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The complexing ability of molybdate vs. o‐diphenols has been exploited for their selective electrochemical detection. Graphite screen printed and carbon paste electrodes have been evaluated as electrochemical transducers for the selective mediated detection of o‐diphenol compounds in the presence of Na2MoO4. Immobilization of the mediator onto the electrode surface has also been achieved using different types of single and multiwall carbon nanotubes. The best sensor in terms of selectivity, sensitivity and stability was the Mo‐MW‐CNT‐NH2 modified electrode. Using the mediator either in solution or immobilized, detection of o‐diphenols with linearity in the ppm range was achieved. An amperometric flow injection analysis set‐up was used to detect the o‐diphenolic content of phenolic extracts obtained from olive oil samples.

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The effect of sugars (sucrose, lactose, glucose, fructose, 10%w/v) on the liquid-vapour partition of selected volatile compounds of coffee beverages has been investigated in espresso coffee and ready-to-drink (RTD) canned coffee prepared and obtained by using the same Arabica roasted coffee beans blend. Aroma composition of coffee beverages has been preliminary investigated by headspace-gas chromatography (HS-GC) and solid phase microextraction-HS-GC-mass spectrometry to characterize the volatile pattern of the systems and to evaluate the effects of sugars on the aroma release/retention. Then, the liquid-vapour partition coefficient (k) of 4 selected key aroma compounds (diacetyl, 2,3-pentanedione, ethylpyrazine, hexanal) was determined in water, sugars solutions as well as RTD coffee brews added with the same sugars (10%w/v). Sugars added in coffee beverages affected the release of the volatiles and thus its aroma profile with differences due to the type of added sugar and coffee brew type. The k values of the selected volatile compounds resulted different depending on the model system composition (water, coffee brew) and sugar type added. In particular, melanoidins as well as other non-volatile components (lipids, acids, carbohydrates) in the RTD coffee brews could be implied in the change of k of the volatile compounds in respect to that observed in water. The effects of the sugar type on the release/retention of the four key coffee aroma compounds were partly explained in terms of 'salting out' especially for the more polar volatile compounds and in the sucrose-added model systems. The change of chemical and physico-chemical properties of the water and brews induced by the sugars as well as the occurrence of interactions between volatile compounds and non-volatile components may be implied in the reduction of the vapour partition of the aroma compounds.

The potential of an electronic nose to discriminate olive oil samples based on their sensory profiles is proposed. The e-nose was constituted by an array of seven quartz crystal microbalance sensors modified with Gold Nanoparticles (GNPs) conjugated to short peptides. Forty olive oil samples headspaces were characterised by headspace solid-phase microextraction gas chromatography-mass spectrometry analysis to evaluate chemical composition; in parallel, they were chemically and sensory evaluated according to European Regulation EEC 2568/91 and amendments and EU Regulation 640/2008. The steady state sensor responses obtained with the e-nose setup were used to evaluate the discrimination properties of the system by principal component analysis and partial least square method. The results of this study provided a promising perspectives for the use of the electronic nose as a low-cost, easy to use and rapid system for the quality control of extra virgin, virgin and lampante (non-edible) olive oil. This system will also be useful to quantify the prevalent defect level in virgin and lampante olive oil samples.