Lecithins are a mixture of acetone-insoluble phospholipids and other minor substances (triglycerides, carbohydrates, etc.). The most commonly processes used for lecithin modification are: fractionation by deoiling to separate oil from phospholipids, fractionation with solvents to produce fractions enriched in specific phospholipids, and introduction of enzymatic and chemical changes in phospholipid molecules. The aim of this work was to evaluate the emulsifying properties of different modified sunflower lecithins in oil-in-water (O/W) emulsions. In this study, five modified sunflower lecithins were assessed, which were obtained by deoiling (deoiled lecithin), fractionation with absolute ethanol (PC and PI enriched fractions), and enzymatic hydrolysis with phospholipase A 2 from pancreatic porcine and microbial sources (hydrolyzed lecithins). Modified lecithins were applied as an emulsifying agent in O/W emulsions (30:70 wt/wt), ranging 0.1-2.0% (wt/wt). Stability of different emulsions was evaluated through the evolution of backscattering profiles (%BS), particle size distribution, and mean particle diameters (D [3, 4], D [3, 2]). PC enriched fraction and both hydrolyzed lecithins presented the best emulsifying properties against the main destabilization processes (creaming and coalescence) for the analyzed emulsions. These modified lecithins represent a good alternative for the production of new bioactive agents.

Native or modified lecithins are widely used as a multifunctional ingredient in the food industry. A fractionation process of sunflower lecithin (a non GMO product) with absolute ethanol was used for obtaining enriched fractions in certain phospholipids under different experimental conditions (temperature 35-65°C, time of fractionation 30-90 min, ethanol/lecithin ratio 2:1, 3:1). Phospholipid enrichment in PC and PI fractions was obtained and analyzed by 31 P NMR determinations. The percent extraction coefficients for different phospholipids (%E PC , %E PE and %E PI ) in both fractions were calculated. Values of %E PC in PC fractions significantly increased (p \ 0.05) from 12.8 (35°C, 30 min, 2:1) to 57.7 (65°C, 90 min, 3:1) at increasing temperature and incubation time. %E PE varied from 3.0 to 18.3 in the same fraction while %E PI presented lower values (\3%) under all the conditions assayed. The study of the effect of the operating conditions on the fractionation process evidenced a relevant influence of temperature, incubation time and to a minor extent of the ethanol/lecithin ratio on the enriched fraction yield% and selectivity of the main phospholipids (PC, PI, PE) estimated by %E PL . Response surface methodology (RSM) was utilized to explain the influence of the different parameters to optimize this process.

a b s t r a c tThe aims of this work were to obtain different samples of insoluble soybean polysaccharides (ISPS) from defatted soy flour and to study their potential application as O/W emulsifier. In this regard, the insoluble residue (okara) resulting from an aqueous extraction (60 C, pH 9.0), was submitted to an acidic extraction (pH 3.5, 120 C) without or with a pretreatment (high pressure homogenization or sonication). The insoluble residues of these extractions were dried (oven, 70 C or vacuum post-treatment with 2propanol, 40 C) yielding different ISPS samples. Aqueous dispersions of ISPS samples (1e2% w/w, pH 3 and 7), were used to prepare coarse and fine O/W emulsions. Emulsion stability against creaming and coalescence processes, and the rheological behavior were analyzed. ISPS samples obtained by okara pretreatment and vacuum dried post-treatment with 2-propanol allow to produces emulsions with high values of flocculation degree, increasing the stability of the particle size, and allowing the formation of stronger gel-like emulsions. These pretreatments expose internal sites of the polysaccharide and protein structures, increasing their superficial hydrophobicity and, therefore, allow a strong absorption of the macromolecules at the oil-water interface and/or the formation of external layers, increasing the rigidity of the interfacial film and contributing to the formation of hydrated flocs. Also, these treatments could solubilize certain compounds in okara that would interfere negatively in the formation of the interfacial film. Particularly, sample obtained by high pressures homogenization of the okara presented the best emulsifying properties and it was not significantly affected by variations in the pH of the emulsion. The results of this research work demonstrate a high potential of application of the ISPS samples as O/W emulsifier, under acid and neutral conditions, increasing the added value of an important by-product of the soybean industry.