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A novel crushing process which involves increasing the level of oxygen during the virgin olive oil (VOO) extraction has been applied to develop new knowledge on the biosynthesis of the compounds responsible for sensory, nutritional, and technological quality of VOO. The singular composition of VOO is the result of a series of physical, chemical, and biochemical processes that occur during its extraction procedure. The extraction conditions, temperature, time, addition of water, and oxygen availability, can modulate the final composition of VOO. The last parameter, oxygen, is a known co-factor for the many endogenous enzyme activities present in the olive fruit, mainly oxide-reductases. The present study focuses on the influence of oxygen during the crushing of olive fruits on enzyme activities and the process yield. Three different cultivars, namely "Picual," "Arbequina," and "Blanqueta", were selected for the study. The increase of oxygen concentration during crushing produces a significant change in the volatile composition and sensory profile; however, no significant differences were shown on the content of fatty acid composition, total phenols, pigments, tocopherols, and qualitative parameters. This could be a useful analysis tool while designing new prototypes of mills or while working with breeding selection programs. Practical applications: The application of oxygen during olive fruit crushing in the oil extraction process has been studied. The information provided by this study enables to increase the knowledge on metabolism pathway in olive fruit while working with breeding selection programs. The present study can be useful to clarify the optimum time, crushing, or malaxation to apply atmospheric control to the VOO extraction. Moreover, the results obtained in this work suggest new research opportunities in order to design new prototypes of mills that allow the modification of the sensory characteristics VOO. [ABSTRACT FROM AUTHOR]

Continuous application of high power ultrasound (HPU) on olive paste previous to malaxation at laboratory scale for virgin olive oil (VOO) extraction and its effect on process yield and the VOO quality have been studied. For the VOO samples, we determined the quality indices (free acidity value, peroxide value, K232, K270), bitterness, volatile composition, phenolic content (total and biophenols), tocopherol content, and pigments. The application of ultrasound induced a quick heating of the paste from 20 to 28°C. The sonication treatment improved the industrial oil yield by 1% and the oil extractability by 5.74%. Moreover the HPU treatment did not cause changes in the quality indices, fatty acid composition and volatile aromatic compounds of the VOO. Furthermore the fat autoxidation process was not accelerated by this treatment. Meanwhile oil obtained from olive pastes treated with HPU showed higher content of tocopherol, chlorophylls and carotenoids whereas a reduction in phenolic content and bitterness index was observed. Practical applications: The high power ultrasound (HPU) treatment of olive paste, before malaxation during the virgin olive oil (VOO) elaboration process, can improve the oil extraction yield without alteration of its quality parameters. The olive paste instantaneous heating observed with the HPU can allow the reduction of the malaxation step duration. The results obtained nowadays at laboratory scale are promising for the possibility of the continuous HPU treatment introduction in the olive oil elaboration process as aid or alternative to the malaxation. For this purpose further experiment at pilot and industrial scale are needed. Continuous application of high power ultrasound before malaxation and its effect on the oil extractability and virgin olive oil characteristics. [ABSTRACT FROM AUTHOR]