Liquid-liquid equilibria in aqueous two-phase ethanol/salt systems at different temperatures and their application to anthocyanins extraction

Abstract Aqueous two-phase systems (ATPS) are formed by mixtures of chemical species that, under certain conditions, separate into two immiscible phases, with water as the major component in global terms and, at lower concentrations, polymers, salts, ionic liquids and alcohols, depending on the system type. Different parameters influence ATPS equilibrium such as temperature, alcohol carbon chain size, salt type, pH, etc. The present work aimed to obtain the binodal curves for ATPS made up of ethanol, sodium citrate/ammonium sulfate and water at different temperatures (15, 25 and 35 °C) as well as to evaluate the potential of the ethanol/ammonium sulfate system in anthocyanins partition. The results showed that the increase in temperature did not alter the biphasic region in the temperature range investigated, not influencing the formation of phases. Nonlinear equations were satisfactorily fitted to binodal curves data, except for sodium citrate-containing ATPS at 15 °C. Higher concentration of the overall mixture resulted in longer tie-line of ammonium sulphate-containing ATPS. Higher values of partition coefficient and recovery yield of Syzygium cumini fruit anthocyanins were obtained at longer tie-lines

Rheological and structure characterization of α-lactalbumin, β-lactoglobulin and gliyomacropeptide acid gels

As características reológicas e morfológicas de géis de proteínas do soro acidificados com glucona-δ-lactona foram estudadas. Foi avaliado o efeito da composição proteica (concentrações de β-Lactoglobulina, α-Lactalbumina e Glicomacropeptídeo) nas propriedades de gelificação e reológicas utilizando o planejamento experimental de modelagem de mistura. Essas análises foram complementadas pela análise da morfologia das superfícies dos géis com microscopia de força atômica. Todas as misturas avaliadas gelificaram e, com exceção da mistura com maior proporção de GMP, formaram géis autossustentáveis. Géis compostos com menor proporção de β-Lg apresentaram menor módulo elástico. Maior proporção de α-La aumentou o tempo de gelificação da mistura e consequentemente diminuiu o pH de gelificação, enquanto maior proporção de GMP apresentou efeito contrário. Na análise do ensaio de fluência e recuperação, observou-se diminuição dos parâmetros do modelo simplificado de Burgers com o aumento da proporção de α-La e/ou GMP na mistura. A deformação total foi composta principalmente pela deformação elástica retardada e a deformação recuperável foi superior à irreversível. Verificou-se que o processo de relaxação de tensão foi mais pronunciado nas misturas com menor proporção de β-Lg. Misturas com maior proporção de GMP formaram géis com superfícies mais rugosas e com poros maiores, enquanto maior proporção de α-La resultou em efeito contrário. Com exceção dos géis constituídos puramente por β-Lg e da mistura binária β-Lg/α-La com maior proporção de α-La, foi observada a formação de géis particulados. Géis mistos foram estruturalmente mais frágeis, sendo a β-Lg a principal componente responsável pela estruturação e força da rede.The rheological and morphological characteristics of whey protein gels acidified with glucono-δ-lactone were studied. The effect of protein composition (β-Lactoglobulin, α-Lactalbumin and glycomacropeptide concentration) on gelation and rheological properties, using a mixture experimental design, was evaluated. These analyses were complemented by surface morphology analysis of the gels by atomic force microscopy. All mixtures evaluated gelled and, except the highest GMP concentration gel, self supported gels were obtained. Gels made with low proportion of β-Lg presented lower elastic modulus. A higher proportion of α-La increased the gelling time of the mixture and consequently reduced the pH of gelation, while a higher proportion of GMP presented the opposite effect. In the creeprecovery test, there was a decrease of the modified Burgers model parameters with the increased of proportion of α-La and/or GMP in the mixture. The main strain was caused by the retarded elastic deformation. The reversible deformation was higher than irreversible deformation. It was also found that the process of stress relaxation was more pronounced in mixtures with lower proportion of β-Lg. Mixtures with higher proportion of GMP formed gels with rougher surfaces and larger pores, while a higher proportion of α-La resulted in opposite characteristics. With the exception of gels formed by β-Lg and β-Lg/α-La binary mixture with a higher proportion of α-La, micrographs of gels showed particulate networks. Mixed gels were structurally more fragile, and the β-Lg was the main component responsible for the structure and strength of the network.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Emulsifying properties of Quillaja saponin and β-lactoglobulin: effects of pH, ionic strength and homogenization conditions

