Production of fat-based emulsion powder by prilling process using twin-fluid atomizer for controlled release of iron

Encapsulation of iron is necessary to supply bioavailable iron to large number of population possess iron deficiency. In the present study, we dispersed the iron solution in a fat matrix of palm stearin, and prepared the simple emulsion (water-in-oil) at 60 ◦C, where fat was a continuous phase. Using that emulsion, we produced fat based emulsion particles through prilling (spray + chilling) process using twin fluid atomizers (internal mixing). We characterized the particle in terms of size and size distribution, and investigated the internal structure of the fatparticles by cryogenic scanning electron microscopy (cryo-SEM) for observing the distribution or homogeneity of dispersed phase. Present study includes mainly the iron release kinetics through the fat matrix of the emulsion particle in an in-vitro gastric system (pH ≈ 2.0 ) as a function of (a) particle size of prills, (b) thickener concentration (polyethylene glycol, PEG) in dispersed phase, (c) droplet size of dispersed phase, (d) mixing properties (Reynolds number, Re), and (e) shelf-life of particles. The release kinetics was explained by the second order kinetics, where we estimated the release kinetic constant, and co-related with the viscosity ratio of dispersed phase to continuous phase, mean particle size of emulsion, and shelf-life of particles. The result showed that the control of the release properties can be obtained by choosing particle size and thickener concentration

Modification of the CAB Model for Air-Assist Atomization of Food Sprays

The Cascade Atomization and Drop Breakup (CAB) model has been originally developed for pressure atomizers. In this study, the CAB model is modified to accommodate the atomization of low-pressure, air-assist atomizers. The modifications include the first breakup which is modeled by estimating theWeber number due to the increased liquid-gas relative velocity caused by the air flow. This breakup depends on whether the Weber number is in the catastrophic, stripping or bag breakup regime. The second modification includes a change in the product drop distributions, namely, instead of a uniform distribution, as used in the original CAB model, a X-squared distribution with the same average drop size is assumed. The model changes are validated with experimental data obtained by means of two different air-assist atomizers using an oil-in-water emulsion. The simulations are performed with a modified version of the KIVA-3 CFD code; they show good agreement with the experiments

PRETREATMENT OF MUNICIPAL WASTE ACTIVATED SLUDGE FOR ENHANCED ANAEROBIC DIGESTION AND VOLATILE SULFUR COMPOUNDS CONTROL

Although anaerobic digestion (AD) is a very old and widely accepted sludge stabilization process, the traditional digestion process is very slow due to the rate limiting hydrolysis step. The quality of biogas is another major concern, as the presence of volatile sulfur compounds is detrimental to thermo-catalytic conversion equipment and may generate harmful emissions. This study investigated the impact of various pretreatment techniques on volatile sulfur compounds control leading to enhanced anaerobic digestion of municipal waste activated sludge. Initially, the effect of combination of mechanical and chemical pretreatment of municipal waste activated sludge (WAS) prior to anaerobic digestion was studied using a laboratory-scale sludge pretreatment system with an objective to decrease volatile sulfur compounds in biogas and digested sludge. Mechanical pretreatment was conducted using depressurization of WAS through a valve from a batch pretreatment reactor pressurized at 75±1 psi, while combined pretreatments were conducted using six different dosages of hydrogen peroxide (H2O2) and ferrous chloride (FeC^) along with mechanical pretreatment. About 37%- 46% removal of H2S in biogas occurred for different combined pretreatment conditions. Sludge solubilization achieved due to the mechanical pretreatment increased total cumulative methane production by 8%-10% after 30 days during the biochemical methane potential (BMP) test. The pretreatment also decreased methyl mercaptan generation potential of the digested sludge. In the next phase, combined sono-thermal pretreatment was conducted using three different ultrasound specific energy inputs (1000, 5000, and 10,000 kJ kg\u271TSS’1) and thermal pretreatment temperatures (50, 70 and 90°C) to enhance the anaerobic digestion of waste activated sludge. Prior to anaerobic digestion, sono-thermal pretreatments have significantly iii improved VSS destruction by 29%-38%. A maximum of 30% increase in methane production was observed for 30 minutes of thermal pretreatment at 90°C followed by ultrasound pretreatment at 10,000 kJ kg\u271 TSS\u271 specific energy input. Sono-thermal pretreatments have improved the dimethyl sulfide (DMS) removal efficiency from the biogas by 42%-72%, but did not show further improvement in hydrogen sulfide (H2S) removal compared to ultrasound and thermal pretreatment alone. Economic analysis has shown that sono-thermal pretreatment combining 1000 kJ kg^TSS\u271specific energy input and thermal pretreatments at different temperatures (50-90°C) can reduce the operating costs by $44-66/ton dry solid compared to conventional anaerobic digestion without any pretreatment. In the final phase, thermo-oxidative pretreatment of municipal waste activated sludge was conducted using thermal pretreatment at 60°C in presence of 0.6 mg H2O2+I.5 mg FeC^/mg S2 as oxidants with the objective of achieving sludge disintegration for enhancing anaerobic digestion as well as to remove volatile sulfur compounds generation potential in biogas in continuous flow anaerobic digestion. For the pretreated feed digester, the hydrogen sulfide (H2S) and dimethyl sulfide (DMS) concentrations in biogas significantly decreased by average 75%, and 40%, respectively, while methanethiol (MT) removal efficiency was statistically insignificant compared to the control digester. Compared to the control, overall TSS and VSS removal efficiency were 10% and 11% higher for the pretreated feed digester operated at 10 days solid residence time (SRT), and methane production rate (L CFE/Day) increased by -20

