Magda Aniołowska

Content of polyphenols in coloured and yellow fleshed potatoes during dices processing.

The purpose of the research was to examine the effect of the laboratory production of dried potato dice on the content of phenolic compounds in one yellow-fleshed potato variety and four blue-fleshed potatoes varieties. Coloured-flesh potato varieties were characterised by about three times higher amount of total phenolic content than traditional yellow-fleshed ones. The predominating phenolic acids in potato were chlorogenic acid and its isomers, which account about 90% of total phenolic content in tubers. The phenolic acid content decreased by 80% after peeling the blue-fleshed potatoes and by 60% after peeling the yellow variety. The dried potato dice obtained from yellow-fleshed potatoes had no content of phenolic acids but produced from colour-fleshed potatoes contained about 4% of the original phenolic content of the raw material. Chlorogenic acid amounted about 97% of total phenolic acid content, and the rest was neochlorogenic acid.

The quality of protein of coloured fleshed potatoes

Potatoes of purple varieties and red flesh colour were estimated as the important food product containing valuable protein. Amino acids concentration and protein nutritive value of coloured potatoes were analysed and compared with traditional yellow-fleshed varieties. Studies comprised potatoes of 13 varieties: 7 of purple-fleshed, four of red-fleshed and two of yellow-fleshed. There were observed differences between studied potatoes with respect to dry matter, starch and protein content as well as to amino acids concentration and protein quality independently on flesh colour. Potatoes of low as well of high content of total protein, independently on flesh colour, characterised similar protein quality, like for example varieties of Blaue Anneliese and Highland B. Red or Blue Congo and Salad Blue. Leucine limited the quality of majority of coloured fleshed potato varieties used for the experiment. The best amino acid profiles and protein quality confirmed by chemical scores and EAA index values characterised purple fleshed Vitelotte and Blaue Anneliese, yellow fleshed Verdi as well as red fleshed Herbie 26, Highland B. Red and Rosemarie.

The influence of dehydrated potatoes processing on the glycoalkaloids content in coloured-fleshed potato.

The aim of this study was to determine the effect of different temperatures of blanching and pre-drying used in the laboratory production of dried potato dice on the content of glycoalkaloids in red and blue fleshed potato varieties. Studied potatoes of coloured fleshed varieties were characterised by a low glycoalkaloids content at 5.47 mg 100 g(-1). The production of dehydrated potato dice influenced on the decrease in glycoalkaloids content in potato products. The majority of these compounds were removed during the peeling (70%) and blanching process (29%). Potato dice blanched at the highest temperature (85 °C) and pre-dried at 120 °C was characterised by the lowest quantity of glycoalkaloids content, whereas the highest content of these compounds was found in dice blanched potato at the lowest temperature (65 °C) and pre-dried at 120 °C. The blanching process much influenced on the decrease in glycoalkaloids content than pre-drying process.

The effect of frying on glycidyl esters content in palm oil

The changes in palm oil, as affected by frying temperature, and content of the glycidyl esters (GEs) were studied. Potato chips were fried intermittently in palm oil, which was heated for 8 h daily over five consecutive days. Frying was conducted at three frying temperatures: 150, 165 and 180 °C. Thermo-oxidative alterations of the oil were measured by acid and anisidine values, changes in fatty acid composition, total polar components, polar fraction composition and colour components formation. Content of GE was measured by liquid chromatography-mass spectrometry. Results showed that amount of products of hydrolysis, oxidation and polymerization (excluding decrease of degree of unsaturation) increased significantly as a function of frying temperature and time. Between GEs of fatty acids the most abundant were esters of palmitic and oleic acids. With increasing temperature and frying time, the content of GE decreased. The extent of GE decrease was correlated with degree of oil degradation.

The effect of raw materials on thermo-oxidative stability and glycidyl ester content of palm oil during frying.

BACKGROUND The objective of this research was to determine the effects of the water content of food incorporated into frying oil on oil degradation and the content of glycidyl esters. Potato chips, French fries and snacks were fried intermittently in palm oil, which was heated at 180 °C for 8 h per day over five consecutive days. Thermo-oxidative and physical alterations, changes in fatty acid composition, total polar components, polar fraction composition, and water content were analysed. The content of glycidyl esters was measured by liquid chromatography-tandem mass spectrometry. RESULTS More polar compounds were formed in the oil used for frying chips (252 g kg(-1)) than for French fries (229 g kg(-1)) or snacks (196 g kg(-1)). Reductions in glycidyl esters were found in oils used for frying--greater for frying snacks and French fries (95% and 93%) than for potato chips (87%). The rate of decrease of glycidyl esters was correlated with frying parameters, most strongly with the concentrations of diacylglycerols (r = 0.98) and total polar components (r = -0.98). CONCLUSION The raw material had a greater influence on polymerization conversion and glycidyl ester content than on hydrolytic and oxidative changes in the frying oil.

Monitoring of glycidyl fatty acid esters in refined vegetable oils from retail outlets by LC–MS

BACKGROUND Glycidyl fatty acid esters (GEs) are a newly identified class of food process contaminants. The main source of these compounds is refined oils. Because of the potential release of free glycidol, it is necessary to enable a more accurate exposure assessment. In this study a method based on liquid chromatography-single-quadrupole mass spectrometry was used for the analysis of GEs in refined vegetable oils from retail outlets in Poland. RESULTS The amount of GEs detected in 20 edible oils ranged from 0.00 to 44.33 mg kg(-1) . Refined palm oils exhibited a several times higher contamination ratio in comparison with other oils (average 31.24 mg kg(-1) ). The average content of esters in sunflower oils (2.46 mg kg(-1) ) was higher than in rapeseed oils (1.04 mg kg(-1) ). C18:2-GE was found to be the prevailing GE in sunflower oil, with the highest concentration in all studied samples, while C18:1-GE was the prevailing GE in rapeseed and palm oils. No trace of C18:3-GE was found in the analysed oils. CONCLUSION The concentrations of major GEs were correlated with the fatty acid composition of the oils. The GE content varied with the type of oil and the producer. The tested oils had a higher or similar GE content compared with those analysed by other researchers.