DETERMINATION OF LACTULOSE AND FUROSINE CONTENTS DURING HEAT TREATMENT OF CAMEL MILK: AS A NEW METHOD FOR DISCRIMINATING THE DEGREE OF HEAT TREATMENT GIVEN TO CAMEL MILK

The present study aimed to evaluate the thermal indicator markers (furosine and lactulose) as new suitable indicator markers in heat-treated camel milk under different thermal and storage conditions. The concentrations of lactulose and furosine were determined in raw camel milk and after pasteurized Low Temperature Long Time (LTLT), High Temperature Short Time (HTST) and boiling at various holding times and storage at 4 ºC or 30 ºC for 1, 7 and 14 days. The results showed that, lactulose content was not detected in raw camel milk. In all samples, lactulose and furosine contents were gradually increased with rising heat temperature. Lactulose content in camel milk, treated with LTLT, HTST and boiling ranged from 2.93 to 3.40, 3.7 to 4.8 and 12.1 to 14.75 mg/100 ml milk, respectively. Further, the average content of furosine in treated camel milk with LTLT, HTST and boiling ranged from 7.55 to 8.95, 11.23 to 13.85 and 28.85 to 34.90 mg/100 g protein, respectively. During storage, the lactulose and furosine contents of camel milk samples gradually increased up to 14 days of storage. Furthermore, the results showed that, there were significant differences (P<0.05) in lactulose and furosine content between boiling of camel milk samples and both of milk samples treated with LTLT and HTST. Also, there were significant differences (P<0.05) between heat process temperature and holding time within the same heat treatment in all camel milk samples. Lactulose and furosine concentrations of LTLT, HTST and boiling milk samples were noticeably increased during storage at 30ºC, compared to the storage at lower temperature (4ºC). Furosine formation was more much higher than lactulose content in all camel milk samples. The present study confirmed that, lactulose and furosine contents could be successfully used as suitable indicators to assess the heat load of camel milk.