Efeito do resfriamento sobre açúcares solúveis, taxa de respiração, fenóis totais, atividade de peroxidase e dormência de bulbos de cebola

Além de ser uma das hortaliças mais cultivada e consumida, bulbos de cebola são afetados, durante a armazenagem, por fatores fisiológicos, bioquímicos e tecnológicos, que podem afetar seus atributos de qualidade. Taxa de respiração (RR O2), açucares solúveis (SS), fenóis totais (TP) e atividade de peroxidase (POD) foram medidos em tecidos internos de brotos, durante uma quebra de dormência de bulbos de cebola, tratados por quatro semanas a 0ºC e armazenados no escuro a 20ºC. Bulbos controle foram armazenados simultaneamente na mesma condição. A quebra da dormência foi verificada através do aparecimento das primeiras folhas internas verdes, cortando 30 bulbos longitudinalmente. Depois de oito semanas a RR O2 de bulbos brotados foi 52% maior em relação a bulbos recentemente colhidos e bulbos dormentes. Os SS diminuíram uma semana após resfriamento, de 15 para 9 mg g-1 de peso fresco e depois apresentaram um pico, de 9 para 19 mg g-1 depois de três semanas. Para os bulbos controle também foi observado um pico similar depois de seis semanas. Para os brotos internos de cebolas tratadas com frio, foi observado um pequeno aumento de TP (de 0,17 a 0,2 mg g-1 de peso fresco), durante as duas primeiras semanas de resfriamento e, depois, um decréscimo para 0,11 mg g-1 depois de oito semanas. Para os brotos internos de bulbos controle, os TP também aumentaram pouco, de 0,17 para 0,2 mg g-1 depois de cinco semanas, decrescendo para 0,15 mg g-1 depois de sete semanas, quando começaram a brotar. A atividade de POD apresentou uma tendência similar em relação aos TP. Para bulbos tratados a frio, a atividade POD aumentou para 1,7 U g-1 de peso fresco depois de duas semanas, decrescendo para 1,1 U g-1 durante as últimas quatro semanas. Para as amostras controle, a atividade POD permaneceu estável por quatro semanas e decresceu progressivamente de 29% durante as últimas quatro semanas. O decréscimo da atividade de POD coincidiu com o decréscimo de TP e coincidiu com o início da brotação. Com o tratamento frio, os primeiros brotos foram observados durante a terceira semana, enquanto o brotamento total se deu depois de oito semanas. Em comparação, apenas 20% dos bulbos controle brotaram depois de oito semanas.Besides onions being one of the most cultivated and consumed vegetables, during storage onion bulbs are still affected by many physiological, biochemical and technological factors which can influence their quality. Respiration rate (RR O2), soluble sugars (SS), total phenolics (TP), and peroxidase (POD) activity were measured in inner bud tissues during a dormancy break of onion bulbs treated four weeks at 0ºC and stored in the dark at 20ºC. Control bulbs were stored simultaneously in the same condition. Breakage of dormancy was checked by the appearance of first green internal leaves by cutting longitudinally 30 bulbs. After eight weeks, RR O2 of sprouted onions was 52% higher than that of freshly harvested and dormant bulbs. One week after cooling SS decreased from 15 to 9 mg g-1 fresh weight, and then peaked from 9 to 19 mg g-1 after three weeks. For control bulbs, a similar peak was observed after six weeks. For inner buds of cold-treated onions, a slight increase of TP (from 0.17 to 0.2 mg g-1; fresh weight) was observed during the first two weeks of cooling, and then a decrease to 0.11 mg g-1 was observed after eight weeks. For inner buds of control bulbs, TP also increased slightly from 0.17 to 0.2 mg g-1 after five weeks, and decreased to 0.15 mg g-1 after seven weeks when bulbs began to sprout. POD activity showed a similar pattern in relation to TP. For cold-treated bulbs, POD activity increased to 1.7 U g-1 fresh weight after two weeks, and decreased to 1.1 U g-1 during the last four weeks. For control samples, POD activity was stable during 4 weeks and decreased progressively by 29% during the last four weeks. This decrease in POD activity coincided with the decrease in TP, and coincided with onset of sprouting. With cold treatment, first sprouts were observed during the third week, while total sprouting was observed after eight weeks. In comparison, only 20% of the control bulbs sprouted after the period of 8 weeks

