Evolution of endogenous enzyme activities and virgin olive oil characteristics during Chétoui and Chemlali olive ripening

The composition and biochemical characteristics of olive fruits, mainly olive enzymes system, are crucial in determining the final quality of virgin olive oil (VOO). Thus, olives endogenous olive enzyme activities were studied during Chétoui and Chemlali olive ripening. The compositional quality of the corresponding VOO was also studied. Peroxidase (POX) and β-glucosidase activities increased during olives ripening. However, polyphenoloxidase activity decreased slowly. Moreover,the POX enzyme appears to play an essential role in determining VOO total phenol amounts, as the decrease in phenol content registered during olive ripening coincided with the increase in POX activity. A positive correlation between oil antioxidant activity and the total phenol content was established for both the olive cultivars studied. With regard to pigments, chlorophyll content wasmuch higher than that of carotenoids in both Chétoui and Chemlali oils. Moreover, different trends in chlorophyll and carotenoid contents were observed, depending on the olive cultivar. Concerning volatile compounds, our results showed that the highest content of total C6, C5 LOX compounds and pentene dimers was observed at a RI of approximately 3 for both cultivars. However, C6 alcohols and total C5 compounds decreased in Chétoui and Chemlali oils, respectively, during olive ripening

Monitoring endogenous enzymes during olive fruit ripening and storage: Correlation with virgin olive oil phenolic profiles

© 2014 Elsevier Ltd. All rights reserved. The ability of olive endogenous enzymes β-glucosidase, polyphenol oxidase (PPO) and peroxidase (POX), to determine the phenolic profile of virgin olive oil was investigated. Olives used for oil production were stored for one month at 20°C and 4°C and their phenolic content and enzymatic activities were compared to those of ripening olive fruits. Phenolic and volatile profiles of the corresponding oils were also analysed. Oils obtained from fruits stored at 4°C show similar characteristics to that of freshly harvested fruits. However, the oils obtained from fruits stored at 20°C presented the lowest phenolic content. Concerning the enzymatic activities, results show that the β-glucosidase enzyme is the key enzyme responsible for the determination of virgin olive oil phenolic profile as the decrease in this enzyme activity after 3 weeks of storage at 20°C was parallel to a dramatic decrease in the phenolic content of the oils.This work was supported by research projects AGL2008-00258 and AGL2011-24442 from Programa Nacional de Recursos y Tecnologías Alimentarias funded by the Spanish Government. R.H.H. received financial support from Tunisian Ministry of Higher Education and Scientific Research.Peer Reviewe

Evaluation of functional phytochemicals in destoned virgin olive oil

Processing destoned olives by means of extracting adjuvants micronised food talc and depolymerising Cytolase 0 enzyme complex have been studied in the present work. This innovative processing technology increased the plant efficiency (amounts of olives processed per hour) by 20%, as well as the nutritional quality of the end product with respect to functional compounds. The oils showed higher contents of biophenols, aromas, and tocopherols. An intense and balanced flavor and a potentially higher stability and endurance to oxidation (shelf-life) was found. Contents of chloroplast pigments (chlorophylls, pheophytins, carotenes, and xanthophylls) appeared to be lower in comparison to conventional processing. The processing aids allowed to increase significantly the oil yields and to reduce the oil percentage in the byproducts. Traceability of the new products was still possible applying chemometric data analysis for discriminating between cultivars. © Springer Science + Business Media, LLC 2008

Effect of Tunisian olive ripeness on endogenous enzymes and virgin olive oil phenolic composition

The aim of the present work was firstly to study the impact of olive fruit ripening on olive endogenous enzyme activities and virgin olive oil (VOO) phenolic composition and secondly to determine the key enzymes contributing to VOO phenolic content, in order to define the optimum harvesting dates for Ch\ue9toui and Chemlali olives. An increase of \u3b2-glucosidase and peroxidase (POX) activities during olive ripening, followed by a slight decrease at advanced ripening stages was observed. However, 2 peaks of polyphenoloxidase (PPO) activity were obtained during olive ripening. An increase of total phenols content reached a maximum at ripening index (RI)\ua0=\ua04 of Chemlali olives. However, the highest amounts of total phenols were observed at RI\ua0=\ua03 of Ch\ue9toui olives. VOO phenolic composition depends considerably on olive cultivar and ripening degree. On the basis of phenolic profile, results showed that the best RI is between 3 and 3.7 for Ch\ue9toui olives, and between 3 and 4 for Chemlali olives. Furthermore, the three enzymes studied contribute differently in determining VOO total phenols content according to olive cultivar. Results of the discriminative analysis showed three clusters of Ch\ue9toui and Chemlali VOOs according to olive ripeness

Ripening and storage conditions of Chétoui and Arbequina olives: Part II. Effect on olive endogenous enzymes and virgin olive oil secoiridoid profile determined by high resolution mass spectrometry

Several factors affect virgin olive oil (VOO) phenolic profile. The aim of this study was to monitor olive hydrolytic (β-glucosidase) and oxidative (POX and PPO) enzymes during olive ripening and storage and to determine their capacity to shape VOO phenolic profile. To this end, olives from the cultivars Chétoui and Arbequina were stored at 4 °C or 25 °C for 4 weeks and their enzymatic activities and oil phenolic profiles were compared to those of ripening olives. We observed different trends in enzymes activities according to cultivar and storage temperature. Secoiridoid compounds, determined by HRMS, and their deacetoxylated, oxygenated, and deacetoxy-oxygenated derivatives were identified and their contents differed between the cultivars according to olive ripening degree and storage conditions. These differences could be due to β-glucosidase, POX and PPO activities changes during olive ripening and storage. Results also show that oxidised phenolic compounds could be a marker of VOO ''freshness'