Re-ignitions and soil importance on wildfire risk and management research proposals in a Mediterranean ecosystem

European Journal of Forest Research - This study was conducted following the fires that took place in Rocallaura (Spain) between 23/06/2016 and 19/07/2017. The aim is to analyse the importance of...     

Influence of cultivar and fruit ripening on olive (Olea europaea) fruit protein content, composition, and antioxidant activity

Proteins of olive fruit mesocarp are not very well-known at present. However, they have been shown to pass, at least partially, to the olive oil during its elaboration and therefore might be contributing to some of the special characteristics of this vegetable oil. In this study, protein content and composition were determined in olive fruits, cv. Arbequina and Picual, at three stages of ripening: green, spotted, and purple. Mesocarp proteins constituted 1.3-1.8% of the dry weight of the olive fruit, and cultivar and fruit ripening did not produce important changes in mesocarp protein content or composition. In addition, this composition was also similar to the amino acid composition of a 4.6-kDa polypeptide, which is the major protein component of olive oils and of oil bodies of olive fruit mesocarp, suggesting that this polypeptide is likely to be a major component of mesocarp proteins. There was, also, a relationship between the oil content of the olive fruit and the protein content determined, suggesting a stabilizing function of these proteins in the oil bodies of the olive fruit, analogously to the role suggested for oleosins. This stabilizing function does not seem to be extended to olive oils because when the polypeptides isolated were added at 20 ppm to soybean oil, the stability of the oil increased only slightly, suggesting that if these compounds play some role in the stability of the oils, this should be mostly a consequence of the possible interactions among these protein components and other olive oil antioxidant constituents.     

Evaluation of the formulated diet MySpat for feeding hatchery‐reared spat of the green‐lipped mussel,Perna canaliculus (Gmelin, 1791)

As with most bivalves, a high cost component of hatchery and nursery culture of the green‐lipped mussel (Perna canaliculus) is the raising of live micro‐algae feeds. To remedy this, artificial feeds have been developed, however, these have had mixed success for this species. In this experiment, we tested the formulated diet MySpat (sourced from INVE Aquaculture) on P. canaliculus spat of approximately 1 mm in size. Performance measures under study were mussel spat growth and survivorship after 21 days feeding on varying proportions of MySpat. The experimental diets tested, consisted of a mix of T‐Isochrysis galbana, Pavlova lutheri and Tetraselmis suecica micro‐algae that were replaced with increasing proportions of MySpat, i.e. 25%, 50%, 67%, 75%, 90% and 100% MySpat replacement. Our results revealed no significant increase in spat mortality with increasing MySpat diet levels, and growth was equivalent to the micro‐algae only dietary control in all diets except the 90% and 100% MySpat replacement diets. Such results highlight the role MySpat could have for P. canaliculus hatchery operations, particularly with regard to reducing the costs of raising micro‐algae when producing seed for industry. A greater understanding of the particle selection process of this species would be beneficial for future studies seeking to employ artificial diets.     

Amine degradation by 4,5-epoxy-2-decenal in model systems

The reactions of 4,5-epoxy-2-decenal with octylamine, benzylamine, and 2-phenylglycine methyl ester were studied to investigate if amines may suffer a Strecker type degradation by epoxyalkenals analogously to amino acids. In addition to other reactions, the studied amines were converted into their corresponding Strecker aldehydes (octanal, benzaldehyde, and methyl 2-oxo-2-phenylacetate, respectively) to an extent that depended on the pH, the temperature, the amount of epoxyalkenal, and the amine involved. Each amine exhibited an optimum pH for the reaction, but the corresponding Strecker aldehydes were produced to a significant extent within a broad pH range. In addition, the temperature mostly influenced the reaction rate, which was increased between 6.5 and 9.5 times when the reaction was carried out at 60 degrees C than when it took place at 37 degrees C. Furthermore, Strecker aldehyde formation was linearly correlated with the amount of the epoxyalkenal present in the reaction mixture. Nevertheless, the reaction yield mostly depended on the amine involved. Thus, octylamine only produced trace amounts of octanal, benzylamine was converted into benzaldehyde with a yield of 4.3%, and 2-phenylglycine methyl ester was converted into methyl 2-oxo-2-phenylacetate with a reaction yield of 49%. All of these results suggest that suitable amines can be degraded by epoxyalkenals to their corresponding Strecker aldehydes to a significant extent.     

