Caracterização física e química de melão durante o seu desenvolvimento

O objetivo deste trabalho foi estudar algumas alterações físicas e químicas durante o desenvolvimento de frutos de melão de quatro cultivares. Para isto foram plantadas quatro cultivares de melão na área experimental do Departamento de Ciências Vegetais da Universidade Federal Rural do Semi-Árido - UFERSA, onde foram monitorados os períodos da antese. O delineamento experimental foi em blocos completos casualizados, com três repetições, em esquema de parcela subdividida. As parcelas foram constituídas pelas cultivares de melão ('AF 1749', Hy-Mark, Rochedo e Caipira) e as subparcelas pelas idades dos frutos (14; 21; 28; 35 e 42 dias após a antese). Quatro frutos por subparcela foram colhidos nestas idades e foram analisados quanto à massa média, firmeza, sólidos solúveis, acidez total, vitamina C e pH. Verificou-se interação significativa entre os fatores estudados (idades x cultivares) para massa média dos frutos, firmeza de polpa, acidez total, pH, vitamina C e sólidos solúveis. A massa dos frutos, firmeza, sólidos solúveis, pH e Vitamina C aumentaram, e a acidez diminuiu durante o desenvolvimento dos frutos.

Karyotype characterization of Malpighia emarginata (Malpighiaceae)

Malpighia emarginata Sessé & Mociño ex DC. or West Indian cherry (acerola) is a wild plant originated in southern Mexico, Central America and the northern region of South America. The species was introduced to Brazil about 60 years ago and now the country is the world's biggest producer. Even though the fruits of acerola have high commercial value, as they are an important source of the natural vitamin C, very little chromosome information is available for this species. Previous studies showed that most Malpighia species are diploids, including M. emarginata with 2n = 20. In the present paper, the chromosome number of acerola was confirmed, and for the first time, its karyotype was described, providing the identification of the homologues for the ideogram construction. The acerola chromosomes are small (1.71 to 2.56 µm) and metacentric with the exception of chromosome 2 that is classified as submetacentric. In addition, it is recommended a protocol to produce rooted-plantlets in vitro for mitotic studies that could be also used for micropropagation of acerola.

Anthocyanins, pigment stability and antioxidant activity in jabuticaba [Myrciaria cauliflora (Mart.) O. Berg]

Different solvents were evaluated for the extraction of jabuticaba anthocyanin pigments, identifying, quantifying and verifying the stability of the anthocyanins, as well as the conduction of three antioxidant activity assays and determination of the vitamin C levels. The maceration with ethanol acidified with HCl 1.5 mol L-1 (85:15) provides better pigment extraction and stability. The skin is anthocyanin rich, presenting 1.59 and 2.06 g 100 g-1 of dry matter in the Paulista and Sabará varieties, respectively. Cyanidin 3-glucoside is the majority pigment of the skins, followed by delphinidin 3-glucoside. The highest level of vitamin C was found in the skins and seeds of both varieties. It was verified that the skins, presented more antioxidant activity, in free radical capture, as well as in retarding the lipid oxidation process.

AVALIAÇÃO DA QUALIDADE FÍSICO-QUÍMICA DE POLPAS DE FRUTA CONGELADAS COMERCIALIZADAS NA CIDADE DE CUIABÁ-MT

RESUMO O presente trabalho teve como objetivo avaliar a qualidade físico-química das polpas de frutas congeladas comercializadas na cidade de Cuiabá-MT, comparando com os padrões estabelecidos pela legislação vigente. O experimento foi desenvolvido em delineamento inteiramente casualizado, sendo cinco tratamentos (marcas denominadas A, B, C, D e E) e três repetições, para as polpas de abacaxi, acerola, caju, goiaba e maracujá. Foram analisados os parâmetros pH, acidez titulável expressa em ácido cítrico, sólidos solúveis, ratio, vitamina C, açúcar redutor e quantificação da perda de vitamina C após 90 dias de armazenamento sob congelamento, em polpas de acerola e caju. Os dados obtidos foram submetidos à análise de variância, e as médias, comparadas pelo teste de Tukey, ao nível de 5% de probabilidade. A marca D apresentou não conformidade com a legislação para todas as polpas em, pelo menos, um dos parâmetros avaliados. Foi observado maior número de amostras em inadequação para o teor de vitamina C e, de forma geral, as polpas avaliadas apresentaram valores abaixo das especificações exigidas pelos Padrões de Identidade e Qualidade (PIQ) para as mesmas. Todas as amostras avaliadas tiveram redução do teor de vitamina C durante armazenamento sob congelamento, sendo que nenhuma marca de polpa de acerola e apenas uma de caju apresentou, ao final de 90 dias, teor de vitamina C de acordo com o estabelecido pelo PIQ. Conclui-se que é necessária uma intensificação na fiscalização no processamento de polpas de frutas congeladas para garantia da saúde do consumidor.

