Effect of storage temperature on the microbial and color stability of banana puree with addition of vanillin or potassium sorbate

The microbial and color changes during storage at different temperatures (1 5, 25 and 35 degrees C) of banana puree preserved by the combination of a b lanching, reduced pH (3.4) and water activity (a(w), 0.97) and the addition of 1000 or 3000 ppm of vanillin (VA)I or 1000 ppm potassium sorbate (PS) w ere evaluated and compared. The use of 3000 ppm VA or 1000 ppm PS inhibited for at least 60 days of storage the native flora of the banana puree at an y of the temperatures studied. The addition of 1000 ppm VA was not enough t o stop the microbial growth. However, at 15 degrees C the growth was delaye d 16 days. In the presence of 3000 ppm VA or 1000 ppm PS the banana puree s tored at 15, 25 and 35 degrees C presented several color changes that contr ibuted to browning. The rate of browning was greater in samples with VA tha n in those formulated with PS, but the activation energy was 10% lower in t he former systems. An analysis of the transition state parameters revealed that Gibbs free energy was similar, indicating that the mechanism of browni ng did not change in the presence of one antimicrobial or the other.