Food Biochemistry and Food Processing

274 Part II: Water, Enzymology, Biotechnology, and Protein Cross-linking

pericarp is boiled in ethanol or extracted with tris-
buffered phenol to inactivate enzymes (Huber 1992),
and cell-wall polysaccharides are precipitated with
ethanol. Alcohol-insoluble solids (AIS) are sequen-
tially extracted with 50 mMtrans-1,2-diaminocy-
clohexane-N,N,N’,N’-tetraacetic acid (CDTA), 50

mM sodium acetate buffer (pH
6.5) to obtain the

chelator-soluble (or ionically bound) pectin. Next,

the pellet is extracted with 50 mM sodium carbonate,

20 mM sodium borohydride, which results in break-

ing of ester bonds, to obtain the carbonate-soluble

(covalently bound) pectin. The remaining residue

Figure 12.2.(Continued)