Influence of feed properties on membrane fouling in crossflow microfiltration of particulate suspensions

The effects of the feed concentration (C_feed) and particle size distribution (PSD) on the crossflow microfiltration (CFMF) of suspensions containing lactalbumin particles were investigated. Experiments were carried out in constant transmembrane pressure (TMP) mode using tubular ceramic membrane modules. All the important parameters: permeate flux, internal and surface fouling, cake mass, height, porosity, and PSD were estimated. The steady-state flux (J_ss) decreased, and internal as well surface fouling and cake mass and height all increased with an increase in C_feed from 0.65 to 2.5 gL⁻¹. This was due to the availability of more particles to foul the membrane at higher C_feed. However, above 2.5 gL⁻¹ there was no significant effect of C_feed on any of these parameters. The overall observed behaviour is attributed to steady-state membrane fouling resulting from the availability of sufficient particles for maximum possible deposition under the experimental conditions reached at 2.5 gL⁻¹. The larger the feed particles, the higher was the J_ss. However, the cake mass, height and porosity were not affected by the feed PSD. Significantly, addition of larger feed particles at the steady state increased the flux by about 6%. This behaviour is attributed to the scouring effect of the large particles on the cake surface. There is scope for looking at the possibility of using the scouring effect of large particles to improve the CFMF process performance.     

Effect of operating parameters on performance of nanofiltration of sugar beet press water

Sugar beet press water is one of the main wastewater in the sugar industry, which presently returned to the diffuser with no further treatment. Some form of treatment, such as pretreatment with membrane may however, improved the output efficiency of sugar plants. In this study, nanofiltration membrane (AFC80) were used to investigate the permeate flux, fouling percent and rejection percent of most important molassogenic ions (sodium and potassium) and sucrose. Sugar beet press water was provided by Abkoh sugar beet factory. The effect of operating parameters such as temperature (at levels of 25,40and 55 °C), trans membrane pressure (at levels of 10,15and 20 bar) on nanofiltration performance (permeate flux, fouling and rejection) were investigated. The results show that maximum permeate flux is obtained at 55 °C and 20 bar, while the average value is 49.27 kgm-2h-1. The minimum permeate flux is obtained at 25 °C and 10 bar, and the average value in this conditions is 14.63 kgm-2h-1. Maximum and minimum fouling are reached at 55 °C and 20 bar and 25 °C and 15 bar, respectively. Furthermore maximum rejection of sodium and potassium (84.3% and 72.5% respectively) is obtained at 25 °C and 20 bar, and minimum of rejection of sodium and potassium (74.3% and 69.05% respectively) is obtained on 55 °C and 10 bar. For all operating conditions, sucrose rejection was exceeded 95%. Variation in operating conditions had no significant effect on sucrose rejection.     

Dead end ultra-filtration of sugar beet juice expressed from cold electrically pre-treated slices: Effect of membrane polymer on fouling mechanism and permeate quality

Purification of raw sugar beet juice expressed at ambient temperature (20 °C) from pretreated sugar beet slices by pulsed electric field (E = 600 V·cm^− 1, t_PEF = 10 ms, T = 20 °C) was studied on the laboratory scale by dead-end ultrafiltration tests. Polyethersulfone (PES) and Regenerated Cellulose (RC) membranes with the same nominal molecular weight cut-off of 30 kDa were used. Experiments were carried out in unstirred and stirred (at rotation speed of 500 rpm) mode at constant trans-membrane pressure of 2 bar. The effects of the membrane polymer (Polyethersulfone and Regenerate Cellulose) on the filtration flux and the permeate quality were studied. In order to identify the fouling mechanism, the filtration kinetics was modeled using combined fouling models. Results showed that the filtration productivity (filtration flux) and selectivity (rejection ratio of impurities) depended on the membrane polymer. The juice filterability was better with Regenerated Cellulose (RC) membrane while the polyethersulfone (PES) membrane ensured a better retention of impurities (colorants, proteins and colloids), leading to a higher juice purity. Experimental and models data adjustment showed that combined models were preferable to investigate the fouling mechanism for both unstirred and stirred filtration. The desirable sugar purity (95–96%) of filtrate implies the potential application of a novel process (PEF treatment-cold pressing-ultrafiltration) for sugar industrial production.Industrial relevancePre-treatment by pulsed electric field PEF allowed cold or mild extraction of sucrose from sugar beet roots. The combination of PEF and ultra-filtration allowed high yield sucrose extraction and purification with less energy consumption. Membrane fouling analysis led to better filtration producibility. The obtained data can be useful for optimization of the sucrose production with high yield in industrial extraction processes.     

