Determination of CO₂ Content in the Headspace of Spoiled Yogurt Packages

Table 1

Values (±SD) of pH, CO₂ content, and number of lactic acid bacteria (LAB) and yeast in yogurt not-contaminated (Ø) and contaminated with the yeast Candida kefyr (initial cell concentrations 1 and 5 CFU/cm³), and packed in cups and bottles at the beginning (0) and the end of monitoring (end).

		Cup, 180 g		Bottle, 500 g			Bottle, 1000 g
		Initial concentration (CFU/cm^3)
	t, h	Ø	5	Ø	1^23	5	Ø	1	5
pH	0	4.3 ± 0.04		4.4 ± 0.05			4.4+0.07
	End	4.2 ± 0.09	4.2 ± 0.09	4.3 ± 0.04	4.3 ± 0.04	4.3 ± 0.03	4.3 + 0.05	4.3 ± 0.05	4.2 ± 0.1
LAB (log·CFU/cm^3)	0	6.4 ± 1.1		6.8 ± 1.3			6.1+0.4
	End	6.1 ± 0.8	5.5 ± 0.6	5.7 ± 0.3	5.9 ± 0.6	5.6 ± 0.8	7.2 + 0.6	6.2 ± 0.4	7.1 ± 0.5
Yeast (log·CFU/cm^3)	0	—	0.7	—	0	0.7	—	0	0.7
	End	2.1 ± 0.9	6.7 ± 0.5	2.9 ± 0.4	6.2 ± 0.3	6.1 ± 0.2	1.9 + 0.9	6.1 ± 0.6	5.8 ± 0.3
CO2 content (%)	0	3.6 ± 0.5	2.4 ± 0.2	3.3 ± 0.4	2.3 ± 0.3	2.1 ± 0.5	3.6 + 0.5	2.1 ± 0.3	1.9 ± 0.4
	End	5.6 ± 0.9	17.7 ± 0.2	6.2 ± 0.3	16.2 ± 0.6	18.6 ± 0.2	5.3 + 0.2	20.1 ± 0.5	18.6 ± 0.5

Determined on MRS agar, determined on SMA agar with chloramphenicol.