NANOPARTÍCULAS DE PROTEÍNA ISOLADA DE SOJA EM ÁGUA: EFEITO DA FORÇA IÔNICA E DAS CONCENTRAÇÕES DE PROTEÍNA E SURFACTANTE

Soft nanoparticles of size 200-400 nm were obtained from soybean protein isolate (SPI). The particles were formed and suspended in water by the coacervation of aqueous suspensions of SPI in hostile buffered aqueous solutions in the presence of surfactants. We investigate the effect of storage, ionic strength, and concentrations of SPI and surfactant on nanoparticle size and zeta potential. Transmission electron microscopy images and scattering techniques (SLS/ DLS) revealed that the particles are spherical, with hydrophilic chains at the surface

The significance of root growth on cotton nutrition in an acidic low-P soil

Toxic levels of Al and low availability of Ca have been shown to decrease root growth, which can also be affected by P availability. In the current experiment, initial plant growth and nutrition of cotton (Gossypium hirsutum var. Latifolia) were studied as related to its root growth in response to phosphorus and lime application. The experiment was conducted in Botucatu, Sao Paulo, Brazil, in pots containing a Dark Red Latosol (Acrortox, 20% clay, 72% sand). Lime was applied at 0.56, 1.12 and 1.68 g kg -1 and phosphorus was applied at 50, 100 and 150 mg kg -1. Two cotton (cv. IAC 22) plants were grown per pot for up to 42 days after plant emergence. There was no effect of liming on shoot dry weight, root dry matter yield, root surface and length, but root diameter was decreased with the increase in soil Ca. Shoot dry weight, as well as root length, surface and dry weight were increased with soil P levels up to 83 mg kg -1. Phosphorus concentration in the shoots was increased from 1.6 to 3.0 g kg -1 when soil P was increased from 14 to 34 mg kg -1. No further increases in P concentration were observed with higher P rates. The shoot/root ratio was also increased with P application as well as the amount of nutrients absorbed per unit of root surface. In low soil P soils the transport of the nutrient to the cotton root surface limits P uptake. In this case an increase in root growth rate due to P fertilisation does not compensate for the low P diffusion in the soil

Método "cova/préplantio" Na Manutenção da batata-semente própria: Avaliação da Execução e do custo por bataticultores no estado de São Paulo, Brasil

O problema da degenerescência da batata-semente (Solanum tuberosum L.), pelo vírus do enrolamento da folha da batata (Totato Leafroll Virus" - PLRV), (Souza-Dias & Costa, 1984) foi bastante reduzido na Estação Experimental de Itararé-SP (EEI) pelo método de selecto "Cova/pré-plantio". Desde o ano passado, o método vem sendo avaliado em propriedades particulares, por bataticultores de diferentes regiões do Estado. Resultados semelhantes aos da EEI vem sendo notados: incidências do PLRV acima de 20% no campo foram reduzidas a menos de 5% do PLRV nos lotes de batata-semente de covas selecionadas de variedades nacionais ou estrangeiras, entre essas a 'Bintje'. Os produtores que experimentaram! o método confirmaram ser este simples e de baixo custo de execução, sem uso de equipamentos ou mão de obra especializada. A batata-semente produzida pelo método teve um custo mais de 60% inferior a batata-semente certificada ou importada de comparável sanidade. Essa redução no custo da semente representa urna economia de 28% no custo total da produção. O melhoramento indireto da variedade pela selec,3o/manutenção das covas mais produtivas; e a eliminação da introdução de patogenos via batata-semente adquirida "de fora", são vantagens adicionais do método. Acredita-se que em outras regiões com problemas de rápida degenerescência da batata-semente, o método "cova/pré-plantio" também possa servir na manutenção da própria batata-semente com alta sanidade, pelo bataticultor.

Morphology of Soy Protein Isolate at Oil/Water and Oil/Air Interfaces

Herein, the emulsifying properties of soy protein isolate (SPI) were highlighted by showing that the macromolecules undergo conformational changes when adsorbed at interfaces. The conformation of protein chains nested at the interfacial region of oil in water (o/w) emulsions by means of X-ray scattering (SAXS) and direct imaging (scanning electron microscopy (SEM)) techniques was investigated. The mean radius of gyration (Rg) for SPI (aq) is 20 nm and increases up to 30 nm in o/w emulsions; the proteins act as amphiphilic molecules by exposing their hydrophobic core to the oil and their hydrophilic amino acid residues to the water phase. By spray drying the emulsions, it was also possible to measure the size (Rg = 40 nm) and to evaluate the morphology of these proteins at the oil/air interface of the respective microcapsules. The walls of microcapsules are fractals of clustered objects with rough surfaces, which are smoothed by the presence of a cross-linking agent