A formação e a estabilização de emulsões são consideravelmente influenciadas pelo tipo de emulsificante empregado, bem como pelas condições da fase contínua que as compõem e pelas condições de homogeneização. Inicialmente efeitos do número de ciclos de homogeneização, pH e concentração de NaCl sobre a formação e estabilidade de emulsões óleo em água (O/A) contendo mistura de saponina de Quillaja (QBS) e β-lactoglobulina (β-lg) foram estudados separadamente. Posteriormente, as propriedades emulsificantes e estabilizantes da mistura de QBS e β-lg sob diferentes valores de pH e concentração de NaCl foram avaliadas e comparadas às de seus componentes puros. As emulsões foram preparadas em duas etapas: pré-homogeneização sob agitação (7.500 rpm/3 min) e homogeneização à alta pressão (10.000 psi/4-8 ciclos), e então caracterizadas em termos de suas propriedades: tamanho e distribuição de tamanho de gota, carga superficial de gota, comportamento reológico, e estabilidade física após 7 dias de armazenamento, a 25 °C. Verificou-se no presente estudo que a utilização de 4 ciclos de homogeneização mostrou-se adequada para a obtenção de gotas pequenas estabilizadas pela mistura de QBS e β-lg. Todas as emulsões estabilizadas pela mistura e por seus componentes puros apresentaram carga superficial líquida negativa em todas as condições de pH (7, 8 e 9) e concentração de NaCl (0, 100 e 200 mmol L -1 ) avaliadas. As distribuições de tamanho de gota foram multimodais e as emulsões foram polidispersas, embora seus diâmetros médios de gota tenham sido relativamente pequenos (< 500 nm). As emulsões apresentaram comportamento ligeiramente pseudoplástico, com presença de pequena tensão inicial e baixa viscosidade aparente. O comportamento viscoelástico foi característico de gel fraco. A influência do pH e da concentração de NaCl sobre as propriedades das emulsões dependeu do emulsificante utilizado para xvestabilizá-las. As emulsões apresentaram boa estabilidade frente à separação de fase e, em sua maioria, à agregação após o armazenamento. A mistura de QBS e β-lg apresentou desempenho semelhante ao de seus componentes puros quanto à capacidade de formar emulsões com gotas de diâmetro médio inferior a 500 nm. No entanto, a mistura aparenta ter apresentado melhor capacidade de estabilizar as emulsões quando comparada à QBS e à β-lg separadamente, revelando assim um efeito sinergístico da mistura.The formation and stabilization of emulsions are significantly influenced by the emulsifier type, the conditions of the continuous phase that compose them and the homogenization conditions. Initially the effect of the number of homogenization cycles, pH and NaCl concentration on the formation and stability of O/W emulsions containing Quillaja saponin (QBS) and β-lactoglobulin (β-lg) mixture were studied separately. Subsequently, the emulsifying and stabilizing properties of the mixture of QBS and β-lg under different pH and NaCl concentration were evaluated and compared with those of the pure components. The emulsions were prepared in two steps: pre- mixing with stirring (7,500 rpm/3 min) and homogenization at high pressure (10,000 psi/4-8 cycles). Subsequently, they were characterized in terms of droplet size distribution, droplet surface charge, rheological behavior, and physical stability after 7 days of storage at 25 °C. It was found that the use of four cycles of homogenization was adequate for obtaining small droplets stabilized by mixing QBS and β-lg. All emulsions and its pure components showed negative net surface charge at all pH conditions (7, 8 and 9) and NaCl concentration (0, 100 and 200 mmol L -1 ). The droplet size distributions were multimodal and the emulsions were polydisperse, however their average droplet diameters were relatively small (< 500 nm). The emulsions showed slightly pseudoplastic behavior with the presence of small yield stress and low apparent viscosity. The viscoelastic behavior indicated a weak gel-like behavior. The influence of pH and NaCl concentration on the emulsions properties depended on the emulsifier used to stabilize them. The emulsions showed good stability against phase separation and, in most cases, against the aggregation after storage. The mixture of QBS and β-LG showed similar performance compared with its pure components regard to the ability to form emulsions with droplets of average diameter less than 500 nm. However, the mixture appears to have presented the best ability to stabilize the emulsions xviiwhen compared with the QBS and β-lg separately, thus revealing a synergistic effect of the mixture.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Foaming properties of suspensions composed by β-lactoglobulin and polysaccharides, in the presence of sucrose or polyols

