José Edgar Zapata Montoya

Effects of hydrolysis and digestion in vitro on the activity of bovine plasma hydrolysates as inhibitors of the angiotensin I converting enzyme

The angiotensin I-converting enzyme (ACE) inhibiting activity of bovine plasma hydrolyzates obtained by Alcalase 2.4 L at different degrees of hydrolysis (DH) was evaluated. For the evaluation of ACE inhibition (ACEI), Hippuryl-His-Leu was used as substrate and the amount of hippuric acid liberated by non-inhibiting ACE was determined by spectrophotometry at 228 nm. The results showed that the enzymatic hydrolysis increased the ACEI activity as compared with the un-hydrolyzed plasma. The highest activity was onbtained with a DH of 6.7%. The peptide fractions with the maximum activity were isolated using ultrafiltration membranes, ion exchange chromatography and high performance liquid chromatography on reverse phase (RP-HPLC). The fraction with highest ACEI activity, showed an IC50 of 0.18 mg/mL and contained peptides with sequences AGATGVTISGAG, YSRRHPEYAVS, Q(K)AW and L(l)I(I)VR, which were determined by MALDI-TOF-TOF. It was also found that after submitting such fraction to digestive conditions in vitro, the ACEI activity remained constant.

Modelamiento de la respiración del mango (Mangifera indica l.) usando el método de sistema cerrado a diferentes temperaturas

Measuring the respiration rate of fresh products is essential to design correct of packaging systems. For such effect, rates of consumption of O2 and production of CO2, usually are taken are initial data of system comportment. The aim of this work, was modelling the respiration of whole mango (Mangifera indica L.), variety Tommy Atkins using a closed system (CS) at three temperatures (4, 25 and 35°C) and 90 h in storage. Initially, was fitted a mathematic model to predict behavior the concentration of gases as a time function. With this information, two models were fitted to predict the respiration rates. A model based on Michaelis-Menten’s enzymatic kinetics (MM) and a model based on regression model. Also, an equation type Arrhenius was used to evaluate the temperature effect on respiration rate and a semi-empirical model which predict simultaneously the effect of time and temperature. The results showed that the Arrhenius and MM models obtained the best fits. In this system, the respiration rate of whole mango depends of temperature and of gases concentration, in which the respiration rate is inhibited by CO2 and is favored by increased O2.