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Alpha- and beta-carotene stability during storage of microspheres obtained from spray-dried microencapsulation technology

100%

Przybysz M. A., Szterk A., Symoniuk E., Gaszczyk M., Dluzewska E.

Polish Journal of Food and Nutrition Sciences

2018

tom 68

nr 1

This study was aimed at comparing the stability of carotenes (α- and β-carotene) in oil solutions with their stability when spray-dried encapsulation is applied. The carotenes were isolated from carrot. A storage test was subsequently performed. The stability of carotenes in oil solutions was determined with the HPLC method. The color of the samples was also analyzed. The oil solutions of carotenes were microencapsulated with the spray-drying method. A mixture of gum Arabic and maltodextrin was used as a matrix. Degradation of carotenes during storage of the oil solutions followed first-order kinetics. The energies of activation were 58.7 and 33.6 kJ/mol for α- and β-carotene, respectively. Among the studied factors (time, daylight, temperature), it was the time and the temperature that infl uenced carotenes degradation the most. Spray-drying encapsulation caused a signifi cant decrease in the content of carotenes. However, retention of pigments stored in microspheres was longer than retention of pigments stored as oil solutions.

Regional heterogeneity of myocardial blood flow within the rabbit left ventricle during haemorrhagic hypotension

80%

Standa M., Iversen P. O., Flatebo T., Nicolaysen G.

Journal of Physiology and Pharmacology

1992

tom 43

nr 3

Several studies have reported an extensive regional heterogeneity in myocardial blood flow. The reported coefficients of variation for regional myocardial perfusion range from about 0.2 to 0.4 in normotensive animals. The spatial distribution of myocardial perfusion during haemorrhagic hypotension seems not to have been assessed. The goal of the present study was to determine the regional heterogeneity in myocardial blood flow within the rabbit left ventricle during normal conditions and after haemorrhagic hypotension. Radioactive microspheres were infused into the left ventricle in barbiturate anaethetized rabbits over either 30 or 120 sec. The haemorrhagic hypotension was induced by bleeding, so that mean arterial blood pressure was reduced to about 50% of control. The left ventricles were divided into samples of about 0.025 g each. Regional heterogeneity in the blood flow was expressed as the coefficient of variation corrected for the Poisspn distribution of microspheres (CVc). The CVc was 0.37 ±0.09 (mean±SD) during control and 0.41+0.11 after bleeding, the CVc obtained after bleeding being somewhat higher than during control (P<0.05). We obtained a high correlation coefficient (τ about 0.68) between regional perfusion values at control and after bleeding which indicates a stable perfusion pattern within the myocardium. We conclude that the regional distribution of coronary blood flow within the left ventricle is markedly heterogenous during control condition and that this pattern is not changed during haemorrhagic hypotension.

Ograniczanie wyników

1 Journal of Physiology and Pharmacology

1 Polish Journal of Food and Nutrition Sciences

1 Dluzewska E.

1 Flatebo T.

1 Gaszczyk M.

1 Iversen P. O.

1 Nicolaysen G.

1 Przybysz M. A.

1 Standa M.

1 Symoniuk E.

1 Szterk A.

1 2018

1 1992

Wyniki wyszukiwania

Alpha- and beta-carotene stability during storage of microspheres obtained from spray-dried microencapsulation technology

Regional heterogeneity of myocardial blood flow within the rabbit left ventricle during haemorrhagic hypotension