There is a growing interest in using fibrils from food grade protein, e.g. beta-lactoglobulin, as functional ingredients. In the present study, the functionality of fibrillar beta-lactoglobulin from whey protein isolate (WPI) was compared to native WPI in terms of interfacial dilatational rheology and emulsifying activity at acidic conditions (pH 2.0 and 3.0). We report here for the first time data on microencapsulation of fish oil by spray-drying as well as oxidative stability of the oil in emulsions and microcapsules in dependence of WPI conformation. WPI fibrils exerted a significantly higher elasticity at the oil water (o/w) interface and a better emulsifying activity at a fixed oil content compared to native WPI. Microencapsulation efficiency was also higher with fibrillar WPI (> 95%) compared to native WPI (similar to 90%) at pH 2.0 and a total oil and protein content of 40% and 2.2%, respectively, in the final powder. The oxidative deterioration was lower in emulsions and microcapsules prepared with fibrillar than with native WPI. This was attributed to improved interfacial barrier properties provided by fibrils and antioxidative effects of coexisting unconverted monomers, particularly hydrophilic peptides. (C) 2014 Elsevier Ltd. All rights reserved.

The aim of this study was to characterize the process of atomization and drying of layer-by-layer emulsions containing lecithin (single layer emulsion) and lecithin/chitosan (bilayer emulsion) and the oxidative stability of the microcapsules during storage. For this purpose, the analysis of the emulsion spray droplet size during two-fluid nozzle and rotary atomization was carried out to identify suitable process parameters. The drying behaviour of single and bilayer emulsions was investigated by calculation of the volume flow density during single-droplet drying during acoustic levitation. In spray-dried solid particles, the oxidative stability in the single layer microcapsules was higher than in the bilayer microcapsules. This was partly attributed to lower microencapsulation efficiency in the bilayer microcapsules compared to the single layer microcapsules. Furthermore, it could be shown, that excess chitosan in the bulk carrier matrix affects the free volume elements and thus oxygen diffusion.

Aim of the present study was to investigate the impact of atomization and drying on the functionality of emulsions with a bilayered oil–water interface consisting of a globular protein (β-lactoglobulin, bLG) and anionic polysaccharides (pectins with varying degree of methoxylation). With regard to the atomization process, the emulsion spray droplet size generally decreased with increasing atomization energy. The spray droplet size distribution was narrower with rotary atomization compared to two-fluid nozzle atomization. The single droplet drying behaviour of the differently stabilized emulsions was similar as examined by acoustic levitation. With more than 95%, microencapsulation efficiency was high in all spray-dried particles. However, a shift in oil droplet size upon reconstitution indicated that oil droplet coalescence occurred within the process which was less pronounced in bilayer emulsions compared to the bLG-stabilised single layer emulsion. Data from interfacial viscoelasticity measurements showed distinct differences, which may explain oil droplet coalescence. The oxidative stability of encapsulated oil was influenced by both the physical state of the emulsions and the different constituents at the o/w-interface with bLG and low methoxylated pectin giving the best protection of the oil.

During microencapsulation of sensitive (food) ingre dients by spray drying, one important step is the s pray drying process itself, which affects the emulsion droplet size distribution, the emulsion stability with rega rd to the oil droplet size as well as the structural integrity of the interface. The latter has a strong impact on t he encapsulation efficiency and the physical stability of reconstitu ted emulsions. By interfacial engineering the barri er properties and the packing density at the oil/water (o/w) inte rface can be modified. The interface can be enginee red by e.g. layer-by-layer-technology that involves sequential layering of polymers at the o/w-interface of an emu lsion via electrostatic interactions. By that means so-called multilayer emulsions can be obtained. Studies on t he characterization of these multilayer emulsions in relatio n t the spray drying process, especially with resp ect to the type of atomization and the drying behavior are lacking a d literature on the oxidative stability of spraydried multilayer emulsions is scarce. Scope Aim of the present study was to investigate the imp act of atomization and drying on the functionality of emulsions with a modified o/w interface consisting of b eta-lactoglobulin and pectins with varying degree o f methylation. Experimental Approach Beta-lactoglobulin and pectin (low and high methyla ted) were used for preparation of single and multil ayeremulsions containing fish oil. Electrostatic intera ctions were analyzed via zeta potential measurement s. Elasticity of emulsion interfaces was analyzed by droplet shap e analysis. The single droplet drying behavior was characterized by acoustic levitation. Spray droplet and oil droplet size distribution were measured by laser di ff action after two-fluid-nozzle and rotary atomization at differen t energy inputs. Spray drying was carried out at 18 0/70 °C inlet/outlet temperature. The morphology of the par ticles was analyzed by scanning electron microscopy . The oxidative stability of the fish oil was monitored v ia hydroperoxide and propanal content. Major results The single droplet drying behavior of the different ly stabilized emulsions was similar as examined by levitation. With regard to the atomization process, the emulsio n pray droplet size generally decreased with incre asing energy input to the atomizer. In two-fluid nozzle ato mization but not in rotary atomization, the spray d roplet size distribution was markedly influenced by the differe nc s in emulsion viscosity. The spray droplet size distribution was narrower with rotary atomization compared with two-fluid nozzle atomization. The oil droplet size of the emulsions was only slightly affected by the differe nt nergy inputs during atomization. However, in th e reconstituted state, the oil droplet size was higher than i n the original emulsions, which can be attributed t o coalescence. The oxidative stability of the oil was influenced b y oth the physical state of the emulsions and the diff rent constituents at the o/w-interface. For instance, in th e liquid state the oxidative stability was higher i n the original emulsions when compared to the reconstituted emulsi ons. Furthermore, the oxidative stability was affec ted by the type of pectin and thus the intensity of the oi l droplet charge. It can be assumed that in liquid an spray-dried emulsions, not only the particle charge but also th e constitution of the interface itself influences t he oxidative stability of encapsulated oil. * Corresponding author: yvonne.serfert@tu-berlin.de

