I did acid hydrolysis to breakdown pectin into monosaccharides for sugar analysis. The colour of pectin eventually changes into the colour of the fruit itself during the hydrolysis. Wondering what causes the colour change during the hydrolysis. Can anyone help me here?
Pectin from which fruit? You can have two diferent phenomena when hydrolysing pectins.
- you need fairly harsh hydrolysis conditions to get monomers from the homogalacturonic chains, as the glycosidic bonds between uronic acids are very stable; because of this, some of the freed monosacharides actually start to degrade to brown products (formation of furfuric derivatives, polymerisatin etc, akin to caramel formation and badly understood);
- very often during pectin extraction som epolyphenols are co-extracted, adn specially if they are proanthocyanidins, actually bind to the pectin; in acidic conditions these polyphenols are converted to pink derivatives by cleavage and oxidation (like in the Hcl-butanol method for procyanidin quantification)
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