L'oxalate: un déchet organique peu soluble, avec conséquences [Oxalate: a poorly soluble organic waste with consequences].

Oxalate is a highly insoluble metabolic waste excreted by the kidneys. Disturbances of oxalate metabolism are encountered in enteric hyperoxaluria (secondary to malabsorption, gastric bypass or in case of insufficient Oxalobacter colonization), in hereditary hyperoxaluria and in intoxication (ethylene glycol, vitamin C). Hyperoxaluria causes a large spectrum of diseases, from isolated hyperoxaluria to kidney stones and nephrocalcinosis formation, eventually leading to kidney failure and systemic oxalosis with life-threatening deposits in vital organs. New causes of hyperoxaluria are arising recently, in particular after gastric bypass surgery, which requires regular and preemptive monitoring. The treatment of hyperoxaluria involves reduction in oxalate intake and increase in calcium intake. Optimal urine dilution and supplementation with inhibitors of kidney stone formation (citrate) are required. Some conditions may need vitamin B6 supplementation, and the addition of probiotics might be useful in the future. Primary care physicians should identify cases of recurrent calcium oxalate stones and severe hyperoxaluria. Further management of hyperoxaluria requires specialized care.

Ácido L-ascórbico: reações de complexação e de óxido-redução com alguns íons metálicos de transição

The strong reducing action of L-ascorbic acid (Vitamin C) are of fundamental interest in biochemical and related process. The oxidation of ascorbic acid by molecular oxygen and others oxidants are of fundamental importance, involving the intervention of transition metal ions as catalysts and the formation transition metal complexes of ascorbic acid as intermediates. The present article is intended to cover some aspects of the reactions of ascorbic acid and related compounds involving some transition metal ions.

Enhancing cognition before clinical symptoms of dementia.

As the title of the special issue indicates, controversy surrounds augmentation of brain cognition in humans. Lacking efficacious drugs for Alzheimer's disease (AD) and with many AD patients recruited for clinical trials that unfortunately do not provide the expected results, one wonders whether to test cognition enhancement strategies in individuals without symptoms of cognition decline. This opinion article presents the view that safe drugs and or dietary supplements should be tested worldwide in aged individuals under the control of a non-for-profit organization.

Estresse oxidativo: relação entre geração de espécies reativas e defesa do organismo

This work describes the mechanism of action of some reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the oxidative stress of the human body, and their consequences on damage to DNA, RNA, proteins and lipids. It also illustrates the defense system of our organism against these ROS and RNS species. The action of nonenzymatic protection systems is reported, with emphasis on micromolecules like Q10 coenzyme, vitamin C, alpha-tocopherol, carotenoids and flavonoids. The importance of flavonoids is also emphasized, and their body protection mechanism is detailed.

Antioxidantes dietéticos: controvérsias e perspectivas

The generation of reactive oxygen and nitrogen species (ROS and RNS) during metabolism is capable of damaging cellular biomolecules. To be protected against oxidative injury, cells evolved complex cellular defense mechanisms and the capability to use exogenous antioxidants to eliminate ROS/RNS. The potential role of micronutrients as antioxidants (vitamin C, vitamin E, carotenoids and poliphenols) has stimulated intense research efforts. In various human supplementation studies, however, these compounds presented pro-oxidant effects at high doses for most risk groups. Therefore, more studies about the bioavailability, tissue uptake, metabolism and biological activities should be performed before establishing recommendations for disease prevention.

