Ultrasound-vacuum infusion effect on jalapeño pepper (Capsicum annuum L.) blanching and thermal behavior of its pectin methylesterase

Blanching treatment is an indispensable operation on fruit and vegetable processing, nevertheless, it is also capable to produce significant changes in sensory properties of such products, mainly texture and color. Pectin methylesterase (PME) treatments are an important process for texture improvement. These treatments can be applied either by means of endogenous PME activation or by infusion of exogenous PME in combination with or without a calcium salt; along with the use of temperatures around 60 °C, in order to attain the maximum activity of PME. In the present study, jalapeño pepper PME showed its highest activity at 55 °C. Likewise, it displayed a great thermal stability below 50 °C, as well as a long-time retention of its initial activity at such temperature. In the same way, when a solution of 15 U·mL−1 of PME with 10 mM CaCl2 was applied through ultrasound-assisted vacuum-infusion for 5 min, blanching-induced changes in texture and exocarp color of jalapeño pepper were reduced. Simultaneously, an increase of fruit tissue PME activity was observed with specific treatment conditions.