Influence of sample storage on the composition of carbonated beverages by MIR spectroscopy

It is not uncommon for research and quality control samples, including carbonated beverage samples, to be refrigerated or frozen during peak periods of production and/or sampling, when analytical demand exceeds instrumental capacity. However, the effect of sub-ambient temperatures on carbonated beverage composition during storage has not been well characterized. Mid-infrared (MIR) spectroscopy combined with principal component analysis (PCA) and traditional chemical analyses were used to evaluate the effects of refrigeration (for 1 week) and freezing (for 1 or 6 weeks) on the composition of carbonated beverages, including sparkling water, sparkling wine, beer, and cider. Carbonated beverages were generally resistant to changes in pH, titratable acidity, alcohol, total phenolics, sugar, and color, during short-term (1 week) storage. However, long-term (6 week) freezing resulted in decreased total phenolics, with acidity also affected, albeit to a lesser extent. MIR spectroscopy combined with PCA enabled discrimination of carbonated beverages based on composition, with alcohol content having a significant influence. Examination of the MIR ‘fingerprint’ region indicated subtle compositional changes occurred in carbonated beverages following prolonged freezing.