Evidently the aloe contains a certain amount of organic acids, which are decarboxylated to release CO2, which accumulates in vacuoles.
If I were to rewrite the sentence to make maximum sense (not a translation), it would read:
La acumulación vacuolar del CO2 a manera de ácidos orgánicos, específicamente ácido málico, permite cuantificar su contenido y de este modo valorar la presencia de aloe total.=
The vacuolar accumulation of CO2, e.g. from organic acids, in particular malic acid, allows one to quantify the content [of such acids], and thereby to some extent to determine the total content of aloe.