Publications by authors named "Stefan Kasapis"

Article Synopsis
  • * Two high-solid food preparations were used: κ-carrageenan with glucose syrup and genipin-crosslinked gelatin with polydextrose, allowing for microscopic inclusion of fatty acids.
  • * Results showed that structural changes in the matrices due to temperature affect oxidation, with higher mechanical temperatures leading to lower lipid oxidation rates and reduced hydroperoxide production.
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The effect that protein-bioactive interactions may have on diffusion kinetics in foods and nutraceuticals was investigated by examining the diffusion kinetics of phenolic compounds (ferulic acid and epicatechin) of varying size, in the presence and absence of bovine β-casein. In the presence of the protein, the diffusion rate for ferulic acid and epicatechin was shown to decrease from 2.76 × 10 and 1.

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Recent advances in developing and applying therapeutic peptides for anticancer, antimicrobial and immunomodulatory remedies have opened a new era in therapeutics. This development has resulted in the engineering of new biologics as part of a concerted effort by the pharmaceutical industry. Many alternative routes of administration and delivery vehicles, targeting better patient compliance and optimal therapeutic bioavailability, have emerged.

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Previous work has suggested the ability of 4-hydroxybenzoic acid (4HBA) to bind to β -casein following ultra high temperature-like processing (UHT) in model aqueous systems. The present work confirmed directly, using MALDI-TOF-MS, the presence of covalently bound 4HBA following UHT-like treatment. In subsequent molecular dynamics simulations, the 3D structure of the β -casein molecule was modified so that the meta-C of 4HBA ring and the side chain amino group of lys32 were linked covalently.

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This work examines the relationship between microstructural properties of hot-moulded chitosan networks, crosslinked with trisodium phosphate, and diffusive behaviour from these networks. Analysis through infrared spectroscopy (FTIR) confirmed successful crosslinking of the polymer chains and bioactive entrapment, while X-ray diffraction (WAXD) and dynamic oscillation in-shear elucidated the higher order structural properties of each matrix, as they transitioned from solutions to amorphous gels to semi-crystalline matrices. The picture of molecular motion observed in these systems and consequent application of the Flory-Rehner theory further indicated that different extents of chitosan crosslinking yielded a distinct water infusion functionality seen in the levels of swelling.

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Red pitaya (, red pulp with pink peel), also known as dragon fruit, is a well-known species of pitaya fruit. Pitaya seeds and peels have been reported to exhibit higher concentrations of total polyphenols, beta-cyanins and amino acid than pulp, while anthocyanins (i.e.

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Interactions between the dimeric form of β-lactoglobulin and vanillic acid were investigated at pH 7.2, using a variety of spectroscopic techniques and molecular dynamics (MD) simulations. FTIR and CD studies showed alterations in the secondary structure of the protein upon its interaction with the ligand.

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Protein-phenolic compound interactions are commonly investigated with inappropriate linear equations for the analysis of binding strength and stoichiometry. This work utilises more appropriate protocols for the investigation of molecular interactions between vanillic acid and β-lactoglobulin at pH 2.4, where the protein predominately exists as a monomer.

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There is a growing need for clean and green labeling of food products among consumers globally. Therefore, development of green modified starches, to boost functionality, palatability and health benefits while reducing the negative processing impacts on the environment and reinforcing consumer safety is in high demand. Starch modification started in mid-1500s due to the inherent limitations of native starch restricting its commercial applications, with chemical modification being most common.

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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 (KSO) was used to initiate the free radical polymerization reaction and tetramethylethylenediamine (TEMED) to accelerate radical polymerisation.

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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).

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This study examined the release of vitamin B6 from a hydrogel made of whey protein isolate (WPI). Work was carried out at ambient temperature without preheating the whey protein. Native-state macromolecules were crosslinked with a nontoxic compound, genipin.

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High-solid chitosan matrices were prepared to investigate the effect of their swelling on structural relaxation and glass transition. Degree of crosslinking in genipin-crosslinked chitosan networks was measured with a ninhydrin assay and a suitable crosslinker concentration was determined for gels used in swelling and thermomechanical analysis. Fourier transform infrared spectroscopy and wide angle X-ray diffraction examined the intermolecular interactions, crystallinity and amorphicity of the biopolymer networks.