European seabass (Dicentrarchus labrax) ability to discriminate between diets made with different dietary fat sources

The aim of this work was to determine whether juvenile and adult European seabass (Dicentrarchus labrax L.), fed ad libitum manually and with self‐feeding demand feeders, respectively, were able to discriminate between a fish oil‐based diet and a series of diets made with vegetable oils (soybean, linseed, rapeseed and sunflower oil), as well as a fat‐free diet. Adult D. labrax (443.6 ± 108.8 g) selected diets made from soybean (SYO) and rapeseed (RO) in proportions similar to fish oil (FO). Demand levels for the other two diets, sunflower (SUO) and linseed (LO) oils, were significantly lower than FO, whilst juveniles (56.4 ± 11.2 g) displayed a preference for SYO and FO. The lowest demand levels were associated with a fat‐free diet (FF). Selection percentages of the diets for adult and juvenile fish were, respectively, FF—22.96% and 39.76%, SYO—43.02% and 53.26%, LO—36.48% and 36.19%, SUO—39.87% and 37.32%, and RO—46.38% and 40.94%. The animals’ size and feeding method did not significantly affect dietary selection. However, a statistical difference in specific growth rate (1.37% ± 0.26% day^?1) for juveniles was only observed for FO+FF combination. For juveniles, no differences were observed in the conversion index. The juvenile group (FO + FF) had the highest food intake (2.00 ± 0.35 g 100 g^?1 body weight). Moreover, the groups fed FO + SUO and FO + RO consumed the least. In conclusion, this study shows D. labrax can discriminate between diets where the only difference is the lipid source. These findings should be used to understand the acceptance or rejection of different source oils, which are increasingly being used in aquaculture such as aquafeeds for European seabass.     

Effect of dietary common carp by‐product protein hydrolysates on antioxidant status in different organs of zebrafish (Danio rerio)

A feeding trial was conducted to evaluate the effect of dietary protein hydrolysates from common carp (Cyprinus carpio) by‐products on the antioxidant status of zebrafish (Danio rerio). Common carp by‐product was hydrolysed using Alcalase to a degree of hydrolysis of 15%. The zebrafish were fed for 44 days with four different diets with increasing levels of carp by‐product hydrolysates (CBH0: 0 g/kg; CBH25: 25 g/kg; CBH50: 50 g/kg; CBH100: 100 g/kg). The gills, muscle and brain were dissected at the end of the feeding trial in order to evaluate the total antioxidant capacity against peroxyl radicals (ACAP) and lipid peroxidation (TBARS). Although total antioxidant capacity did not show differences in muscle (p > 0.05), lipid peroxidation was reduced in the muscle of fish fed the CBH50 diet. Brain lipid peroxidation showed a significant reduction (p < 0.05) in all groups when compared with the control diet CBH0. Antioxidant properties of protein hydrolysates indicate their potential as nutraceuticals since (a) a reduction in muscle lipid peroxidation was verified, implying that their use could enhance the quality and shelf life of fish fillets; and (b) a decrease in brain lipid peroxidation was registered, highlighting the potential use of fish protein hydrolysates for the prevention of neurodegenerative diseases.     

Effect of tocopherols in the antioxidative activity of oxidized lipid-amine reaction products

Phosphatidylethanolamine (PE), phosphatidylcholine (PC), lysine (Lys), and mixtures of them were tested for antioxidative activity in a tocopherol-stripped olive oil (TSO) and the same oil after addition of 250 microg of alpha-tocopherol g of oil/(tocopherol-added olive oil, TAO) to evaluate the role of tocopherol in the antioxidant activity of oxidized lipid-amine products. Neither PE nor PC nor Lys protected TSO when tested alone, but both PE and Lys increased the induction period (IP) of TAO. On the contrary, PE/Lys and PC/Lys mixtures, but not PC/PE mixtures, protected both TSO and TAO. These results were a consequence of both the formation of oxidized lipid-amine products, which were determined by gas chromatography-mass spectrometry after their conversion into volatile derivatives, and a synergism between alpha-tocopherol and the produced compounds. These results were confirmed by analyzing the antioxidative activity of two of the produced carbonyl-amine products: 6-amino-2-(1H-pyrrol-1-yl)hexanoic acid (1) and 2,3-dipalmitoylpropyl 2-(1H-pyrrol-1-yl)ethyl phosphate (2). The hydrophilic compound 1 was more antioxidant than the analogous lipophilic compound 2, and this antioxidative activity was observed in TAO and not in TSO. All these results suggested that antioxidative activity of carbonyl-amine products may be greatly increased with the addition of tocopherols, and those products derived from Lys are more antioxidant in bulk oils than those derived from PE.