Colourimetrically determining degree of oxidn. of fats - using bromothymol blue, bromocresol green, cresol-indophenol and/or thymol-indophenol redox indicators

摘要

In the colourimetrically determin. of the degree of oxidn. of a fat or fat-contg. food the redox indicator is bromothymol blue (3,3'-dibromothylmol-sulphone-phthalein), bromocresol green (3,3',5,5'-tetrabromo-m-cresol-sulphonephthalein), cresol-indophenol (benzoquinone-(1,4)-mono 4-oxy-2-methylanil ) and/or thymol-indophenol (benzoquinone-(1,4)-mono- 4-oxy-2-methyl-5-isopropyl-anil ). Determn. is completed in 2 min. Process is simple and comprises adding indicator to sample tested and determining the colour change. In an example 1.5 ml molten fat were dissolved in 3.5 ml for a 2% KOH soln. in a 1:1 benzyl alcohol : n-propanol mixt. and mixed with 0.11 ml 0.1% bromothymol blut soln. in n-propanol.