ABSTRACT
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. © 2020 Society of Chemical Industry.
Subject(s)
Esters/analysis , Ethanol/analysis , Food Handling/methods , Olea/chemistry , Olive Oil/chemistry , Food Handling/instrumentation , Food Storage/instrumentation , Food Storage/methods , Fruit/chemistry , Humans , TasteABSTRACT
BACKGROUND: Olives dropped on the ground naturally sometimes are not separated from those fresh and healthy collected from the tree for harvest and processing. In this work we compared the quality, ethanol content and bioactive components of virgin olive oils from ground-picked olives, tree-picked fruits and their mixture. RESULTS: Ground-picked olives produced 'Lampante' virgin olive oils; these are of a lower quality category, because of important alterations in chemical and sensory characteristics. Ethyl esters showed the highest values, although under the regulated limit. The mixture of ground and tree-picked olives gave oils classified as 'virgin' because of sensory defects, although the quality parameters did not exceed the limits for the 'extra' category. Ethanol content showed a significant increase in the oils from ground- picked olives and their mixture with respect to those from tree-picked fruits. Furthermore, bioactive compounds showed a significant decrease as fruit quality was poorer. CONCLUSION: Ground-picked olives must be harvested and processed separately since they produce low-quality virgin olive oils with sensory defects and lower concentrations of bioactive compounds. The higher acidity and ethanol concentration observed in oils from ground-picked fruits or their mixture may help ethyl ester synthesis during storage. © 2015 Society of Chemical Industry.
Subject(s)
Crop Production/methods , Crops, Agricultural/chemistry , Ethanol/analysis , Food Quality , Fruit/chemistry , Olea/chemistry , Olive Oil/chemistry , Centrifugation , Crops, Agricultural/growth & development , Crops, Agricultural/metabolism , Esters/analysis , Esters/metabolism , Ethanol/metabolism , Food Handling , Food Inspection , Fruit/growth & development , Fruit/metabolism , Humans , Hydrogen-Ion Concentration , Olea/growth & development , Olea/metabolism , Olive Oil/isolation & purification , Olive Oil/standards , Sensation , SpainABSTRACT
Volatiles of olive oils from 'tree-picked', 'ground-picked' and both mixed olives were analysed by solid-phase microextraction and gas chromatography with flame ionisation detection (FID). Headspace sampling was carried out for 30min of fibre exposition at 40 degrees C of sampling temperature by the selected 74 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre. Chromatographic data were analysed by principal components analysis (PCA) and then selected 14 compounds from x-loading of first principal component that provides a differentiation of oils accord its sensorial characterisation. Compounds such as 4-ethylphenol and styrene were identified by gas chromatography-mass spectrometry (GC-MS) in 'ground-picked' olive oils.
