Carolina Shene

Extracts of Maqui (Aristotelia chilensis) and Murta (Ugni molinae Turcz.): Sources of Antioxidant Compounds and α-Glucosidase/α-Amylase Inhibitors

The objective of this work was to evaluate the antioxidant and antihemolytic activities of crude, aqueous, and organic-aqueous extracts of maqui ( Aristotelia chilensis ) and murta ( Ugni molinae Turcz.), together with their inhibiting effect on enzymes involved in the metabolism of carbohydrates. Radical scavenging activity, inhibition of linoleic acid oxidation in a micellar system, antihemolytic activity, and inhibition of α-amylases and α-glucosidases were analyzed. Crude extracts of maqui leaves and fruits were found to be important sources of polyphenolic compounds, showing 69.0 ± 0.9 and 45.7 ± 1.1 mg GAE/g dm, respectively. Polyphenols from maqui leaves were active as antioxidants and antihemolytic compounds (p < 0.05), showing a noncompetitive inhibiting effect on α-glucosidase. Flavan-3-ol polymers and glycosylated flavonols, such as quercetin glucoside and kaempferol glucoside, were tentatively identified in extracts. This preliminary observation provides the basis for further examination of the suitability of polyphenol-enriched extracts from maqui and murta as nutritional or medicinal supplements with potential human health benefits.

FLAXSEED AS A SOURCE OF FUNCTIONAL INGREDIENTS

Scientific evidence supports flaxseed consumption; however, a large sector of the population is still unaware of the benefits associated to its consumption and its possible applications as functional food ingredient in foodstuffs. Flaxseed is mainly known by its high alpha-linolenic acid content, but it is also a lignan source, soluble fibre and protein, compounds which are biologically active in the prevention of some non-transmissible chronic diseases. Southern Chile has comparative advantages for the cultivation of this crop. Together with its full processing, this crop could strengthen regional industry. The purpose of the present review is to highlight the nutritional properties of flaxseed.

MICROBIAL OILS AND FATTY ACIDS: EFFECT OF CARBON SOURCE ON DOCOSAHEXAENOIC ACID (C22:6 N-3, DHA) PRODUCTION BY THRAUSTOCHYTRID STRAINS

Thraustochytrids are marine protists found throughout the world in estuarine and marine habitats. These microorganisms have attracted interest, because their lipids contain different long chain polyunsaturated fatty acids (PUFAs). Those able to produce docosahexaenoic acid (C22:6 n-3, DHA) are the most studied because of the physiological importance of this PUFA in human beings. Their heterotrophic cultivation offers several challenges since biomass, lipid content, and fatty acid profile are dependent on growth conditions. In this work the effects of C source and its concentration on DHA production by different thraustochytrid strains are reviewed. Results obtained by different investigators on the use of alternative and low cost nutrient sources for production of DHA by thraustochytrids are also presented.

FLAXSEED AND FLAXSEED CAKE AS A SOURCE OF COMPOUNDS FOR FOOD INDUSTRY

Flax (Linum usitatissimum) has been used for centuries as a source for oil extraction. In recent years it has attracted considerable interest as a result of studies which attribute potential health benefits to its components, including the prevention of chronic non-communicable diseases. Among these compounds presenting biological activity, alpha-linolenic acid, lignans and soluble fibre are of special interest. Southern Chile has comparative advantages for the cultivation of this crop. Together with its full processing, this crop could strengthen regional industry. The purpose of the present work is to learn how the best use can be made of these compounds, by studying flaxseed and flaxseed cake as sources of compounds of interest for food industry. Oil extracted from flaxseed contained 51.86% of linolenic, 16.34% of linoleic and 20.98% of oleic acid. Fractioning of defatted flaxseed cake produced a polyphenol content of 0.73 mg GAEg-1 extract and a protein isolate of considerable purity, 53.15% yield with 0.78 gof albumin equivalent g-1 protein isolate. Additionally, a polysaccharide was isolated with low protein content as impurity, 10.71% yield with 1.37 mg of glucose equivalent per gram of polysaccharide. This information will form the basis for assessing the extraction of products of interest for the food industry from flaxseed cake.

