Determination of pigmentsPasteurized red beet juice was inoculated with seven strains of Saccharomyces cerevisiue after adjusting pH to 5.8. Fermentation was at 26°C. The decay of red beet pigments was spectra-photometrically determined and expressed as betanine. Average percentages of betanine, isobetanine, betanidine, isobetanidine and the saccharide components were monitored by HPLC. After 40 hr fermentation, the strains Oenoferm, 1090 and Tokaj 76D showed pigment retentions and sucrose concentrations (g.L-') of 62% and traces, 58% and 3.4, and 56% and 1.4 respectively, and were considered the most suitable.For determination of pigments, a spectrophotometric method was used which did not require separation of individual pigments and enables betacyanines to be determined. (Nilsson, 1970). HPLC of betacyanine pigments

The selective and reproducible separation of anthocyanins is important not only from the analytical but also from the practical points of view, for judgment the origin of anthocyanins in products of the most frequently occurring cultures of Vitis uinifera.This work deals with the selection of the suitable conditions for the separation of anthocyanins in red wines by HPLC using gradient elution to determine the optimal pH of the mobil phase to improve the detection in the visible range and the selectivity of the column.In the works published up to now, tartaric acid, acetic acid, phosphoric acid and perchloric acid have been used in different systems to adjust the pH value, discussing the formation of a suitable elution strength and the aggressivity of the acids [ 1 -51. Material and methods Results and discussionIn the first stage, the influence of pH in the range of 1.5 to 2.2 on the separation and detection of the pigments has been studied. For the gradient elution, solvent A (HCIO, in water) and solvent B (methanol) have been used, beginning with 25% in A at 1% B/min increase rate and ending with 15% B in A.On the basis of the areas of the peak as a function of pH and of the separative efficiency Ri, j , the range of pH from 1.5 to 1.8 was shown to be the most suitable. For testing the aggressivity of the acids and their influence on the column life, three acids have been used (15% acetic acid solution had a pH value 2.17, what was outside of the optimal detection; the same, the separative efficiency at this value of pH was not satisfied). It was shown that with regard to the elution time, capacity factors k , selectivity a, separation of two components eluting one after another, corrosion (including the detector), HC10, was the most suitable acid to adjust the pH.The determination of the most suitable gradient has been made parallel for H,P04 and HCIO, selecting the composition of the mobile phase at the beginning and the slope of the gradient. The choise of suitable gradient was carried out empirically in two steps: selection of the mobile phase at the beginning and adjustation of a profile of a gradient. The optimal composition of mobile phase was evaluated on the base of both capacity factors and selectivities for peaks No. 4 and 5 in the system studied. A great difference of concentrations of methanol in solvents A and B brought about the deterioration of the separation. The last searched types of gradients are shown in Table 1. The suitability of the selected types of gradient have been judged on the basis of the capacity factors k and the selectivity coefficients a (Table 2).

Red wine represents a complicated system of phenolic compounds which give typical properties to individual varieties. Anthocyanin pigments represent a determinant group and therefore special attention is given to its analysis. The separation in an acceptable time, the selective separation with a typical gaussian curve and the reproducibility are still a problem.Fundamental works regarding the analysis of flavonoids and anthocyanin pigments by HPLC are the isocratic methods using 10% HCOOH in a 50% methanol-water solution [l, 21. In further works, different mobile phases at isocratic and gradient elution for the production and control of wine [3-51 or for comparison of the recommended methods of analysis [6] have been used. Material and methods Samples Resilts and discussionThe problem was solved by determining the optimal composition of the mobile phase in the planned experiment with isocratic solution, in which 3 variables, x1 (from 35 to 65.5% vol of methanol in water), x p (from 0.02 to 0.3 mol . I-' HCIOl in water) and xg (from 0.02 to 0.2 ml . I-' alkylamine in water) have been studied. Diethylamine, butylamine, triethylamine, hexylamine and octylamine have been used as alkylamines. As an example, for butylamine the optimal composition of the mobile phase was x1 = 35%, x2 = 0.16 mol 'l-', x3 = 0.122 mol . I-'. All the alkylamines speed up the elution in different grade, however, the necessary separation of anthocyanins was not reached. With the adjustment of the concentration of methanol, it is possible to adjust the elution strength, but it was necessary to analyse with gradient elution. The solution A (10.5% vol methanol) and B (90% vol methanol) have been used for the gradient program. In both solutions the concentration of HCIO, and butylamine was 0.16 mol . I-' and 0.122 mol . I -', respectively. The type of gradient was set to be 25% B at the beginning and 51% B at the end. Fig. 1 shows the chromatographic record for the analysis of anthocyanins in the Cabernet Sauvignon wine with the identified peaks (1) delphidin-3-glucoside, (2) cyanidin-3-glucoside, (3) petunidin-3-glucoside, (4) peonidin-3-glucoside, ( 5 ) malvidin-3-glucoside, (6) unidentified, (7) delphidin-3-glucoside acetate, (8) cyanidin-3-glucoside acetate, (9) petunidin-3-glucoside acetate, (10) peonidin-3-glucoside acetate, (1 1) malvidin-3-glucoside acetate, (12) delphidin-3-glucoside p-coumarate, (13) peonidin-3-glucoside p-coumarate and (14) malvidin-3-glucoside p-coumarate.The method of separation of anthocyanins with addition of alkylamines and the previous recommended method for separation using gradient elution [7] have been compared. This comparison was made on the basis of the time analysis, separation efficiency (selectivity, differentiation factor, capacity factor) and reproducibility of the gradient. For instance the time of analysis was shortened

No abstract

In this work the influence of the non‐traditional canning method, based on a decreased thermosterilization intensity (15–70 min/121°C) combined with ionizing radiation (0,5–9.5 kGy), upon retention of vitamin B6 contained in model samples of pork in its own juice, being stored for a short time (41 days) at a temperature of 20 °C ± 2 °C is studied. In the experiment, a uniform, central, composite plan of the experiment ROUCE‐KOP which belongs to the group of surface‐response methods (RSM — Response Surface Methodology) [1] was employed.