Adamantini Paraskevopoulou

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.

Aroma formation by immobilized yeast cells in fermentation processes

Immobilized cell technology has shown a significant promotional effect on the fermentation of alcoholic beverages such as beer, wine and cider. However, genetic, morphological and physiological alterations occurring in immobilized yeast cells impact on aroma formation during fermentation processes. The focus of this review is exploitation of existing knowledge on the biochemistry and the biological role of flavour production in yeast for the biotechnological production of aroma compounds of industrial importance, by means of immobilized yeast. Various types of carrier materials and immobilization methods proposed for application in beer, wine, fruit wine, cider and mead production are presented. Engineering aspects with special emphasis on immobilized cell bioreactor design, operation and scale‐up potential are also discussed. Ultimately, examples of products with improved quality properties within the alcoholic beverages are addressed, together with identification and description of the future perspectives and scope for cell immobilization in fermentation processes. Copyright

Volatile Bio-ester Production from Orange Pulp-Containing Medium Using Saccharomyces cerevisiae

The dynamics of orange pulp (OP) as a fermentation feedstock for the production of volatile esters of “fruity” aroma by using a commercial wine yeast strain (Saccharomyces cerevisiae var. cerevisiae) was investigated. To achieve this goal, the kinetic behaviour of yeast (cell growth, substrate assimilation and volatile ester formation) was studied in OP complemented with nutritive medium under two different aeration conditions. The results were compared with those obtained from conventional processes in nutritive medium containing glucose as a sole carbon source. The results obtained revealed that the yeast cells were able to grow in the OP-containing medium after a 12-h lag period, probably due to the inhibitory effect of limonene. OP was found to stimulate the de novo synthesis of isoamyl acetate, phenylethyl acetate and ethyl esters (hexanoate, octanoate, decanoate and dodecanoate) by S. cerevisiae. This was strongly evident in the case of limited oxygen supply. Based on the above findings, OP appears to be a promising choice for bioflavour production by yeast.

Fracture and textural properties of low fat egg yolk gels containing emulsion droplets

The influence of corn oil content and the type of emulsifier on the fracture and textural properties and the expressible liquid of gels prepared by heat-treatment of low-fat yolk protein concentrate (YPC) containing emulsified oil has been investigated. Oil incorporation in the form of fine droplets results in a decrease of gel network strength, the textural parameter values depending on the amount of added oil. Tween 20 (polyoxyethylene sorbitan monolaurate) when used as the oil emulsifier brings about a reduction in gel textural parameter values compared to liquid egg yolk, the result depending on the emulsion droplet size. Additionally, the gels differ in their yielding behaviour since the latter yield but do not fracture at strain values as high as 0.7 while the former fracture at relatively low strains and their fracture stress and strain parameter values depend on oil droplet size. This behaviour is explained in terms of the effect of the surfactant on the yolk constituents and, particularly, its interactions with the yolk apoproteins, which result in stiffer bulk gel network structure.

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.

Encapsulation Technologies for Food Industry

The food processing industry is one of the largest manufacturing industries worldwide. This industry handles and processes numerous raw materials and finished products in powdered and particulate forms. New trends of living impose food which fulfill many criteria (tasteful, healthy, of nice appearance). Therefore, the improvement of the existing technologies and development of the new ones is inevitable. In this sense, future competitiveness may be critically dependent on the knowledge obtained by research activities in the field of encapsulation technologies. Encapsulation has a large impact on different aspects of food industry as it is evidenced from the huge number of published scientific papers, patents, and reports. Driven by the increasing consumers’ demand for more healthy, tasty, and safe food products, the need for edible systems able to protect and release functional compounds and the necessity for creation of a more sustainable industry, encapsulation has covered many issues relevant to food and nutrition.

Exploitation of hazelnut, maize germ and sesame seed aqueous extraction residues in the stabilisation of sesame seed paste (tahini).

BACKGROUND Sesame seed paste is a highly nutritious food product which, upon long-term storage, tends to exhibit undesirable phenomena of oiling-off and particle sedimentation. The ability of rich-in-fibre aqueous extraction powders originating from oleaginous raw materials to enhance the physical stability of sesame paste is investigated in this study. RESULTS The extraction residues remaining after treating hazelnut, sesame seed or maize germ with aqueous media in order to extract and exploit their oil bodies, were collected, dehydrated and milled into fine powders. The powders were then incorporated at various levels into a commercially available sesame paste product to assess their potential as paste stabilisers against oil separation. The solids from maize germ exhibited the highest stabilising ability followed by the solids from hazelnut. In contrast, the solids originating from the sesame seed were less effective in stabilising the sesame paste. Shear stress-rate of shear measurements of sesame paste incorporating the extraction residue solids were conducted in an attempt to explain the different stabilising behaviour of the three powders. CONCLUSION The intensity of interactions between the incorporated solids within the sesame paste structure may determine the rheological properties of the blend and hence its stability against oiling-off upon long-term storage.

Chios Mastic Gum and Its Food Applications

This chapter reviews the traditional Greek product Chios Mastic Gum or Mastiha, primarily known for its distinctive flavor. This is the dried exudate of the shrub-like tree Pistacia lentiscus L. var. chia of the Anacardiaceae family, cultivated exclusively in the south of the Greek island Chios. Emphasis is given on its chemistry and physicochemical properties, health effects, antioxidant and antimicrobial properties. The preparation of traditional food products based on mastic gum or essential oil, such as chewing gum, confectionery, bakery products as well as alcoholic and nonalcoholic beverages, is also discussed.

Exploitation of Orange Peel for the Production of Flavor-Active Compounds with the Use of a Commercial Wine Strain

In the present work, the dynamics of orange peel (OP) was examined for the production of flavor compounds by using a commercial wine strain (Sacharomyces cerevisiae). The effect of OP as a supplementary substrate to glucose for bioflavor production in oxygen limited and non-limited cultures was examined and the results were compared with those obtained from conventional processes on glucose in the absence of OP. OP was found to stimulate the de novo synthesis of isoamyl acetate, phenethyl acetate and ethyl esters (hexanoate, octanoate, decanoate, dodecanoate) by S. cerevisiae. This was strongly evident in the case of limited oxygen supply under semi-anaerobic conditions.