Prediction of necrotic core and hypoxic zone of multicellular spheroids in a microbioreactor with a U-shaped barrier

© 2018 by the authors. Microfluidic devices have been widely used for biological and cellular studies. Microbioreactors for three-dimensional (3D) multicellular spheroid culture are now considered as the next generation in in vitro diagnostic tools. The feasibility of using 3D cell aggregates to form multicellular spheroids in a microbioreactor with U-shaped barriers has been demonstrated experimentally. A barrier array is an alternative to commonly used microwell traps. The present study investigates oxygen and glucose concentration distributions as key parameters in a U-shaped array microbioreactor using finite element simulation. The effect of spheroid diameter, inlet concentration and flow rate of the medium are systematically studied. In all cases, the channel walls are considered to be permeable to oxygen. Necrotic and hypoxic or quiescent regions corresponding to both oxygen and glucose concentration distributions are identified for various conditions. The results show that the entire quiescent and necrotic regions become larger with increasing spheroid diameter and decreasing inlet and wall concentration. The shear stress (0.5-9 mPa) imposed on the spheroid surface by the fluid flow was compared with the critical values to predict possible damage to the cells. Finally, optimum range of medium inlet concentration (0.13-0.2 mM for oxygen and 3-11 mM for glucose) and flow rate (5-20 μL/min) are found to form the largest possible multicellular spheroid (500 μm), without any quiescent and necrotic regions with an acceptable shear stress. The effect of cell-trap types on the oxygen and glucose concentration inside the spheroid was also investigated. The levels of oxygen and glucose concentration for the microwell are much lower than those for the other two traps. The U-shaped barrier created with microposts allows for a continuous flow of culture medium, and so improves the glucose concentration compared to that in the integrated U-shaped barrier. Oxygen concentration for both types of U-shaped barriers is nearly the same. Due to the advantage of using U-shaped barriers to culture multicellular spheroids, the results of this paper can help to choose the experimental and design parameters of the microbioreactor

Inhibitory impacts of natural antioxidants (ascorbic and citric acid) and vacuum packaging on lipid oxidation in frozen Persian sturgeon fillets

This study was aimed to investigate effects of aqueous citric acid (CA) and ascorbic acid (AA) on lipid oxidation in comparison with effect of vacuum packaging in order to find better treatment to delay improper changes in the Persian sturgeon (Acipenser persicus) fillets during frozen storage due to lipid oxidation. In this study traditional packaging, vacuum packaging, ascorbic acid solution (0.5 %) and citric acid solution (0.5 %) were considered as treatments. Rancidity development was measured by several biochemical indicators including Free Fatty Acids, Peroxide values and Thiobarbituric acid. Also pH, expressible moisture and sensory properties were measured during 6 months storage. Results showed that free fatty acid (FFA), primary and secondary oxidation products of control samples were significantly higher than those in other treatments (p<0.05). Also, expressible moisture and pH value of treated samples were significantly lower than those in control (p<0.05). However both antioxidants (AA and CA) extended shelf life of frozen fillets but rancidity development in CA treated samples was higher than other samples during storage. Results showed that all three treatments had significant effect on delaying lipid oxidation (p<0.05) but usage of AA and vacuum packaging had the best effect on delaying lipid oxidation and increasing shelf-life of fillets (p<0.05) . Thus the employment of AA and vacuum packaging alone or in combination with other protective strategies is recommended

Evaluation of the Importance of Multi-objective Particle Swarm Algorithm Parameters in Optimizing the Solutes Rejection of Camel Milk Ultrafiltration Using Partial Least Squares Regression