Easy flowing emulsion (o/w) based spray-dried powder produced using dietary fiber as a wall material

The production of emulsion (o/w) based microstructured food powder through spray drying is a common practice in the food industry due to better shelf-life and easy transportation of the structured material. In general, the emulsion based powder flow behavior is poor due to lipid phase diffusion into the surface. The microstructure transform during spray-drying and the reconstitution of the emulsion powder are also a challenge by preserving the desired physiochemical properties such as emulsion size, stability, the control release kinetics of actives etc. The main objective of this study is to encapsulate the lipid phase using a wall material composed of protein (whey protein) and apple fiber. The stable submicron emulsions (o/w) were prepared using a rotor-stator at room temperature. Different fiber concentrations and different spray drying conditions were tested by varying the air to liquid mass ratio (ALR). The easy flowing of the emulsion powder was achieved when a relatively small amount (max. 5%) of fiber was used; however, the flowing performance declines with higher fiber content. The excellent reconstitution of the emulsion was also found by dissolving the particles at room temperature

Electrosprayed particles derived from nano-emulsions as carriers of fish oil

Fish oil encapsulated submicron particles were produced by electrospraying emulsions. Emulsions were homogenized by various pressures (1000 and 2000 bar) and passes (1,2, 4, and 8). The physical properties of the emulsions were evaluated, namely droplet size, stability, microstructure, and rheology. Various physicochemical characterizations of the prepared particles were carried out, including the morphology and size of the electrosprayed particles, and the encapsulation efficiency of the fish oil. In optimised conditions, nano-emulsions were produced (d50 < 100 nm). It was found that the homogenization parameters of the emulsions affect the structure of the particles. Low emulsion viscosity combined with low oil droplet size and high stability yielded particles with the smallest diameters. The proposed emulsion electrospraying technology could be promising for the production of powdered ingredients enriched with omega-3

Comparative study on the rice bran stabilization processes: A review

Rice bran is an undervalued/underutilized by-product of rice milling, rich in protein, lipids, dietary fibers, vitamins, and minerals. It is an inexpensive source of high-quality protein, fiber and lipids to be incorporated into value-added food products. The issue with rice bran is its susceptibility to rancidity and therefore measures must be taken to stabilize the bran in order for it to be fully utilized. Due to this susceptibility to rancidity, historically the bran has either been disposed and wasted or used as low-grade animal feed. As the nutritional value of the bran has been recognized, along with its potential to add value to food products, research has been increasing in volume in order to determine the most effective methods for stabilizing the bran and extracting the valuable nutrients from it. It’s been reported that a free fatty acid content of over 5% is considered to render the bran unfit for human consumption (Tao, Rao & Liuzzo, 1993). Therefore, controlling this level of rancidity is imperative to being able to store and use rice bran over extended periods of time. In order to achieve control, stabilization procedures can be carried out on the rice bran to slow down the lipase activity within the bran and preserve the nutritional qualities that rice bran possesses. Stabilization of rice bran is particularly important for use over winter months in developing countries, where there may be no crops to harvest and therefore a supply of non- rancid rice bran could be extremely beneficial. This length of storage for stabilized rice bran could be up to a period of 6 months, where it can become important for value-added product development (Bagchi, Adak & Chattopadhyay, 2014). The present review will provide an overview of the traditional and innovation rice bran stabilization techniques, those have been a common interest in the research community, and the suitability of the process in terms of the energy consumption

