Influence of antioxidant location on the protection of oil encapsulated in powder

Encapsulation of Poly Unsaturated Fatty Acids (PUFAs) in solid matrix, by providing a physical barrier, is used to prevent or delay their degradation; and the use of antioxidant is expected to enhance PUFAs oxidative stability. In liquid emulsions, the effectiveness of antioxidants is known to depend on their distribution between the oil and aqueous phase. In this study, the impact of the lipophilic or hydrophilic character of phenolic antioxidants on the oxidative stability of encapsulated PUFAs was investigated following the evolution of conjugated dienes and antioxidant residual content during accelerated ageing test (50\ub0C, 60% RH). Dry emulsions containing 10%wt stripped sunflower oil (60% PUFAs), 89.7%wt maltodextrin DE12 (wall material) and 0.3%wt Tween\uae20 (surfactant) were produced by spray drying. Some were enriched with alpha-tocopherol (lipophilic - 500 ppm in oil) or chlorogenic acid (hydrophilic, 1000 ppm in maltodextrin), two scavengers of lipid radicals implied in oxidation.Antioxidants improved the oxidative stability of encapsulated oil. With chlorogenic acid, oil oxidation occurred after a two days lag phase whilst for alpha-tocopherol, no lag phase was observed but the oxidation rate was smaller than in control and chlorogenic acid powders during the ten first days of ageing (Fig, 1a). The residual concentration of chlorogenic acid deceased rapidly during the first two days and then remained constant whilst the concentration of alphatocopherol decreased regularly ensuring oil protection until it has been totally consumed after ten days (Fig.1b). The better oil protection provided by alpha-tocopherol during the first ten days of storage was attributed to the different location of both antioxidants within the macro-domains of the dry emulsion. Alpha-tocopherol, in oil droplets, was directly in contact with the oil to protect whilst for chlorogenic acid, entrapped in the solid matrix, only the fraction in contact with the oil droplets brought protection and 60% of initial chlorogenic acid remained preserved in the matrix

Milk powder agglomerate growth and properties in fluidized bed agglomeration

[EN] Fluidized bed agglomeration is used to produce large and porous dry agglomerates with improved instant properties. Water (or binder solution) is sprayed in the fluidized bed of particles to render their surface sticky. The agglomerate growth results from the repetition of different steps (wetting of the particle surface, particles collision and bridging, and drying) and depends on the processing conditions and product properties. In this work, skim and whole milk powders were fluidized in hot air and agglomerated by spraying water in a bench-scale batch fluidized bed. The aim was to study the impact of the sprayed water flow rate (0 5.5 g.min−1), particle load (300 400 g), initial particle size (200 350 ìm), and composition (skim whole milk) on the growth mechanisms and on the properties of the agglomerates obtained. Powder samples were regularly taken in the fluidized bed during agglomeration and characterized for the size, size distribution, and water content. Whatever the conditions tested, the size increase and the evolution of the particle size distribution during agglomeration were found to mainly depend on the relative amount of water sprayed in the particle bed. Agglomeration occurred in two stages, with first the rapid association of initial particles into intermediate structures, and second, the progressive growth of porous agglomerates. In any case, agglomeration allowed improving instant properties of the milk powder.Barkouti, A.; Turchiuli, C.; Carcel Carrión, JA.; Dumoulin, E. (2013). Milk powder agglomerate growth and properties in fluidized bed agglomeration. Dairy Science and Technology. 93(4-5):523-535. doi:10.1007/s13594-013-0132-7S523535934-5Banjac M, Stakic M, Voronjec D (1998) Kinetics of agglomeration of milk powder in a vibro-fluidized bed. Proc. 11th International Drying Symposium (IDS'98), B: 998–1005.Banjac M, Stamenić M, Lečić M, Stakić M (2009) Size distribution of agglomerates of milk powder in wet granulation process in a vibro-fluidized bed. Brazilian J Chem Eng 26:515–525Dewettinck K, Deroo L, Messens W, Huyghebaert A (1998) Agglomeration tendency during top-spray fluidized bed coating with gums. Lebensm Wiss Technol 31:576–584Forny L, Marabi A, Palzer S (2011) Wetting, disintegration and dissolution of agglomerated water soluble powders. Powder Technol 206:72–78Fries L, Dosta M, Antonyuk S, Heinrich S, Palzer S (2010) Moisture distribution in fluidized beds with liquid injection. Proc. 17th International Drying Symposium (IDS 2010), Magdeburg, Germany.Heinrich S, Blumschein J, Henneberg M, Ihlow M, Mörl L (2003) Study of dynamic multidimensional temperature and concentration distributions in liquid-sprayed fluidized beds. Chem Eng Sci 58:5135–5160Jimenez T (2007) Agglomération de particules par voie humide en lit fluidisé [Wet fluidized bed agglomeration of particles]. PhD, ENSIA, Massy, France.Jimenez T, Turchiuli C, Dumoulin E (2006) Particles agglomeration in a conical fluidized bed in relation with air temperature profiles. Chem Eng Sci 61:5954–5961Kim EH-J, Dong Chen X, Pearce D (2009) Surface composition of industrial spray-dried milk powder. J Food Eng 94:169–181Koga S, Kobayashi T, Inoue I (1989) Drying and agglomeration of skim milk powder by a vibro-fluidized bed, heat transfer. Japan Res 18:1–8Maronga SJ, Wnukowski P (1997) Establishing temperature and humidity profiles in fluidized bed particulate coating. Powder Technol 94:181–185Maronga SJ, Wnukowski P (1998) The use of humidity and temperature profiles in optimizing the size of fluidized bed in a coating process. Chem Eng Sci 37:423–432Murrieta-Pazos I, Gaiani C, Galet L, Cuq B, Desobry S, Scher J (2011) Comparative study of particle structure evolution during water sorption: skim and whole milk powders. Coll and Surf B Biointerfaces 87:1–10Neff E, Morris HAL (1968) Agglomeration of milk powder and its influence on reconstitution properties. J Dairy Sci 51:330–338Niskanen T, Yliruusi J, Niskanen M, Kontro O (1990) Granulation of potassium chloride in instrumented fluidized bed granulator—part I: effect of flow rate. Acta Pharm Fenn 99:13–22Palzer S (2011) Agglomeration of pharmaceutical, detergent, chemical and food powders—similarities and differences of materials and processes. Powder Technol 206:2–17Saad MM, Barkouti A, Rondet E, Ruiz T, Cuq B (2011) Study of agglomeration mechanisms of food powders: application to durum wheat semolina. Powder Technol 208:399–408Turchiuli C, Smail R, Dumoulin E (2012) Fluidized bed agglomeration of skim milk powder: analysis of sampling for the follow-up of agglomerate growth. Powder Technol 238:161–168Vuataz G (2002) The phase diagram of milk: a new tool for optimizing the drying process. Lait 82:485–500Waldie B, Wilkinson D, Zachra L (1987) Kinetics and mechanisms of growth in batch and continuous fluidized bed granulation. Chem Eng Sci 42:653–66