Introduction  Ultrafiltration is one of the most common membrane processes in the dairy industry, especially for condensing and separating milk components. Using this process, several products can be produced, including milk concentrate used for cheese production, low-lactose dairy products, milk protein concentrate, and serum proteins for dietary supplements. The efficiency and cost of a membrane process depend on the percentage of rejection of the soluble components. Therefore, the use of concentrated milk made by ultrafiltration in the production of various dairy products depends on the efficiency of the membrane process and the changes in milk components during this process. On the one hand, the physicochemical properties of camel milk are different from those of cow milk, especially in terms of type and amount of protein. Because significant differences exist between the physicochemical properties of camel and cow milk, likely, the membrane processing conditions and the physicochemical properties of their products will be different completely. Although many studies have been conducted on the efficacy of the ultrafiltration processing of cow milk, there is no information about the efficacy of camel milk ultrafiltration, and most of the research done regarding optimizing is based on classical algorithms, Therefore, in this study, the effects of transmembrane pressure and temperature on the solutes rejection (protein, lactose, ash, and total solids) during camel milk ultrafiltration process were investigated, Then, these properties were optimized using particle swarm algorithm. Also, because the performance of the particle swarm algorithm is highly dependent on related parameters such as the number of iterations, the number of particles, accelerate constant, inertia weight, and velocity of the particles, so before optimization, the effect of these parameters on optimal responses were examined by partial least squares regression (PLS).   Materials and Methods  In this study, a pilot crossflow ultrafiltration system was used. A UF membrane (Model 3838 HFK-131, Koch membrane systems, Inc., USA) made of polysulfone amid (PSA) with MWCO of 20 kDa was applied. Camel milk was purchased from a local market in Mashhad and for camel skim milk production, its fat was separated by a pilot plant milk fat separator in the Food Research Complex, Ferdowsi University of Mashhad. The weight percentages of protein, fat, lactose, ash, and total solids of UF permeate samples were measured by ISO 8968-1:2014, ISO 1211: 2010, ISO 26462/IDF 214:2010, ISO 5544:2008, and ISO 6731:2010 at two replications, respectively. the process treatments were performed in the form of a central composite design (CCD) (5 replications at the central point) for two independent variables at three levels so that the total number of 13 treatments was obtained. The data were modeled using the statistical software of Design Expert (version 11) based on the response surface methodology and each of the response variables in the form of a regression model was presented as a function of independent variables.   Results and Discussion  The rejection of total solids and protein of the tested samples varied in the range of 45.4-51.03% and 94.09-97.51%, respectively. It means that in each TMP and T, more than 45% of the total solids and 94% of the protein of camel milk were kept by the membrane. The results also showed that none of the linear, quadratic and interactive effects of TMP and T on the total solids and protein rejections were not significant. According to the results, the RL reduced with increasing T. Increasing the TMP also led to a reduction at high T and an increase in RL rate of the samples at lover T. Also, the effect of TMP on RA showed a non-linear trend, so that TMP at high T led to an increase, and at low T, it led to a reduction in the RA of the samples.   Conclusion  The optimization results with the particle swarm algorithm showed that this algorithm has a high convergence speed and by recognizing and analyzing its parameters, the optimal conditions can be easily found. The optimum ultrafiltration conditions in this study with the lowest RL and RA were determined as 80 kPa TMP and 29.85 ͦ C T

Inhibitory impacts of natural antioxidants (ascorbic and citric acid) and vacuum packaging on lipid oxidation in frozen Persian sturgeon fillets

Abstract This study was aimed to investigate effects of aqueous citric acid (CA) and ascorbic acid (AA) on lipid oxidation in comparison with effect of vacuum packaging in order to find better treatment to delay improper changes in the Persian sturgeon (Acipenser persicus) fillets during frozen storage due to lipid oxidation. In this study traditional packaging, vacuum packaging, ascorbic acid solution (0.5 %) and citric acid solution (0.5 %) were considered as treatments. Rancidity development was measured by several biochemical indicators including Free Fatty Acids, Peroxide values and Thiobarbituric acid. Also pH, expressible moisture and sensory properties were measured during 6 months storage. Results showed that free fatty acid (FFA), primary and secondary oxidation products of control samples were significantly higher than those in other treatments (p&lt;0.05). Also, expressible moisture and pH value of treated samples were significantly lower than those in control (p&lt;0.05). However both antioxidants (AA and CA) extended shelf life of frozen fillets but rancidity development in CA treated samples was higher than other samples during storage. Results showed that all three treatments had significant effect on delaying lipid oxidation (p&lt;0.05) but usage of AA and vacuum packaging had the best effect on delaying lipid oxidation and increasing shelf-life of fillets (p&lt;0.05). Thus the employment of AA and vacuum packaging alone or in combination with other protective strategies is recommended

Production of low fat french-fries with single and multi-layer hydrocolloid coatings

Abstract In this study the influence of coating with different hydrocolloids on the oil absorption and quality attributes of French fries was investigated. Our results revealed that hydrocolloid coatings reduced the moisture loss during frying, and hence, reduced the oil uptake of French fries. Among the studied gums as a single layer coating, combination of carboxy methyl cellulose and pectin (0.5 and 1% w/w) lead to the lowest oil uptake of French fries. In samples coated with two and three-layer hydrocolloids, the oil absorption reduced further and the moisture content of final products was higher than the blank samples

