Effect of modified atmosphere packaging and CO2 application on lor whey cheese shelf life

In this thesis, effects of modified atmosphere packaging and CO2 application during production of Lor whey cheese shelf-life was studied. In the first part of the study was to determine the effect of packaging with air (control), vacuum (V) and modified atmosphere (100% N2, 50% CO2 - 50% N2 (MIX), 100% CO2) and on Lor cheese samples stored at 4 °C. Chemical (pH, total solids, fat, protein, lipid oxidation and peroxide value), microbial (total mesophilic aerobic bacteria, Lactobacillus, Pseudomonas, yeast and mold, coliform), package head space, color (CIE L*, a*, b*, and Whiteness Index) and sensory analyses of Lor cheese samples were carried out at days 0, 7, 14, 21, 28 and 35. Changes in pH values of Lor whey cheese were significant among storage days and treatments (p<0,05). Initial pH of Lor whey cheese was 5,66. At the end of storage, pH values of Control, Vacuum, MIX and 100% CO2 samples were ranged between 5,49 and 5,51. The differences of lipid oxidation values of Lor cheese packaged with 100% CO2 and other samples at day 35 was significant (p<0,05). During storage peroxide values of Lor cheese samples gradually increased, control, and vacuum, MIX and 100% CO2 samples reached the highest amount at day 21 while 100% N2 sample reached the highest amount at day 28. It was determined that 2 log reduction in total mesophilic aerobic bacteria counts, 3 log reduction in yeast and molds counts, 2 log reduction in Lactobacillus spp., 1 log reduction in Pseudomonads in 100% CO2 and MIX samples than control and vacuum packaged samples Lor samples. Based on sensory analyses results, flavor score of 100% CO2 and MIX samples were higher than values of control and vacuum samples at day 14. (p<0,05)At the second part of the study, Lor whey cheese was produced from whey with applying CO2. Chemical (pH, total solids, fat, protein, lipid oxidation and peroxide value), microbial (total mesophilic aerobic bacteria, Lactobacillus, Pseudomonas, yeast and mold, coliform), color and sensory analyses were carried out at days 0, 4, 17, 10 and 14th.pH values of control Lor cheese samples were 6,0 and 5,95 at days 0 and 14, respectively whereas pH values of Lor samples treated with CO2 5,77 and 5,76 at the same storage days (p<0,05). Peroxide value reached the were highest content at day 10 in the control sample and then decreased (p<0,05). Total mesophilic bacteria, lactobacillus, yeast and mold contents of control and treated samples were similar (p>0,05). After 10 day storage there was a significant difference between samples for the content of Pseudomonas (p<0,05). Thorough the storage coliform bacteria was not detected in Lor samples treated with CO2. There were significant differences between control and treatment samples at days 7, 10 and 14 for the CIE L* value (p<0,05).Significant improvements on the shelf-life of Lor cheese were achieved with this study.