L'enrichissement d'aliments courants avec des composés bioactifs aide à promouvoir la santé et réduire le risque de maladies. Cependant, la plupart des bioactifs à propriétés biologiques intéressantes sont de nature hydrophobe et donc présentent des limites d’incorporation dans les aliments dues à leur faible solubilité dans les matrices aqueuses. De plus, leurs activités biologiques se heurtent à des facteurs extrêmes lors des procédés de formulation et de fabrication du produit telle que les fluctuations de pH, de température et de pression. Pour ce, l’encapsulation des bioactifs dans des matrices « biosourcée » s’avèrent être une solution pour améliorer leur biodisponibilité et préserver leurs propriétés fonctionnelles. Dans cette étude, nous avons choisi de traiter le cas de la curcumine, composé phénolique hydrophobe présentant diverses activités biologiques intéressantes telles que notamment une activité antioxydante importante, mais dont l'action est limitée de par sa faible biodisponibilité. Le choix de la matrice d’encapsulation s’est porté sur la micelle de caséine, véritable matrice naturelle et efficace aux propriétés technofonctionnelles variées. Cette thèse a permis de démontrer l’interaction hydrophobe entre la micelle de caséine et la curcumine via les résidus tryptophane. L'incorporation de la curcumine au sein de la micelle de caséine n’influence ni les propriétés structurales (taille, charge de surface et structure interne) ni les propriétés fonctionnelles (gélification) de la micelle. Sachant qu'un des objectifs d'application pourrait être la production d’un yaourt enrichi en curcumine, l’étude de l’interaction entre la curcumine et les bactéries lactiques du yaourt est nécessaire. Il a ainsi été démontré que la curcumine s’adsorbe sur les enveloppes bactériennes de Lactobacillus bulgaricus et préférentiellement sur Streptococcus thermophilus sans inhiber leur croissance et leur pouvoir acidifiant. Une fois en contact avec les micelles de caséines et les LAB, la curcumine se partage entre la micelle et les enveloppes bactériennes pour établir un équilibre. Sachant que la plupart des industries agroalimentaires utilisent dans les étapes de formulation des ingrédients sous forme de poudres plutôt que sous forme liquide, la production d’une poudre de micelle de caséine dopée en curcumine préservant l’activité antioxydante du bioactif tout en conservant les propriétés technofonctionnelles de la micelle de caséine a été réalisée par séchage par atomisation / Enriching common foods with bioactive compounds could help promote health and reduce the risk of diseases. However, most bioactives with interesting biological properties are hydrophobic and therefore have incorporation limits in foods due to their low solubility in aqueous matrices. In addition, their biological activities encounter extreme factors in the formulation and manufacturing processes of the product such as pH, temperature and pressure fluctuations. To this end, the encapsulation of the bioactive elements in "bio" matrices is a solution for improving their bioavailability and preserving their functional properties. In our study, we chose to treat curcumin, a hydrophobic phenolic compound, with various interesting biological activities such as its important antioxidant activity. The choice of the encapsulation matrix was turned to the casein micelle, an effective encapsulation matrix with desired technofunctional properties. This thesis has demonstrated the hydrophobic interaction between the casein micelle and curcumin via tryptophan residues. The addition of curcumin in solution to the casein micelle did not influence the structural properties (size, ζ-potential and internal structure) nor the functional properties (gelling) of the micelle. Knowing that the ultimate goal is the production of yogurt enriched with curcumin, the study of the interaction between curcumin and lactic bacteria of yoghurt is necessary. Indeed, curcumin adsorbs on the bacterial envelopes of Lactobacillus bulgaricus and preferentially on Streptococcus thermophilus without inhibiting their growth and their acidifying power. Once in contact with casein micelles and LABs, curcumin is partitioned between the micelle and the bacterial envelopes to establish a balance. Given that most agro-food industries use more powder rather than aqueous solutions in formulation stages, the production of curcumin-doped casein micelle powder protecting the antioxidant activity of the bioactive while preserving the technofunctional properties of the casein micelle was carried out by spray-drying

