For world-wide use, there was a need for an increased upper storage temperature for BioGaia AB´s oil-based probiotic drops containing L. reuteri. The main aim of this study was to investigate volatiles emerging from the product during different storage temperatures, by solid-phase microextraction in conjunction with analyses with gas chromatography/mass spectrometry (SPME/GCMS). Absorption of volatiles on Tenax in combination with GC analysis equipped with an olfactometry outlet (Tenax/GC-O) was also executed. Sensory properties of the product were documented by a sensory panel. Amount of L. reuteri, total aerobic bacteria, peroxide values and free fatty acids were analysed. Increased storage temperature from 5°C to 25°C did not influence the parameters studied significantly and in-use samples did not differ from controls. In samples stored at 30°C, more volatiles and peroxides were formed and the samples exhibited darker colours. Possible explanations are lipid oxidations, lipid hydrolyses, non-enzymatic browning reactions and adsorption of compounds related to plastics in the package material. Products with lower water concentrations seemed less prone to undergo Maillard and hydrolysis reactions.

According to the results of this study a storage temperature of 25°C can be used instead of 5 °C. If the temperature rises above 25°C the product will start to change its smell and colour.