Abstract:

In order to reveal the influences of extraction and purification on the properties of beet dietary fibre and promote the value increment of beet pulp,the effects of beet pulp materials and pretreatment method on the quality of beet pectin were discussed. Then,the physiochemical properties of the beet pectin graded by acid extraction and alcohol precipitation were analyzed by using a HPLC and a Haake rheometer,and the morphological and structural changes of the insoluble dietary fibre ( IDF) after the deproteinization by enzymes were investigated by means of SEM. The results indicate that the pretreatment with dilute acid or warm water is unnecessary for the extraction of pectin from 3 kinds of beet pulp,that the product of yield and purity reaches the maximum in the extraction of pectin from grain pulp under optimal conditions,and that the beet pectin graded by acid extraction and alcohol precipitation includes a suspended layer and a deposited layer,and that the suspended pectin layer is of lower density,lighter color,higher viscosity and greater percentage of large molecules. Moreover,it is found that,after the pectin extraction,the cavernous skeleton structure of the pressed beet pulp becomes smoother and the filler particles in cavity disappear,and that further deproteinzation treatment enlarges the cavity and results in the lamellar skeleton structure.

Key words: beet dietary fibre, fractionation, deproteinization, alcohol precipitation, rheological behaviour, skeleton structure