NIR PLS prediction of quality parameters of olive oils at different stage of ageing

Autor: Plard, Jérôme, Rébufa, Catherine, Le Dréau, Yveline, Dupuy, Nathalie
Přispěvatelé: Laboratoire d'Instrumentation et Sciences Analytiques (LISA), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
Jazyk: angličtina
Rok vydání: 2013
Předmět:
Zdroj: 16ème colloque international sur la spectroscopie proche infrarouge (NIR 2013)
16ème colloque international sur la spectroscopie proche infrarouge (NIR 2013), Jun 2013, La Grande Motte, France. 2013
Popis: International audience; The chemical composition of olive oil depends on olive variety, climatic conditions during growth and olive maturity. There are mainly composed of triglycerides (95 to 98%) and minor compounds include phenolic compounds, tocopherols, alcools, esters, hydrocarbons, and pigments (Cert, Moreda, & Pérez-Camino, 2000). The nutritional and health benefits of olive oil can be attributed to antioxidants (phenolic compounds and tocopherols) and to the fatty acid composition of triglycerides: an abundance of monounsaturated fatty acid (MUFA), namely oleic acid, compared to saturated fatty acids (SFA) and an appropriate presence of polyunsaturated fatty acids (PUFA) especially ω6 and ω3 essential fatty acids. This leads to a good influence on cardiovascular diseases and cellular ageing (López-Miranda et al., 2010). But unsaturated lipids are particularly susceptible to oxidative phenomena that occur during cooking processing and storage. A series of reactions such as hydrolysis, oxidation, polymerisation, isomerisation and cyclisation (at 180°C or above) (Gertz, Klostermann, & Kochhar, 2000) may occur and lead first to the formation of peroxides and hydroperoxides, instable products that may involved into secondary oxidative products as hydrocarbons, alcohols, aldehydes and ketones which may also be oxidized in carboxylic acids (Gertz et al., 2000). Oxidized oil will have a less nutritional interest than a well conserved oil (Frankel, 1984).To estimate the oil quality, the international oleic council (IOC) and the international standardisation organisation (ISO) recommend to measure peroxide value (PV) (ISO 3960, 2007), spectroscopic indexes (K232 and K270) (International Olive Council, 2001a) the p-anisidine value (AV) (ISO TC34/SC 11, 2003), free acidity (FA) (ISO 660, 2009) and fatty acid composition by chromatographic analyse (International Olive Council, 2001b). PV, often used to evaluate the degree of oxidation, measures the amount of total peroxides. It increases at the beginning of the oxidation process and then decreases, because peroxides are transient chemical compounds. Its evolution depending on the heating time and temperature, is related to the antioxidant concentration of oil (Bešter, Butinar, Bučar-Miklavčič, & Golob, 2008; Nissiotis & Tasioula-Margari, 2002). K232 and K270 indexes measure the specific absorbance at 232 and 270 nm respectively of the conjugated dienes and trienes formed in autooxidation process from the hydropreroxides of unsaturated fatty acids and their oxidation products (Pristouri, Badeka, & Kontominas, 2010; Shahidi & Wanasundara, 2002). AV provides a good estimation of aldehydes especially conjugated dienals and 2-alkenals, main secondary oxidation compounds (Shahidi & Zhong, 2005), and completes the PV determination (Casal, Malheiro, Sendas, Oliveira, & Pereira, 2010). The total oxidation value (TOTOX = 2 PV + AV) gives a better estimation of the progressive oxidative deterioration of fats and oils because it measures both hydroperoxides and their breakdown products, i.e. aldehydes (Poulli, Mousdis, & Georgiou, 2009). Determination of fatty acids composition (which constitute the triacylglycerols) allows to follow their evolution individually (Bešter et al., 2008 ; Bouaziz, Fki, Jemai, Ayadi, & Sayadi, 2008) or grouped in class (SFA, MUFA and PUFA) (Casal et al., 2010; Maggio et al., 2009).In this work, two oils were studied because of their own method of manufacture, which is supposed to induce a difference in oil composition. Knowing that the degradation rate of olive oil was influenced by temperature, light, presence of oxygen and storage time, the aim was to study the stability of oils stored in different conditions of light, temperature and oxygen supply, via the determination of the quality indices and to evaluate the combined effects of these storage parameters. , Fourier transform infrared (FT-IR) spectroscopy has become an emerging well-accepted analytical technique, due to its simplicity with advantages in terms of cost per sample. It achieves high analysis speed and requires little or no sample preparation. FT-IR spectroscopy has been widely used as an analytical tool in various laboratories and industrial sectors such as food agricultural, petrochemical, textual and pharmaceutical. Up to date, a lot of studies have been published on the utilization of Near and Mid FT-IR for authentication, identification or classification of many agro-foods, notably olive oils (Casale et al., 2010a; Dupuy et al., 2010b; Galtier et al., 2007; Sinelli et al., 2010) and table olives (Casale et al., 2010b; Dupuy et al., 2010a) by multivariate statistical analysis of spectral data. Near FT-IR (FT-NIR) has been applied on olive leaves to discriminate between the juvenile and adult leaves (Leon & Downey, 2006) and for prediction of nutritive composition (Fernandez-Cabanas, Garrido-Varo, Delgado-Pertinez & Gomez-Cabrera, 2008). The present work investigates this methodology for two olive oils aged under different storage conditions.
Databáze: OpenAIRE
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