Influência da concentração de ácidos no processo de extração e na qualidade de pectina de bagaço de maçã

Abstract

In concentrated apple juice processing units the pomace is washed with tap water in order to increase the yield so that the industrial by-product contains no more soluble pectin but only insoluble protopectin. In this article the main objectives were to establish a procedure to prepare the apple pomace as raw material and to extract pectin with several kinds and concentration of mineral and organic acids considering its degree of esterification, determined by titrimetric and spectroscopic techniques, as quality references. Dried apple pomace, with 12% moisture, showed 33.4% reducing sugars and 40% dietary fiber in dry weigth basis, with proper color. The extraction processing parameters (97ºC/10 min/solute: solvent ratio 1:40 ) of pectic substances allowed to establish the efficiency of each acid for protopectin solubilization, from 1 up to 750 mMol/L. Two acidic mechanisms were clearly observed. [1] The first, pectin-releasing at low and pectin-degrading reactions at high concentrations and [2] the second, increasingly gravimetric yields reaching values higher than possible, suggesting an attachment of organic groups in the pectic structure. HNO3 was defined as the more interesting acid for pectin extraction.