Chemical,Microbial and Sensory Properties of Candied-Pineapple and Cherry Cakes

The chemical, sensory and microbial qualities of candied-pineapple and cherry cakes were investigated. Both cake samples were also analyzed for chemical composition and microbial load before, during and after 56 days storage at room temperature. There were significant differences (p < 0.05) in the physico-chemical composition of the cherry cake and candied pineapple cake except for protein values of 9.00% and 8.63% respectively and magnesium content with values of 0.23% and 0.27% respectively. Sensory evaluation results showed significant differences (p < 0.05) between the two samples with the exception of colour (7.84) for both samples and texture (7.84 and 7.80) for cherry and candied pineapple cakes, respectively. In terms of general acceptability, the candied-pineapple cake was most preferred (8.52). The microbial loads (bacterial and fungal) of the candied pineapple cake were lower than the cherry cake throughout the duration of the 56 days storage at room temperature. The highest bacterial load was recorded after the 28th day (148.0 × 10⁵ cfu/g) and (194.30 × 10⁵ cfu/g) for candied pineapple and cherry cakes respectively. The fungal load was also highest at 28th day of storage (14.33 × 10¹ cfu/g) and (12.67 × 10³ cfu/g) for candied pineapple and cherry cakes respectively. The total viable counts (TVC) were within acceptable limits for human consumption. Therefore, candied-pineapple can readily substitute cherry in fruit cake making in Nigeria.     

An economic assessment of proteins recovery from fish meal effluents by ultrafiltration

The main objective of this work was to assess the technical and economical feasibility of proteins recovery from fish meal effluents using crossflow membrane technology, namely, ultrafiltration (UF) and nanofiltration (NF).Mackerel processing effluents were pre-treated by microfiltration (MF cartridges battery of 80, 20 and 5 μm pore size) followed by UF (membrane Carbosep M2, 15 kDa MWCO) or NF (membrane Kerasep NanoN01A, 1 kDa MWCO). A suitable treatment for the fish meal effluents consisted of a MF pre-treatment followed by UF operating at 4 bar, 4 m/s, natural pH and ambient temperature. UF yielded an average permeation flux of 28 l/(m² h),¹ and 62% proteins rejection for a volume reduction factor of 2.3. Both membranes fully recovered their original permeabilities through an acidic/basic washing cycle. The economic assessment of proteins recovery from fish meal effluents by UF was accomplished for a production of 544 ton/yr of fish meal (66% protein content), yielding a net present worth of 160×10³ US$, interest rate of return of 17% and payback time of 8 years.     

Nanoencapsulation of date palm pit extract in whey protein particles generated via desolvation method

An alkaline solution of whey protein isolate was charged with absolute ethanol resulting in precipitation of whey protein particles. The vacuum-dried particles were then dispersed either in water or aqueous ethanol. Heat-treatment of whey proteins before desolvation process decreased the mean size of particles when dispersed in aqueous ethanol from 280 nm to 183 nm. The range and mean size of particles prepared from heat-treated protein solution when dispersed in water were 41–212 nm and 103 nm, respectively. Date palm pit aqueous extract was encapsulated inside the particulating heat-treated whey proteins during the desolvation stage with encapsulation efficiency of ~ 78%. Extract-loaded particles had mean size of 163 nm in alcoholic dispersion and 92 nm in water dispersion. Scanning electron microscopy imaging showed spherical nanoparticles aggregated in dry state. Fourier transform infrared spectroscopy suggested that extract and whey proteins did not covalently bind. Heat-treatment of whey proteins before desolvation resulted in the absence of denaturation endotherm in differential scanning calorimetry curve of extract-free particles. Extract loading in particles interrupted the continuity of protein matrix causing the occurrence of mild glass transition phenomenon in extract-loaded particles when heated.     