Tropical Crops and Resilience to Climate Change

It is anticipated that agricultural output will have to increase by 70% to feed a global population of more than 9 billion by the year 2050 (Benkeblia 2012). The capacity of global high-intensity farming systems to continue to guarantee productive returns while maintaining system stability will eventually decline, and thus new opportunities for agriculture are being realized in tropical environments. As population growth is greatest in tropical regions, and commensurate with rapid industrialization and change in traditional land use practices, it is presumed that equatorial production systems will be some of the most vulnerable to climate change

Three novel oligosaccharides synthesized using Thermoanaerobacter brockii kojibiose phosphorylase

<p>Abstract</p> <p>Background</p> <p>Recently synthesized novel oligosaccharides have been produced primarily by hydrolases and glycosyltransferases, while phosphorylases have also been subject of few studies. Indeed, phosphorylases are expected to give good results via their reversible reaction. The purpose of this study was to synthesis other novel oligosaccharides using kojibiose phosphorylase.</p> <p>Results</p> <p>Three novel oligosaccharides were synthesized by glucosyltransfer from β-D-glucose 1-phosphate (β-D-G1P) to xylosylfructoside [<it>O</it>-α-D-xylopyranosyl-(1→2)-β-D-fructofuranoside] using <it>Thermoanaerobacter brockii </it>kojibiose phosphorylase. These oligosaccharides were isolated using carbon-Celite column chromatography and preparative high performance liquid chromatography. Gas liquid chromatography analysis of methyl derivatives, MALDI-TOF MS and NMR measurements were used for structural characterisation. The ¹H and ¹³C NMR signals of each saccharide were assigned using 2D-NMR including COSY (correlated spectroscopy), HSQC (herteronuclear single quantum coherence), CH₂-selected E-HSQC (CH₂-selected Editing-HSQC), HSQC-TOCSY (HSQC-total correlation spectroscopy) and HMBC (heteronuclear multiple bond correlation).</p> <p>Conclusion</p> <p>The structure of three synthesized saccharides were determined, and these oligosaccharides have been identified as <it>O</it>-α-D-glucopyranosyl-(1→2)-<it>O</it>-α-D-xylopyranosyl-(1→2)-β-D-fructofuranoside (saccharide <b>1</b>), <it>O</it>-α-D-glucopyranosyl-(1→2)-<it>O</it>-α-D-glucopyranosyl-(1→2)-<it>O</it>-α-D-xylopyranosyl-(1→2)-β-D-fructofuranoside (saccharide <b>2</b>) and <it>O</it>-α-D-glucopyranosyl-(1→[2-<it>O</it>-α-D-glucopyranosyl-1]₂→2)-<it>O</it>-α-D-xylopyranosyl-(1→2)-β-D-fructofuranoside (saccharide <b>3</b>).</p

Chapter 5: Food Security

The current food system (production, transport, processing, packaging, storage, retail, consumption, loss and waste) feeds the great majority of world population and supports the livelihoods of over 1 billion people. Since 1961, food supply per capita has increased more than 30%, accompanied by greater use of nitrogen fertilisers (increase of about 800%) and water resources for irrigation (increase of more than 100%). However, an estimated 821 million people are currently undernourished, 151 million children under five are stunted, 613 million women and girls aged 15 to 49 suffer from iron deficiency, and 2 billion adults are overweight or obese. The food system is under pressure from non-climate stressors (e.g., population and income growth, demand for animal-sourced products), and from climate change. These climate and non-climate stresses are impacting the four pillars of food security (availability, access, utilisation, and stability)

Preparation, characterization and antimicrobial properties of electrospun polylactide films containing Allium ursinum L. extract

