EXTRACCIóN Y MEDIDA DE ACTIVIDAD DE PECTIN METIL ESTEARASA EN PITAYA AMARILLA (Acanthocereus pitajaya), ENZIMA RELACIONADA CON EL ABLANDAMIENTO

using diverse techniques applied to keep the freshness of yellow pitaya (acanthocereus pitajaya) fruit it has been found that excessive softening of its crust leads to quality deterioration. since pectinmethyl esterase (pme) has been related to fruit softening in this study we evaluated the protein levels and the pme activity after the addition of triton x-100 1% and nacl in concentrations from 0 to 2 m in buffer 20 mm phosphate ph 7.0. effects of cysteine addition and dialysis were also evaluated for the extraction processes. factors that can affect the activity of pme such as incubation time, different nacl concentration, as value level of ph during the incubation, temperature and pectin (citric pectin) concentration were evaluated. the best system found in this study for pme extraction was buffer phosphate 20 mm, ph 7.0 and nacl from 0.0 to 1.0 m. the best system for the activity measurement is to use pectin from 0.40 to 0.75%, keep the ph between 5 and 8 and incubate from 40 to 45 a°c during 2.5 min.