There is nowadays more awareness on the impact on health of pollutants emitted even during cooking both from commercial as well as from domestic activities. In this study, it has been set up a new system allowing to analyse by solid-phase microextraction and gas chromatography coupled to mass spectrometry (SPME-GC-MS) the volatile organic compounds (VOCs) emitted during cooking. This could be done by aspiring into a polyethylene terephthalate (PET, Nalophan) bag the air over a cooking process. The bag allows to transport the sample to the instrument location and to perform the SPME extraction of the sampled air. The efficiency of different systems to perform the SPME extraction from the air contained in the bag was assessed by using a standard mixture of alkanes in order to obtain a sufficient sensitivity. Then the defined system was used to extract and analyse VOCs in air obtained during frying fries in sunflower oil. Several SPME extraction times (1h, 3h, 5h, 7h and 24h) were evaluated bringing to results that can be useful both with short extraction times and with long extraction times. Then the evaluation of three different filters was performed. Thus, the developed system, combining the use of olfactometric bags and the SPME-GC-MS, is applied for the first time to the study VOCs emitted during cooking and it allows to perform the analysis, even on samples produced in sites far from the instrument location, in an easy way and with instrumentations available in most of the laboratories. The results show a different retention effect for each filter under investigation on the classes of molecules detected. In particular, it has been found that, one of the three examined filters gives better filtering performance than the other two, confirmed also by the statistical analysis. This study draws the attention on the characterization of high quality monovarietal extra virgin olive oils (EVOOs) produced in Marche Region (Italy), in order to find new possible markers of quality. Five different cultivars were selected and investigated: Ascolana Tenera, Coroncina, Mignola, Piantone di Mogliano and Raggia. The study was developed in two different years (2015 and 2016) to underline possible correlation between the same varieties. Meanwhile, a comparison with EVOOs from the large scale distribution was carried out. Chemical analysis and sensory characterization were performed, paying particular attention to the determination of molecules responsible for the sensory and healthy properties, such as volatile and polyphenols substances. Ergosterol ((3β,22E)-ergosta-5,7,22-trien-3-ol) is produced by fungi and yeasts, i.e. organisms involved in the degradation of olives. In the present study, it was investigated whether ergosterol could be used as a marker to assess the quality of the olives from which the oil is produced. Ergosterol was quantified in extra virgin olive oils (EVOOs) having different level of quality developing an on-line HPLC-GC-MS method based on the on-line HPLC-GC method previously used to determine total sterol content. Oils were transmethylated to liberate ergosterol that was isolated from the far larger amounts of other sterols by HPLC on silica gel and transferred to GC by concurrent eluent evaporation. Preliminary results will be presented and discussed.
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|Titolo:||Chemical tools for food quality assessment|
|Data di pubblicazione:||6-mar-2019|
|Appare nelle tipologie:||Tesi di dottorato|