How olive washing and storage affect fruit ethanol and virgin olive oil ethanol, ethyl esters and composition

BACKGROUND Olives are stored for a short time after harvesting pending processing in the oil mills. Furthermore, olives are often washed prior to fruit storage. In this work we study how washing and storage affect fruit ethanol content and the effect on virgin olive oil ethanol content and quality. RESULTS Olive storage produced an increase in the fruit ethanol content, achieving values six times higher when storage was in silos. Washing the olives resulted in an increase in fruit ethanol content, although when washed olives were processed immediately no difference was found. The increase in fruit ethanol content during storage was reflected in higher oil ethanol concentration. Similarly, olive washing resulted in oils with higher ethanol concentration. Industrial conditions gave more important increases in oil ethanol content than that from olives processed by hand. For quality parameters all the olive oils were classified as 'extra virgin'. In general, oils showed a slight decrease in some sensory attributes. At industrial scale after 24 h storage oils were classified as 'virgin' because sensory defects were found. CONCLUSION Olive storage should be avoided or reduced to less than 12 h; if possible, olives should not be washed before storage since this practice favors losses in sensory characteristics and the synthesis of ethanol, a precursor of ethyl esters. (c) 2020 Society of Chemical Industry

Automated summary

Storage and washing of olives can affect the ethanol content in the fruit as well as in the virgin olive oil. Storage of olives results in higher ethanol content in both the fruit and oil, while washing also leads to increased ethanol concentration in the oil. Industrial processing can cause greater increases in ethanol content compared to hand processing, and extended storage can lead to sensory defects in the oil.