Influence of gas sparging on clarification of pineapple wine by microfiltration

A microfiltration process with a tubular ceramic membrane was applied for clarification of pineapple wine. The process was operated with the membrane pore size of 0.2 μm at transmembrane pressure of 2 bar and crossflow velocity of 2.0 m/s. The effects of gas sparging on permeate flux, fouling and quality of clarified wine were studied. It was found that a relatively low gas sparging rate could increase permeate flux up to 138%. Further increase of the gas sparging rate did not improve permeate flux compared with that without gas sparging. Gas sparging affected the density of cake layer. Increasing gas sparging rate led to an increase in specific cake resistance. It was observed that increasing gas sparging rate could reduce reversible fouling rather than irreversible fouling. The turbidity of pineapple wine was reduced and a clear product with bright yellow color was obtained after microfiltration. The negative effect of gas sparging which caused a loss of alcohol content in the wine was also observed.     

Effects of Particle Size,Applied Pressure and Pressing Time on the Yield of Oil Expressed from Almond Seed

An investigation of the effects of particle size, applied pressure and pressing time on the yield of oil expressed from almond seeds was undertaken. The oil was expressed mechanically using a mini laboratory oil press. The fixed processing parameters were: moisture content of 17% wet basis, heating temperature of 65 – 70°C and heating time of 15 min. The pressing pressures used were 60.6 kPa, 101.3 kPa and 116.6 kPa. Pressing times used were 2, 4, 8 and 12 min, and particle size of Φ < 0.5 mm (fine sample) and Φ > 0.5 mm (coarse sample) were used. The result shows that oil yield increased with increase in applied pressure and pressing time, however result obtained from fine and coarse sample sizes are similar. Pressing time and applied pressure had significant (p < 0.05) difference on oil yield; particle size had no significant (p > 0.05) difference on oil yield. Regression and correlation analysis gave a reasonable experimental prediction between oil yield and applied pressure with correlation coefficient r = 0.952 and also with pressing time with r = 0.7342. Higher oil yields were obtained from samples with fine particles size (Φ < 0.5 mm) and coarse particles size (Φ > 0.5 mm) samples pressed at 116.6 kPa pressure for 12 min. Maximum oil yields of 48.44% and 48.40% were obtained from coarse and fine samples respectively. The results obtained can be used in the design of a suitable process and machine for the expression of oil from almond seed.     

Suspension stability and size distribution of particles in reconstituted,commercial calcium caseinates

Four commercial calcium caseinates were reconstituted in water and various properties of the particles or aggregates were determined. Particle size distribution was determined with a Malvern Mastersizer. All the dispersions exhibited bimodal particle size distributions with modes at about 0.4 and 10 μm. The particle size distributions changed quite rapidly for the first 2 h after reconstitution and then changed more slowly for up to 6 h. The mode of the first peak did not change significantly during this time, but the mode of the second peak decreased. It appeared that the larger particles were either dissociating into smaller particles or dissolving with time. The sample with the lowest suspension stability had the largest particles. Sediment formed by centrifuging the dispersions at 700 g had a moisture content of about 77% and was slightly enriched in ash compared to the original dispersion. The density of the hydrated sediment was calculated from the sediment composition to be about 1073 kg m⁻³. This appears to be much higher than the density of the sedimenting particles as estimated from Stokes law.     

Effects of surfactants on the physical properties of capsicum oleoresin-loaded nanocapsules formulated through the emulsion–diffusion method

Capsicum oleoresin encapsulation by poly-ε-caprolactone (PCL) was investigated using the emulsification–diffusion method. Here, the emulsifier concentration affected the characteristics of both the nanoemulsion (NE) and nanocapsules (NCs). The process parameters were optimized by varying the Pluronic® F68 (PF68) concentration in the aqueous phase of the formulation. In this research, the optimal parameters of the preparation process were established, and the physical properties of NE and NC were compared. The size of the NC particles decreased according to an increase in the emulsifier concentration. NE showed insignificantly different particle sizes with mean diameters of 320–460 nm depending on the emulsifier concentration. On the contrary, the size of the NC particles prepared with 1.25% PF68 was 5.43 ± 0.29 μm, while the NC with 5% PF68 produced smaller particles (310 nm). The surfactant concentration also had an important effect on the encapsulation efficiency and release properties of the NCs while maintaining the loading capacity of the capsicum oleoresin.     

