Concentrated oils were prepared by vacuum distillation from coldpressed Valencia orange oil and analysed quantitatively by capillary GLC. The influence of that process on oxygenated compounds was studied. The contents of total aldehydes and alcohols, measured by GLC, increased linearly with concentration of the cold‐pressed orange oil upon six‐ to tenfold. Therefore, any of these compounds can be used to evaluate the degree of concentration.