Ce travail de thèse a permis d’étudier l’influence de l’ajout d’ingrédients fonctionnels laitiers sur l’encapsulation de L. rhamnosus GG (LGG). Deux ingrédients laitiers (ß-lactoglobuline et membrane des globules gras du lait - MFGM) ont été identifiés comme étant capables d’adhérer fortement à LGG par l’intermédiaire de ses pili. Le rôle clé de ces adhésions dans la localisation spatiale des bactéries dans la matrice laitière a été mis en évidence, ainsi que le rôle des constituants de la matrice dans sa structuration. Cela a permis de sélectionner, in vitro, une matrice d’encapsulation capable de protéger de manière efficace les bactéries des conditions gastriques et de libérer les bactéries vivantes au niveau de l’intestin. En parallèle, la MFGM dans l’encapsulation des bactéries s’est révélée prometteuse. Ce travail a également démontré l’importance primordiale du choix de la matrice d’encapsulation. En effet, une compétition entre l’adhésion de LGG aux cellules intestinales et l’adhésion de LGG à certains composants de la matrice laitière a été démontrée. Les deux phénomènes impliquent probablement les mêmes mécanismes : adhésion aux pili glycosylés de LGG. Pour terminer, un procédé de séchage par atomisation a été développé pour encapsuler LGG. Il permet une bonne survie des bactéries après séchage et la production de microparticules présentant des propriétés fonctionnelles innovantes liées à la température du milieu de réhydratation / The aim of this work was to understand how functional dairy components influence L. rhamnosus GG (LGG) encapsulation. First, two dairy components (-lactoglobulin and milk fat globule membrane - MFGM) able to strongly adhere to LGG through their pili are identified. The key role of these adhesions on bacteria spatial location in the matrix is highlighted, as well as the role of matrix dairy components in their structuration. This allowed to select, in vitro, a matrix able to protect bacteria in gastric conditions and to release them viable in the intestine. Simultaneously, the use of MFGM in bacteria encapsulation has proven to be promising. This work demonstrated the importance of the matrix choice in the encapsulation procedure. Results demonstrated that adhesion between LGG and dairy matrix may compete with adhesion of LGG to epithelial intestinal cell. The two phenomena likely involve the same mechanisms: adhesion to glycosylated pili of LGG. To finish, a spray drying encapsulation process is developed to encapsulate bacteria. It leads to a high bacteria survival after drying and the production of microparticles with innovative properties depending on rehydration temperature

Orientador: Marcelo Cristianini / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-08T04:19:13Z (GMT). No. of bitstreams: 1 Pedras_MarceloMonteiro_M.pdf: 951624 bytes, checksum: 118f33f7311ebd4a32deb6f15dc8a20a (MD5) Previous issue date: 2007 / Resumo: O tratamento de homogeneização a ultra alta pressão (HUAP) é uma tecnologia que vem sendo utilizada tanto para inibir o crescimento de microorganismos, como para alterar as propriedades físico-químicas e funcionais do leite e de sua fração proteica. O objetivo deste estudo foi avaliar algumas das principais alterações físico-químicas de leite desnatado submetido a diferentes níveis de HUAP. Além disso, avaliar solubilidade, propriedades de aeração e emulsificação de caseína e proteínas de soro isoladas de leite processado por HUAP. Leite cru desnatado foi submetido a 3 níveis de pressão de homogeneização (100 MPa, 200 MPa e 300 MPa) onde foram avaliadas as alterações físico-químicas do leite (pH, composição centesimal, estabilidade ao álcool, luminosidade, desnaturação de proteínas do soro, hidrofobicidade e viscosidade) e as propriedades funcionais da caseína e proteínas do soro (solubilidade, aeração e emulsificação). O processo apresentou boa repetibilidade e aumento de temperatura de no máximo 55°C. As medidas de pH e nitrogênio não proteico (NNP) foram as únicas variáveis que não apresentaram alteração estatisticamente significativa para nenhum dos níveis de pressão. Estabilidade a precipitação com álcool, luminosidade e hidrofobicidade apresentaram aumento a partir de 100 MPa. A desnaturação de proteínas do soro ocorreu somente a partir de 200 MPa, aumentando ainda mais com uso de 300 MPa. A única variável que apresentou alteração somente no nível de 300 MPa foi a viscosidade. A caseína e as proteínas do soro foram isoladas por acidificação a pH 4,6 e centrifugação, o sobrenadante e precipitado foram neutralizados e liofilizados. Foram avaliadas as seguintes propriedades: solubilidade, capacidade de formação de espuma, estabilidade de espuma, capacidade emulsificante e estabilidade de emulsão. A caseína não sofreu alteração de solubilidade, já as propriedades de aeração e emulsificação apresentaram melhora de performance, sendo estatisticamente significativas a partir de diferentes níveis de pressão de acordo com a propriedade avaliada. As proteínas do soro apresentaram diminuição da solubilidade nos níveis de 100 MPa e 200 MPa, as