Carbon dioxide emission from olive oil pastes during the transformation process: technological spin offs

The emission of carbon dioxide (CO2) from olive paste during malaxation was investigated in a lab experiment using a hermetically sealed malaxation chamber. A rapid increase in the concentration of CO2 during malaxation was observed, with an average increase of 32 ml/(l min) for the initial 5 min. Then, the emission progressively decreased to a mean rate of 1.1 ml/(l min). This was probably the result of an initial acceleration in respiration followed by the gradual onset of fermentation processes as ambient oxygen was depleted. After malaxation, small amounts of cellular fermentation products (e.g. ethanol and lactic acid) were detected in the wastewater. In order to examine this phenomenon of the inhibition of oxidation due to evolved CO2, malaxation experiments were conducted in both a sealed and an open-air mixing apparatus. The differences in chlorophyll concentration of the resulting oils were then measured. Large amounts of chlorophyll, about twice as much, were found in the oil produced under sealed conditions. This increase in the concentration of chlorophyll resulted from the limited oxidation of the sample by atmospheric oxygen due to the protection of the evolved CO2.