The Use of Gas Chromatography to Measure Carbon Dioxide Production by Dairy Starter Cultures

A gas chromatographic method was developed to quantify CO₂ produced by dairy starter cultures. The procedure was used to measure CO₂ production by Lactococcus lactis ssp. lactis KB, a lactic dehydrogenase-deficient mutant of L. lactis ssp. lactis C2. Lactococcus lactis ssp. lactis KB produces CO₂, diacetyl, and acetoin from lactose in milk. Lactococcus lactis ssp. lactis biovar. diacetylactis 18-16, which converts citrate to CO₂, diacetyl, and acetoin, and L. lactis ssp. lactis C2, which does not produce CO₂, were also used. Samples were introduced to the column through an injection loop. Thermal conductivity was used for CO₂ detection. This method was relatively simple, results were reproducible, and CO₂ production by other fermentative bacteria could be measured.