European Drying Conference -EuroDrying

Abstract: Fluidized bed agglomeration of skim milk powder by spraying water was used to produce dry agglomerates with improved instant properties. The growth of agglomerates was studied following the evolution of the particle size distribution during agglomeration under different conditions of processing. During the first minutes, initial particles (180µm) associated to form two size populations (250 and 400 µm). The smallest one disappeared quickly while the largest one increased in size until 650-700 µm at the end of experiment (30-40 min). The tested conditions corresponding to a lower final particle moisture content (6.8-7.0 % d.b.) generated the smaller agglomerates (650-640 µm)

Development and characterization of phytosterol-enriched oil microcapsules for foodstuff application

Phytosterols are lipophilic compounds contained in plants and have several biological activities. The use of phytosterols in food fortification is hampered due to their high melting temperature, chalky taste, and low solubility in an aqueous system. Also, phytosterols are easily oxidized and are poorly absorbed by the human body. Formulation engineering coupled with microencapsulation could be used to overcome these problems. The aim of this study was to investigate the feasibility of encapsulating soybean oil enriched with phytosterols by spray-drying using ternary mixtures of health-promoting ingredients, whey protein isolate (WPI), inulin, and chitosan as carrier agents. The effect of different formulations and spray-drying conditions on the microencapsules properties, encapsulation efficiency, surface oil content, and oxidation stability were studied. It was found that spherical WPI-inulin-chitosan phytosterol-enriched soybean oil microcapsules with an average size below 50 μm could be produced with good encapsulation efficiency (85%), acceptable level of surface oil (11%), and water activity (0.2–0.4) that meet industrial requirements. However, the microcapsules showed very low oxidation stability with peroxide values reaching 101.7 meq O2/kg of oil just after production, and further investigations and optimization are required before any industrial application of this encapsulated system

Application of Pleurotus ostreatus β-glucans for oil–in–water emulsions encapsulation in powder

