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Acta Alimentaria
Authors: I. Dalmadi and M. Tóth-Markus
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Galactosaemia is a rare, life-threatening inborn error. It is treated by life-long galactose restriction. People with galactose intolerance cannot consume milk and milk products. The aim of this work was to produce fermented milk products with low galactose content. Lactose hydrolysed milk and two types of mixture of lactose hydrolysed milk supplemented with galactose free nutriments (Pregomin and Nutrilon) were fermented in a 2:1 ratio. For fermentation traditional kefir culture (Lactococcus lactis sp. lactis + Lactococcus lactis sp. cremoris + Lactobacillus casei + Lactobacillus kefir + Candida kefir) was used. Number of viable cells, pH and galactose level were measured. Data were evaluated by one-way analysis of variance and t-test. Level of galactose reduction was measured by UV spectrometry for the determination of lactose and D-galactose in foodstuffs (Boehringer Mannheim enzyme test). Galactose content was below 200 mg/100 cm3 in the mixtures of lactose hydrolysed milk and galactose free nutriments after 48 h of fermentation. So, the kefir-like products based on mixed milk with nutriments are suitable for use in the diet of patients suffering from galactosaemia.

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Acta Alimentaria
Authors: G. BujdosÓ, M. Tóth-Markus, H. Daood, N. Adányi, and P. Szentiványi

Eight registered Hungarian walnut cultivars were tested for composition and sensory properties. The samples were collected at the Experimental Fields of the Research Institute for Fruitgrowing and Ornamentals in Érd-Elvira major. Proximate composition, fatty acids, minerals (P, Na, Ca, Mg, Ca, Fe and Se), polyphenols and vitamins (C, E) were determined in four consecutive years 2003–2006. The tested cultivars have an oil content, which falls within the upper range of the literature values. Polyphenols, iron and selenium contents are also high while the values for potassium and phosphorus are in the lower part of the given range. In our case, the crop years make a larger difference in the composition than the cultivars. Tiszacsécsi 83 is the only cultivar slightly differing from the others in lower mineral and protein content.

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Volatile flavour substances were isolated from the minced pulp of half ripe and full ripe fruits of guava (Psidium guajava L.) cv. Lucknow-49 by simultaneous steam distillation extraction (SDE) with diethyl ether as extracting solvent. The concentrate was analysed by GC-MS. Acetic, butyric and hexanoic acids were the predominant acids, trans-2-hexenal and hexanal the predominant aldehydes and ethyl propanoate, methyl butyrate, ethyl butyrate, methyl hexanoate, ethyl hexanoate, cis-3-hexen-1-yl acetate, hexyl acetate, methyl benzoate, methyl octanoate, ethyl benzoate, phenylpropyl acetate and cinnamyl acetate, the esters responsible for the characteristic guava flavour were also present. The amount of total volatile substances was about 20% higher in full ripe fruits. The concentration of acids and most esters increased and that of C6 aldehydes decreased during ripening. The enzyme analysis showed that the polygalacturonase (PG) activity was lower in the ripe fruit, than in the half ripe one, while the β -galactosidase activity was not influenced by maturity stage. The surface and the cell walls of full ripe guava became wrinkled, and parenchyma cells were empty (SEM).

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Acta Alimentaria
Authors: M. Tóth-Markus, I. Magyar, K. Kardos, L. Bánszky, and A. Maráz

In this study the role of different yeast strains in the production of volatile flavour components of Tokaji Aszú wine was tested. The effect of a Saccharomyces cerevisiae starter and that of the typical endogenous Candida stellata strain as well as spontaneous fermentation were studied and compared. For the fast comparison of aroma profile, a solid phase microextraction (SPME) sampling and a GC-MS separation and identification were used. Thirty of the present compounds were selected to characterise the changes of flavour. Significant differences were found between wines fermented with different yeast strains. Application of a Saccharomyces cerevisiae starter alone accelerated the fermentation but this caused only little change in the aroma profile and content. Candida stellata contributed weakly to the production of aroma, especially to that of the longer carbon chain ethyl esters. Characteristic compounds of aged wine were detected in bottle aged Tokaji Aszú. The change of aroma profile as a function of bottle storage time was studied. The concentrations of vitispirane, trimethyl dihydronaphtalene, 2-phenylethanol and diethyl succinate increased in the course of ageing time, while those of 3-methyl-butyl acetate, ethyl hexanoate, ethyl octanoate, ethyl decanoate and ethyl dodecanoate decreased.

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Colour (L*, a*, b*, h o and chroma), β-galactosidase, polygalacturonase (PG) activity, pectin content, ultrastructure and volatile compounds were determined, in mature green and in yellow ber fruits ( Zizyphus mauritiana Lamk. cv. Umran).The L* did not, but a*, b* and h o significantly differed between mature green and yellow ber fruit. The pectin content and its solubilization (soluble pectin and neutral sugars), the activity of PG was higher in yellow ber fruits and in the outer part of fruits. Activity of β-galactosidase was higher in mature green ber fruits. The cell walls of mature green fruits were usually homogeneous, the density of the middle lamellae decreased in yellow bers, and at the same time, the structure of chloroplastids disintegrated. The aroma of yellow ber is characterized by the presence of even carbon number of ethyl esters from C4 to C14.

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