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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.

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We examined the morphology of a network made with native BSA molecules being crosslinked with genipin at ambient temperature. Ninhydrin assay, FTIR, WAXD, SEM and mechanical tests documented successful crosslinking that enhanced the structural properties of the three dimensional structure. Its hydrophilic nature allows swelling with water absorption, which can be monitored with the modified Flory-Rehner theory to predict the molecular weight between adjacent crosslinks, network mesh size and crosslinking density as a function of crosslinker addition.

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The Chaplin E peptide is a surface-active agent that can adsorb to the air/water interface and form interfacial films that display distinct interfacial properties as a function of pH. The ~2 nm thick homogeneous Chaplin E film formed under acidic conditions contains ordered structures that give a high dilatational elasticity. In contrast, the heterogeneous film formed under basic conditions contained fibrils resulting in a rough ~17 nm thick film with predominantly viscoelastic properties, probably due to the reduced intermolecular interactions.

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Low-frequency sonication (20 kHz) was applied to sodium caseinate suspensions (4%, 7% and 10% protein concentrations) at pH 4.0, 4.6, 6.

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Studying the phase behaviour of composite gels facilitates understanding of their structural and textural properties at low and intermediate levels of solids. In this work, the phase behaviour of a model system of agarose including various concentrations of canola oil was studied. This was pursued using a variety of techniques including SEM, FTIR, microDSC and dynamic oscillation in-shear.

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Structural relaxation and glass transition were examined in the swelling behaviour of a high-solid biopolymer matrix; genipin-crosslinked gelatin. Degree of swelling was quantified by the Flory-Rehner theory that furnishes estimates of average molecular weight between crosslinks and network mesh size. Fourier transform infrared spectroscopy and wide angle X-ray diffraction described intermolecular interactions and the extent of amorphicity in the crosslinked matrix.

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Dynamic rheological and mechanical properties of seven commercial (xanthan [XG], guar [GG], high methoxylated pectin [HMP], κ-carrageenan [κ-Car], agar [AG], alginate [ALG], and carboxymethylcellulose [CMC]) and four emerging hydrocolloids (basil seed gum [BSG], sage seed gum [SSG], Balangu-Shirazi seed gum [BSSG], and cress seed gum [CSG]) were investigated and the classification of the hydrocolloids were carried out based on them. AG belonged to the first class with 0.81 membership function (MF), κ-Car and HMP grouped in the second class with 0.

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Honey is a biologically active material functioning antibacterial, anti-inflammation and immune responses that enhance wellbeing. This research aims to record and rationalise the structural properties of honey as part of a convenient delivery system in the presence of gelatin that provides the structuring matrix. In doing so, we employ dynamic oscillation in-shear, micro and modulated DSC, WAXD, FTIR and ESEM.

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We examine the morphology of hydrogels made of bovine serum albumin and gelatin following high pressure processing at 300 MPa for 15 min at 10 and 80 °C. Emphasis is on the distribution of added calcium counterions between the polymeric phases seen in changes in the structural properties of the composite gel. Protocol includes thermal and HPP treatments, dynamic oscillation rheology, ESEM, and modeling from the "synthetic polymer approach" to rationalize results.

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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.

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In this study, we proposed an objective classification of seven commercial hydrocolloids and four novel hydrocolloids. Total of 74 rheological parameters was generated by steady (flow behavior, hysteresis loop, single shear decay, in-shear structural recovery experiments), dynamic (strain sweep and frequency sweep tests), and transient (creep/recovery and stress relaxation) shear measurements. Subsequently, the parameters were classified into seven categories with more than 60% similarity indexes in each group using agglomerative hierarchical clustering based on those properties related to the number of linkage, strength of linkage, distance of linkage, rupture and flow, rate of destruction, the extent of destruction, and the state of destructured samples in the absence of flow field.

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Functionalized halloysite nanotubes were prepared by surface activation of halloysite (Hal) with sodium hydroxide and deposition of zinc oxide nanoparticles (ZnONP). The surface charge of Hal was changed from 0.18 ± 0.

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