The aim of the present study was to describe the fundamental physical characteristics of spray-dried carrier matrices based on sodium caseinate and casein hydrolyzate and microcapsules as well as their impact on the stability of a microencapsulated functional ingredient. Spray-dried carrier matrix was characterized by different physical methods (helium pycnometry, nitrogen displacement for surface area analysis, X-ray photoelectron spectroscopy, positron annihilation lifetime spectroscopy). Surface viscoelasticity of protein-stabilized oil–water interfaces was analyzed using dynamic pendant drop tensiometry. Fish oil was microencapsulated and microencapsulation efficiency as well as oxidative stability over time was monitored.Surface accumulation of proteins at the air–water interface led to a modified surface composition of spray-dried carrier matrix particles for microencapsulation. However, interfacial elasticity was markedly altered when using hydrolyzed casein as emulsifier, which is related to a decrease in microencapsulation efficiency. Lipid oxidation during storage of the microencapsulated oil increased with the protein content in the formulation. Excess protein led to an increase in free volume elements and is suspected to negatively affect oxygen diffusion.

Aim of the present study was to investigate the imp act of atomization and drying on the functionality of emulsions with an oil/water-interface (o/w-interface) c onsisting of beta-lactoglobulin (single layer emuls ion) and sequentially adsorbed pectins with varying degree of methylation at pH<pI (bilayer emulsions). Thus, the emulsion systems were characterized with respect to their be havior during atomization, their drying behavior in single droplet experiments and the oxidative stability of the dispersed phase (fish oil) during storage of li quid and spray-dried single and bilayer emulsions. The o/w-interface of the emulsions was predominantl y elastic, although the elasticity was higher in si gle layer emulsions compared to bilayer emulsions. The drying behavior of the different emulsions duri ng levitation of single droplets was similar. Regarding the atomization process, the emulsion spray droplet siz generally decreased with increasing energy input irrespective of the type of atomizer. With rotary atomization, the spray droplet size distribution of the different emulsion s was similar. The oxidative stability of the oil w as influenced by both the physical state of the emulsions and the diff rent constituents at the o/w-interface. In th e liquid state, the oxidative stability was higher in the original emulsions when compared to the reconstituted emulsi ons. The differences in oxidative stability in the spray-dri ed emulsions can partly be attributed to the microe ncapsulation efficiency, but also the physical characteristics o f the o/w-interface, which needs to be investigated in more detail.

At the request of the Managing Editor the following paper has been retracted: F. Pop. (2011). 'Chemical stabilization of oils rich in long-chain polyunsaturated fatty acids during storage', Food Science and Technology International 17: 111-117, DOI: 10.1177/1082013210368738.

Aim of the present study was to characterize the pr ocess of atomization and drying of layer-by-layer emulsions containing lecithin (single layer emulsio n) and lecithin/chitosan (multilayer emulsion) and the oxidative stability of the spray-dried emulsions du ring storage. For this purpose, the analysis of the emulsion spray droplet size during atomization by two differ ent atomization devices, i.e. two-fluid nozzle and rotary atomizer, was carried out to identify suitable proc ess parameters. The drying behaviour of single laye r nd multilayer emulsions was investigated by single-dro p drying via calculation of the mass transfer durin g acoustic levitation. In spray-dried emulsions, the oxidative stability in the single layer emulsions w as higher than in the multilayer emulsion. This was partly a ttributed to a lower microencapsulation efficiency in the spray-dried multilayer emulsion compared to the spr ay-dried single layer emulsion. Furthermore, it cou ld be shown, that excess chitosan in the bulk carrier mat rix ffects the free volume elements and thus oxyge n diffusion.

Accumulation of surface-active compounds may significantly alter the surface composition of food powders compared to the bulk composition of the product and therefore affects the functional properties. Through modification of a commercial contact angle meter surface accumulation of milk proteins and protein hydrolysates could be analysed via surface tension measurements in a time interval relevant for atomisation of emulsions during microencapsulation. The different caseins showed a slower surface occupation compared to industrially processed sodium caseinate and casein hydrolysate with β-casein being more surface-active than α- and κ-casein. In a similar manner, β-lactoglobulin showed a lower surface activity than whey protein isolate and whey protein hydrolysate. It is concluded that molecular weight profile plays an important role for the surface activity of milk proteins, but other factors like surface hydrophobicity, number of ionisable groups and state of aggregation also need to be considered.