propriedades de aeração foram melhoradas em 300 MPa, e as propriedades de emulsificação não foram influenciadas. O tratamento de leite fluido por tecnologia de HUAP promove alterações significativas em propriedades funcionais de caseína e proteínas do soro. As alterações estão relacionadas à desestruturação das micelas de caseína, desnaturação de proteínas do soro, interação das micelas entre si e com as proteínas do soro, e com o aumento da hidrofobicidade e capacidade de hidratação das mesmas / Abstract: The ultra high-pressure homogenisation (UHPH) is a recent technology used to inhibit microorganisms¿ growth, as to modify the physical-chemical properties of milk and its protein fraction. The purpose of this study was to evaluate the main physical-chemical characteristics caused by different levels of high-pressure homogenisation in skim milk. Besides to evaluate solubility, foaming properties and emulsifying properties of casein and whey proteins isolated from milk processed by UHPH. Raw skimmed milk was submitted to 3 pressure levels (100 MPa, 200 MPa e 300 MPa), the processing parameters and the modifications on milk physical-chemical properties has been evaluated. The process presented good repeatability and the maximum temperature increase was 55°C. The measurements of pH and non-protein nitrogen (NPN) were the only variables that did not present any statistically significant change. Ethanol stability, lightness (L*) and hydrophobicity showed an improvement or increment from 100 MPa to 300 MPa. Whey protein denaturation occurred only from 200 MPa to 300 MPa. The only variable that presented changes only at 300 MPa was viscosity. Casein and whey proteins were isolated by acidification at pH 4.6 and centrifugation, further they were neutralized and freeze-dried. The following properties were evaluated: solubility, foaming capacity, foam stability, emulsifying capacity and emulsion stability. The freeze-dried casein did not show any modification on solubility, however all foaming and emulsifying characteristics presented improved performance, being statistically significant for different pressure levels according to each analysed property. UHPH decreased the solubility of the whey proteins obtained from milk treated at 100 MPa and 200 MPa, foaming properties increased for the freeze-dried protein obtained from milk treated at 300 MPa, and no influence were noted on the emulsifying properties. The treatment of fluid milk by UHPH was able to promote significant alterations on the functional properties of casein and whey proteins. The modifications were related to casein micelles disruption, whey proteins denaturation, interaction among the micelles and with denaturated whey proteins, and also with increase of molecular hydrophobicty and water retention / Mestrado / Mestre em Tecnologia de Alimentos

Orientador: Rosiane Lopes da Cunha / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-10T21:18:09Z (GMT). No. of bitstreams: 1 Picone_CarolinaSiqueiraFranco_M.pdf: 4173181 bytes, checksum: 1983f6f0b95d4a90fd3fe987a6b067b3 (MD5) Previous issue date: 2008 / Resumo: Tendo em vista a necessidade do entendimento das interações entre ingredientes para o desenvolvimento de novos produtos lácteos e para o controle e manipulação de suas características de estabilidade e textura, este trabalho teve como objetivo elucidar as interações entre as proteínas do leite e a goma gelana. Foi estudado o efeito de diferentes concentrações de gelana, caseinato de sódio e concentrado protéico de soro de leite, assim como o estado conformacional do polissacarídeo, nas propriedades de textura, microestrutura e estabilidade em relação à perda de água dos sistemas formados. A transição conformacional da gelana em diversos valores de pH foi estudada por ensaios reológicos oscilatórios a baixas freqüências. Foi observado que a transição de estado desordenado ¿ ordenado do polissacarídeo é irreversível com a temperatura em pH 3,5, enquanto em maiores valores de pH os géis formados são termorreversíveis. Além disso, sistemas em pH 3,5 apresentaram viscosidade e caráter elástico mais pronunciados, enquanto que na faixa de pH de 5,3 a 7,0, não foram observadas mudanças significativas nas características reológicas do material. Em sistemas mistos proteínas-polissacarídeos, diferentes estruturas foram observadas de acordo com as concentrações de biopolímeros e o estado conformacional do polissacarídeo, resultando em alterações das propriedades mecânicas, de retenção de água e de solubilidade dos sistemas. Sistemas bipoliméricos caseinato de sódio ¿ gelana formaram coacervados em altas concentrações de proteína e apresentaram microestrutura compacta, refletindo em maiores valores de tensão de ruptura, elasticidade e baixa capacidade de retenção de água. Já nos sistemas tripoliméricos, não foram observados