**4.2.1 Methodology**

Reagents:

Reagent A: 10g p-hydroxy benzoic acid dissolved in 60mL water, add 10mL hydrochloride acid and complete volume to 200mL.

Reagent B: 24.9g trisodium citrate in 500mL water, 2.2g calcium chloride, 40g sodium hydroxide, and to complete the volume to 2.000mL.

In the day of analysis, mix reagents A and B in proportion of 1:10, after keep at 4°C.

Get an aliquot 50µg.mL-1 of the reducing sugar sample, add 5mL p-hydroxy benzoic acid hydrazide reagent (mixed in the same day) shake in vortex, incubate in water bath at 100°C by six minutes, cool until room temperature, and read the absorbance in spectrophotometer at 410nm.