The aim of the present study was to evaluate the suitability of defined odour attributes for the sensory evaluation of bulk fish oil and reconstituted microencapsulated fish oil as well as the active modification of the sensory profile during storage. Common attributes previously described for bulk fish oil (fishy, metallic, pungent, green notes) proved to be suitable for the sensory evaluation of reconstituted microencapsulated fish oil. Additional attributes were identified in dependence on the bulk fish oil processing (sweet/biscuit-like) and of constituents of the microcapsule carrier matrix (seasoning-like). Reconstituted sodium caseinate-based microcapsules exhibited a lower fishy odour during storage than did n-octenylsuccinate-derivatised starch-based microcapsules, probably due to the oxidative status. Flavour binding of caseinate may be of minor importance in reconstituted microencapsulated fish oil. Improvement of the sensory profile was achieved by the addition of an odour-masking compound (β-cyclodextrin) or flavouring (vanillin and apple flavour).

Fish oil was encapsulated by spray-drying into different matrices based on n-octenylsuccinate-derivatised starch (nOSA starch) and carbohydrate blends varying in dextrose equivalent and molecular weight profile. Based on the development of the hydroperoxide and propanal content upon storage significant differences in the stability of the microencapsulated oil were observed. With 40 mmol/kg oil the hydroperoxide content after eight weeks of storage at 20 °C and 33% relative humidity was lowest in fish oil encapsulated in a matrix containing nOSA starch and maltose. In contrast, the lowest stability was observed in fish oil encapsulated in a matrix based on nOSA starch and maltodextrin with a dextrose equivalent of 18. Physical characteristics like viscosity of the feed emulsion and oil droplet size, which influence drying behaviour as well as particle characteristics like particle size, density or surface area did not differ and thus cannot explain the differences in the rate of autoxidation. Positron annihilation lifetime spectroscopy clearly showed distinct differences in the ortho-positronium lifetime, and thus in the size of free volume elements between the carrier matrices. It is suggested that as a consequence, the matrices differed in oxygen diffusivity, which must be considered to be a key determinant in autoxidation of fish oil encapsulated in glassy carbohydrate matrices.

The aim of this study was to systematically investigate the impact of chemical stabilisation on the autoxidation of microencapsulated oils rich in long-chain polyunsaturated fatty acids. During the microencapsulation process, the fish oil undergoes multiple changes of its physical properties: bulk oil, dispersed oil in aqueous phase, and dispersed oil in dry matrix. Autoxidation already occurred in the first stages of the microencapsulation process itself during emulsification and spray-drying. An efficient stabilisation was achieved using a ternary combination of lipophilic antioxidants, synergistic compounds and a trace metal chelator, e.g. a combination of tocopherols, rich in the δ-derivative and low in the α-derivative, with ascorbyl palmitate and lecithin. Trace metal chelation by, e.g. Citrem or lecithin in combination with ascorbyl palmitate proved to be of particular importance in the emulsion, but not during the storage of the microencapsulated oil. In the microencapsulated oil, the addition of rosemary extract rich in carnosic acid to ternary blends of tocopherols, ascorbyl palmitate and lecithin or Citrem significantly retarded autoxidation.

The aim of the present study was to investigate the possible impact of the antioxidative activity and the altered technological properties of glycated caseinate on the oxidative stability of microencapsulated fish oil. Glucose, glucose syrup or dextrans were used for glycation of caseinate and the resulting blends were intensively characterised prior to their use for microencapsulation. After microencapsulation, hydroperoxide and propanal content of the encapsulated fish oil was monitored over a period of up to eight weeks.Heating in aqueous solution, but not dry heating, led to an increase in redox-active compounds in the caseinate–glucose syrup-based carrier matrix and in an increase in oxidative stability of the encapsulated oil. In contrast, microencapsulation in a dry-heated caseinate–glucose blend did not increase oxidative stability compared to the unheated carrier system although the content of redox-active Maillard reaction compounds was increased. Oil droplet size did not significantly change when using glycated caseinate and thus, neither an antioxidative effect of Maillard reaction products nor an improved emulsifying activity is responsible for the increase in oxidative stability. Results of the present study rather indicate that the molecular weight profile of the carrier matrix is one of the key determinants for the oxidative stability of the encapsulated oils.

ABSTRACT: The influence of high‐pressure treatment on the 3 main folate species present in orange juice was assessed under conditions similar to those used in high‐pressure pasteurization and sterilization using freshly squeezed orange juice and different model orange juices. The latter were used also to determine the influence of matrix components, pH, and excess ascorbic acid. Excess ascorbate strongly protected folates against pressure and heat. Pressurization at 600 MPa and 80°C affected model juice folates synergistically, and pressure increased the formation of 5,10‐methenylfolate. In fresh orange juice, components other than ascorbate additionally stabilized folates, thus pressure preservation and pressure sterilization appeared very feasible.