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1

Wpływ ogrzewania mikrofalowego o mocy 400 W na zmiany oksydacyjne wybranych olejów rafinowanych

100%
Ostasz L.
Zeszyty Naukowe Uniwersytetu Ekonomicznego w Krakowie
|
2011
|
issue 874
125-138
EN
The study analyses qualitative changes occurring in refined oils during microwave heating at 400 watts of power. Sunflower, maize, soy and peanut oils were considered. The temperature of the oil samples was raised to 170–180°C in a microwave. Based on the anisidine peroxide and acid values, oxidative and hydrolytic changes were stated. The highest value of peroxide (higher by about 20 mEq/kg) was observed in the corn, sunflower, and peanut oils while the largest value of anisidine was observed in sunflower oil (124,02). The value of acid in microwave heating increased by between 0.4–0.6 mg KOH/g. The analysis of fatty acid content indicated changes in the palmitate, oleic and linoleic acids.
2

Analiza zmian oksydacyjnych i zawartości kwasów tłuszczowych w oleju „Kujawski” pod wpływem ogrzewania mikrofalowego

100%
Ostasz L.
Zeszyty Naukowe Uniwersytetu Ekonomicznego w Krakowie
|
2013
|
issue 912
73-88
EN
The goal of this study was to analyse the qualitative changes occurring in oil during microwave heating. The subject of the study was Kujawski oil, manufactured by ZT Kruszwica, and purchased retail. Oil samples were heated in an RM 800 microwave reactor. Microwaves at a power of 200, 400, 600 and 800 W were used. The heating duration for the oil samples ranged from 3 to 30 minutes. As a result of heating, the oils were observed to increase in temperature depending on the microwave power. This resulted in oxidative changes in the oil samples, as evidenced by the increase in the values on the peroxide, anisidine and Totox index. The values for these parameters increased over time in all the analysed oil samples. In oils heated by a microwave power of 400–800W, changes in the anisidine value and Totox index over time are illustrated by increasing convex curves. The higher the power of the microwave, the higher the value of this parameter observed in the samples. The highest anisidine value, equal to 143.8, was found in oil samples heated by 800 W microwaves for 30 minutes. The highest Totox value – 155.4 mEq O2/kg – occurred in oil samples heated by 800 W microwaves for 30 minutes.
3

Analiza zmian fizykochemicznych w wybranych olejach rafinowanych pod wpływem ogrzewania mikrofalowego o mocy 600 W

100%
Ostasz L.
Zeszyty Naukowe Uniwersytetu Ekonomicznego w Krakowie
|
2012
|
issue 899
47-61
EN
The aim of the study was to analyse qualitative changes occurring in selected Italian refined oils (Oleificio Zucchi) when heated to 600 W in a microwave. Sunflower, corn, soybean and peanut oils were studied. The oils were heated in a RM 800 microwave reactor. 50 g weight samples were heated for 6, 12, 18, 24 and 30 minutes. To evaluate the qualitative changes occurring in fresh and heated oils, quality indices determined according to PN/ISO standards were employed: peroxide, anisidine, acid and iodine values, and higher fatty acid content. Upon heating, the temperature of the oils rose to 187–215°C. The oxidative and hydrolytic changes that occurred were found based on the analysis of the anisidine, peroxide and acid value indices. The highest peroxide value (18 mEq O2 / kg) was observed for sunflower oil, while the rest had maximum values between 13.0 and 15.2 mEq O2 / kg. Maximum anisidine values in the investigated oils were 147.3 for soybean oil, 139.9 for corn oil, 133.2 for peanut oil and 124.7 for sunflower oil. In the fatty acid composition, a rise in the proportion of saturated fatty acid was found, above all, in palmitic acid. In the unsaturated fatty acid group, the changes occurred in oleic and linolic acids.
4

Wpływ modelowych czynników fizycznych na dynamikę przemian oksydacyjnych olejów tłoczonych na zimno

63%
Kondratowicz-Pietruszka E., Ostasz L.
Zeszyty Naukowe Uniwersytetu Ekonomicznego w Krakowie
|
2017
|
issue 7(967)
33-51
PL
Celem badań było określenie wpływu temperatury i naświetlania promieniami UV na dynamikę oksydacji wybranych olejów tłoczonych na zimno. Oznaczono skład kwasów tłuszczowych olejów oraz liczby charakterystyczne. Próbki olejów ogrzewano w temperaturach 80°C, 100°C i 110°C bez naświetlania promieniami UV oraz po naświetlaniu. Do określenia zmian oksydacyjnych oleju wykorzystano pomiar liczby nadtlenkowej w czasie ogrzewania. Wraz ze wzrostem temperatury ogrzewania olejów stwierdzono wzrost wartości tej liczby. Badane procesy zachodziły z różną dynamiką, co potwierdzają wartości stałych szybkości oraz stosunki tych stałych. Obliczono odchylenie wartości doświadczalnych od teoretycznych dla funkcji opisowych, a także okresy stabilności prób olejów ogrzewanych w podanych temperaturach i ogrzewanych po uprzednim naświetleniu promieniami UV. Stwierdzono, że zarówno wzrost temperatury, jak i naświetlenie powoduje znaczne skrócenie okresu stabilności badanych olejów.
EN
The objective of this research project was to determine the effect of high temperatures and UV irradiation on the dynamics of oxidation of selected cold-pressed oils. The composition of fatty acids in the oil samples and their characteristic numbers were determined. The oil samples were heated to temperatures of: 80, 100 and 110ºC without irradiation, and after UV irradiation. Measurements of the peroxide value during heating were used to determine the oxidation changes. It was determined that that value rose along with the temperature. The processes studied were characterised by varying dynamics, a fact confirmed by the values of rate constants and the ratios of these rate constants for comparable processes. Stability periods were calculated for oil samples heated at the three temperatures, and subjected to UV irradiation prior to heating. The tests demonstrated that both an increase in temperature and irradiation result in the oils having a clearly shorter stability period.
5

Charakterystyka kwasów tłuszczowych omega-3 oraz ocena poziomu wiedzy o ich działaniu zdrowotnym

63%
Ostasz L., Kondratowicz-Pietruszka E.
Zeszyty Naukowe Uniwersytetu Ekonomicznego w Krakowie
|
2011
|
issue 874
139-161
EN
The study presents a survey on knowledge about fatty acids and their effects on human health. The survey questions were about supplements. Respondents were familiar with the term “omega-3 fatty acid”. The vast majority of respondents indicated fish and vegetable oils as the main natural source of these acids. They came by this information from the Internet, newspapers and television. The dominant view among those questioned was that fatty acids are good or very good for the body. The survey results suggest that the concept of polyunsaturated omega-3 fatty acid family and its effect are well-known. This is a highly satisfying result as it instills hope that omega-3 fatty acids are present in the diet of most of those surveyed.
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