Vibration-induced particle formation during yogurt fermentation — Industrial vibration measurements and development of an experimental setup

The aim of the study was to investigate the effects of vibrations during yogurt fermentation. Machinery such as pumps and switching valves generate vibrations that may disturb the gelation by inducing large particles. Oscillation measurements on an industrial yogurt production line showed that oscillations are transferred from pumps right up to the fermentation tanks. An experimental setup (20 L) was developed to study the effect of vibrations systematically. The fermenters were decoupled with air springs to enable reference fermentations under idle conditions. A vibration exciter was used to stimulate the fermenters. Frequency sweeps (25–1005 Hz, periodic time 10 s) for 20 min from pH 5.4 induced large particles. The number of visible particles was significantly increased from 35 ± 4 (reference) to 89 ± 9 particles per 100 g yogurt. Rheological parameters of the stirred yogurt samples were not influenced by vibrations.     

Controlling moisture transport in a cereal porous product by modification of structural or formulation parameters

Equilibrium and dynamic water sorption properties of sponge cakes with varying porosity (86–52%) and fat content (0–0.30 g/g d.b.) were determined using a water vapour sorption microbalance. Contrary to porosity, addition of fat decreased equilibrium moisture contents. The effective moisture diffusivity (D_eff) was identified from a numerical solution of Fick’s second law, taking into account an external mass transfer coefficient and the swelling of the solid matrix. D_eff increased from 1.61 to 8.67 × 10⁻¹⁰ m²/s with moisture content, reached a threshold at moisture content 0.15 g/g d.b. and then decreased until water saturation. D_eff decreased from 8.67 to 2.97 × 10⁻¹⁰ m²/s with decreasing porosity. This effect was attributed to a change of water diffusion mechanism, from predominant vapour to liquid. D_eff decreased from 8.67 to 2.12 × 10⁻¹⁰ m²/s with increasing fat content. Addition of fat had an effect on the water diffusion in two ways, decreasing porosity (sagging of the foam) and increasing tortuosity.     

Prebiotic potential of barley derived β-glucan at low intake levels: A randomised,double-blinded,placebo-controlled clinical study

This randomised, double-blinded, placebo-controlled clinical study aimed to evaluate the in vivo prebiotic potential of barley β-glucan. Fifty-two healthy volunteers aged 39–70 years were randomly assigned to consume daily a cake containing 0.75 g of barley β-glucan or a placebo for 30 d. Stool samples were collected before, during and 2 weeks after the intervention for bacterial enumeration. Gastrointestinal side effects were recorded during the treatment period. In older subjects (?50 years old), barley β-glucan induced a strong bifidogenic effect and an increase of bifidobacteria into traceable range in cases of no detectable baseline levels. A concurrent significant increase in bacteroides was also observed in this age group. Ingestion of the experimental food resulted in no undesirable gastrointestinal side effects in older subjects. We concluded that the daily intake of a cake containing barley β-glucan is well-tolerated and demonstrated significant bifidogenic properties in older healthy volunteers consuming their usual diets.     

Effect of Substitution of Melon with Soybean on the Nutrient Content and Sensory Properties of Traditional Cakes

Traditional cakes were prepared from a blend of melon and soybean meal. The blended meal contained 10% and 20% soybean respectively while unblended meal contained 100% melon meal which served as control. Cakes obtained from the blends were analysed for proximate composition, amino acid content and organoleptic properties. The moisture content and protein content of the cakes increased significantly (p < 0.05) as the level of soybean inclusion was increased while the fat, ash and crude fibre contents of the cakes decreased significantly (p < 0.05) as the level of soybean inclusion was increased. Inclusion of as little as 10% soybean increased the quantity of amino acids in the cake than the control cake. The organoleptic properties of the cakes were also acceptable at 10% level of soybean inclusion.     