coacervados devido ao favorecimento das interações entre as proteínas que ocasionou um aumento dos valores de capacidade de retenção de água das amostras. A gelana e as proteínas do soro apresentaram incompatibilidade termodinâmica em altas concentrações poliméricas, confirmada pelos ensaios de solubilidade protéica em água, levando a formação de sistemas mais frágeis, menos deformáveis e com uma estrutura mais porosa, que contribuiu para o aumento da capacidade de retenção de água e redução da sinerese dos mesmos. O uso de gelana em estado desordenado no preparo das amostras com alta concentração protéica induziu a formação de complexos eletrostáticos entre as proteínas e as moléculas de gelana individuais, diminuindo a rigidez dos sistemas / Abstract: As the ingredient interactions are important for the development of new milk products and for the control and management of its stability and texture properties, the aim of this work was to elucidate the milk proteins and gellan gum interactions. The effect of different concentrations of gellan gum, sodium caseinate and whey protein concentrate, as well as the polysaccharide conformational transition on the systems texture properties, microstructure and water release were studied. The gellan gum conformational transition was studied in different pH values by oscillatory shear measurements at low frequencies. It was observed that the conformational polysaccharide transition (coil-helix) was thermoirreversible at pH 3.5 while at higher pH values the gels were temperature reversible. Moreover, systems at pH 3.5 showed higher viscosity and storage modulus, but at 5.3 ¿ 7.0 pH range it was not observed significant differences on the material rheological properties. Protein-polysaccharide systems showed different structures according to the polymers concentration and polysaccharide conformation, resulting on variations of its mechanical properties, water binding and solubility. Bi-polymeric systems composed of caseinate and gellan formed coacervates at high protein concentration leading to a compact structure which reflected in higher rupture stress, elasticity and water holding capacity. Nevertheless, on multipolymeric samples it was not observed coacervates probably due the enhance of protein-protein interactions that lead to increase on water holding capacity values. Gellan gum and whey proteins showed thermodynamic incompatibility at high polymer concentrations, confirmed by the solubility measurements, and induced the formation of weaker and less deformable gels, which had a porous structure with more ability to hold water. The use of coil gellan on the preparation of the samples with high protein concentration resulted on electrostatic complexes formation between the proteins and the individual gellan molecules, reducing the gels hardness / Mestrado / Mestre em Engenharia de Alimentos

<p>U radu je ispitivana mogucnost unapređenja membranske filtracije mleka primenom promotora turbulencije razlicitog geometrijskog oblika i dimenzije. Eksperimentalna istraživanja su izvedena na keramickoj membrani velicine 100 nm koja se najce&scaron;ce koristi u procesu mikrofiltracije mleka. Istraživanja su obuhvatila ispitivanje uticaja<br />promotora helikoidne geometrije (uvrnuta traka i Keniks mikser) i geometrije u obliku seciva (Koflo mikser) razlicitih karakteristicnih dimenzija na fluks permeata, prljanje i selektivnost membrane. Efikasnost primene razlicitih promotora analizirana<br />je kako sa aspekta povecanja fluksa tako i sa aspekta smanjenja potro&scaron;nje energije.<br />Istraživanje uticaja tipa promotora turbulencije na mikrofiltraciju proteina mleka<br />pokazalo je da se izborom geometrije, karakteristicne dimenzije i radnih uslova mogu<br />postici znacajna i energetski isplativa povecanja fluksa permeata.<br />Primenom uvrnute trake kao promotora Uticaj tipa promotora turbulencije na unapređenjemembranskefiltracije tubulencije ostvarena su povecanja fluksa i od 200<br />do 600% u zavisnosti od karakteristicne dimenzije uvrnute trake, i rad pri dva ili tri puta manjim protocima u odnosu na rad bez promotora. Najvece povecanje fluksa od oko 600% ostvareno je primenom najgu&scaron;ce uvrnute trake karakteristicne dimenzije 1,0 (UT1,0). UT1,0 kao promotor turbulencije uzrokuje najvece ubrzanje fluida tj. nivo turbulencije i najdužu helikoidnu putanju strujnica &scaron;to doprinosi intenzivnom odno&scaron;enju cestica sa povr&scaron;ine membrane. Ispitivanje primene Keniks miksera kao<br />promotora turbulencije je pokazalo da se znacajna i isplativa povecanja fluksa postižu vec pri veoma malim protocima. Keniks mikser je takođe helikoidne geometrije kao i uvrnute trake, ali se razlikuje po tome &scaron;to su helikoidni elementi<br />postavljeni pod uglom od 90o i levo desno jedan u odnosu na drugi. Ovakva