Extracellular Electron Transport in Microbial Electrochemical Cells

Microbial electrochemical cells (MxCs) are engineered biological systems that use microbial metabolism of anode-respiring bacteria (ARB) to catalyze electron transfer from a soluble electron donor to the anode via extracellular electron transfer (EET). Although several EET mechanisms (via direct contact, mediators, and conduction) have been proposed, understanding of EET in biofilm anodes generating high current density is limited. Recent findings suggested that electrical conduction would be a key EET pathway in MxCs producing high current density, in which biofilm conductivity (Kbio) would mainly regulate EET kinetics. However, there is no clear understanding of the influence of various environmental factors, such as anode potential, local pH, and substrate limitation in biofilm anodes on EET kinetics and Kbio. In addition, scalable, economical designs of MxCs producing high current density still need improvement for deployment of MxCs in field, such as multi-anode MxCs. Hence, the goals of this study were to systematically characterize the effects of (a) anode potential (Eanode), (b) local pH in biofilm anodes and (c) substrate limitations on EET kinetics and Kbio for a key fundamental aspect of MxCs, and develop scalable, economical MxCs using multi-anode configurations in an engineering aspect of MxCs. A biofilm anode enriched with Geobacter spp. showed high Kbio (0.96-1.24 mS/cm) to Eanode change from -0.2 V to +0.2 V vs. standard hydrogen electrode (SHE), while the steady-state current density varied significantly in the MxC. Change of Eanode shifted population of Geobacter genus in the biofilm anode, influencing intracellular electron transfer (IET) kinetics. However, high Kbio was consistently kept in the biofilm at Eanode change. This result suggests that EET kinetics would be relatively insensitive to Eanode dynamics. A step-wise decrease in phosphate buffer concentration from 100 to 2.5 mM caused pH gradient of ~0.5 pH unit between the outmost and inmost layers of a biofilm anode, showing a pH of 6.5-6.7 near the anode in a thick (>100 m) biofilm. This pH gradient substantially dropped current density from 2.38 to 0.64 A/m2 in an MxC, and Kbio decreased by 69% for the 2.5 mM phosphate buffer. These results imply that the metabolic activity of ARB inhibited by acidic pH is closely associated with conductive nature of biofilm anodes and EET kinetics. In a steady-state MxC, Kbio dynamically decreased from 0.53 mS/cm to 0.14 mS/cm during the long starvation (4-5 days) lacking exogenous electron donor. However, the poor Kbio was recovered to 0.55 mS/cm after acetate spiking, indicating that ARB’s activity profoundly influences Kbio and EET kinetics. A multi-anode MxC equipped with three anode modules showed a non-linear increase of current density to the number of anodes. The anode closest to a reference electrode (i.e., low ohmic energy loss) contributed to 65% of the overall current density of 9.15 A/m2 from the multi-anode MxC, where Geobacter species were dominant at 87% and half saturation potential (-0.251 to -0.242 V vs. SHE) was lowest among all anode electrodes. In comparison, the current density from the other two anodes distant from the reference electrode was as small as 1.4-1.7 A/m2, along with negligible population of Geobacter species. These results suggest that Eanode changed by ohmic energy losses in individual anodes can shift microbial communities, and lead to different electron transfer kinetics and current density on each anode

Double emulsions fortified with plant and milk proteins as fat replacers in cheese

The aim of this work is to investigate the possibility of producing low-fat cheddar cheeses using double emulsions, enriched with milk or vegetable proteins. Primary w/o emulsions were produced by dissolving various proteins as aqueous phase. An increase of the protein concentration led emulsions with smaller droplet size (down to 128 nm). Three low fat (LF) cheeses containing double emulsions enriched with proteins were produced. The addition of whey protein in the inner aqueous phase of the double emulsion, led to a decrease of fat, from 17% (LF) to 15.8% (WPI), and salt in cheese. The cheese with the double emulsions showed lower hardness, and oil loss compared to the LF cheddar cheeses. The proposed fat-based emulsions with high encapsulation efficiencies of protein could have potential applications in many dairy and other food products

Faba Bean Flavor Effects from Processing to Consumer Acceptability

Faba beans as an alternative source of protein have received significant attention from consumers and the food industry. Flavor represents a major driving force that hinders the utilization faba beans in various products due to off-flavor. Off-flavors are produced from degradation of amino acids and unsaturated fatty acids during seed development and post-harvest processing stages (storage, dehulling, thermal treatment, and protein extraction). In this review, we discuss the current state of knowledge on the aroma of faba bean ingredients and various aspects, such as cultivar, processing, and product formulation that influence flavour. Germination, fermentation, and pH modulation were identified as promising methods to improve overall flavor and bitter compounds. The probable pathway in controlling off-flavor evolution during processing has also been discussed to provide efficient strategies to limit their impact and to encourage the use of faba bean ingredients in healthy food design