Physicochemical and antioxidant properties of the pequi (Caryocar brasiliense Camb.) almond oil obtained by handmade and cold-pressed processes.

Abstract: The aim of this study is to characterize physical and chemically and determine the antioxidant capacity of pequi almond oils (PAO) extracted by handmade and by cold-pressing. Both oils showed good quality by acid, peroxide and thiobarbituric acid values. The fatty acid (FA) profile showed a significant presence of monounsaturated FA, mainly oleic acid (53.48 to 55.41%); saturated FA, such as palmitic acid (33.30 to 35.89 %); and polyunsaturated FA (PUFA), such as linoleic acid (5.85 to 7.23%). The total phenolic (TP) and carotenoid content ranged in concentration from 87.56 to 392.00 mg GAE/100 g and 36.03 to 262.40 mg/100 g, respectively. The tocopherol and phytosterol results indicated the predominant presence of α-tocopherol (52 to 67%) and stigmasterol (63 to 68 %). The antioxidant capacity of PAO as measured using the 2,2-diphenyl-1-picrylhydrazyl (DPPH?) method oscillated from 58.48 mg/mL to 76.46 mg/mL (IC50), from 10.61 to 40.46 µmol TE/g by the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS?+) method, and from 113.93 to 280.85 µmol TE/100 g and 164.49 to 277.86 µmol TE/100 g, by the lipophilic and hydrophilic oxygen radical absorbance capacity (ORAC) methods, respectively. The oils presented a good oxidative and thermal stability by Rancimat method (IP of 7.33 a 15.91 h) and curves thermogravimetric and differential scanning calorimetry (To 337-363 °C and 159-184 °C, respectively). The results confirmed the presence of compounds that conferred antioxidant capacity and oxidative and thermal resistance for PAO made by handmade or cold-pressing, indicating that these oils can potentially be used for food and non-food applications.

Thermal tool for evaluation of essential oils of Eucalyptus spp susceptible and resistant to Glycaspis brimblecombei attack.

Eucalyptus spp genus is economically important to different industry fields. There are pests that damage the development of eucalypts and Glycaspis brimblecombei, a sap-sucking insect, is one of them. Studies about this insect attack to the eucalypts showed preferences. This work aim was to compare the preferences of the insect with thermoanalytical characteristics of different eucalypts (susceptible, less susceptible and resistant to Glycaspis brimblecombei) essential oils. The leaves of six species of Eucalyptus were crushed and the essential oil was extracted using Clevenger apparatus. The Shimadzu DTG-60H was used to analyze the samples. The results showed that the samples from more susceptible eucalypts had total mass loss at about 124ºC to 156ºC, lower than samples from more resistant eucalypts (from 168ºC to 175ºC). Furthermore, the study suggests that the susceptibility or the resistance of eucalypts to the pest may be related to their essential oil composition and concentration of monoterpenes and sesquiterpenes.

Evaluation of double treated starches using thermal tools.

Starch is the main polysaccharide found in cereals, composed by amylose and amylopectin. Corn is the principal source of starches worldwide. Starches treatment, through physical, chemical and/or biological methods, can improve the applications range. Acid modification in alcoholic solution promotes minimally degradation in the granule. Ball mill is one physical method poorly explored. The aim was to treat the starches using HCl 0.5 mol L-1 for 1 hour in 100 ml of aqueous, ethanol or methanol solutions with subsequent ball milling processes. One sample was selected as native sample. The four others, one native sample and three acid modified samples, were treated by physical process with the oscillating ball mill. The DTG-60H equipment was used for the TG and DTA analysis. The TG curves showed three mass losses related to dehydration, decomposition and oxidation. The native sample without physical modification showed major resistance to total degradation. This occurs because the physical modification cleaves hydrogen bonds, leaving a weakened granule. The TGDTA results showed that the mass loss in the 2nd event was minor in the hydrolyzed samples compared with native samples. The acid modification can provide starch higher resistance to degradation up to 340 °C. These results showed that chemical and physical treatment changed the thermal behaviors of the starches.