orjentacija elemenata uzrokuje preraspodelu i promenu smera stujnica posle svakog elementa zbog cega je pad pritiska za Keniks mikser i do cetiri puta veci u odnosu na<br />uvrnutu traku iste karakteristicne dimenzije, ali uz veci utro&scaron;ak energije. Promotori geometrije u obliku seciva (Koflomikseri) takođe obezbeđuju povecanje fluksa od<br />200 do 650% pri nižem protoku u odnosu na rad bez promotora. Vece povecanje fluksa od 500 do 600% postignuta su primenom Koflo miksera manje karakteristicne dimenzije 1,3. Koflo mikseriobezbeđuju promenu slike strujanja u membrani koja se manifestuje takođe raspodelom toka fluida i pojavom helikoidnih strujnica, ali i sudaranjem i me&scaron;anjem struja usled udara o seciva pod određenim uglom. Po sudaranju struja se ovaj tip miksera razlikuje u odnosu na uvrnute trake i Keniks mikser. Ipak pad pritiska ovog miksera je veci u odnosu na pad pritiska uvrnute trake, a manji u odnosu na pad pritiska Keniks miksera. Ispitivanje smanjenja prljanja membrane pokazalo je da se primenom promotora smanjuje otpor prljanja membrane kao i otpori usled povratnog i nepovratnog prljanja. Naročito je zapaženo smanjenje otpora usled povratnog prljanja koje se javlja na povr&scaron;ini membrane. Na ovaj nacin potvrđeno je da svi tipovi miksera uzrokuju promenu nacina strujanja u membrani koja obezbeđuje pobolj&scaron;anje prenosa mase u graničnom sloju. U granicnom sloju najintenzivnije deluje Uticaj tipa promotora turbulencije na unapređenje membranske filtracije. Keniks mikser kod kog sem preraspodele stujanja dolazi i do promene smera strujnica nakon svakog elementa. Izvođenje procesa primenom promotora je energetski isplativije u odnosu na konvencionalan nacin rada i važi za sve ispitivane tipove promotora bez obzira na geometriju i karakterističnu dimenziju. Za vrednosti flukseva do 60 Lm-2h-1 uvrnute trake sve tri karakteristicne dimenzije zahtevaju istu potro&scaron;nju energije. Primena uvrnute trake UT1,0 je najisplativija za flukseve vece od 60 do 100 Lm-2h-1 iako uzrokuje veci pad pritiska u odnosu na UT1,5 i UT2,5, ali obezbeđuje i proporcionalno veci fluks pri protocima tri puta manjim u odnosu na rad bez promotora. Primenom UT1,0 moguće su u&scaron;tede energije u rasponu od 50 do 75 % u odnosu na rad bez promotora. Potro&scaron;nja energije kod primene Keniks miksera je veća u odnosu na uvrnutu traku iste karakterisitčne dimenzije, a opseg radnih protoka i TMP uslovljen velikim padom pritiska. U&scaron;tede energije u slučaju primene Keniks miksera su od 30 do 65% u odnosu na rad bez promotora. Međutim, primenom UT1,0 umesto Keniks miksera iste dimenzije obezbeđuju se od 10 do 35 % vece u&scaron;tede energije pri istom radnom fluksu. Sa aspekta potro&scaron;nje energije, Koflo mikseri su najmanje efikasni. KF1,3 mikser je manje efikasan u odnosu na KF2,5 zbog većeg pada pritiska i ne proporcionalno veceg fluksa. Primenom ovih promotora se postižu u&scaron;tede energije od 20 do 70% u odnosu na konvencionalan način rada, ali je ipak njihova efikasnost manja u odnosu na uvrnutu traku iste dimenzije zbog razlike u padu pritiska Pravilnim izborom geometrije promotora može postici povecanje fluksa uz nisku potro&scaron;nju energije odnosno niže padove pritiska. Slika strujanja koja zavisi od geometrije promotora najvi&scaron;e utice na povecanje fluksa pri čemu je najbitnije da se pored povećanja brzine obezbedi pojave strujnica helikoidnog oblika u graničnom sloju. Upravo ovakav nacin strujanja najvi&scaron;e doprinosi odno&scaron;enju cestica istaloženih na povr&scaron;ini membrane i povecanju prenosa mase. Pojave radijalnog me&scaron;anja ili sudaranja struja mogu se smatrati sporednim pojavama u odnosu na to koliko doprinose povecanju fluksa međutim, njihovo postojanje doprinosi povećanju pada pritiska i smanjuju energetsku efikasnost promotora. Uticaj tipa promotora turbulencije na unapređenje membranske filtracije. Rezultati istraživanja su potvrdili polaznu pretpostavku, definisanu ciljem istraživanja, da helikoidna putanja strujanja kod uvrnutih traka obezbeđuje najintenzivnije odno&scaron;enje istaloženog materijala sa povr&scaron;ine membrane uz najmanji pad pritiska odnosno gubitak energije. Sa druge strane, pojava me&scaron;anja koje je primarno kod Keniks i Koflo miksera izaziva, pored odno&scaron;enja istaloženih čestica i dodatno vrtloženje koje za posledicu ima veći pad pritiska i manju energetsku efikasnost.