Phase separation in protein and polysaccharide gels remains one of the basic tools of achieving the required structural properties and textural profile in food product formulations. As ever, the ...industrialist is faced with the challenge of innovation in an increasingly competitive market in terms of ingredient cost, product added-value, and expectations of a healthy life-style to mention but a few. It appears, however, that a gap persists between the fundamental knowledge and a direct application to food related concepts with a growing need for scientific input. Furthermore, within the context of materials science, there is a tendency to examine research findings in either low- or high-solid systems without considering synergistic insights/benefits to contemporary needs, spanning the full range of relevant time-, length-, and concentration scales. This review highlights the latest attempts made to utilize and further develop fundamental protocols from the advanced synthetic polymer research as a source of inspiration for contemporary bio-related applications in low- and intermediate-solid composite gels. Then, it takes advantage of this school of thought to “force a passage” through the phase topology and molecular dynamics of binary biopolymer mixtures at high levels of co-solute. It is hoped that these phenomenological and fundamental tools should be able to bridge the divide in the analysis of the two “types” of composite materials (from low to high solids) thus dealing effectively with the specific and often intricate problems of their science and applications.
In the food industry, proteins are regarded as multifunctional systems whose bioactive hetero-polymeric properties are affected by physicochemical interactions with the surrounding components in ...formulations. Due to their nutritional value, plant proteins are increasingly considered by the new product developer to provide three-dimensional assemblies of required structure, texture, solubility and interfacial/bulk stability with physical, chemical or enzymatic treatment. This molecular flexibility allows them to form systems for the preservation of fresh food, retention of good nutrition and interaction with a range of microconstituents. While, animal- and milk-based proteins have been widely discussed in the literature, the role of plant proteins in the development of functional foods with enhanced nutritional profile and targeted physiological effects can be further explored. This review aims to look into the molecular functionality of plant proteins in relation to the transport of bioactive ingredients and interaction with other ligands and proteins. In doing so, it will consider preparations from low- to high-solids and the effect of structural transformation via gelation, phase separation and vitrification on protein functionality as a delivery vehicle or heterologous complex. Applications for the design of novel functional foods and nutraceuticals will also be discussed.
Honey, a natural sweetener has been used universally as a complete food and in complementary medicine since early antiquity. Honey contains over 180 substances, including sugars mainly fructose and ...glucose, water and a plethora of minor constituents such as vitamins, minerals and phytochemicals. The chemical composition of honey varies depending on floral origin, environment and geographical conditions. The sugar components dominate honey composition and they are accountable for sensory and physicochemical properties in food industry. Although present in small quantities, non-sugar components are the major contributors to the health benefits of honey. Our review summarizes and discusses composition of honey, its protective effects and possible action modes on risk factors of atherosclerosis.
Manuka honey and newly developed honeys (arjuna, guggul, jiaogulan and olive) were examined for their physicochemical, biochemical properties and effects on oxidative stress and cholesterol ...homeostasis in fatty acid-induced HepG2 cells. The honeys exhibited standard moisture content (<20%), electrical conductivity (<0.8 mS/cm), acidic pH, and monosaccharides (>60%), except olive honey (<60% total monosaccharides). They all expressed non-Newtonian behavior and 05 typical regions of the FTIR spectra as those of natural ones. Guggul and arjuna, manuka honeys showed the highest phenolic contents, correlating with their significant antioxidant activities. Arjuna, guggul and manuka honeys demonstrated the agreement of total cholesterol reduction and the transcriptional levels of
,
,
,
,
. Jiaogulan honey showed the least antioxidant content and activity, but it was the most cytotoxic. Both jiaogulan and olive honeys modulated the tested gene in the pattern that should lead to a lower TC content, but this reduction did not occur after 24 h. All 2% concentrations of tested honeys elicited a clearer effect on
gene expression. In conclusion, the new honeys complied with international norms for natural honeys and we provide partial evidence for the protective effects of manuka, arjuna and guggul honeys amongst the tested ones on key biomarkers of oxidative stress and cholesterol homeostasis, pending further studies to better understand their modes of action.
There is an increasing demand for the design of complex bio-composites with customized structural characteristics for use in processed food products. Phase behaviour of these mixtures determines ...textural properties, encouraging the pursue of a rapid technique that can accurately quantify it. The present work tests the efficacy of confocal laser scanning microscopy (CLSM) coupled with image analysis software (Imaris), for the quantification of phase behaviour in complex tertiary systems. In doing so, it develops phase separated gels of agarose and gelatin supporting inclusions of canola oil. The polysaccharide was replaced with whey protein isolate (WPI) and the topology of the tertiary dispersion with gelatin and canola oil was also examined. Reproducible phase volume estimates were obtained, including those of the lipid phase, which were a close match to the actual concentrations added to the hydrocolloid gel. The approach could offer an alternative to the rheological estimation, via theoretical blending law analysis, of phase volumes in bio-composites.
