their cut-off points depended on the compression speed and loading direction, which was validated further by the corresponding visible browning processes in tissues from fruit longitudinal equatorial section. The peak force and absorbed energy depended on the loading direction and compression speed while the percentage of damaged mass only depended on the loading direction. The fruit was most susceptible to mechanical damage when it was compressed along its stem-blossom axis at low percentage deformation and along its radial axis at high percentage deformation. The absorbed energy and percentage of damaged mass of the strawberry fruit was correlated, which suggested that the absorbed energy could be an appropriate and easily measurable mechanical parameter for quantitatively assessing the degree of fruit damage. The failure stress, failure energy and elastic modulus of fruit tissues increased with the compression speed, while this factor did not affect the failure strain. The average failure stress, failure strain, failure energy and elastic modulus of fruit inner tissue were 0.093 MPa, 17.7%, 8.09 mJ, 0.53 MPa, which was 1.27, 1.14, 1.47, 1.15 times enhanced compared to values of outer tissue (p < 0.05), respectively.This work was supported by a European Marie Curie International Incoming and Return Fellowship (326847 and 912847), a Special Foundation for Talents of Northwest A&F University, China (Z111021801), two Key Research and Development Plans of Shaanxi Province, China (2019NY-172 and 2019TSLNY01-01) and a Project for Sino-German Cooperation on Agricultural Science and Technology in 2018–2019 (15).Published versio

Thermo-mechanical analysis of microcapsules containing phase change materials for cold storage

This is an accepted manuscript of an article published by Elsevier in Applied Energy on 18/12/2017, available online: https://doi.org/10.1016/j.apenergy.2017.12.021 The accepted version of the publication may differ from the final published version.Microencapsulated phase change material slurries (MEPCMSs) offer a potentially efficient and flexible solution for cryogenic-temperature cold storage. In this paper, the phase change material (PCM) microcapsules prepared to form MEPCMSs for cryogenic-temperature cold storage consist of Dowtherm J (DJ) as core material and melamine formaldehyde (MF) as primary shell material. DJ is an aromatic mixture with diethylbenzene as the main component. Composite shell materials are adopted to avoid cracking by adding aluminium oxide (Al2O3) nanoparticles or copper (Cu) coating into/on MF shell. In order to explore the heat transfer behaviour and mechanical stability of the microcapsules during the solidification process of PCM, a thermo-mechanical model is established by taking into account of energy conservation, pressure-dependent solid-liquid equilibria, Lamé’s equations and buckling theory. Based on the proposed model, the effects of shell thickness, shell compositions and microcapsule size are therefore studied on the variations of pressure difference, freezing point, and latent heat. The cause of shell deformation is clearly explained and the shell buckling modes are predicted using the model, which agree well with the experimental observations. The critical core/shell size ratios of avoiding buckling are proposed for the microcapsules with different compositions. Simultaneously incorporation of Al2O3 nanoparticles and Cu coating into/on MF shell can markedly enhance the resistant to buckling. In addition, special attention is paid to cold energy storage capacity of MEPCMSs, which has considerable superiority compared to packed pebble beds

Building a circular economy around poly(D/L-γ-glutamic acid)- a smart microbial biopolymer

© 2022 The Authors. Published by Elsevier. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1016/j.biotechadv.2022.108049Bio-derived materials have long been harnessed for their potential as backbones of biodegradable constructs. With increasing understanding of organismal biochemistry and molecular genetics, scientists are now able to obtain biomaterials with properties comparable to those achieved by the petroleum industry. Poly-γ-glutamic acid (γ-PGA) is an anionic pseudopolypeptide produced and secreted by several microorganisms, especially Bacillus species. γ-PGA is polymerised via the pgs intermembrane enzymatic complex expressed by many bacteria (including GRAS member - Bacillus subtilis). γ-PGA can exist as a homopolymer of L- glutamic acid or D- glutamic acid units or it can be a co-polymer comprised of D and L enantiomers. This non-toxic polymer is highly viscous, soluble, biodegradable and biocompatible. γ-PGA is also an example of versatile chiral-polymer, a characteristic that draws great attention from the industry. Increased understanding in the correlation between microbial genetics, substrate compositions, fermentation conditions and polymeric chemical characteristics have led to bioprocess optimisation to provide cost competitive, non-petroleum-based, biodegradable solutions. This review presents detailed insights into microbial synthesis of γ-PGA and summaries current understanding of the correlation between genetic makeup of γ-PGA-producing bacteria, range of culture cultivation conditions, and physicochemical properties of this incredibly versatile biopolymer. Additionally, we hope that review provides an updated overview of findings relevant to sustainable and cost-effective biosynthesis of γ-PGA, with application in medicine, pharmacy, cosmetics, food, agriculture and for bioremediation.This work was partially supported the University of Wolverhampton Research Investment Fund (RIF4); ERDF Science in Industry Research Centre (SIRC 01R19P03464) project and BBSRC Algae-UK for Proof of Concept project BB/S009825/1; UCL Ref: 5749484.Published versio