Use of applied air pressure to improve the baking properties of whey protein isolates in angel food cakes

Whey protein isolate (WPI) possesses limited application in angel food cake baking compared to liquid egg white (LEW). This study was conducted to determine whether applying air pressure in the oven during baking would improve the baking properties of WPI in angel food cakes. A special oven was designed for baking at oven air pressures up to 1.5 bar. Control angel food cakes were formulated with LEW (100/0) as its protein source and WPI-containing cakes were formulated with a mixture of 75 mL/100 mL LEW and 25 mL/100 mL WPI solution (75/25) or a mixture of 50 mL/100 mL LEW and 50 mL/100 mL WPI solution (50/50). Cakes were baked at atmospheric air pressure (AP) and at constant applied air pressure (CAP) or variable applied air pressure vs. baking time (VAP) to prevent overexpansion and collapse of WPI-containing cake batter. Cakes 75/25 and 50/50 baked at VAP exhibited improved physical, textural and sensory properties compared to those baked at AP or CAP conditions. Cakes 75/25 baked at VAP compared well with control angel food cakes baked at AP. Although 50/50 cakes baked at VAP were improved slightly over those baked at AP, none of them exhibited satisfactory properties. Therefore, additional research is needed to optimize baking conditions for cakes formulated with less than 75 mL/100 mL LEW.     

Physical stability of emulsion encapsulated in alginate microgel particles by the impinging aerosol technique

Emulsion filled alginate microgel particles can be applied as carrier systems for lipophilic actives in pharmaceutical and food formulations. In this study, the effects of oil concentration, emulsifier type and oil droplet size on the physical stability of emulsions encapsulated in calcium alginate microgel particles (20–80 μm) produced by a continuous impinging aerosol technique were studied. Oil emulsions emulsified by using either sodium caseinate (SCN) or Tween 80 were encapsulated at different oil concentrations (32.55, 66.66 and 76.68% w/w of total solids content). The emulsions were analysed before and after encapsulation for changes in emulsion size distribution during storage, and compared to unencapsulated emulsions. The size distribution of encapsulated fine emulsion (mean size ~ 0.20 μm) shifted to a larger size distribution range during encapsulation possibly due to the contraction effect of the microgel particles. Coarse emulsion droplets (mean size ~ 18 μm) underwent a size reduction during encapsulation due to the shearing effect of the atomizing nozzle. However, no further size changes in the encapsulated emulsion were detected over four weeks. The type of emulsifier used and emulsion concentration did not significantly affect the emulsion stability. The results suggest that the rigid gel matrix is an effective method for stabilising lipid emulsions and can be used as a carrier for functional ingredients.     

Effect of Pre-Treatments on Mechanical Oil Expression from Dika Kernels

The effect of pre-treatments on mechanical oil expression from dika kernels was investigated in this study. The parameters considered were particle sizes (fine and coarse), moisture content (4, 6, and 8%), heating temperature (30, 40, and 50°C), heating time (15, 35 and 45 min) and applied pressure (5, 10 and 15 MPa). The results showed that the oil point pressure of dika kernels reduced with increase in heating temperature and time and moisture content. The highest oil point pressure for coarse particles was recorded at 2.11 MPa; whereas oil point pressure for fine particles was below 1 MPa. The lowest pressure at which oil began to flow was 0.41 MPa (at 50°C and 8.3% MC) while the highest was 0.65 MPa (at 30°C and 4.2% MC). The optimal oil point pressure ranged from 0.55 to 0.65 MPa for fine particles and 1.51 to 2.11 MPa for coarse particles. The least oil yield was at 4% moisture content at 5 Mpa for coarse particles; whereas the highest yield was obtained at 4% moisture content at 15 MPa for fine particles. For coarse particles, resistance to oil flow decreased significantly with increase in moisture content, heating temperature and heating time. The optimal oil expression occurred at pressure range of 0.55 to 0.65 MPa for fine particles and 1.51 to 2.11 MPa for coarse particles. Dika kernel has a high oil content, which makes it valuable for oil production. An understanding of the response of oil yield to various pre-treatments will provide valuable information for the optimization of dika oil expression.     

