The colour of apple juice was measured using a Minolta colorimeter
(CS-100A, Minolta Co. Ltd, Japan) according to Lu et al.
(2007) with some modifications. The degree of browning was
expressed by the percent decrease in the L-value. calculated by
subtracting the L-value of treated and control samples measured
at evaluation times from the time-zero L-value obtained from
untreated samples measured immediately after juicing, divided
by the time zero value and multiplied by 100.