Određivanje sadržaja heljde u hlebu analizom metil estara dominantnih masnih kiselina

Five samples of bread were prepared by mixing wheat and buckwheat flour. The content of buckwheat flour is raised from 0, 20, 40, 50 to 60%. Fatty acids were extracted from bread crusts and crumbs using n-hexane, and derivatised with TMSH (trimethylsulfonium hydroxide in methanol). Fatty acid methyl esters were then subjected to GC-MS analysis. The surface areas of the most abundant fatty acid methyl esters were integrated, and further subjected to the multivariate data analysis. The results show a clear relationship between the content of dominant fatty acid methyl esters and content of buckwheat flour in bread.Pet uzoraka hleba je pripremljeno mešanjem pšeničnog i heljdinog brašana. Udeo heljdinog brašna je povećavan od 0, 20, 40, 50 do 60%. Ekstrakcijom sa heksanom iz kore i sredine hleba su ekstrahovane masne kiseline, koje su derivatizovane sa TMSH (trimetilsulfonijum hidroksid u metanolu) i podvrgnute analizi na GC-MS uređaju. Integrisana je površina metil estara najzastupljenijih masnih kiselina. Pri obradi rezultata primenjena je i multivarijantana analiza. Dobijeni rezultati pokazuju jasnu vezu između sadržaja metil estara dominantnih masnih kiselina i procenta heljde u hlebu

Microwave-assisted preparation of naphthenic acid esters

The synthesis of esters of natural petroleum acids of the naphthenic type assisted with microwave irradiation under the conditions of acid catalysis was carried out with various alcohols: methanol, ethanol, n-butanol and tert-butyl alcohol. Microwave dielectric heating of the reaction mixture in an unmodified microwave oven with activation of the naphthenic acids with sulfuric and p-toluenesulfonic acid afforded the esters of the naphthenic acids. Depending on the catalyst and the steric and nucleophilic properties of the alcohols, the yield of naphthenic esters ranged from 31.25 % to 88.90 %. As a consequence of microwave dielectric heating, the esterification time was reduced from 6–10 h to 5 min