The aim of the study was to evaluate the stability of vitamin C and beta-carotene in the freeze-drying process compared to other thermal drying methods. Tomato puree was selected as a model product for testing the stability of vitamin C and vitamin A in drying processes, due to its properties, such as: appropriate consistency, which was favorable for the analyzes performed, and the presence of the above-mentioned vitamins. Model studies were performed on the stability of vitamin C and betacarotene under the conditions of air-drying at 105°C, drying under reduced pressure at 70°C and freeze-drying on a tomato puree matrix. Results proved that freeze-drying is superior to other drying methods with the lowest losses of both vitamin C (losses of 4%) and beta-carotene (losses of 25%) in tomato purée. In the case of drying at 70°C under reduced pressure, the loss of beta-carotene is 55%, and vitamin C - 78%. In the case of air-drying at 105°C, vitamin C is 100% degraded, and the loss of beta-carotene is 91%. Moreover, it can be concluded that vitamin C in a higher dose has a protective effect on carotenoids.
The aim of the work was to determine dietary fibre content (total, soluble and insoluble) in kale. Packages of the vegetable were bought in local stores in Lodz. Dietary fibre content determined during the research was compared with the information given by producers. Conducted research proved that kale is rich in dietary fibre (from 4.36 to 5.05 g per 100 g of product in fresh weight, mostly in form of insoluble dietary fibre). The results of determinations carried out in the laboratory coincide with the data declared by the producers.
The content of alcohol insoluble solids (AIS), polysaccharide composition of cell walls and uronic acids content calculated as galacturonic acid in rose hips (Rosa villosa (Rosa pomifera Herrm) ‘Karpatia', Rosa canina L., Rosa rugosa Thunb.). Rose hips were extracted by means of pectin sequential extraction. Rose achenes contained more alcohol insoluble solids than flesh. The main saccharide building cell walls of rose fruit was glucose from cellulose. The achenes were rich in xylose and the flesh was rich in arabinose. The content of galacturonic acid in flesh was 2 to 3 times higher than in the case of achenes. The largest polysaccharide fraction both in whole fruit and achenes was Concentrated Alkali-Soluble Polysaccharides fraction, while in flesh it was Water Soluble Pectins fraction. Chelating Agent Soluble Pectins fraction was the smallest in the flesh, achenes and the whole hypanthium. Differences in the polysaccharide composition, the content of AIS and galacturonic acid were found, depending on the species of rose hips. In addition, differences in composition were found in the case of wild growing and controlled cultivation hips. Rose hips achenes contain more total dietary fiber than the flesh, but the flesh contains more pectin fraction (soluble dietary fiber) while the achenes contain more cellulose (insoluble dietary fiber).
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