Graphical Abstract
Crosslinking of hydroxypropyl methyl cellulose (HPMC) and acrylic acid (AAc) was carried out at various compositions to develop a high-solid matrix with variable glass transition properties. The ...matrix was synthesized by the copolymerisation of two monomers, AAc and N,N'-methylenebisacrylamide (MBA) and their grafting onto HMPC. Potassium persulfate (K
S
O
) was used to initiate the free radical polymerization reaction and tetramethylethylenediamine (TEMED) to accelerate radical polymerisation. Structural properties of the network were investigated with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), modulated differential scanning calorimetry (MDSC), small-deformation dynamic oscillation in-shear, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The results show the formation of a cohesive macromolecular entity that is highly amorphous. There is a considerable manipulation of the rheological and calorimetric glass transition temperatures as a function of the amount of added acrylic acid, which is followed upon heating by an extensive rubbery plateau. Complementary TGA work demonstrates that the initial composition of all the HPMC-AAc networks is maintained up to 200 °C, an outcome that bodes well for applications of targeted bioactive compound delivery.
This study indicates that controlled depolymerization of plant (PC) and bacterial (BC) celluloses can be achieved by employing suitable ultrasonication settings. Size exclusion chromatography results ...indicate that reduction in the molecular weight of the two polymers was accompanied by a parallel drop in the polydispersity index of PC and an unexpected increase in the said index of BC. X-ray diffraction patterns of the fractionated materials were found to be Cellulose II crystals whereas experimentation on microcrystalline cellulose unveiled the Cellulose I conformation. The crystallinity index revealed no obvious changes in PC as a function of the time of sonication whereas a major increase in the crystalline component was encountered for BC. Furthermore, thermal degradation using TGA and FTIR spectra suggest that the processes of dissolution and regeneration in cuprammonium hydroxide of PC and BC followed by ultrasonication do not affect the chemical fingerprints
via oxidative reactions of the cellulosic materials.
The need for a rapid and direct alternative to the rheology-based blending laws in quantifying phase behaviour in biopolymer composite gels is explored in this study. In doing so, the efficacy of ...confocal laser scanning microscopy (CLSM) paired with image analysis software – FIJI and Imaris - in quantifying phase volume was studied. That was carried out in a model system of agarose with varying concentrations of microcrystalline cellulose (MCC) in comparison to the rheological blending laws. Structural studies performed using SEM, FTIR, differential scanning calorimetry and dynamic oscillation in-shear unveiled a continuous, weak agarose network supporting the hard, rod-shaped MCC inclusions where the composite gel strength increased with higher ‘filler’ concentration. The phase volumes of MCC, estimated with the microscopic protocol, matched the predictions obtained from computerized modelling using the Lewis-Nielsen blending laws. Results highlight the suitability of the microscopic protocol in estimating the water partition and effective phase volumes in the agarose-MCC composite gel.
There is a substantial volume of research articles in the field of protein-ligand interactions, with a large proportion using inappropriate methodology for the fluorescence spectroscopy analysis of ...binding interactions. The most common issues being overlooked are the inner filter effect and the use of unsuitable equations to calculate binding strength and stoichiometry, leading to the propagation of questionable methodology and reported results throughout multiple fields. In this communication, we carefully explain these issues and approaches to overcome them, including accounting for the inner filter effect, the use of appropriate equations to obtain dissociation constant (Kd) values (as opposed to the commonly misused Stern-Volmer equation), and carefully dealing with binding stoichiometry using the Job plot (often misjudged using the Hill coefficient instead). We hope that the work will bring attention to critical and often common issues in fluorescence spectroscopy, as well as improving the approaches used in the binding analysis of protein-ligand systems. Thus, it should provide a good example of how to go about this type of research, as well as being of interest to the broad readership of the journal.
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•Errors in fluorescent quenching of food protein-phenolic complexes are discussed.•Filter effects are commonly overlooked as a contributor to quenching.•Inappropriate (linear) equations are often used to determine binding constants.•Binding stoichiometry often (incorrectly) determined using the Hill coefficient.
A cursory exploration of the recent literature on the vitrification of food materials using a scientific search engine downloads a plethora of documents. Thermal analysis has been an effective tool ...in mapping out the physical behaviour of pure ingredients, but it has not been the technique of choice in synthetic polymer research for the rationalisation of molecular dynamics in the rubber-to-glass transition. A new concept of ‘the network
T
g’ has been developed using small deformation mechanical analysis and a combination of the WLF/free volume theory with the modified Arrhenius equation. The network
T
g is distinct from the empirical DSC
T
g and the two indicators should be used in tandem to rationalise phase phenomena in biomaterials. Applications of the network
T
g are explored in model confections, dehydrated foodstuffs, state diagrams and adsorption isotherms.
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