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1

Oxidative Changes of Milk Fat in Dry Milk Stored under Various Conditions

Okénová E., Krejči J., Hrabe J., Vicha R.

Ecological Chemistry and Engineering. A

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2010

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Vol. 17, nr 1

119-128

EN

Oxidative changes of milk fat in whole dry milk during 50 days of storage under various conditions were examined. Whole dry milk with 26.47 % of fat and insolubility index l .27 was taken as a sample. Whole dry milk was manufactured by roller drying in YOG s. r. o. Bojkyice. Whole dry milk was stored in desiccators at temperature 37 stC in thermoregulator under various water activities (0.23 and 0.82). Water activity was made by 100 cm3 of saturated salt solution. Water activity 0.23 was made by saturated solution of potassium acetate and water activity 0.82 was madę by saturated solution of potassium bromide. The milk powder was stored for 50 days. The sample with water activity 0.82 became dark brown during storage thanks to products of Maillard reaction. The oxidative changes were examined as a content of hydroperoxides, TBARS (thiobarbituric reactive substances), peroxide value, neutralization number, content of conjugated dienes and fatty acids composition. The content of hydroperoxides, TBARS and fatty acids, especially unsaturated fatty acids (oleic acid and linoleic acid) decreased during storage. Neutralization number and peroxide value increased during storage. Ali chemical parametrer were significantly changed during 50 days of storage under various water activities.

PL

Badano zmiany oksydacyjne powstające w tłuszczu mleka suszonego przechowywanego przez 50 dni w różnych warunkach. Próbki przygotowano z mleka o wskaźniku nierozpuszczalności 1.27 i zawartości tłuszczu 26,47 %. Badane mleko zostało wyprodukowane w zakładach YOG Bojkovice. Mleko przechowywano w eksykatorze w temperaturze 37 st C. Aktywność wody na poziomie 0,23 uzyskano dzięki zastosowaniu nasyconego roztworu octanu potasu, natomiast aktywność wody na poziomie 0,82 uzyskano, stosując nasycony roztwór bromku potasu. Proszek mleczny był przechowywany przez 50 dni. Próbki mleka przechowywane przy aktywności wody 0,82 przybrały kolor ciemnobrązowy w wyniku reakcji Maillarda. Zmiany oksydacyjne zostały zmierzone jako zawartość wodoronadtlenków, TBARS, zawartość nadtlenków, liczba zobojętnienia, zawartość dienów sprzężonych oraz skład kwasów tłuszczowych. Zawartość wodoronadtlenków, TBARS, kwasów tłuszczowych, a w szczególności nienasyconych kwasów tłuszczowych (kwas oleinowy, kwas linolowy) uległy zmniejszeniu w czasie przechowywania. Wartości liczby zobojętnienia i zawartości nadtlenków wzrosły w czasie przechowywania. Wszystkie parametry chemiczne uległy znacznym zmianom w czasie 50 dni przechowywania przy zróżnicowanej aktywności wody.

2

Mild Conditions Synthesis of Mixed Organic Peroxides from Alkyl Halides and Organic Hydroperoxides

Baj S., Krawczyk T., Siewniak A., Rączkowska A.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 3

381-384

EN

The synthesis of mixed organic peroxides by reaction of alkyl halides with tertiary hydroperoxides under basic phase-transfer catalysis conditions was described.

3

Badania utleniania 4,4'-diizopropylobifenylu w fazie ciekłej tlenem do wodoronadtlenków

Stec Z., Zawadiak J., Zellerhoff R., Orlińska B.

Przemysł Chemiczny

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2003

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T. 82, nr 8-9

637-639

4

Hydroperoxide Oxidation of Benzylamines Catalyzed by Selenium Compounds

Brząszcz M., Kloc K., Młochowski J.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 11

1579-1586

EN

Selenium(IV) oxide, poly(bis-1,2-phenylene) diselenide, bis[2-(N-benzisoselenazol- 3(2H)-onyl]diselenide and particularly 2-phenyl-1,2-benzisoselenazol-3(2H)-one (ebselen), were employed as the catalysts for hydrogen peroxide and t-butyl hydroperoxide oxidation of benzylamines. A reaction of primary amines proceeded via hydroxylamine and oxime, and the nitriles accompanied by imines, carboxylic acids and aldehydes were the final products. The secondary amines produced mainly the nitrones, while tetrahydroisoquinoline was dehydrogenated to isoquinoline.

5

Kinetics of the Reaction Between Ethylallyl Ethylacrylate and tert-Butyl Hydroperoxide in the Presence of Molybdenum Catalysts

Trach Y., Nykypanchuk M., Komarenska Z.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 9

1323-1332

EN

The reaction of ethylallyl ethylacrylate with tert-butyl hydroperoxide in the presence of molybdenum catalysts (Mo2B and Mo2B5) was studied. The general kinetic model for the process is proposed, which adequately explains the hydroperoxide consumption up to 80% conversion. The equilibrium constants of the complex formation were calculated. It was shown that Mo/B ratio in the catalyst affects the catalyst-hydroperoxide complex stability.

6

Hyrdoperoxide Oxidation of Azomethines and Alkylarenes Catalyzed by Ebselen

Giurg M., Wójtowicz H., J. Młochowski J.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 4

537-542

EN

2-Phenyl-1,2-benzisoselenazol-3(2H)-one (ebselen), known as glutathione peroxidase mimic, is found as an efficient catalyst for hydrogen peroxide and tert-butyl hydroperoxide oxidation of the azomethine group in azines, aldoximes, and methyl or methylene group in alkylarenes. Depending on the substrate used and the reaction conditions, the major products are aldehydes, ketones, carboxylic acids or their derivatives. It is postulated that ebselen is involved in the free-radical oxidation mechanism.