Keila dos Santos Cople Lima

EFEITO DA IRRADIAÇÃO IONIZANTE gama NA QUALIDADE PÓS-COLHEITA DE CENOURAS (Daucus carota L.) cv. NANTES

The goal of this work was to evaluate the effect of g irradiation on the post harvest physical and chemical characteristics of cv. Nantes carrots. According to the Family Budget Survey (FBS, 1991) carried out in the Brazilian Southeast, within the roots and tubers group, carrots are widely consumed. It is also well known that the carrot is one of the best sources of provitamin A (a and b-carotene). Doses of 0.25, 0.50, 0.75 and 1.0kgy of g ionizing irradiation, from a cesium source, in accordance with the maximum dose allowed by the FDA (1995), were used on the carrots. The different treatments and the control group were evaluated by analysing for pH, total soluble solids (TSS), total titratable acidity (TTA), TSS/TTA ratio, weight loss, hardness, colour, total carotenoid content, ascorbic acid concentration and volatiles. The variance analysis (F of the Fisher treatment) of the results showed no significant difference at the 5% level between the irradiated samples and the control group for most of the tests, except for the colour intensity, which faded with increase in the irradiation dose, total acidity and TSS/TTA ratio, which decreased due to the decrease in the organic acid concentration after harvest. The results show that the low dose irradiation process is very promising to maintain the quality of the product, being a good alternative to avoid post harvest losses.

Avaliação dos efeitos da radiação gama nos teores de carotenóides, ácido ascórbico e açúcares do futo buriti do brejo (Mauritia flexuosa L.)

Buriti (Mauritia flexuosa L.), a typical fruit from the Northeast and Center-West Amazon of Brazil, is used in many regional dishes. It is considered an excellent source of carotenoids that are A vitamin precursors, showing a majority of β-carotene. It also presents ascorbic acid and sugar contents. Many studies have indicated that the lack of A vitamin is the main cause of night blindness and xerophthalmia. Also, ascorbic acid deficiency may cause scorbutic disease. The use of food irradiation is growing and represents an economic benefit to agriculture through the reduction of post-harvesting losses while maintaining food nutritional quality. In this study, Buriti in natura was treated with gamma irradiation with doses of 0.5 kGy and 1.0 kGy. The objective was to evaluate the irradiation effects on total carotenoids, ascorbic acid and sugars concentrations of Buriti. The fruit was evaluated through the total carotenoids analysis, by spectrophotometry, and the carotenoids (α and β-carotene and lutein), ascorbic acid and sugars were determined by High Performance Liquid Chromatography (HPLC). The results showed that buriti is an excellent source of total carotenoids (44600 μg/100g). The irradiation of buriti with the dose of 0.5 kGy did not significantly change carotenoids and sugars contents. However, there was a reduction of ascorbic acid concentration with an increase of the dose, which may have been caused by irradiation or by intrinsic and extrinsic factors that alter ascorbic acid stability in food, converting ascorbic to dehydroascorbic acid, while keeping the C vitamin active form.

Efeito de baixas doses de irradiação nos carotenóides majoritários em cenouras prontas para o consumo

This study aims was to evaluate the effect of low doses of g radiation on the total carotenoids, a and b-carotene content in minimally processed carrots, during the shelflife. Carrots are the mains vegetable source of carotenoids provitamin A (a and b-carotene). According to the Family Budget Survey (FBS) carried out in the Brazilian Southeast, within the roots and tubers group, carrots are widely consumed. The carotenoid stability varies largely during the stages of processing and storage, depending upon structure, temperature, oxygen availability, light exposure, humidity content, water activity and acid, metal anti-oxidant and pro-oxidant presence. The minimally processed carrots in this experiment were manually peeled, rinsed, cutted into diskis, packaged under 5% O2 / 10% CO2 and 21% O2 (sintetic air), g ionizing radiation treatments was carried out with a 137Cs source, of 0,25, 0,50, 0,75 and 1,0kGy doses, and shelf-stored at 5°C for 24 days. Total carotenoids quantification was by 449nm spectrophotometer. Determination of a and b-carotenes was made by High Performance Liquid Chromatography (HPLC). The different treatments and control group were, too, evaluated by analysing of colour and volatiles, by gas chromatography/mass spectroscopy with solid phase microextration (CG-MS/SPME), for study the significant carotenoids losses during the process.

Cenouras minimamente processadas em embalagens com atmosferas modificadas e tratadas com radiação gama: avaliação microbiológica, físico-química e química

As cenouras sao as principais fontes de origem vegetal em carotenoides provitaminicos A (a e o b-caroteno) e podem ser transformados em vitamina A dentro do organismo animal. Segundo a Pesquisa de Orcamento Familiar realizada na regiao Sudeste do Brasil, no grupo de raizes e tuberculos, a cenoura e amplamente consumida. As cenouras minimamente processadas foram acondicionadas em embalagens com atmosferas modificadas de 5% O2/10% CO2 e 21% O2 (ar sintetico), e tratadas com radiacao ionizante gama, fonte de cesio, nas doses de 0,25, 0,50, 0,75 e 1,00kGy. Os produtos apos o emprego da radiacao foram armazenados em refrigeracao de 5°C durante 24 dias. Os diferentes tratamentos da cenoura e o grupo controle foram avaliados atraves das analises de pH, solidos soluveis totais (SST), acidez total titulavel (ATT) e microbiologia. Os resultados de microbiologia evidenciaram que os produtos tratados com as doses de 0,50, 0,75 e 1,0kGy apresentaram reducao de 3 a 4 ciclos logaritmicos na contagem total de mesofilos (CTM) logo apos a irradiacao e uma vida-util de 20 dias. Nao foram detectados coliformes totais e E. coli ate o 24o dia. Os patogenos B. cereus, Salmonella e Estafilococos coagulase positivos em 0,1g do produto, tambem nao foram detectados. As contagens de bacterias laticas mantiveram-se menores que 100UFC/g. O processo de irradiacao em baixas doses mostra-se promissor na manutencao da qualidade e apresenta-se como uma medida alternativa na reducao de perdas pos-colheita.