Bioconversion of plastic waste based on mass full carbon backbone polymeric materials to value-added polyhydroxyalkanoates (PHAs)

© 2022 The Authors. Published by MDPI. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.3390/bioengineering9090432This review article will discuss the ways in which various polymeric materials, such as polyethylene (PE), polypropylene (PP), polystyrene (PS), and poly(ethylene terephthalate) (PET) can potentially be used to produce bioplastics, such as polyhydroxyalkanoates (PHAs) through microbial cultivation. We will present up-to-date information regarding notable microbial strains that are actively used in the biodegradation of polyolefins. We will also review some of the metabolic pathways involved in the process of plastic depolymerization and discuss challenges relevant to the valorization of plastic waste. The aim of this review is also to showcase the importance of methods, including oxidative degradation and microbial-based processes, that are currently being used in the fields of microbiology and biotechnology to limit the environmental burden of waste plastics. It is our hope that this article will contribute to the concept of bio-upcycling plastic waste to value-added products via microbial routes for a more sustainable future.This research was funded by the University of Wolverhampton Research Investment Fund (RIF4), the ERDF Science in Industry Research Centre (SIRC 01R19P03464) project, and the Schlumberger Foundation Faculty for the Future Fellowship. Additionally, partial support was provided by the European Regional Development Fund Project via EnTRESS No 01R16P00718 and the PELARGODONTProjectUM0-2016/22/Z/STS/00692financedundertheM-ERA.NET2Program of Horizon 2020.Published versio

Glycaemic index of gluten-free biscuits with resistant starch and sucrose replacers: An in vivo and in vitro comparative study

© 2022 The Authors. Published by MDPI. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.3390/foods11203253The glycaemic index (GI) is used to demonstrate the tendency of foods to increase blood glucose and is thus an important characteristic of newly formulated foods to tackle the rising prevalence of diabetics and associated diseases. The GI of gluten-free biscuits formulated with alternate flours, resistant starch and sucrose replacers was determined using in vivo methods with human subjects. The relationship between in vivo GI values and the predicted glycaemic index (pGI) from the in vitro digestibility-based protocols, generally used by researchers, was established. The in vivo data showed a gradual reduction in GI with increased levels of sucrose substitution by maltitol and inulin with biscuits where sucrose was fully replaced, showing the lowest GI of 33. The correlation between the GI and pGI was food formulation-dependent, even though GI values were lower than the reported pGI. Applying a correction factor to pGI tend to close the gap between the GI and pGI for some formulations but also causes an underestimation of GI for other samples. The results thus suggest that it may not be appropriate to use pGI data to classify food products according to their GI.Published onlin

Bioactive and functional oligomers derived from natural PHA and their synthetic analogs

This is an accepted manuscript of a chapter published by CRC Press in The Handbook of Polyhydroxyalkanoates Postsynthetic Treatment, Processing and Application on 05/11/2020, available online: https://www.taylorfrancis.com/books/e/9781003087663/chapters/10.1201/9781003087663-5 The accepted version of the publication may differ from the final published version.Polyhydroxyalkanoate oligomers (oligo-PHA) are low molar mass PHA consisting of a small number of 3-hydroxyacid repeat units (usually not more than 200 residue units). They can be synthesized either naturally in eukaryotic cells and in prokaryotic cells through intracellular or extracellular degradation of storage PHA to yield natural oligomers, or via several chemical modifications such as basic hydrolysis or transesterification. The synthetic analogs of natural PHA oligomers are obtained by anionic ring-opening polymerization (ROP) of β-substituted β-lactones. These synthetic and biodegradable oligomers, through various chemical modifications, can further allow the preparation of bioactive oligomers with attractive properties for novel and high value-added applications, especially in medicine, agrochemistry, and cosmetology. Bioactive oligomers are also biodegradable: they possess enhanced properties, controlled functional end groups, and thus can be potential components of copolymers or blends with other biodegradable polymers. The natural and synthetic routes used for the preparation of selected bioactive PHA oligomers and their detailed characterization by mass spectrometry are discussed in this chapter