The ratio of total sugar to reducing sugar (TS RS−1) expresses the amount of total glucose units versus the amount of reducing ends of glucose chains or free glucoses, both expressed as mMoles of glucose mL−1, not involving the concept of degree of branching chain.
The elution volume of each chromatographic peak was considered to calculate percentage values in order to facilitate the comparative study.
The study of the fractions was complemented with paper chromatography analysis using (butanol:pyridine:water) (4:3:4) as developing solvent. The separated spots were stained by 1% silver nitrate in acetone followed by 0.5 N NaOH in 96% ethanol and finally washed with 2.5% sodium thiosulfate to clarify.
Characterization of the utilized polysaccharides was performed by means of spectrophotometric studies following Curá and Krisman (1990), Curá et al. (1995). It is considered that α1,4 α1,6 glucopolysaccharides in the presence of I2–KI in CaCl2 saturated solution reagent presents an absorbance between 380 and 800 nm. If the λmax value is lower than 500 nm, it is highly possible to find a branched starch such as amylopectin. On the other hand, a maximum absorption peak at lambda higher than 575 nm would indicate the presence of linear glucopolysaccharides such as amylose. It is possible to estimate the length of the external chains of the α-d-glucan using the parameter “A”, that is, the quotient between the maximum absorbance value of the polysaccharide and the maximum absorbance of the shoulder ( Tolmasky and Krisman, 1987). It has been shown that long external chains of glucopolysaccharides give a high “A” parameter value (around 2–4), indicating a low degree of branching in the α-d glucan indicative of amylose. Accordingly, the smaller values of “A” parameter (around 1.6) are characteristic of short and branched chains indicative of amylopectin.