No abstract

Essential oils are substances originated from plants in general. These compounds are well known to have a high biological activity, specially the antioxidant and antimicrobial. Several extraction techniques are employed to obtain these substances. However, the majority of these techniques require a long extraction time. In this sense, innovative and alternative extraction techniques, such as ultrasound, have recently been the target of studies. In view of the small amount of publications using ultrasonic pretreatment, this review aimed to congregate current relevant information on ultrasound-assisted extraction of essential oils. In this sense, theoretical aspects, such as the main factors that influence the performance of this technique as well as the advantages and disadvantages of the use of ultrasound as an environmental friendly alternative technique to improve the extraction of essential oil in comparison to traditional methods, are shown. Considering the available studies in the literature on essential oil extraction using ultrasonic pretreatment, low frequencies ranged from 20 to 50kWz and times ranged from 20 to 40min were used. The use of ultrasonic pretreatment represents a time reduction to near 70% in relation to the conventional hydrodistillation. Also, these conditions enabled a growth in the extraction of bioactive compounds and consequently improving the antioxidant and antimicrobial activities of essential oils.

No abstract

No abstract

No abstract

No abstract

In this work, a method for sample preparation of high-purity polyimide was proposed for halogens and sulfur determination by ion chromatography (IC) with conductivity detection and, alternatively, by inductively coupled plasma mass spectrometry (ICP-MS). A relatively high polyimide mass (600mg) was completely digested by microwave-induced combustion (MIC) using 20bar of O2 and 50mmolL(-1) NH4OH as absorbing solution. These conditions allowed final solutions with low carbon content (<10mgL(-1)) and suitable pH for analysis by both IC and ICP-MS. The accuracy was evaluated using a certified reference material of polymer for Cl, Br and S and spike recovery experiments for all analytes. No statistical difference (t-test, 95% of confidence level) was observed between the results obtained for Cl, Br and S by IC after MIC and the certified values. In addition, spike recoveries obtained for F, Cl, Br, I and S ranged from 94% to 101%. The proposed method was suitable for polyimide decomposition for further determination of halogens and sulfur by IC and by ICP-MS (Br and I only). Taking into account the lack of methods and the difficulty of bringing this material into solution, MIC can be considered as a suitable alternative for the decomposition of polyimide for routine quality control of halogens and sulfur using IC or ICP-MS.

Mycotoxins are secondary metabolites produced by some filamentous fungi, which can cause toxic effects in humans and animals. The purpose of the study was to report the influence of postharvest conditions of grains and animal feed on the occurrence of mycotoxins in milk and dairy products which are widely consumed worldwide and have several health benefits for consumers. Among the most toxic mycotoxins are aflatoxins (AFs), with AFB 1 being the most toxic and present in grains and cereals used in the feeding of dairy cows. After ingestion, AFB 1 is converted to AFM 1 , which is excreted in milk, being a source of direct contamination to consumers of this product and dairy products. Thus, knowledge about this substance and the care that can be taken to reduce the consumption of contaminated food is a matter of great importance concerning public health and food safety. This review reports that the temperature and humidity at which the grains are stored, are the main conditions that can be controlled during storage, aiming to reduce the growth of fungi and the production of mycotoxins. This work reinforces that the continuous control of mycotoxins in milk and dairy products is of vital importance to obtain a safe product. Besides, strategies to mitigate the development of fungal contamination have been carefully revised to prevent the formation of these toxic substances.