Vassilis Kiosseoglou

Development of a novel whey beverage by fermentation with kefir granules. Effect of various treatments

The development of a novel whey‐based beverage with acceptable organoleptic properties is reported, where various treatments were studied. Kefir yeast immobilized on delignified cellulosic materials (DCM) or gluten pellets proved to accelerate whey fermentation significantly, with the latter support being not so preferable. Kefir granules seemed to achieve similar fermentation times as DCM. The final pH of the product is suggested to be 4.1 since the profile of the volatile byproducts was higher than other pH values tested. The addition of fructose seemed to be beneficial on the volatile content of the product, although its acceptability as determined by a preference panel was similar to that of the control. Finally, black raisin extract appeared to promote fermentation without any positive effect on the preference of the evaluators.

Influence of polysaccharide addition on stability of a cheese whey kefir-milk mixture

Abstract A kefir-type drink was prepared by fermentation with kefir granules of cheese whey containing fructose and black raisin extract. Milk (20%) was then added to improve its rheological and sensory properties and in order to prevent casein coagulation and sedimentation in the acid environment of the mixture, a number of polysaccharides were evaluated as stabilizers. Xanthan appears to be more effective at relatively low concentration levels (0.2%) compared to guar gum while high methoxyl pectin, a well-known acid milk drink stabilizer was less effective in this respect even at concentrations as high as 1%. Particle size and rheology measurements pointed out to the importance of the weak gel properties of xanthan solution in stabilizing the system against ‘wheying off’ while other stabilization mechanisms such as particle network formation as a result of depletion flocculation in the case of guar gum or pectin adsorption at the casein particle surface resulting in steric stabilization appear to be less dominant.

Functional properties of single cell protein produced by kefir microflora

Single cell protein (SCP) was produced by aerobic fermentation of cheese whey by kefir microorganisms. A feed-batch system was developed on a bioreactor of 4 1. The experiments were conducted under controlled pH (5.5) and temperature (30 °C) conditions. The biomass was analyzed for protein, lipids, carbohydrates and ash and its functional properties (emulsification, foaming, gelation) were studied. Single cell protein (53.9% protein) exhibited emulsifying properties similar to those of defatted soy flour, while its Ibaming activity and foam liquid stability were much higher. Finally, texture profile analysis of gels, formed by heating water dispersions of SCP, showed that the structures produced were stronger compared with those of gels made with soy flour.

Effect of recovery methods on the oxidative and physical stability of oil body emulsions

Three natural oil body emulsions of a similar fat content (∼5%), but differing in their protein composition were obtained from an aqueous maize germ extract. The first was prepared by concentrating the aqueous oil body extract with ultrafiltration to a fat content of ∼5%. The other two were prepared by initially recovering the oil bodies from the extract by centrifugation, either in the presence of sucrose or by applying isoelectric precipitation at pH 5.0 and then diluting the resulting oil body creams with deionized water. The oxidative and physical stability of the three emulsions, either as they were or after submission to thermal treatment (100°C for 15 min), were studied following storage at 45°C. The emulsions differed both in their oxidative and physical stability, depending on the recovery method that in turn influenced their continuous phase and/or interfacial membrane protein and/or polar antioxidant composition. Ultrafiltration resulted in the most stable emulsion. Mixtures of the natural oil body emulsions with green tea extracts, aiming to serve as a base for functional beverages, were then prepared and studied for their creaming behaviour. The green tea polyphenols seem to interact with the oil bodies leading to intensive dispersion destabilisation which, however, was halted following carrageenan addition at a relatively very low level.

Functional and physicochemical properties of pulse proteins

This chapter explores the functional and physicochemical properties of pulse proteins. A common feature of pulses such as dry pea, chickpea, lentil, or the various types of dry bean, is their high protein content. The proteins of pulses are mainly storage proteins belonging to the groups of albumins, globulins, and glutelins, with the salt-soluble globulins constituting the main proteins found in the seeds. There are also a number of proteins, other than the water-soluble storage proteins, mainly enzymes, enzyme inhibitors, and lectins, which constitute part of the defensive mechanism of the seed but are considered as antinutritional factors for the human diet. The chapter discusses the functional properties of pulse proteins that include solubility, water- and oil-absorption capacity, Emulsifying and foaming properties, and protein gelatin characteristics.

Influence of reduced-cholesterol yolk on the viscoelastic behaviour of concentrated O/W emulsions

Abstract A stress-controlled Carri-Med rheometer was used to carry out dynamic oscillatory experiments within the linear viscoelastic region on mayonnaise emulsions prepared with low-in-cholesterol egg yolk protein concentrates. Spray-dried egg yolk as well as yolk protein concentrates prepared by extracting with 20:80 ethanol/water or supercritical carbon dioxide were used. The type of egg product varied, while the composition of the emulsions was held constant. The method of lipid extraction influenced both the emulsion droplet size and the viscoelastic parameters. The small deformation properties of the emulsions are interpreted in connection with the interdroplet interactions as they are affected by the presence of yolk protein concentrates.

Foaming properties of potato proteins recovered by complexation with carboxymethylcellulose.

A protein isolate, with a 74.4% (w/w) protein content, was recovered from a simulated potato processing plant waste effluent by complexation with carboxymethylcellulose. The protein solubility of the isolate was satisfactory, it decreased in the presence of NaCl, but was not markedly affected by heat treatment. The isolate exhibited remarkable foaming and foam stabilizing properties, compared with lyophilized egg white, which are attributed to the very high surface activity of the potato protein molecules, which following adsorption at a/w interfaces, result in a much higher surface pressure development compared with egg albumen. A significant part of the foaming ability and the high surface activity of the isolate should be connected with the presence in the isolate of a small fraction of proteins with a relatively low molecular weight. The sulfhydryl groups of these proteins, following adsorption at the a/w interface, during the process of foam formation and denaturation are oxidized leading to the possible formation of intermolecular disulfide linkages.