Many investigations used the agar-based methodology to assess the enzymatic profile of yeasts, but the examiner
calibration before the readings are rarely mentioned. So, it was very difficult to make comparisons of our results
and even to discuss our findings based on the literature. Ingeneral, it was accepted that differences between repeated
measurements of the same sample may result from the instrument/method itself and the circumstances in which the
measurements are performed, such as luminosity and the calibration of the examiner/equipment.25 Based on the results
obtained for both phospholipase and SAPs, there appears to be no consensus on the protocol chosen for each
particular examiner. Measuring the colonies in triplicate may be the main factor associated with the increase in measurement
accuracy and should therefore take precedence
over measuring only one colony. When only one examiner
was responsible for taking measurements, a standard protocol
should be put in place and the statistical calibration
of this researcher should be done prior to data collection.
However, if two or more researchers are involved in the
assessment of agar plates, our results suggest that the protocols
using digital images to undertake plate reading are
preferred