Mesophase evolution in heat-treated solid petroleum pitches

A combination of analytical techniques was used to follow the mesophase evolution of petroleum pitches in the solid phase. The samples were characterized by matrix assisted laser desorption and time of flight analysis by mass spectrometry (MALDI-TOF-MS), high field 13C nuclear magnetic resonance (13C NMR), low field 1H NMR, electron spin resonance (EPR), polarized optical microscopy and thermogravimetric analysis (TGA). MALDI-TOF-MS revealed an oligomeric distribution of molecular weights in the pitch: monomeric (m/z 200 to 400), dimeric (m/z 400 to 650), trimeric (m/z 650 to 950) and tetrameric (m/z 950 to 1600), an essential factor for the production of carbon fibers, among other advanced composite of carbon. Relaxation time (T1) studies permitted to observe two large areas: the aromatics and the mesophases. These results also showed that the heating time increases the mesophasic area. Also through direct and non-destructive 13C NMR measurements, we obtained the content of aromatic and aliphatic carbons, as well as the degree of protonation of these carbons. Optical microscopy with polarized light showed the interfaces between the anisotropic and isotropic regions as well as the process of coalescence of mesophase. The results obtained by the other techniques corroborate the MALDI-TOF-MS and NMR results.

Aplicacao de baixas doses de radiacao ionizante no fruto brasileiro tucuma (Astrocarium vulgare Mart.)

The tucuma (Astrocaryum vulgare Mart.) is a native fruit of Amazonia, occurring mainly in the state of Para, but also found in the Brazilian northeast states and in the Brazilian central-western states. The tucuma is considerated an excellent source of carotenoids with a very high concentration of β-carotene, which is a precursor of vitamin A. In addition to carotenoids it is an important source of vitamin B2 (riboflavin) in fruits. This study aimed to analyze the effects of gamma radiation on the nutritional value of tucuma. The fruits were irradiated at doses of 0.5, 1.0 and 2.0 kGy irradiator with a source of cesium 137. The carotenoids were determined by spectrophotometry. The analysis of α and β-carotene, thiamin, riboflavin were carried out by high performance liquid chromatography (HPLC). The β-carotene accounts for 80% of total carotenoids in tucuma, and with a dose of 2 kGy, it showed the highest reduction of β-carotene, about 7.5% in relation to the control. The tucuma fruit showed high levels of riboflavin from 0.183 to 0.222 μg 100 g -1 , and maintained stability after the gamma radiation process. However, it had low levels of thiamine from 0.050 to 0.033 μg 100 g -1 , and irradiated at a dose of 2 kGy showed significant

Ricin and the Chemical Weapons Convention in Brazil

This article presents a brief review of the literature on ricin. This toxin is considered as a case of vulnerability in Brazilian responsibilities related to The Chemical Weapons Convention (CWC). Ricin is a glycoprotein present in seeds of castor beans (Ricinus communis L). It is very lethal and considered a chemical weapon. Brazil is the third world place in production of castor beans. Tons of residues with high quantities of ricin are produced every year. In this paper, examples of the ricin in terrorist attacks are remembered. It also mentions aspects on the action mechanism in the human body. The importance of the fast detection and identification is emphasized with description of methods used by first emergency responders and specialized chemical laboratories. Ricin detoxification has military interest and also may aggregate value to castor beans residues. At last, there is a brief on vaccines development against ricin.

Mycotoxins and their Potential as Warfare Agents

This article is a brief review of mycotoxins , emphasizing its potential as a warfare agent . Mycotoxins are secondary metabolites of fungi, with varying toxicity, which greatly affect agricultural products worldwide. In addition to its natural occurrence, their characteristics provide conditions that would enable its use in combat or attacks, thus constituting cause for concern. Here we present just some of them, among the ones which generate more losses and the ones more risky. The mycotoxins covered are aflatoxin, ochratoxin, zearalenone, fumonisin B1, patulin, Ergot alkaloids and trichothecenes, with their chemical properties and structures, their symptoms of mycotoxicosis and other information deemed relevant. Historical facts show that there are precedents that justify the need for developing techniques for detection, determination, decontamination and detoxification, aspects also explored in this paper. Are also addressed the mechanisms of action of these substances in the body and the resulting impacts on the economy.

Degradation of phenylethylamine and tyramine by gamma radiation process and docking studies of its radiolytes

Biogenic amines (BA) are toxic low molecular weight organic bases with aliphatic or heterocyclic structures that can be found in several foods. The consumption of food containing large amounts of BA can result in allergic reactions, rash, vomiting, and hypertension. Besides, BA are also known as possible precursors of carcinogens. In the present study we evaluated the effect of different gamma irradiation doses on methanol and water solutions of the BA phenylethylamine and tyramine. Our best results showed that, at a dose of 5 kGy (SI unit used for measurement of absorbed dose of ionizing radiation), it was possible to reduce the content of these two BA up to 85 and 60%, respectively, suggesting that the use of the irradiation process can be an efficient tool for its degradation. Further docking studies also suggested that the radiolytes produced in the irradiation process have more affinity for the human detoxifying enzymes monoaminoxidases type A and B (MAO-A and MAO-B) being, therefore, less toxic than its precursors.