ABSTRACT Microalgal lipids exhibit physical-chemical characteristics similar to vegetable oils, representing alternative sources of long-chain fatty acids for food supplements. However, separating intracellular lipids from microalgae biomass is still challenging due to downstream processing technology limitations that depend on the particular microalgal species and its cultivation conditions. Thus, this work evaluated a multistep process for lipid extraction from Tetradesmus obliquus biomass instead of conventional single extraction methods to improve the lipid yield. The wet biomass was freeze-dried, the cells of the dried biomass were disrupted in a ball mill, and the milled biomass was suspended in water to obtain solid contents of 5 % and 10 % w v–1. Lipids were extracted from the aqueous suspension using the ethanol polar solvent and the hexane apolar solvent with ethanol:hexane ratios of 1:1, 1:2, and 3:5 v v–1. Tests were also carried out on the deproteinized biomass to evaluate the effect of proteins on emulsion formation since deproteinization can avoid emulsion formation. Thus, lipid downstream processing could be designed without an emulsion removal stage. The biomass was deproteinized before lipid extraction with NaOH at pH 10. The highest lipid content was verified for the 1:2 ethanol:hexane ratio, in which up to 42 % of the total lipids were extracted from the biomass. With the 3:5 ratio, the organic and aqueous phases emulsified due to the presence of lipoproteins, which hindered the lipid extraction process. Under the studied conditions, no increase in lipid extraction yield was observed with increases in the solid content or biomass deproteinization. physicalchemical physical chemical oils longchain long chain supplements However conditions Thus freezedried, freezedried freeze dried, freeze-dried mill 1 v1 v–1 ethanolhexane 11, 11 1, 1:1 12, 12 2, 2 35 3 3: stage 1: ratio 4 lipoproteins v–

ABSTRACT Saturated salt solutions produce environments with specific relative humidities used in several applications, such as determining water sorption isotherms of foods. However, the preparation of saturated solutions requires knowledge of solubility data. Thus, the objective of this work was to determine the solubility of 14 salts: lithium bromide (LiBr), lithium chloride (LiCl), lithium iodide (LiI), magnesium chloride (MgCl2), sodium iodide (NaI), potassium carbonate (K2CO3), magnesium nitrate (Mg(NO3)2), sodium bromide (NaBr), potassium iodide (KI), sodium chloride (NaCl), ammonium sulfate ((NH4)2SO4), potassium chloride (KCl), potassium nitrate (KNO3), and potassium sulfate (K2SO4) in the temperature range of 275.15 to 363.15 K at 101.3 kPa. The apparatus for the solubility determination consists of a jacketed glass cell and a magnetic stirrer. Furthermore, polynomial and exponential empirical models were fitted to the observed data to determine salt solubilities. Salt solubilities ranged from 7.39 to 80.41 g of salt·(100 g of solution)-1. Sodium iodide (NaI) presented the highest (p<0.05) solubility, up to 343.15 K, and lithium iodide (LiI) up to 363.15 K. The specific equilibrium moistures afforded by saturated saline solutions were associated with water activity data. A general mathematical model to determine the solubility of different salts was not obtained because the dissolution behaviors of each salt are distinct. However, the availability of solubility data of saline solutions covering a wide range of temperatures is helpful since the salts have different behavior.

RESUMO Soluções salinas saturadas produzem ambientes com umidades relativas específicas utilizadas em diversas aplicações, como na determinação de isotermas de sorção de água de alimentos. No entanto, a preparação de soluções saturadas requer conhecimento de dados de solubilidade. Assim, o objetivo deste trabalho foi determinar a solubilidade de 14 sais: brometo de lítio (LiBr), cloreto de lítio (LiCl), iodeto de lítio (LiI), cloreto de magnésio (MgCl2), iodeto de sódio (NaI), carbonato de potássio (K2CO3), nitrato de magnésio (Mg(NO3)2), brometo de sódio (NaBr), iodeto de potássio (KI), cloreto de sódio (NaCl), sulfato de amônio ((NH4)2SO4), cloreto de potássio (KCl), nitrato de potássio (KNO3) e sulfato de potássio (K2SO4) na faixa de temperatura de 275,15 a 363,15 K a 101,3 kPa. O aparelho para a determinação da solubilidade consiste em uma célula de vidro encamisada e um agitador magnético. Além disso, modelos empíricos polinomiais e exponenciais foram ajustados aos dados observados para determinar solubilidades de sal. A solubilidade do sal varia de 7,39 a 80,41 g de sal·(100 g de solução)-1. Iodeto de sódio (NaI) apresentou o maior (p<0.05) solubilidade, até 343,15 K, e iodeto de lítio (LiI) até 363,15 K. Específicas umidades de equilíbrio proporcionadas pelas soluções salinas saturadas foram associadas aos dados de atividade de água. Um modelo matemático geral para determinar a solubilidade de diferentes sais não foi obtido porque os comportamentos de dissolução de cada sal são distintos. No entanto, a disponibilidade de dados de solubilidade de soluções salinas cobrindo uma ampla faixa de temperaturas é útil, pois os sais têm comportamento diferente.