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Proximate composition and vitamin E levels in egg yolk: losses by cooking in a microwave oven
Author(s) -
Murcia M Antonia,
MartínezTomé Magdalena,
Cerro Isabel del,
Sotillo Fernando,
Ramírez Antonio
Publication year - 1999
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/(sici)1097-0010(199909)79:12<1550::aid-jsfa402>3.0.co;2-3
Subject(s) - food science , microwave oven , chemistry , polyunsaturated fatty acid , yolk , linoleic acid , tocopherol , palmitic acid , vitamin e , fatty acid , myristic acid , oleic acid , arachidonic acid , biochemistry , microwave , antioxidant , physics , enzyme , quantum mechanics
The proximate composition, fatty acid and tocopherol levels of egg yolk were determined in raw eggs and after different cooking processes: boiling for 3 and 10 min, heating in a microwave oven, and frying. Of the protein, lipid, ash and moisture contents, only the last decreased with microwave cooking. The predominant fatty acid was oleic (18:1) (36.10–42.6%), followed in decreasing amounts by palmitic (16:0), linoleic (18:2), linolenic (18:3) = arachidonic(20:4) = docosanoic (22:0), docosahexanoic (22:6) and myristic acid (14:0). Of the polyunsaturated fatty acids, 18:2, 18:3, 20:4 and 22:6 decreased in the samples subjected to microwaves. α‐Tocopherol (6.1–2.9 mg per 100g) was the predominant isomer in all the samples followed by (β + γ)‐tocopherol and δ‐tocopherol, while α‐tocotrienol was detected in trace amounts. All these tocopherols were reduced during cooking by up to 50% in omelettes and microwave treatments. © 1999 Society of Chemical Industry