APPLICATION OF COMBINED METHODS FOR ENZYMATIC BROWNING CONTROL OF 
MINIMALLY PROCESSED PEAR (variety BLANQUILLA) 

ABSTRACT 

In this study different combined methods were applied for development of enzymatic 
browning control in minimally processed pears (variety Blanquilla). 

First of all, effects of thermal treatments applied with vapour and water solutions immersions 
at 87ºC were evaluated through colour and mechanical properties in fresh fruits cylinders and 
stored at different conditions. Results do show that both treatments produced significant 
changes in samples colour and mechanical behaviour. The longer the treatment time, the 
greater the changes. 

Subsequently, effectiveness of antibrowning agents application (citric and ascorbic acids) in 
osmotic and isotonic media was studied, by colour changes evaluation during refrigerated 
storage. The obtained results show that lightness (L*) and hue (hab*) parameters are the 
best indicators of browning degree in pear. Osmotic media (which are associated to produce 
partial dehydration) were not suitable for enzymatic browning inhibition, possibly by 
enhancing tissue osmotic stress. Moreover, neither citric or ascorbic acid resulted effective 
for Blanquilla pear enzymatic browning inhibition. 

Finally, effectiveness of various antibrowning agents (citric, ascorbic, 4-HR, EDTA and 
isotonic solution) with and without calcium lactate, applied using the vacuum impregnation 
technique with neutral pH solutions, was analysed. Different quality parameters such as 
colour, mechanical properties, sensorial evaluation, shelf life, respiratory rate, volatile 
production and microbiological stability during refrigerated storage, were evaluated. Results 
showed that the use of antibrowning compounds combined with calcium salts were not 
effective to keep sample colour stability throughout the storage time. Nevertheless, 
application of such combinations leads to diminish impact process by slowing down 
respiration and enhancing microbiological stability of samples. 

Key Words: Minimally processed pear, colour, antibrowning agents, combined methods