In this study, sunflower oil containing \u3b1-tocopherol (model for oxidizable lipophilic compounds) was encapsulated using a wall material made of maltodextrin and two different extracts rich in \u3b2-glucans and proteins, obtained from the basidiomycete Pleurotus ostreatus. A mixture of maltodextrin and acacia gum was used as control wall material. The aim was to assess P. ostreatus extracts as a sustainable and healthy alternative to common emulsifiers. After the evaluation of the emulsion stability, four powders were produced by spray drying and then analysed for the particle morphology and oil droplets distribution within the solid matrix (by scanning electron microscopy), the emulsion microstructure after their dissolution in water (by laser light diffraction) and the encapsulation efficiency (by solvent extraction of surface oil). In addition, powders were analysed in terms of oil protection against oxidation by spectroscopic determination of conjugated dienes and HPLC evaluation of vitamin E. Results showed that P. ostreatus extracts provided suitable emulsifying properties both in the liquid and in the spray dried emulsions. Moreover, it allowed excellent protection of vitamin E and polyunsaturated fatty acids against oxidation. Hence, P. ostreatus extracts can be exploited as innovative emulsifier to provide physical protection to functional, oxygen sensitive lipophilic ingredients by microencapsulation

Impact of Pleurotus ostreatus beta-glucans on oxidative stability of active compounds encapsulated in powders during storage and In vitro digestion

Polyunsaturated fatty acids and -tocopherol were encapsulated in powders by spray drying using maltodextrins DE 12 as wall material and different emulsifiers (Tween\uae20, acacia gum or beta-glucans-rich extracts from Pleurotus ostreatus). The aim was to study the effects of the surfactants on: (a) the oil droplet size distribution and alpha-tocopherol stability during in vitro digestion, and (b) the oxidative stability during 15 days of accelerated storage. Acacia gum sample had the most stable particle size distribution up to the gastric phase, but showed a significant alpha-tocopherol degradation prior to the intestinal stage. On the contrary, beta-glucan-samples displayed a bimodal distribution in the oral and gastric phases but retained alpha-tocopherol up to the beginning of the intestinal stage. At the end of intestinal stage, no alpha-tocopherol was found in the samples. The storage study showed that beta-glucans improved the oxidative stability of the powders, which displayed 82% alpha-tocopherol retention after 5 days under accelerated conditions (60 \ub0C), corresponding to 310 days at 20 \ub0C, while acacia gum and Tween\uae 20 did not delay alpha-tocopherol degradation. Results highlight the potential antioxidant activity of beta-glucans used as emulsifying agents during in vitro digestion and accelerated aging conditions

Experimental study of fluidized bed agglomeration of acerola powder

The aim of this work was to study the main effects of acerola powder on fluidized bed agglomeration. A 2(4-1) fractional factoring design was used to evaluate the main operating conditions (fluidizing air temperature, fluidizing air velocity, atomizing air flow and height of nozzle in the bed). The mechanical and physicochemical product changes were determined by analysis of particle diameter, moisture content, wetting time and bed porosity. The particle enlargement by agglomeration occurred when the relative humidity in the bed increased and, thus, the moisture of the product increased. However, the excessive increase in relative humidity resulted in a decrease in yield, caused by caking and product incrustation. The consolidation of small granules resulted in an increase in the instant properties, decreasing the wetting time and increasing the solubility in a short period of agitation

Changes in oil-in-water emulsion size distribution during the atomization step in spray-drying encapsulation

© 2015 Elsevier Ltd. All rights reserved. During atomization of emulsions, dispersed oil droplets are susceptible to breakup changing the emulsion size distribution, a critical parameter in encapsulation applications. We investigated the influence of the different atomization parameters on the size and size distribution of the sprayed emulsion and defined rules for the choice of conditions which will make it possible to maintain a specific emulsion size. Oil-in-water emulsions were prepared with different aqueous phase viscosity, oil fraction, and emulsion droplet size and sprayed with two different atomization systems: a two-fluid nozzle with external mixing and a rotary atomizer. For both systems, two different breakup regimes were identified: (1) monomodal and (2) bimodal distribution breakup; and a critical Capillary number was determined for each breakup regime. These findings can be used to predict oil droplet breakup and define the right atomization conditions and/or emulsion formulation for controlling sprayed emulsion structure in microencapsulation applications

Measurement of Agglomerates Shape Parameters with Threedimensional Reconstruction Based on a Laser Displacement Sensor

The agglomeration of particles is a process that modifies the physical properties of a product originally manufactured as a powder. During milk powder agglomeration of fluidized bed, resulting agglomerates are sufficiently porous to improve the solubility of the final product but, at the same time, their rigidity decreases and agglomerates can be destroyed during packing. The porosity and rigidity properties depend on both the volume and shape characteristics of the agglomerates. This paper presents a three-dimensional reconstruction technique based on a laser displacement sensor (LDS) applied to characterize milk agglomerates. This technique allows three-dimensional scanning to estimate particle volume and extract shape parameters such as: sphericity, elongation and flatness ratio, shape factor and aspect ratio. This technique was implemented using a mechatronic device with two degrees of freedom. The device is composed of an angular positioning system to rotate the agglomerate and a linear positioning system to displace the LDS. Experimental result allows agglomerates classification according to shape parameters