A process and molecular biomarker for platelets stored in blood banks provides for efficient verification of which platelet concentrate bags are in good condition for transfusion by measuring, by real-time polymerase chain reaction, expression levels of hsa-miR-127 and hsa-miR-320a microRNAs as the first process and biomarker predictor of platelet's cell aging during storage and the consequent presence of storage lesions as a quality test of these bags.