Integral valorization of agro-food biomass through pressurized fluids. Case study: Brewery Spent Grain (BSG)

Póster presentado en: 1er Encuentro Ibérico de Fluidos Supercríticos/1º Encontro Ibérico de Fluidos Supercríticos. 2020, 18-19 de febrero, Santiago de CompostelaThe biorefinery concept involves the valorization and conversion of biomass into different bioproducts, including energy, materials and chemicals that can replace products derived from fossil carbon sources. The integral valorization of biomass requires the extraction and fractionation of the different constituents thereof, extractables, lipids, proteins and structural components such as cellulose, hemicellulose and lignin. In this work, the use of emerging and clean technologies for the integral valorization of different types of biomass is proposed. First, the use supercritical CO2 (SCCO2) extraction is proposed for recovering the lipid fraction and ultrasonic assisted extraction to recover the hydrophilic fraction, to subsequently perform a fractionation and hydrolysis of the residual biomass using pressurized liquid water. Several types of biomass are being studied, both second and third generation. Among second generation biomass, the brewery spent grain (BSG), which accounts for 85% of the by-products generated in beer processing [1], has been selected as case study of this communication. The extraction of the lipid fraction with SCCO2 has been carried out in a 26.5 mL capacity extractor at different pressures (20-40 MPa) and temperatures (40-80 °C). The lipid fraction obtained has been characterized by determining its lipid profile and antioxidant capacity. The experiments of fractionation and hydrolysis in subcritical water (scW) have been carried out in a semi-continuous reactor, varying the extraction temperature. The different fractions obtained have been characterized by HPLC with two series detectors, UVD and RID, to determine the content in monomeric sugars and oligomers. Protein, free amino acids, total polyphenols and total organic carbon have been also determined. The composition of the BSG according to the biomass characterization protocols of NREL [2] was 21.1 % arabinoxylans, 25.6 % glucanes, 5.1 % soluble lignin, 10.5 % insoluble lignin, 1.2 % ashes, 16.7 % proteins, 5.6 % lipids and 14.4 % extractables. Worth noting the presence of insoluble lignin as well as the high content of arabinoxylans and glucanes, 10% of which were residual starch. The extraction curves obtained when studying the extraction of the lipid fraction of BSG with SCCO2, showed that the extraction rate and the extraction yield increased with increasing temperature and pressure, with the major fatty acid being linoleic acid. Regarding fractionation of the carbohydrate fraction, we have observed that, as temperature increases, hydrolysis increases. Figure 1a shows the sugars yield, including monomeric sugars and oligomers. Degradation of sugars due to the high residence times produces acids (Fig. 1b), hydroxymethylfurfural (HMF) and furfural (Fig. 1c). The treatment of biomass by scW, allows also recovering the entire protein fraction by increasing the temperature up to around 185ºC. In addition, partial hydrolysis of the protein fraction occurs, obtaining as major free aminoacids valine, aspartic acid, alanine and glycine. We can conclude that the fractionation of BSG through emerging and clean technologies allows an integral recovery of BSG, obtaining extracts with high antioxidant capacity. Pressurized water hydrolysis allows the recovery and fractionation of the carbohydrate and protein fraction.JCyL and ERDF for financial support of project BU301P18. To Hiperbaric, S.A. for financial support of Project BIOLIGNO

Determinação das curvas de secagem das sementes de andiroba em secador solar

The oil of crabwood is commonly extracted in Amazon by traditional or by pressing method. The extraction efficiency is related to the heating and water content of the seeds. Thus, the determination of a drying model that represent satisfactorily the experimental data is of paramount importance to minimize the changes introduced by the process, consequently obtaining a quality product. The objective of this study was to describe the drying kinetics of seeds of crabwood as well as adjust the mathematical models to the experimental data, using solar dryer. The coefficient of determination, the magnitude of the mean relative error and standard deviation of the estimate was used as the criterion of fit of mathematical models. Drying in a shorter period of time (14 days) of Carapa surinamensis to reach the water equilibrium content (12.28%) may be attributed to the smaller size of the seeds and the greater amount of oil compared to Carapa guianensis. Logarithmic and Midilli et al. were the model that best fitted the experimental data for seeds of both species of Andiroba. © 2015, Departamento de Engenharia Agricola - UFCG/Cnpq. All rights reserved