This study compares the effect of different combinations between β-lactoglobulin (β-lact, 1.0–1.5% w/v), a polysaccharide (carrageenan gum, CG, or locust bean gum, LBG, 0.0–0.5% w/v) and a sweetener (sucrose, maltitol or sorbitol, 0.0–0.5% w/v) on the foaming capacity and half-life time. The experimental design was defined according to a simplex centroid mixture design with a restriction of at least 1.0% w/v of β-lact in each mixture. Measurements of particle size, zeta potential, surface tension, flow curve, foaming capacity and foam half-life time were obtained. All mixtures evaluated showed a wide particle size distribution with diameters between 5.35 and 4494 nm. Mixtures containing CG presented higher values for apparent viscosity and average particle size than mixtures containing LBG, according to the gum concentration in solution. All mixtures showed negative zeta potential values (−14.27 to −40.42 mV) due to the presence of negatively charged β-lact at the pH 7. However, CG exerted a dominant effect on the zeta potential when present in the mixtures. The surface tension and foaming capacity were affected by the combined effect of the gums and sweeteners used. These molecules seemed to concentrate the protein at the interface due to the exclusion volume effect. The foam half-life time was mainly improved by the CG due to the higher bulk apparent viscosity, regardless of the sweetener used. Replacing sucrose with maltitol or sorbitol lead to comparable foam characteristics, mainly the foam capacity and foam half-life time, which confirms the potential of these polyols for sucrose replacement in model foams

Rheological and physicochemical studies on emulsions formulated with chitosan previously dispersed in aqueous solutions of lactic acid

Chitosan, a natural, cationic polysaccharide, may be a hydrocolloid strategic to formulate acidic food products, as it can act as both bio-functional and technofunctional constituent. Typically, acetic acid is used to disperse chitosan in aqueous media, but the use of this acid is limited in food formulations due to its flavor. In this study, chitosan was firstly dispersed (0.1% m/V) in lactic acid aqueous solutions (pH 3.0, 3.5 or 4.0), and then evaluated regarding its thickener and emulsion stabilizer properties. O/W emulsions were prepared and characterized in terms of rheological properties, droplets average diameters and droplets ζ-potential. Emulsions containing chitosan were 3 times more viscous than controls without chitosan, and presented storage modulus (G’) higher than loss modulus (G”). Furthermore, they displayed two different populations of droplets (average diameters of 44 and 365 nm) and positive ζ-potential values (+50 mV). Droplets average diameters and ζ-potential did not present significant changes (p > 0.05) after storage at 25 °C during 7 days. This study showed that i) food organic acids other than acetic acetic acid can be used to disperse chitosan for technological purposes, and ii) chitosan dispersed at very low concentrations (0.1 m/V %) had relevant effects on rheological and physicochemical aspects of food-grade emulsions

Brazilian Flora 2020: Leveraging the power of a collaborative scientific network

International audienceThe shortage of reliable primary taxonomic data limits the description of biological taxa and the understanding of biodiversity patterns and processes, complicating biogeographical, ecological, and evolutionary studies. This deficit creates a significant taxonomic impediment to biodiversity research and conservation planning. The taxonomic impediment and the biodiversity crisis are widely recognized, highlighting the urgent need for reliable taxonomic data. Over the past decade, numerous countries worldwide have devoted considerable effort to Target 1 of the Global Strategy for Plant Conservation (GSPC), which called for the preparation of a working list of all known plant species by 2010 and an online world Flora by 2020. Brazil is a megadiverse country, home to more of the world's known plant species than any other country. Despite that, Flora Brasiliensis, concluded in 1906, was the last comprehensive treatment of the Brazilian flora. The lack of accurate estimates of the number of species of algae, fungi, and plants occurring in Brazil contributes to the prevailing taxonomic impediment and delays progress towards the GSPC targets. Over the past 12 years, a legion of taxonomists motivated to meet Target 1 of the GSPC, worked together to gather and integrate knowledge on the algal, plant, and fungal diversity of Brazil. Overall, a team of about 980 taxonomists joined efforts in a highly collaborative project that used cybertaxonomy to prepare an updated Flora of Brazil, showing the power of scientific collaboration to reach ambitious goals. This paper presents an overview of the Brazilian Flora 2020 and provides taxonomic and spatial updates on the algae, fungi, and plants found in one of the world's most biodiverse countries. We further identify collection gaps and summarize future goals that extend beyond 2020. Our results show that Brazil is home to 46,975 native species of algae, fungi, and plants, of which 19,669 are endemic to the country. The data compiled to date suggests that the Atlantic Rainforest might be the most diverse Brazilian domain for all plant groups except gymnosperms, which are most diverse in the Amazon. However, scientific knowledge of Brazilian diversity is still unequally distributed, with the Atlantic Rainforest and the Cerrado being the most intensively sampled and studied biomes in the country. In times of “scientific reductionism”, with botanical and mycological sciences suffering pervasive depreciation in recent decades, the first online Flora of Brazil 2020 significantly enhanced the quality and quantity of taxonomic data available for algae, fungi, and plants from Brazil. This project also made all the information freely available online, providing a firm foundation for future research and for the management, conservation, and sustainable use of the Brazilian funga and flora