</p> / <p> This work investigates influence of tubulence promotor geometry and its characteristic dimension on the improvement of membrane filtration of milk proteins. The investigation was performed using a ceramic tubular membrane with 100 nm pore size which is commonly used in the dairy industry. As turbulence promoters two main geometry types were chosen: a helical (twisted tape and Kenics mixer) and a blade shaped (Koflo mixer). Except the geometry type, influence of an aspect ratio was studied, also. Efficiency of turbulence promoters was evaluated from the point of view of flux improvement and specific energy consumption. The experimental results clearly show that microfiltration process can be improved by proper choice of a turbulence promoter geometry, its aspect ratio and operating conditions. The process efficiency is increased by achievement of a significant flux increase and lowered energy consumption. Application of twisted tapes as turbulence promoters yields in the flux improvement of 200 to 600% depending on the aspect ratio of twisted tape but at two or three times lower cross-flow rates compared to conventional MF. The higher flux improvement of 600% was achieved by using twisted tape with aspect ratio 1.0, which induces the highest turbulence and the longest helical stream path so the scouring of particles from the membrane surface is the most intensive.<br /> By applying Kenics mixer as turbulence promoter significant flux improvement can be<br /> achieved at five fold lower cross-flow rates. Kenics mixer is also helical insert but its elements are right and left-hand orientated what causes the local resistances and much higher pressure drop compared to the twisted tape of the same aspect ratio. This resulted in higher energy consumption and in lower efficiency of the process fitted with Kenics mixer. Application of blade type insert, such is Koflo mixer, enables flux improvement of 200 to 650% and operation at lower cross-flow rates compared to conventional MF. The higher flux improvement, 500 to 600%, was yielded using the<br /> mixer of lower aspect ratio, 1.3. Blade mixers divide and redistribute streamlines after each element and also induce helical flow path near the membrane surface. Flow field defers from the flow field of twisted tape and Kenics mixer by the appearance of stream collision in the center of blade structure. This causes grater pressure gradient than for the twisted tape but lower than for the Kenics mixer. Investigation of membrane fouling confirmed that the membrane fitted with promoter is less fouled compared to the plane membrane. The reversible fouling resistance is reduced for<br /> order of magnitude especially for the case of Kenics mixer application. All types of promoters improve the mass transfer in the boundary layer at membrane surface inducing the helical path streamlines which take away deposited material. Energy consumption analysis has shown that the energy consumption can be significantly<br /> reduced by proper promoter geometry and aspect ratio. Operation with promoters proved to be more efficient from energy consumption point of view compared to the conventional operation. Using twisted tape of 1.0 aspect ratio energy can be saved for 50 to 75%. Blade type mixers are the less efficient, but still more efficient than the<br /> conventional filtration. In general, when the twisted tapes were used as promoters generated helical streamline path enables the most intensive fouling reduction with lowest pressure drop i.e. energy consumption. On the other hand, when the Kenics<br /> and blade mixers were used, except helical streamline path the secondary flows and mixing are induced what along with fouling reduction causes the higher pressure loss making these promoters energetically less efficient.</p>

With the increased demands of therapeutic proteins, there is going to be a need for new purification technologies which have high throughput, high yield and high resolution. Three purification technologies were explored as potential new technology to isolate recombinant and endogenous milk proteins: Expanded bed adsorption chromatography(EBAC) combined with hydrophobic interaction chromatography(HIC), Recycle continuous flow electrophoresis(RCFE) and Free flow isoelectric focusing(FFIEF). The first process(EBAC/HIC) used with Zn2+ as a selective precipitating agent, purified recombinant human protein C(rhPC) and IgG(contaminated with less than 1% IgA) from swine milk with high resolution and high yield while processing about 10-20 grams in a single operation. The second process(RCFE) was able to isolate the active sub-populations of rhPC from major milk contaminants( - and -pig casein) as wells as from the inactive sub-populations of rhPC. RCFE was able to process 1.5g total protein per hour on a small scale and is currently being researched to process 1kg total protein per hour. The third and final purification process(FFIEF) sub-fractionated 100mg of immuno-purified rhPC into 50 fractions. The FFIEF was able to produce a linear pH gradient over the range of 3-10 using 2% ampholytes. The fractionated rhPC showed differing degrees of activity that resulted from the -carboxylated glutamic acids and the sialic acids. / Ph. D.

Tiger nuts (Cyperus esculentus L) are recognized as a high potential, alternative source of food nutrients. However, there is limited scientific literature on the technological possibilities for developing value-added foods, such as fermented products from tiger nut milk. Therefore, strategies for producing and improving the properties of fermented tiger nut milk were investigated for generating lactose-free, nutritious yogurt-like products with acceptable sensory properties and a prolonged shelf life quality. A wet-milling procedure was standardized for extracting tiger nut milk from tiger nuts, and the effects of the extraction process on nutrient distribution, colour properties and colloidal stability of the milk were analyzed. Next, tiger nut milk was enriched with proteins and/or hydrocolloids and the impact of the additives on the physical properties of the milk were determined. Enriched tiger nut milk was fermented by using classical yogurt cultures and the obtained products were analyzed for the microbiological, physico-chemical and sensory characteristics. Additionally, effects of enriching tiger nut milk with microbial transglutaminase cross-linked proteins on the microbiological and physico-chemical properties were evaluated. Higher wet-milling intensity improved the nutrient composition, colloidal stability and colour of the milk. Enrichment of tiger nut milk with milk proteins and xanthan gum enhanced the viscosity and stability, and after fermentation, led to homogenous gel-like products with superior microbiological, physico-chemical and different sensory properties compared to the fermented plain tiger nut milk. Microbial transglutaminase cross-linked proteins improved the physical characteristics of the fermented product, especially during storage. This product would be relevant in many developing countries with high prevalence of lactose intolerance, limited access to nutritious food but show a high distribution of tiger nut vegetation. / Erdmandeln (Cyperus esculentus L) haben ein hohes Potential als alternative Quelle Lebensmittelinhaltsstoffen. Allerdings gibt es nur in begrenztem Ausmaß Literatur über technologische Möglichkeiten zur Entwicklung von Mehrwert-Lebensmitteln wie fermentierter Erdmandelmilch. Daher wurden Strategien zur Herstellung und Verbesserung der Eigenschaften von fermentierter Erdmandelmilch zur Erzeugung laktosefreier joghurtähnlicher Produkte mit akzeptablen sensorischen Eigenschaften untersucht. Für die Extraktion der Erdmandelmilch wurde ein Nassmahlverfahren standardisiert und der Einfluss des Verfahrens auf die Nährstoffverteilung, die Farbeigenschaften und die kolloidale Stabilität der Milch analysiert. Als nächstes wurde Erdmandelmilch mit Proteinen und/oder Hydrokolloiden angereichert, und der Einfluss der Additive auf die physikalischen Eigenschaften des Extrakts bestimmt. Angereicherte Erdmandelmilch wurde mit klassischen Joghurtkulturen fermentiert, und die mikrobiologischen, physikalisch-chemischen und sensorischen Eigenschaften der Produkte wurden untersucht. Zusätzlich wurden Effekte der Anreicherung von Erdmandelmilch mit enzymatisch vernetzten Proteinen auf die mikrobiologischen und physikalisch-chemischen Eigenschaften bewertet. Eine höhere Nassmahlintensität verbesserte die Nährstoffzusammensetzung, die kolloidale Stabilität und die Farbe der Milch. Die Anreicherung erhöhte die Viskosität und Stabilität und führte nach der Fermentation zu homogenen gelartigen Produkten mit verbesserten mikrobiologischen, physikalisch-chemischen und sensorischen Eigenschaften im Vergleich zur fermentierten Erdmandelmilch. Mikrobielle Transglutaminase-vernetzte Proteine verbesserten die physikalischen Eigenschaften des fermentierten Produkts, insbesondere während der Lagerung. Dieses Produkt wäre in vielen Entwicklungsländern mit hoher Prävalenz von Laktoseintoleranz und begrenztem Zugang zu nahrhaften Lebensmitteln als Alternative von Interesse.

Various methods for extraction and analysis of high value minor proteins (lactoferrin, lactoperoxidase and immunoglobulins) directly from raw milk were explored. Extraction, purification and analysis of high-value minor proteins directly from milk without pre-treatment are major challenges for dairy industry, largely due to the complexity of milk and the presence of colloidal solids (casein micelles and milk fat globules). To overcome some of these challenges, this work focused on three main objectives: 1) characterization of cryogel monolith chromatography for purification of lactoferrin (LF) and lactoperoxidase (LP) directly from raw milk in single step, 2) identification and characterization of Protein A Mimetic affinity ligands for purification of immunoglobulins (Igs) from milk and 3) development and validation of a surface plasmon resonance method for simultaneous quantification of five whey proteins in multiple samples. Results portrayed the possibility of 40–50 column volumes of various milk samples (whole milk, skim milk and acid whey) to pass through a 5 mL cryogel monolith chromatography column at 525 cm hr⁻¹ without exceeding its pressure limits if the processing temperature is maintained around 35–37°C. Ideally, this should be the milk secretion temperature. The dynamic binding capacity obtained for the cryogel matrix (2.1 mg mL⁻¹) was similar to that of the binding capacity (2.01 mg mL⁻¹) at equilibrium with 0.1 mg mL⁻¹ of lactoferrin in the feed samples. Lactoferrin and lactoperoxidase was selectively bound to the cryogel column with trivial leakage in flowthrough fractions. Lactoferrin was recovered from elution fractions with a yield of 85% and a purity of 90%. These results, together with the ease of manufacture, low cost and versatile surface chemistry