2.3. Pectin Degradation Index (PDI) %The diameter of the yeast colonies and the pectin degradation zones were measured using a ruler after growing the yeasts on a Petri dish (YPDA + pectin) for five days. The degraded area showed a clear zone after flooding with iodine solution. The clear zone and colony diameters were used to compute the pectin degradation index (PDI), according to the following formula: