Dairy Foods IV: Dairy Ingredients

480 Formation of surface composition on spray-dried milk powder. M. Foerster1, T. Gengenbach2, M. W. Woo1, and C. Selo-mulya*1, 1Monash University, Clayton, VIC, Australia, 2CSIRO, Clayton, VIC, Australia.

Milk is often spray-dried for better preservation, easier handling, and a reduced bulk volume for transportation. An unwanted dominance of fat typically occurs on particle surface, leading to lower solubility, oxidative stability and increase stickiness. Here we used 2 convective drying methods, single droplet drying and spray drying, to understand the mechanisms of component segregation in drying milk droplets. Modified single droplet drying allowed tracking of surface composition at discrete drying times, in addition to changes in temperature, diameter and mass. The fat was observed to accumulate at the surface during droplet generation (surface covered by about 97% wt/wt fat as measured by x-ray photoelectron spectroscopy, for a bulk fat content of 44% wt/wt). The hydrophobic fat shell resulted in less droplet shrinkage and greater resistance to water evaporation compared with a protein-rich shell. Comparison of surface compositions of spray-dried milk particles and their atomized droplets indicated that the atomization stage strongly influenced final surface composition. For instance, milk emulsions with a dry matter bulk composition of 32, 24 and 44% wt/wt in lactose, protein and fat, respectively, resulted in atomized droplets featuring a surface composition with approximately 5, 12 and 83% wt/wt in lactose, protein and fat, which was relatively unchanged after drying (0, 11 and 89% wt/wt in lactose, protein and fat). When the emulsions were modified by addition of λ-carrageenan before spray drying, rheological analysis revealed that the presence of a dispersed fat phase significantly reduced the extensional viscosity (from 26 to 12 mPa·s for a fat content from 0.3 to 31% wt/wt in dry matter), which increased by stabilization with λ-carrageenan (31 mPa·s for 0.3% wt/wt carrageenan). Milk emulsions were least stable against disintegration along the oil/water interface of fat globules under extensional stress and hence preferably broke up during atomization, leading to the observed fat coverage as soon as individual droplets were formed. A numerical model incorporating drying and shrinkage kinetics confirmed that the initial surface composition after droplet generation is not induced by diffusive component segregation, but by the droplet generation process itself.

Key Words: surface fat, milk powder, spray drying

481 Influence of composition and microstructure on flow-ability and wetting behaviour of α-lactalbumin enriched whey protein ingredients. G. Barone*1, J. O’Regan2, and J. O’Mahony1, 1School of Food and Nutritional Sciences, University College Cork, Cork, Cork, Ireland, 2Nestlé R&D Center, Wyeth Nutritionals Ireland, Askeaton, Co.Limerick, Ireland.

α-Lactalbumin enriched ingredients are being used increasingly in the formulation of nutritional products (e.g., infant formulae). Technolo-gies used to produce such ingredients include selective precipitation, membrane filtration and ion exchange chromatography. The aim of this study was to determine the effects of differences in macro-chemical composition and microstructure of 3 commercially available a-lactalbumin-enriched whey protein ingredients (LAC 1, LAC 2 and LAC 3) on powder flowability and rehydration properties. The protein content was 78.8, 78.2, and 92.5% wt/wt for LAC 1, LAC 2 and LAC 3, respectively. The lipid content was higher in LAC 2 (9.32% wt/wt) than

in LAC 1 (0.84% wt/wt) or LAC 3 (0.40% wt/wt). The LAC 1 powder had the largest particles, with a D[4,3] of 159 µm and the lowest specific surface area (SSA); the particles in this powder were observed to have crater-like dents and vacuoles using scanning electron microscopy. The powder particles in LAC 3 were smaller, with a D[4,3] of 36.4 µm, had the highest SSA and were observed to have shell-like, partially fragmented particles. Particles of LAC 2 with a D[4,3] of 72.7 µm were more spherical with smooth surfaces and a SSA similar to LAC 1. The analysis demonstrates that the lipid content influenced powder flow properties, as LAC 2 was very cohesive, with a flow index (i) of 3.29, (where a low value indicates poor flowability). In contrast, LAC 1 and LAC 3 (both with lower fat content) were easy flowing and free flowing, with i values of 6.48 and 11.3, respectively. However, LAC 3 had poor rehydration properties, with contact angle (θ) > 89°, whereas LAC 1 and LAC 2 had similar θ of ~70°. This study clearly shows that flowability was influenced more strongly by composition than the microstructure or particle size of the powders, while the total protein content significantly influenced the rehydration properties of the powders.

Key Words: α-lactalbumin-enriched whey protein, flowability, wettability

482 Characterization of dairy mix powders with maltodextrin and inulin produced by spray drying. C. Raimundo da Silva1, R. Stephani2, E. Martins1, P. Schuck3, A. Fernandes de Carvalho*1, and Í. T. Perrone1, 1Federal University of Viçosa, Viçosa, MG, Brazil, 2Federal University of Juiz de ForaJuiz de Fora, MG Brazil, 3UMR STLO-INRA, Agrocampus-Ouest, Rennes, France.

Products made from the mixing of milk, whey and other food substances have been gaining space in the dairy market due to their nutritional characteristics, competitive price and capacity to supply specific neces-sities of some consumers. By contrast, dairy mixes containing high content of whey are subject to stickiness and caking during and after the drying process which is a drawback for the dairy industries. This work aimed to evaluate the use of drying aids (maltodextrin or inulin) on the physicochemical and techno-functional properties of dairy mixes with increasing concentrations of whey. Mixtures of whole milk and crystallized-lactose concentrated whey (50% of crystallization) were added of maltodextrin or inulin, and dried in a pilot single stage spray dryer. The dairy mixes were evaluated as to their centesimal composi-tions, powder particle agglomeration profiles, particle size during the hydration process, theoretical glass transition temperatures, objective color and the spectroscopic profile. Higher whey concentrations reduced the proportion of protein and fat in the mixes as well as reduced the mean hydrodynamic diameter of particles during the rehydration of powders in water. Otherwise, the increase in the whey concentration was accompanied by increasing of the carbohydrate concentration and the browning saturation index. Furthermore, the higher whey content promoted greater particle agglomeration during drying and induced changes in the Raman spectrum profile with respect to the spectral contribution of lactose. The addition of maltodextrin and inulin reduced the powder agglomeration and the browning of products. It was also observed that the drying aids increased both the average hydrodynamic diameter of particles during rehydration in water and the theoretical glass transition temperature. The addition of maltodextrin and inulin favorably contribute to the conservation and drying of powders; however, such

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addition increases the hydrodynamic particle size during rehydration, which can be an advantage in the technological point of view.

Key Words: spray drying, glass transition, size distribution of particles

483 Effect of milk protein composition on in vitro digestion of a model infant formula. N. R. Tari*1, E. Arranz1, and M. Corre-dig1,2, 1Department of Food Science, University of Guelph, Guelph, ON, Canada, 2Gay Lea Foods Research and Development, Guelph, ON, Canada.

Objective of this work was to study the effect of protein composition, and in particular, the presence of whey proteins (WP) or β-casein (β-cas), on the digestion behavior of a model infant formula. Three model formulas were prepared with the same concentration of protein, fat and lactose, as well as same caloric content. One formula contained only WP and 2 others contained a casein to WP ratio of 40:60, but dif-fering by 24% in β-cas amount. The formula was obtained by mixing milk protein isolates and permeates prepared with a 80 KDa molecular weight cut-off membrane, and with addition of whey protein. An in vitro gastric digestion was performed to better understand the physico-chemical properties of the gastric curd, and it was then followed by an intestinal digestion for studying physiological responses. There were no differences in the properties of the gastric digestate, within a treatment, at both 60 or 120 min of digestion. All curds showed a shear-thinning behavior, with a significantly higher viscosity and a higher modulus for curds obtained from casein/WP formula, compared with the curds from WP formula. Electrophoretic analysis of digestate samples after the gastric stage showed caseins extensively hydrolysed to peptides, while β-lg and α-la still largely intact after 60 or 120 min of digestion. Confocal microscopy showed structures with a higher density through-out the matrix for digestates obtained from cas/WP formula, compared with the WP formula digestate. The effect of in vitro intestinal digestate on secretion of pro-inflammatory cytokines was also studied on LPS stimulated human macrophages treated with the basolateral fraction of Caco-2 cells. Cas/WP formulas resulted in lower TNF-α secretion than WP formula. Moreover, high β-cas digestate showed lower secretion of IL-6, compared with WP and low β-cas formula. There was not a significant difference in secretion of IL-1β, between the 3 formulas. The results bring significant advances to our understanding of the effect of milk protein composition on the digestion of dairy matrices and physical properties of the gastric digestate, as well as their role on physiological responses.

Key Words: milk proteins, in vitro digestion, infant formula

484 Withdrawn

485 Hydrogenation of lactose for the production of nutri-tive sweeteners. S. Martínez-Monteagudo*, M. Enteshari, and L. Metzger, Dairy and Food Science Department, South Dakota State University, Brookings, SD.

Due to its chemical structure, low cost and large-scale production, lactose is a promising source for the production of nutritive sweeten-ers or sugar alcohols. Lactose is converted into lactitol through a set of chemical reactions known as catalytic hydrogenation. Although lactitol is the predominant product, there is a considerable formation of lactu-litol, lactobionic acid, sorbitol, and galactitol. These subproducts are

formed through a combination of isomerization, hydrolysis, oxidation, and hydrogenolysis. Reaction products are strongly dependent on the reaction conditions and catalyst type. This presentation will summarize our laboratory efforts and elsewhere in understanding reaction kinetics of catalytic hydrogenation of lactose. We studied the effects of temperature (90–150°C) and pressure (40–150 bar) on lactitol selectivity using 5% Ru/C as a catalyst system. Experimentation utilized a laboratory scale high-pressure reactor with custom fabricated catalyst basket. Such con-figuration allows the catalytic hydrogenation of lactose to be controlled by intrinsic kinetics rather than diffusion and mass transfer. Preliminary data followed the Langmuir–Hinshelwood–Hougen–Watson kinetics under the assumption of surface reaction as rate-determining step. We have developed a mathematical model to describe the influence of tem-perature and pressure on the reaction rate based on the Arrhenius and Eyring theory. The activation energy for lactitol formation was 73.54 ± 6.71 kJ mol−1, while the activation volume was 57.25 ± 11.2 cm3 mol−1. Research in this area is not as advanced as enzymatic catalysis, and there are opportunities for further studies in the field of reaction optimization, detailed characterization of products and their properties, and system scale up.

Key Words: lactose hydrogenation, lactitol, kinetics

486 Enzyme-triggered microcapsules to selectively color Cheddar cheese and obtain white whey powder. R. Ravanfar* and A. Abbaspourrad, Cornell University, Ithaca, NY.

The yellow color of Cheddar cheese whey is due to the presence of annatto, which partitions into the whey during the Cheddar cheese making process. Currently, bleaching of the color using strong oxidiz-ing agents such as hydrogen peroxide or benzoyl peroxide brings up the challenges such as health issues for asthmatic people, generation of off-flavors as a result of lipid oxidation, and loss of nutritive value due to whey protein oxidation. As the global market for whey protein is projected to reach $13.5 billion by 2020, providing an appropriate method to obtain high quality whey from the colored Cheddar cheese process to avoid challenges associated with current bleaching processes is of significant importance. The objective of this study is to selectively add colorant to Cheddar cheese and prevent partitioning of color into whey. In this work, we designed a controlled-release platform to selec-tively deliver and release annatto within Cheddar cheese matrix. We encapsulated annatto within a protein-polysaccharide complex shell using emulsification followed by spray drying steps (42% encapsulation efficiency). The engineered shell material disintegrates by the enzymes secreted during the ripening period of Cheddar cheese and releases the encapsulated annatto into the Cheddar cheese matrix. The Hunter CIE Lab color analysis shows an increase in the yellowness (b* value) of the cheese during the ripening period of 1 mo. Exploiting this method, we produced colored Cheddar cheese and white Cheddar cheese whey without any need to discolor whey. This enzymatically triggered microcapsule design possess a great potential to be commercialized and utilized worldwide to enhance the quality of both Cheddar cheese and its recovered whey.

Key Words: encapsulation, Cheddar cheese whey, discoloring

408 Effect of lactoferrin on metallic taste and immunity dysfunction induced by chemotherapy. A. Wang*1, S. Duncan1, G. Lesser2, W. Ray1, and A. Dietrich1, 1Virginia Polytechnic Institute and State University, Blacksburg, VA, 2Comprehensive Cancer Center of Wake Forest University, Winston-Salem, NC.

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Cancer patients receiving chemotherapy often experience metallic taste and immunity dysfunction, which negatively impacts their nutritional status. However, there has been no effective treatment for this frequent side-effect. In this study, dietary supplementation through lactoferrin (LF) was developed as a treatment to reduce metallic taste disorder and improve immune system for cancer patients. Sixteen patients with self-reported metallic taste disorder since undergoing chemotherapy and 10 healthy subjects were recruited in this study. All participants took LF supplements, 3 tablets per day (250 mg/tablet), for 30 d. Saliva samples were collected at baseline, 30 d after LF supplements daily intake, and 30 d after LF supplementation ended. Taste function of cancer patients was assessed by a self-perceived taste abnormal-ity questionnaire. Salivary proteome and minerals were analyzed at each time point of LF supplementation. LF supplementation for 30 d

significantly decreased (P < 0.05) taste abnormality score and salivary Fe in cancer patients. Production of metallic taste was related with the loss of salivary immune proteins. LF supplementation led to an overall increase of immune defense proteins in saliva of all human subjects, including α-amylase, zn-α-2-GP, prolactin-inducible protein (PIP), and low-abundance proteins (pH 5.5–8.5, MW 25–75 kDa) such as immunoglobulin heavy chain, annexin A1, carbonic anhydrase VI pre-cursor (CAVI), proteinase inhibitor, and α-amylase. For 60% of cancer patients, a post-LF supplementation effect further increased the intensity of α-amylase. LF treatment effectively reduced metallic taste disorder induced by chemotherapy and increased production of salivary defense proteins in human subjects.

Key Words: lactoferrin, metallic taste, immunity

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