<b>Linearization of the titration curves for determination of buffering capacity of feed fiber in a wide pH range</b> - DOI: 10.4025/actascianimsci.v32i1.5384

Abstract

A method for linearization of titration curves and its application to determine the buffering capacity (BC) of neutral detergent fiber (NDF) from 13 feeds and their mixtures was evaluated. Individual data from 2 essays, including samples of white oat, black oat, ryegrass, red clover and white clover (essay 1), and samples of corn, soybean meal, wheat straw and mixtures of these five feeds (essay 2). Titration was performed just to the pH 2.0. The titratable acidity was measured as the amount of HCl needed (mEq g^-1 NDF) to reduce the initial pH of the solution down to 4.0, 3.0 and 2.0, and the linear buffer (LB) measure were determined as the inverse of the slope of the linear regression between linearized pH, calculated as EXP (1 pH^-1), and the accumulated HCl in each interval. The transformation presented satisfactory fitting to linear regression for all materials evaluated, with r² higher than 0.85 and standard error residual lower than 0.059. A positive correlation between TA and LB evaluated in the different ranges of pH was obtained. Unlike TA, the LB method makes it possible to obtain the BC as a single linear ratio, valuable for every pH interval from 8.0 to 2.0.