Evaluation of different natural antioxidants as affecting volatile lipid oxidation products related to off-flavours in corn flakes

Different types of natural antioxidants (tocopherols – alone, in two different doses, or combined with ascorbic acid – and a rosemary extract) were employed in the production of corn flakes, to select the most effective ones for achieving low levels of volatile lipid oxidation products, related to off-flavours, after long-term storage. Samples were submitted to SPME/GC/MS and sensory analyses. Multivariate analysis elucidated the contribution of the volatile compounds to the sensory properties of corn flakes. Under the experimental conditions, tocopherols conferred better antioxidant activity than did rosemary extract, leading to low levels of off-flavour compounds, with a further improvement provided by the synergistic activity of ascorbic acid. This could be attributed to interfacial and phase partitioning phenomena involving antioxidants, depending on their lipo- or hydrophilicity, in heterogeneous food products. Acids, n-alkanols, lactones and some aldehydes appeared to have a considerable influence on the intensity of the off-flavours.     

Influence of the exposure to light on extra virgin olive oil quality during storage

An experimental investigation was carried out to study the influence that exposure to light has on the quality of extra virgin oil during a 12-month storage period by comparing it with the quality of extra virgin oil stored in the dark. The results showed that the oils stored in the light had significantly lower tocopherol, carotenoid and chlorophyll contents than did the same oils kept in the dark. Moreover, the oils stored in the dark mainly contained primary oxidation products, while the oils kept in the light contained secondary oxidation products as confirmed by the K₂₇₀ values which exceeded the legal limits even after purification by means of alumina. Overall, the results obtained showed that the shelf life of the oils exposed to light is shorter than that of oils kept in the dark, and that after only 2 months of exposure to light the oils examined could no longer be considered as extra virgin.     

Assessment of the Influence of the Decanter Set-up During Continuous Processing of Olives at Different Pigmentation Index

New generation decanters allow operators to make real-time adjustments during the virgin olive oil extraction process in order to gain the best performance possible. However, the opportunity to act in line requires a deep understanding of the consequences of changing machine parameters. To this purpose, an experiment was carried out at industrial scale. The decanter feed rate (Fr), ranging from 4075 to 5820 kg h^?1, the bowl/screw conveyor differential speed (?n), set at 18 and 22, and two ripening degrees of the olives were considered as process variables. Two combinations Fr-?n, namely 4620 kg h^?1 at ?n-18 and 5210 kg h^?1 at ?n-22, were found to similarly maximize the process efficiency, regardless the raw material features. After pointing out the best working settings, the corresponding virgin olive oils were compared. The analysis of variance showed that peroxide value, K ₂₃₂, K ₂₇₀, phenols, chlorophylls, β-tocopherol, fruity and bitter notes, and C6 volatile compounds were significantly affected by the machine parameters. An inverse proportionality was observed between the combination Fr-?n and the phenolic compounds. On the whole, the sampling factor exerted a larger influence on the product quality than the decanter set-up.     

Investigating the impact of botanical origin and harvesting period on carbon stable isotope ratio values (13C/12C) and different parameter analysis of Greek unifloral honeys: A chemometric approach for correct botanical discrimination

The aim of this study was to investigate the impact of botanical origin and harvesting period on carbon stable isotope ratio (¹³C/¹²C), colour intensity (CI), radical scavenging activity (%RSA), P and Sn content of Greek unifloral honeys. Thus, twenty‐four honey samples were collected during harvesting periods 2011–2012 and 2012–2013, from four different regions in Greece. ¹³C/¹²C ratios and minerals were determined using isotope ratio mass spectrometry (IRMS) and inductively coupled plasma optical–emission spectroscopy (ICP‐OES), respectively. CI and %RSA were measured using spectrophotometric assays. Results showed that only ¹³C/¹²C values and %RSA were affected by both botanical origin and harvesting period (P < 0.05). Applying then chemometric analyses to the collected data set, honeys were correctly classified according to honey type (correct classification rate 87.5% and 79.2% using the original and cross‐validation method, respectively). The use of different origin parameters has the potential to aid in honey authentication.