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Biodiesel is a renewable fuel produced from vegetable oils and animal fats transesterification. However, due to its chemical characteristics, it is susceptible to oxidation causing losses to its manufacturers and users. In this work a series of salicylates were synthesized and employed as secondary antioxidants in biodiesel B100. The accelerated oxidation tests were carried out against copper and iron. The biodiesel oxidation degree was followed by the acidity index. Among the synthesized compounds, isopropyl salicylate was able to inhibit the oxidation process by 55% when induced by copper and 52% when it was induced by iron after 8 hours exposure. The commercial antioxidant TBHQ was used as a positive control presenting lower inhibition values than isopropyl salicylate. It should be noted that salicylates are accessible molecules in just one reaction step, high yields and low cost, these being desirable characteristics for the biodiesel industry.

Abstract Bovine infectious mastitis is largely resistant to antibacterial treatment, mainly due to mechanisms of bacterial resistance in the biofilms formed by Staphylococcus aureus. Melaleuca (MEO) and citronella essential oils (CEO) are promising agents for reducing or eliminating biofilms. Free melaleuca oil presented a medium Minimum Inhibitory Concentration (MIC) of 0.625% and a Minimum Bactericidal Concentration (MBC) of 1.250%, while free citronella oil showed medium MIC and MBC of 0.313%. Thus, free CEO and MEO demonstrate bacteriostatic and bactericidal potential. We generated polymeric nanocapsules containing MEO or CEO and evaluated their efficacy at reducing biofilms formed by S. aureus. Glass and polypropylene spheres were used as test surfaces. To compare the responses of free and encapsulated oils, strains were submitted to 10 different procedures, using free and nanoencapsulated essential oils (EOs) in vitro. We observed no biofilm reduction by MEO, free or nanoencapsulated. However, CEO nanocapsules reduced biofilm formation on glass (p=0.03) and showed a tendency to diminish biofilms on polypropylene (p=0.051). Despite nanoencapsulated CEO reducing biofilms in vitro, the formulation could be improved to modify the CEO component polarity and, including MEO, to obtain more interactions with surfaces and the biofilm matrix.

Abstract The antioxidants used in the food industry are essential to inhibit the formation of free radicals, preserving the existing properties in the different matrices. However, the insecurity of the synthetic antioxidants regarding human health propels search for natural substrates with potential antioxidant activity as an alternative to synthetic compounds. In this way, the work had as objective obtaining extracts from the seed pomace of the Hevea brasiliensis (rubber tree), relating the contents of flavonoids and total phenols in the application as an antioxidant. The methodology consisted of the extraction using four solvents, varying extractive methods, time, and seed concentrations. The antioxidant activity in vitro was evaluated by capturing the DPPH (2,2-diphenyl-1-picryl-hydrazil) radical. The optimized results demonstrate that the aqueous extracts produced in the Soxhlet in the concentrations of 85 g L−1 and retention time of 4 h reached 37.73 ± 1.69% in the antioxidant tests of the free radical DPPH capture, 1405.15 mg EAC 100 g−1 in the quantification of phenolic compounds and 223.34 mg 100 g−1 of total flavonoids. Thus, this work may contribute to the realization of studies and future research for characterization and identification concerning which phenolic compounds and flavonoids attribute the antioxidant characteristic to the extracts produced, enabling the discovery of products with high added value in the production chain. In addition, because the water used as a solvent showed greater antioxidant potential between the extracts, the non-toxic and environmentally friendly character is highlighted, allowing a wide variety of applications in the food industry.

The intensive use of fossil fuels has had consequences coming from the instability of the reserves, due to the finitude of the resource, as well as the environmental impacts that the use of these fuels entails, such as the increasement of greenhouse gases. In this way, a promising alternative found to attenuate such problems is the production of biofuels, such as biodiesel, in which are used raw materials from renewable sources. They contribute to decrease dependence on oil and reduce the greenhouse effect. However, after biodiesel is produced, it is subject to degradation reaction when in contact with air, light, and temperature, which promotes the reduction of its quality. To slow down the degradation reaction, antioxidants are added to the biodiesel, providing greater oxidation stability. Antioxidants are substances that retard oxidation and can be natural, such as ascorbic acids or synthetic substances. Thus, this work aimed to evaluate the efficiency of ascorbic acid as an antioxidant in soybean biodiesel. Oxidative stability tests were performed and it was observed that the best concentration of ascorbic acid in soybean biodiesel, as antioxidant, is 27.5 g L-1. DOI: http://dx.doi.org/10.17807/orbital.v10i3.1097

Abstract Biodiesel is subject to radical reactions that promote degradation. To decrease the speed of these degradation reactions and increase oxidative stability, either natural or synthetic antioxidants are added to biodiesel. Thus, the objective of this study is to evaluate the effect of extracts of pecan nutshell (Carya illinoensis) as natural antioxidants derived from biomass using water, ethanol, and methanol/water (50/50) as a solvent for extraction. The addition of these antioxidants is performed during the soybean biodiesel washing process in an unconventional manner. The results obtained are statistically analyzed and compared to the control. The induction time (IT) for the biodiesel samples washed with ethanolic extract of pecan nutshell (5 g L−1), aqueous extract of pecan nutshell (12 g L−1) and methanol/water extract of pecan nutshell (12 g L−1), are, respectively, 9.46, 7.60, 7.43 h. The activation energy and the storage time of the biodiesel samples washed with the extracts are also studied. The order of reaction of the oxidation kinetics of biodiesel is first order.

The intensive use of fossil fuels has had consequences coming from the instability of the reserves, due to the finitude of the resource, as well as the environmental impacts that the use of these fuels entails, such as the increasement of greenhouse gases. In this way, a promising alternative found to attenuate such problems is the production of biofuels, such as biodiesel, in which are used raw materials from renewable sources. They contribute to decrease dependence on oil and reduce the greenhouse effect. However, after biodiesel is produced, it is subject to degradation reaction when in contact with air, light, and temperature, which promotes the reduction of its quality. To slow down the degradation reaction, antioxidants are added to the biodiesel, providing greater oxidation stability. Antioxidants are substances that retard oxidation and can be natural, such as ascorbic acids or synthetic substances. Thus, this work aimed to evaluate the efficiency of ascorbic acid as an antioxidant in soybean biodiesel. Oxidative stability tests were performed and it was observed that the best concentration of ascorbic acid in soybean biodiesel, as antioxidant, is 27.5 g L-1. DOI: http://dx.doi.org/10.17807/orbital.v10i3.1097