Resumo

RAMIREZ AYALA, Acacia; VEGA Y LEON, Salvador; PRADO FLORES, Guadalupe  e  GUTIERREZ TOLENTINO, Rey. Application of three analytic methods for the detection of cheese serum in UHT  milk commercialized in Mexico city. INCI [online]. 2009, vol.34, n.6, pp.406-412. ISSN 0378-1844.

The presence of cheese serum was detected in ultra pasteurized milks (UHT) commercialized in Mexico City. This was achieved through sodium dodecyl sulphate poliacrylamide gel electrophoresis (SDS-PAGE), by high performance liquid chromatography (HPLC) and by the calculation of the fourth derivative of the absorption spectrum (UV-4^thDS). Monthly, ten (10) skimmed UHT milk samples were analyzed during September, October and November, and the values obtained through the three methods were compared against those from authentic raw milk with addition of cheese serum in different amounts. The percentage of positive samples to cheese serum analyzed through electrophoresis, HPLC and UV-4^thDS was 70.50 and 90%, respectively. The applied techniques related to the detection and estimation of the glycomacropeptide (GMP) by electrophoresis or by HPLC, and the results obtained indicated that the quantification of the serum protein/total protein (PS/PT) relationship by UV-4^thDS was a more sensitive indicator of cheese serum additions.

Palavras-chave : Absorción UV; Adulteración; Electroforesis; Cromatografía; Leche UHT; Suero.