Rhizodeposition of organic carbon by plants with contrasting traits for resource acquisition: responses to different fertility regimes

Background and aims Rhizodeposition plays an important role in mediating soil nutrient availability in ecosystems. However, owing to methodological difficulties (i.e., narrow zone of soil around roots, rapid assimilation by soil microbes) fertility-induced changes in rhizodeposition remain mostly unknown. Methods We developed a novel long-term continuous 13C labelling method to address the effects of two levels of nitrogen (N) fertilization on rhizodeposited carbon (C) by species with different nutrient acquisition strategies. Results Fertility-induced changes in rhizodeposition were modulated by root responses to N availability rather than by changes in soil microbial biomass. Differences among species were mostly related to plant biomass: species with higher total leaf and root biomass also had higher total rhizodeposited C, whereas species with lower root biomass had higher specific rhizodeposited C (per gram root mass). Experimental controls demonstrated that most of the biases commonly associated with this type of experiment (i.e., long-term steady-state labelling) were avoided using our methodological approach. Conclusions These results suggest that the amount of rhizodeposited C from plants grown under different levels of N were driven mainly by plant biomass and root morphology rather than microbial biomass. They also underline the importance of plant characteristics (i.e., biomass allocation) as opposed to traits associated with plant resource acquisition strategies in predicting total C rhizodeposition.

Determinação simultânea dos ácidos orgânicos tartárico, málico, ascórbico e cítrico em polpas de acerola, açaí e caju e avaliação da estabilidade em sucos de caju

The aim of the present study was determining the main organic acids in pulp and juices, as well as evaluating their stability, after opening the package, by liquid chromatography in a C18 column with isocratic elution and UV detection. In açaí pulp tartaric, malic and citric acids were found. Cashew samples presented all of the organic acids evaluated, besides high concentrations of ascorbic and malic acids. Acerola pulp had the highest ascorbic acid concentration. A small decrease in organic acid content during storage was observed. Malic and citric acids seem to be more stable than tartaric and ascorbic acids.

Indicadores químicos de qualidade da matéria orgânica de solo da sub-bacia do Rio das Mortes sob manejos diferenciais de cafeeiro

This work evaluated the chemical quality of organic matter (OM) of a Brazilian Oxisol cultivated with coffee plants, under organic and conventional managements. Total organic C (TOC), light fraction C (LF-C) and C in humic (HA-C) and fulvic (FA-C) acids fractions was measured. Amongst the evaluated indexes, TOC and LF-C discriminated better OM attributes as a function of management. The stratification ratio (TOC5-10cm/TOC10-20cm) did not show differences between the systems studied. The organic system can contribute to the sustainability of coffee plantations in Brazil, because it maintains the chemical attributes of OM closer to the indexes verified under forest conditions.

Optimization of methodology to analyze ascorbic and dehydroascorbic acid in vegetables

In this study, different solutions to extract vitamin C were tested. High-performance liquid chromatography was chosen and the conditions were based on isocratic elution in reverse phase column. Dehydroascorbic acid was determined indirectly after its reduction using dithiothreitol. The use of metaphosphoric acid to stabilize the vitamin C was shown to be required and it was necessary to neutralize the pH of the extract to apply dithiothreitol. The average recovery was 90% in collard and tomato samples. The presence of oil did not interfere in extraction and the methodology can be used to analyze stir fried vegetables.

Atividade antioxidante de extratos e taninos condensados das folhas de Maytenus ilicifolia Mart. ex Reiss.

Maytenus ilicifolia (Celastraceae) is a native plant of South America and popularly known as "espinheira-santa". The aim of this study was to evaluate the antioxidant capacity of extracts and isolated compounds from this plant. The antioxidant activity of the crude and semipurified extracts and isolated compounds was evaluated through DPPH-radical and phosphomolybdenum-complex assays. By both methods, the ethyl-acetate fraction demonstrated better antioxidant capacity compared with vitamin C and trolox. In the compounds, the higher the number of hydroxyls, the greater the antioxidant activity. In addition, stereochemistry influenced antioxidant activity, i.e., compounds with 2R,3R showed greater activity than those with 2R,3S.

Relationship between botanical origin and antioxidants vitamins of bee-collected pollen

This study quantified vitamin C, E and β-carotene in samples of fresh bee-collected pollen and correlating them with the botanical origin. Vitamin content varied between 13.5 and 42.5 µg/g for vitamin E; 56.3 and 198.9 µg/g for β-carotene and 273.9 and 560.3 µg/g for vitamin C. It was concluded that the botanical origin and collecting season influenced the vitamin contents. There is a relationship between the vitamins and its botanical origin: Raphanus sp and Macroptilium sp, Mimosa caesalpineafolia with β-carotene; Raphanus sp, Eucalyptus sp, Macroptilium sp, Mimosa caesalpineafolia with vitamin E and Anadenanthera sp, Arecaceae type and Philodendron sp with vitamin C.