Before processing, all milk donations were mixed in sterile conditions (under a laminar flow cabinet; Telstar AV-100®) reaching a final volume of 700–800 mL. Milk was mixed for a better evaluation of the effect of the processing. Milk aliquots (10 mL) were vacuum packed in polyethylene bags (9.3 mL O2/m2/24 h at 0 °C) for HPT processing. Control samples were also vacuum-packed in plastic bags. All bags have the same dimensions of 3.5 × 1.5 cm. Milk samples were protected from the light by using aluminum foil during sample manipulation. The time between mixing, packaging, processing and freezing the samples was less than 3 h. After processing, samples (processed and unprocessed samples) were stored at − 80 °C (all at once) until analysis