Pressurization and cold storage of strawberry purée: Colour, anthocyanins, ascorbic acid and pectin methylesterase

The effect of pressurization and cold storage of strawberry purée on colour, anthocyanins, ascorbic acid and pectin methylesterase was investigated. Samples were treated at pressures of 100, 200, 300 and 400 MPa, at two temperatures, 20 °C and 50 °C, for 15 min. Ascorbic acid content remained fairly constant after all the high pressure treatments in comparison to the control. However, the values of the samples pressurized at 50 °C were lower than the samples pressurized at 20 °C. Concentration of anthocyanins remained similar after all pressure treatments at both temperatures. Pectin methylesterase decreased in the samples pressurized at 50 °C, and it is remarkable that with this enzyme inactivation a gel-network formation in the strawberry purée was not found. However, a gel-network was observed in the control and in all the samples pressurized at 20 °C throughout cold storage. Immediately after pressurization, strawberry colour showed significant differences between the two temperatures, but no differences were observed between pressures. However, after cold storage no significant differences were observed, for hue and chroma parameters, between the samples pressurized at the two temperatures.