11.07.2015 Views

Benders'dictionary of nutrition and food technology

Benders'dictionary of nutrition and food technology

Benders'dictionary of nutrition and food technology

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

362acid. The intermediate compounds, with varying numbers <strong>of</strong>methoxyl groups, are pectinic acids. Also known as pectinesterase, pectin methyl esterase <strong>and</strong> pectin methoxylase. Unlikepectinase, present in both ripe <strong>and</strong> unripe fruit, <strong>and</strong> not associatedwith s<strong>of</strong>tening <strong>and</strong> ripening.pectic acid Demethylated pectin.pectin Plant tissues contain hemicelluloses (chemically polymers<strong>of</strong> galacturonic acid) known as protopectins, which cement thecell walls together.As fruit ripens, there is maximum protopectinpresent; thereafter it breaks down to pectin, pectinic acid <strong>and</strong>finally pectic acid <strong>and</strong> the fruit s<strong>of</strong>tens as the adhesive betweenthe cells breaks down. High methoxypectins (with >50% esterification)form rigid gels at low pH; low methoxypectins (

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!