High carotenoid bioaccessibility through linseed oil nanoemulsions with enhanced physical and oxidative stability

Carotenoid (astaxanthin or lycopene) emulsions obtained by high pressure homogenization were investigated for their physical, oxidative and storage stability and biological fate on an in vitro digestion model of bioaccessibility. Emulsion stability evaluated at various processing environments (20-50°C, 2-10 pH, 0-500 mM NaCl, and 0-35 days storage at 25°C) depended on carotenoid and homogenization pressures (5, 10, 100 MPa). Trolox increased the oxidative stability of nanoemulsions (100 MPa) and acted synergistically with BHT in increasing the stability of lycopene nanoemulsion. Intestinal digestibility depended on homogenization pressures with the fastest release and lower amount of free fatty acids observed at 100 MPa. Carotenoid nanoemulsions (100 MPa) were partially (66%) digested and highly bioaccessible (>70%). Therefore, nanoemulsions provide an effective and stable system for efficient astaxanthin or lycopene delivery and bioavailability in foods, beverages, nutraceuticals and/or other agriproducts.

Mathematical Modeling of Elution Curves for a Protein Mixture in Ion Exchange Chromatography Applied to High Protein Concentration

Protein elution curves in ion exchange chromatography (IEC) were simulated with a rate model. Three pure proteins and their mixture were used (α‐lactalbumin, BSA, and conalbumin) under different operational conditions. The anionic matrix Q‐Sepharose FF was used packed in a 1 mL column. A high protein concentration (37.5 mg/mL of total protein injected into the column) was used in order to extend the utility of the model. Mass transfer parameters were calculated using empiric correlations, where the axial dispersion was negligible (Pe > 300) and the mass transfer was controlled by the intraparticle diffusion (Bi > 10). The model assumes a modulator–eluite relationship were the equilibrium constant of the Langmuir isotherm was a function of salt concentration. Adsorption kinetic parameters were estimated from experimental data. The parameters for pure proteins were determined, and elution curves for changes in flow rate, ionic strength gradient, concentration, and sample size were predicted by the model. Then the kinetic parameters of the mixture were determined under the same operational conditions and some of the parameters had to be modified to take into account effects such as protein–protein interactions, competition, and displacement. Experimental elution curves obtained for changes in operational conditions such as flow rate and ionic strength gradient were simulated by the rate model for the protein mixture with a relative error in retention time of visible peaks <5%. IEC operational conditions and the peak fraction collection can be selected using a cost function of the production process which considers yield, purity, concentration, and process time that are obtained from simulations. Operational conditions that gave the minimum cost were selected. Simulations allows to diminish experimental time and cost. Biotechnol. Bioeng. 2009; 104: 572–581

Production of the exopolysacchzrides by Streptococcus thermophilus: Effect of growth conditions on fermentation kinetics and intrinsic viscosity

Production of exopolysaccharides (EPS) by a commercial Streptococcus thermophilus strain was evaluated at different growth conditions [temperature (32-45 degrees C), carbon source and initial nitrogen (N) content]. Lactose from deproteinized whey and sucrose allowed to obtain EPS yields higher than 1200 mg/mM of the consumed carbon source. Intrinsic viscosity of the EPS was significantly reduced by ionic strength indicating a polyelectrolyte behavior. Growth conditions used for the production of the EPS had a significant effect (p<0.05) on the intrinsic viscosity. This was attributed to the effect of growth conditions on the molecular properties of the EPS [stiffness and molecular weight (MW)]. High MW EPS were produced when the bacteria grew at a high specific growth rate; however MW of the EPS and specific growth rate were not linearly associated. In the lactose fermentations carried out at different temperatures specific EPS synthesis rate was positive and linearly associated with the specific lactose consumption rate (R2=0.967) and specific galactose production rate (R2=0.967). Critical coil overlap parameter, [eta]C*, for the EPS produced in the lactose fermentations carried out at 43 and 45 degrees C was determined to be approximately 7.6, and their critical overlap concentrations (C*) were 0.45 and 0.87 g/dL, respectively.

