Linkages total hydrolysis with acid

To analyze free-form phenolic acids in fmit or vegetable juice, the sample preparation is straightforward and simple. The juice can be directly injected into an HPLC system after it is filtered to remove any insoluble particles. However, for a sample with a solid fraction containing both free and bound phenolic acids, the sample preparation is not as simple. A mechanical method is needed to physically break down the sample and release the free phenolic acids, which are blocked in the inner core of the sample matrix. Chemical (acid or alkaline) or enzymatic hydrolysis must be applied to break down linkages in the bound phenolic acids to release free phenolic acids. However, the recovery of total phenolic acids is significantly affected by hydrolysis and other extraction conditions. An intensive hydrolysis condition may increase the release rate of bound phenolic acids to free phenolic acids however, it can also cause degradation of some phenolic acids and lower... 

This method has been applied by Aspinall and Nicolson to the determination of the nature of the linkages in the highly branched arabino-xylans. 2 Rye-flour arabinoxylan was oxidized, during 4 days at 65°, with oxygen in the presence of Adams catalyst and sodium hydrogen carbonate. A total of 4% of uronic acid residues was introduced into the polysaccharide. After partial hydrolysis, the disaccharide 0-(L-arabinofurano-syluronic acid)-(l- 3)-D-xylose was isolated. As a result, it was determined... 

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