Carbon Dioxide Treated Milk in the Production of Some Dairy Products

Attempts have been made to use of CO2-treated milk in the production of some dairy products. The present work included three parts as follows:In the first part, a trial has been made to design a laboratory apparatus for the injection of CO2 into milk and its estimation. Meanwhile, the effect of adding CO2 on the changes of the keeping quality of both raw and pasteurised milks at refrigerated storage was also evaluated. The results showed that the treatment of both raw milk and pasteurised milk with 20 mML-1 of CO2 was found to be an effective method to improve the keeping quality of raw and pasteurised milk.In the second part, both carbonated yoghurt and sweetened carbonated yoghurt beverage containing 15 and 20 mML-1 of CO2 were prepared and examined for their acceptability. The obtained results indicated that the protein degradation and total volatile fatty acids in both carbonated yoghurt and sweetened carbonated yoghurt beverage containing 20 mML-1 of CO2 were significantly lower than the control. However, the sensory evaluation of carbonated yoghurt and sweetened carbonated yoghurt beverage containing 20 mML-1 of CO2 showed higher scoring points than the control and it was superior in the overall acceptability to the control. The third part was concerned with the effect of CO2 addition to cheese milk on the coagulation properties as compared with certain acidulants. The addition of all acidulants accelerated the clotting time at pH5.8 Meanwhile, the effect of carbonation of cheese milk on the changes of the compositional, bacteriological and organoleptic quality of Tallaga cheese during storage at 4º C was evaluated. The results revealed that there was significant effect for the concentration of CO2 added to milk (15 and 20 mML-1) on the acidity and pH of cheese milk as well as the resultant cheese. Moreover, CO2 treatments had a significant effect on the coagulation time and the yield of fresh cheese. The acidity of carbonated milk cheese was significantly higher, whereas, total volatile fatty acids and soluble nitrogen and non protein nitrogen contents were significantly lower in fresh and stored cheese. CO2-treated cheese contained less numbers for total, psychrotrophic, lipolytic and proteolytic bacterial counts than the control cheese when fresh or during storage. Regarding the organoleptic properties of cheese, the results indicated that carbonated milk cheese samples had higher scoring points than the control. So, it was concluded that Tallaga cheese with accepted organoleptic quality could be successfully produced by using carbonated milk.