Effective Lactobacillus plantarum and Bifidobacterium infantis encapsulation with chia seed (Salvia hispanica L.) and flaxseed (Linum usitatissimum L.) mucilage and soluble protein by spray drying

Mucilage (M) and soluble protein (SP) extracted from chia seed and flaxseed were used as encapsulating material for two probiotic bacteria: Bifidobacterium infantis and Lactobacillus plantarum by spray drying. Probiotic survival and viability after spray drying and during storage were evaluated. B. infantis and L. plantarum displayed high survival (⩾98%) after encapsulation with mixtures of maltodextrin (MD) combined with M and SP from flaxseed (MD:FM:FSP - 7.5:0.2:7.5%, w/w/w) and chia seed (MD:CM:CSP - 7.5:0.6:7.5%, w/w/w), respectively. These ternary blends protected the probiotics and enhanced their resistance to simulated gastric juice and bile solution. Probiotics encapsulated with the ternary blends incorporated in instant juice powder exhibited high viability (>9Log10CFU/g) after 45days refrigerated storage. Encapsulation with the ternary blends reduced particle size of the probiotic powders thereby offering additional functional benefits. Our results reveal that chia seed and flaxseed are excellent sources of probiotic encapsulating agents.

Extension of the selection of protein chromatography and the rate model to affinity chromatography.

The rational selection of optimal protein purification sequences, as well as mathematical models that simulate and allow optimization of chromatographic protein purification processes have been developed for purification procedures such as ion‐exchange, hydrophobic interaction and gel filtration chromatography. This paper investigates the extension of such analysis to affinity chromatography both in the selection of chromatographic processes and in the use of the rate model for mathematical modelling and simulation. Two affinity systems were used: Blue Sepharose and Protein A. The extension of the theory developed previously for ion‐exchange and HIC chromatography to affinity separations is analyzed in this paper. For the selection of operations two algorithms are used. In the first, the value of η, which corresponds to the efficiency (resolution) of the actual chromatography and, Σ, which determines the amount of a particular contaminant eliminated after each separation step, which determines the purity, have to be determined. It was found that the value of both these parameters is not generic for affinity separations but will depend on the type of affinity system used and will have to be determined on a case by case basis. With Blue Sepharose a salt gradient was used and with Protein A, a pH gradient. Parameters were determined with individual proteins and simulations of the protein mixtures were done. This approach allows investigation of chromatographic protein purification in a holistic manner that includes ion‐exchange, HIC, gel filtration and affinity separations for the first time. Copyright

Effect of feeding strategy on Zymomonas mobilis CP4 fed-batch fermentations and mathematical modeling of the system

Abstract In this work, the effect of the feeding strategy in Zymomonas mobilis CP4 fed-batch fermentations on the final biomass and ethanol concentrations was studied. Highest glucose yields to biomass (0.018 g/g) and to ethanol (0.188 g/g) were obtained in fed-batch fermentations carried out using different feeding rates with a glucose concentration in the feed equal to 100 g/l. Lower values (0.0102 g biomass/g glucose and 0.085 g ethanol/g glucose) were obtained when glucose accumulated to levels higher than 60 g/l. On the other hand, the highest biomass (5 g/l) and ethanol (39 g/l) concentrations were obtained using a glucose concentration in the feed equal to 220 g/l and exponentially varied feeding rates. Experimental data were used to validate the mathematical model of the system. The prediction errors of the model are 0.39, 14.36 and 3.24 g/l for the biomass, glucose and ethanol concentrations, respectively. Due to the complex relationship for describing the specific growth rate, a fed-batch culture in which glucose concentration is constant would not optimize the process.