[EN] Novel active films of polylactide (PLA) containing extract of Allium ursinum L. (AU), also called wild garlic, at 10 wt% were succesfully prepared by the electrospinning technology. Electrospinning of the AU-containing PLA solutions yielded fibers in the 1-2 mu m range with a beaded-like morphology, suggesting that the AU extract was mainly encapsulated in certain fiber regions. The resultant electrospun mats were then subjected to annealing at 135 degrees C to obtain continuous films of application interest in active packaging. The film cross-sections revealed that the AU extract was incorporated into the PLA matrix in the form of micro-sized droplets. The thermal properties showed that the AU extract addition plasticized the PLA matrix and also lowered its crystallinity degree as it disrupted the ordering of the PLA chains by hindering their folding into the crystalline lattice. Thermal stability analysis indicated that the natural extract positively contributed to a delay in thermal degradation of the biopolymer and it was thermally stable when encapsulated in the PLA film. The AU extract incorporation also produced a mechanical reinforcement on the electrospun PLA films and improved slightly the water barrier performance. Finally, a significant antimicrobial activity of the electrospun PLA films containing the natural extract was achieved against foodborne bacteria.This paper has been supported by the COST Action FP1405 Active and intelligent fiber-based packaging - innovation and market introduction (ActInPak), FOODStars project Food Product Development Cycle: Frame for stepping Up Research Excellence of FINS (Grant Agreement 692276), the Spanish Ministry of Science, Innovation, and Universities (MICIU, project AGL2015-63855-C2-1-R) and the EU H2020 project YPACK (reference number 773872). 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Analysis of subcellular metabolite levels of potato tubers (Solanum tuberosum) displaying alterations in cellular or extracellular sucrose metabolism

The expression of a heterologous invertase in potato tubers (Solanum tuberosum) in either the cytosol or apoplast leads to a decrease in total sucrose content and to an increase in glucose. Depending on the targeting of the enzyme different changes in phenotype and metabolism of the tubers occur: the cytosolic invertase expressing tubers show an increase in the glycolytic flux, accumulation of amino acids and organic acids, and the appearance of novel disaccharides; however, these changes are not observed when the enzyme is expressed in the apoplast [Roessner et al. (2001). Plant Cell, 13, 11-29]. The analysis of these lines raised several questions concerning the regulation of compartmentation of metabolites in potato tubers. In the current study we addressed these questions by performing comparative subcellular metabolite profiling. We demonstrate that: (i) hexoses accumulate in the vacuole independently of their site of production, but that the cytosolic invertase expression led to a strong increase in the cytosolic glucose concentration and decrease in cytosolic sucrose, whereas these effects were more moderate in the apoplastic expressors; (ii) three out of four of the novel compounds found in the cytosolic overexpressors accumulate in the same compartment; (iii) despite changes in absolute cellular content the subcellular distribution of amino acids was invariant in the invertase overexpressing tubers. These results are discussed in the context of current models of the compartmentation of primary metabolism in heterotrophic plant tissues

Genetic diversity in tef [Eragrostis tef (Zucc.) Trotter]

Tef [Eragrostis tef (Zucc.) Trotter] is a cereal crop resilient to adverse climatic and soil conditions, and possessing desirable storage properties. Although tef provides high quality food and grows under marginal conditions unsuitable for other cereals, it is considered to be an orphan crop because it has benefited little from genetic improvement. Hence, unlike other cereals such as maize and wheat, the productivity of tef is extremely low. In spite of the low productivity, tef is widely cultivated by over six million small-scale farmers in Ethiopia where it is annually grown on more than three million hectares of land, accounting for over 30% of the total cereal acreage. Tef, a tetraploid with 40 chromosomes (2n = 4x = 40), belongs to the family Poaceae and, together with finger millet (Eleusine coracana Gaerth.), to the subfamily Chloridoideae. It was originated and domesticated in Ethiopia. There are about 350 Eragrostis species of which E. tef is the only species cultivated for human consumption. At the present time, the gene bank in Ethiopia holds over five thousand tef accessions collected from geographical regions diverse in terms of climate and elevation. These germplasm accessions appear to have huge variability with regard to key agronomic and nutritional traits. In order to properly utilize the variability in developing new tef cultivars, various techniques have been implemented to catalog the extent and unravel the patterns of genetic diversity. In this review, we show some recent initiatives investigating the diversity of tef using genomics, transcriptomics and proteomics and discuss the prospect of these efforts in providing molecular resources that can aid modern tef breeding