Tag Archives: HPLC

1509-1516 J. Táborský, A. Hejtmánková, E. Hlavatá and L. Chládek
A study of dynamics of bitter acids and xanthohumol in hop pellets during storage
Abstract |

A study of dynamics of bitter acids and xanthohumol in hop pellets during storage

J. Táborský¹*, A. Hejtmánková¹, E. Hlavatá¹ and L. Chládek²

¹Czech University of Life Sciences, Faculty of Agrobiology, Food and Natural Resources, Department of Chemistry, Kamýcká 129, CZ165 00 Prague 6, Czech Republic
²Czech University of Life Sciences, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 00 Prague 6, Czech Republic
*Correspondence: taborsky@af.czu.cz

Abstract:

Eight varieties of hop pellets were analyzed for the contents of α-acids, ß-acids and xanthohumol according to the EBC 7.7 analytical method. The pellets were extracted with acidified mixture methanol – diethylether and analyzed using HPLC with a diode-array detector and a Nova-Pak column C18. Four series of analyses were performed: immediately after the unpacking of the pellets and then after five, seven and nine months of storage at 4 °C. According to the first series of analyses, the contents were assayed as following (α-acids, ß-acids, xanthohumol resp., all in weight % in pellets): Galaxy (13.4, 8.0, 0.74), Citra (11.1, 3.0, 0.48), Tradition (8.2, 8.0, 0.58), Cascade (4.5, 5.2, 0.25), Northern Brewer (4.0, 2.9, 0.37), Sládek (3.5, 4.0, 0.48), Saaz (2.0, 3.4, 0.24), and Triskel (1.7, 3.6, 0.18). According to these results, variety Galaxy was found as the richest in all three parameters. After nine months of storage at 4 °C, the weight loss of α-acids ranged from 4.1% (Citra and Triskel) to 66.4% (Galaxy). The losses of β-acids and xanthohumol were less distinctive (from zero to 31.3% and 25.7%, resp.) and indicated good long storage possibilities of these compounds at convenient conditions (darkness, low temperature, elimination of direct influence of oxygen).

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705-716 D. Baranenko, V. Kolodyaznaya and Y. Broyko
Effect of cold treatment on the amino acid composition of veal
Abstract |
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Effect of cold treatment on the amino acid composition of veal

D. Baranenko*, V. Kolodyaznaya and Y. Broyko

Institute of refrigeration and biotechnologies, ITMO University, 191002, Lomonosova Street 9, Saint-Petersburg, Russia; *Correspondence: denis.baranenko@gmail.com

Abstract:

Veal is a promising raw material for use in the daily diet, as well as for production of functional and dietary foods. However the effect of cold treatment on the amino acid composition of veal has not been sufficiently studied. The aim of this study was the amino acid composition analysis of veal subjected to various variants of cold treatment. The selected material under research was muscle tissue of hip parts from calves, grown in the Leningrad Region, Russia and aged no more than 3 months. Cooling to 4 ± 1°C and rapid freezing to the temperature of minus 18°C at the cooling air temperatures of minus 24°C and minus 35°C were used as variants of cold treatment. Amino acid composition analyses were carried out using precolumn derivatization with phenylisothiocyanate and reversed-phase gradient HPLC on the Shimadzu 20-AD chromatograph with spectrophotometric detection at 254 nm. The results show the effect of cold treatment on the content of free amino acids and total amino acid composition of veal. In many respects changes in amino acid composition are concerned with moisture losses during the refrigerating treatment. The dependence between the change in amino acid content and the structure of its side chain group type is shown. Amino acid score for essential amino acids was calculated and conclusions about changes in biological value of veal protein were made. The obtained data can be used in biological value calculation of the multi-component products and food rations with veal subjected to refrigerating treatment.

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