Dietary fiber,fructooligosaccharides, and physicochemical properties of homogenized aqueous suspensions of yacon (Smallanthus sonchifolius)

Yacon roots are a promising source of inulin­type fructans (35 g/100 g dry matter) with a total amount of dietary fiber of about 45 g/100 g dry matter. The polydispersity of the particle size distribution of yacon aqueous suspension was reduced with increasing the degree of homogenization due to two phenomena: aggregation of particles, and disruption of large particles. Non­homogenized yacon suspensions exhibited large cell clusters that were disrupted into small cell clusters, single cells, and aggregates. The most concentrated suspension exhibited mainly aggregates.The volume fraction of the suspensions decreased significantly with increasing the degree of homogenization. This was attributed to a denser packing of small particles and aggregates in between large particles thus allowing the water within the structure to be released.Yacon suspensions exhibited high elastic modulus (750 Pa) at low water insoluble solids content (0.9% WIS). Additional results suggested that inulin­type fructans contributed to the elastic properties of yacon suspensions.The yacon suspensions studied in this work can be considered as semi­concentrated suspensions, i.e. the plot elastic modulus of the suspensions versus concentration exhibited a region immediately after the transition region. Particle interactions seem to be of great importance in this region in the particular case of yacon suspension since the elastic modulus (G′) reached 750 Pa at low water insoluble solids content (< 1%).     

Destructuration mechanisms of bread enriched with fibers during mastication

Three breads of different densities and salt contents were chewed by 16 healthy subjects, with controlled physiological characteristics, for three different stages of mastication until swallowing. The distribution of chewed bread particle size was determined by imaging of the boluses at each stage, for the 3 breads and all subjects. Bread piece was reduced into an increasing number of small particles with a median size, function of mastication time, taking an average value of 1.9 mm at swallowing. Bolus moisture content could be predicted from theoretical salivary flow and particle median size. Bolus consistency was derived from the apparent viscosity measured by capillary rheometry. It decreased with chewing time, and this decrease was linked to bolus moisture by a plasticization coefficient, which varied with the individual (12 < α < 30). A basic model involving hydration and fragmentation could be suggested to predict bread destructuration, defined by the ratio of consistency of the bolus on that of initial bread.     

Ultrasound-assisted encapsulation of annatto seed oil: Retention and release of a bioactive compound with functional activities

This paper brings forward the encapsulation of annatto seed oil (rich in geranylgeraniol) assisted by high intensity ultrasound using gum Arabic (GA) as stabilizing agent. We studied the effects of time (min) and ultrasonication power (W) over the emulsion characteristics. After forming microparticles from the best emulsion using freeze-drying (FD) and spray-drying (SD) techniques, we evaluated particle size distribution, moisture, water activity, surface oil, entrapment efficiency, encapsulation efficiency, geranylgeraniol retention, oxidative stability and kinetic release of geranylgeraniol, a biocompound with functional activities. The combined intensification of time and ultrasonication power reduced the superficial mean diameter (D₃₂) and polydispersity (PDI) of emulsions. Drying the continuous phase of the optimized emulsion (smallest D₃₂ = 0.69 ± 0.03 μm) using FD and SD formed microparticles with different morphological characteristics, Brouckere diameter (D₄₃), particle size distribution, moisture and water activity. SD process led to microparticles with the highest oil encapsulation efficiency (85.1 ± 0.1 wt.%) as a consequence of their lowest surface oil (SO). However, GA-FD microparticles presented the highest oil entrapment efficiency (97 ± 1 wt.%). Geranylgeraniol retention (80–86 wt.%) was similar for both drying techniques. GA-FD microparticles were more stable against oxidation through accelerated test Rancimat, even though presenting higher SO. This behavior is associated with the likely phase transition on the GA-SD matrix. The difference on the kinetic release of geranylgeraniol is linked to the difference on the particles morphology and particle size distribution.