Antioxidants, radical-scavenging and protein carbonylation inhibition capacity of six monocultivar virgin olive oils in Istria (Croatia)

Six monocultivar virgin olive oils (VOOs) produced from five autochthonous (Buža, Buža Puntoža, Istarska Bjelica, Porečka Rosulja, and Rosinjola) and one referent cultivar (Leccino), were investigated. The mass fractions of orthodiphenols (ORT) and tocopherols (TOC) were analysed by VIS spectroscopy and HPLC. The radical-scavenging capacity was evaluated by electron spin resonance spectroscopy (ESR) using galvinoxyl free radical and the DPPH test. Results revealed a high level of total TOC in VOOs of Buža Puntoža (243 mg kg−1) and Porečka Rosulja (325 mg kg−1). VOOs contained in 100 g from 79% (Istarska Bjelica) to 261% (Porečka Rosulja) of recommended daily allowance of α-tocopherol. The mass fraction of ORT in Istarska Bjelica and Rosinjola was >250 mg kg−1 (on average 30–40% higher in comparison to other studied cultivars). Istarska Bjelica and Porečka Rosulja showed the highest antioxidant capacity in both methods of measurement. The highest capacity to inhibit protein carbonylation (PC) in response to oxidative stress (54–56%) was displayed by Buža Puntoža, Leccino, and Buža. High level of positive linear correlation between ORT mass fraction and radical-scavenging capacity measured by DPPH test (r=0.768), as well as strong negative correlation between PC inhibition and mass fraction of ORT (r= −0.697), were observed

Influencia de la temperatura de almacenamiento sobre los parámetros de calidad, fenoles y compuestos volátiles de aceites de oliva vírgenes croatas

The influence of low storage temperature (+4 °C and －20 °C) and conventional storage room temperature on the quality parameters, phenolic contents and volatile profiles of Buža, Črna and Rosinjola monovarietal virgin olive oils after 12 months of storage was investigated in this study. Virgin olive oils stored at low temperatures maintained better quality parameters than oils stored at room temperature. A negligible decrease in the total phenols was detected after 12 months of storage at all investigated temperatures. The total volatile compounds, aldehydes, alcohols and esters in almost all stored samples were unchanged compared to fresh oils. Total ketones increased after storage, although at a lower temperature these changes were less notable. An increase in the oxidation indicators hexanal and hexanal/E-2-hexenal ratio was the lowest in oils stored at +4 °C.Storage at temperatures lower than room temperature could help to prolong the shelf-life of extra virgin olive oil by maintaining high quality parameters and preserving the fresh oil’s volatile profile.Se ha estudiado la influencia, durante 12 meses, de temperaturas bajas (+4 °C y −20 °C) y convencional (ambiente), sobre los parámetros de calidad, contenido fenólico y perfil de volátiles de aceites de oliva vírgenes monovarietales Buža, Črna y Rosinjola. Los aceites de oliva vírgenes almacenados a bajas temperaturas mantienen mejores propiedades de calidad que los aceites almacenados a temperatura ambiente. Se encontró una disminución no significativa de los fenoles totales después de 12 meses de almacenamiento a todas las temperaturas estudiadas. Los compuestos volátiles totales, aldehídos, alcoholes y ésteres, en casi todas las muestras almacenadas, se mantuvieron sin cambios en comparación con los aceites frescos. Las cetonas totales incrementaron tras el almacenamiento, aunque a temperaturasmas bajas estos cambios fueron menos notables. El incremento de los indicadores de la oxidación hexanal y la relación hexanal/E-2-hexenal fue más bajo en los aceites almacenados a +4 °C. El almacenamiento a temperaturas inferiores a la temperatura ambiente ayuda a prolongar la vida útil de los aceites de oliva virgen extra, manteniendo la alta calidad y preservando el perfil de volátilesde un aceite fresco

Regiospecific analysis of Mono and Diglycerides in Glycerolysis products by GC x GC TOF-MS.

Comprehensive bidimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOF-MS) was used for the characterization of regiospecific mono- and diglycerides (MG-DG) content in the glycerolysis products derived from five different lipids included lard (LA), sun flower seed oil (SF), corn oil (CO), butter (BU), and palm oil (PA). The combination of fast and high temperature non-orthogonal column set namely DB17ht (6 m × 0.10 mm × 0.10 μm) as the primary column and SLB-5 ms (60 cm × 0.10 mm × 0.10 μm) as the secondary column was applied in this work. System configuration involved high oven ramp temperature to obtain precise mass spectral identification and highest effluent’s resolution. 3-Monopalmitoyl-sn-glycerol (MG 3-C16) was the highest concentration in LA, BU and PA while monostearoyl-sn-glycerol (MG C18) in CO and 1,3-dilinoleol-rac-glycerol (DG C18:2c) in SF. Principal component analysis accounted 82% of variance using combination of PC1 and PC2. The presence of monostearoyl-sn-glycerol (MG C18), 3-Monopalmitoyl-sn-glycerol (MG 3-C16), 1,3-dilinoleol-rac-glycerol (DG C18:2c), 1,3-dipalmitoyl-glycerol (DG 1,3-C16), and 1,3-dielaidin (DG C18:1t) caused differentiation of the samples tested

Specific components of virgin olive oil as active participants in oxidative processes

The oxidative changes in the chain of unsaturated fatty acids are the main problem of preserving quality and nutritive value of vegetable oils. According to numerous researches, virgin olive oil is one of the most stable oils. It is a complex system of active substances whose role in the oxidation processes is determined by their interactions and by influence of external factors. From this system we selected the most important components -phenolic substances, tocopherols, carotenoids, chlorophylls and oleic acid, and explained their importance in the oxidative changes of olive oil

Influence of Olive Fruit Storage in Bags on Oil Quality and Composition of Volatile Compounds

The composition of olive oil volatile components depends on genetic factors, ripening grade of the fruit, fruit storage and processing conditions. Storage of olives in reticular or plastic bags is still a frequently used practice that has negative effects on oil quality, particularly on sensory characteristics. The changes of volatile compounds during this procedure were determined using headspace solid phase microextraction (HS-SPME). The method was optimised as regards sample conditioning and extraction time, and verified by testing the repeatability and linearity of the response. The main changes during fruit storage in bags are increase of methanol and ethanol concentration and decrease of 1-penten- 3-one, trans-2-hexenal and cis-3-hexenyl acetate concentration. The changes in plastic bags are more evident and significant differences between the two types of storage are established