of cryogels suggest that they may be a good alternative to packed-bed chromatography for direct capture of proteins from milk, provided that the binding capacity can be increased. A Protein A Mimetic (PAM) hexapeptide (HWRGWV) peptide ligand that binds to the Fc portion of antibody molecules was explored for affinity purification of immunoglobulins from milk. The peptide has the ability to purify IgG from various milk and whey samples with a purity of greater than 85% in single step. More than 90% bound IgG was recovered with 0.2 M acetate buffer at pH 4.0 and total column regeneration was successfully achieved by 2.0 M guanidine-HCl. At 9.0 mg mL⁻¹ of IgG feed concentration, an equilibrium binding capacity of 21.7 mg mL⁻¹ and dynamic binding capacity of approximately 12.0 mg mL⁻¹ of resin was obtained. Recoveries and yields of IgG were significantly influenced by the feed IgG concentration. PAM hexamer ligand also contributed a significant amount of cross-reactivity with casein, glycomacropeptides and β-lactoglobulin proteins, however majority of these proteins were recovered in the regeneration step, except β-lactoglobulin, which co-eluted with IgG. Higher IgG concentration in feed vastly reduced the amount of cross-reactivity whilst increasing the recoveries and purities in the final product. PAM affinity ligands also showed interactions towards other classes of bovine immunoglobulins. These findings established the possibility of using PAM hexamer peptide as an alternative to conventional Protein A/G affinity chromatography for the isolation of Igs from milk in single step process. A surface plasmon resonance (SPR) method was developed for simultaneous, quantitative determination of commercially important whey proteins in raw and processed milk samples, whey fractions and various milk-derived products, with six samples per assay. Immobilized antibody stability and reproducibility of analyses were studied over time for 25 independent runs (n=300), giving a relative standard deviation (RSD) of <4%. Immobilized antibodies showed negligible non-specific interactions (<2–4 SPR response units (RU)) and no cross-reactivity towards other milk components (<1 RU). Regeneration of immobilised antibodies with glycine at pH 1.75 was determined to be optimal for maintaining the SPR response between samples. This method compared and validated well with reversed phase high performance liquid chromatography (RP-HPLC) and standard enzyme-linked immunosorbent assays (ELISA).

Downstream purification and analysis of a model biopharmaceutical protein (recombinant human myelin basic protein) is described. The recombinant protein was expressed in the milk of transgenic cows and was found exclusively associated with the casein micellar phase. Binding of milk calcium to the active sites of a cation exchanger resin was used beneficially in this study in order to gently disrupt the casein micelles and liberate the recombinant protein. This approach was found superior to the conventional micelle disruption procedures with respect to product recovery, resin fouling due to milk components and column hydrodynamic properties. Further purification was carried out using Ni2+ affinity chromatography and resulted in purity more than 90% and a total recovery of 78%. A capillary electrophoresis total protein assay employing large volume sample stacking and a microsphere-based, sandwich-type immunoassay were developed and validated. Both methods were successfully integrated with the downstream purification protocol in order to evaluate various quality attributes of the recombinant protein. A onestep capillary isoelectric focusing protocol was developed in order to monitor the recombinant protein in milk samples. The results showed extra protein bands in the transgenic milk that had isoelectric points significantly lower than the theoretically calculated one which indicated that the protein had been modified during expression. The association between the recombinant protein and bovine milk caseins was explored at the molecular level using the surface plasmon resonance technique. Results showed a calciummediated interaction between the recombinant protein and the phosphorylated caseins. This selective interaction was not noted between the human myelin basic protein and milk caseins which indicated mammary gland-related posttranslational modifications, most likely phosphorylation. The co-expression of the recombinant protein and caseins in the mammary gland, along with the ability of the recombinant protein to form calcium bridges with caseins explained its association with the casein micellar phase in the transgenic milk. Despite this and owing to the low expression levels of the recombinant protein in milk, light scattering investigations using diffusing wave spectroscopy showed no significant differences between the transgenic and the non-transgenic milk samples with respect to the average micelle size and the micelle surface charges.

Τα γαλακτώματα είναι η κολλοειδής διασπορά δύο μη αναμίξιμων υγρών, τα οποία είναι κατά κανόνα θερμοδυναμικά ασταθή συστήματα. Οι πρωτεΐνες γάλακτος είναι γνωστές επιφανειοδραστικές ουσίες και ως εκ τούτου χρησιμοποιούνται ως συστατικά σε ένα ευρύ φάσμα γαλακτωμάτων τροφίμων. Σκοπός της παρούσας εργασίας είναι η εύρεση των κατάλληλων συνθηκών για την παρασκευή σταθερών γαλακτωμάτων πρωτεϊνών γάλακτος. Το μέγεθος των λιποσφαιριδίων διαδραματίζει τον κυρίαρχο ρόλο στη σταθερότητα του γαλακτώματος πρωτεϊνών γάλακτος. Η μέτρηση του μεγέθους των λιποσφαιριδίων έγινε με την τεχνική της Μονοφασικής Χρωματογραφίας Φυγοκεντρικού Πεδίου. Πιο συγκεκριμένα, μελετήθηκε η επίδραση της συγκέντρωσης (0,5 έως 3,0% w/w) και του τύπου (πρωτεΐνες ορού και καζεΐνες) των πρωτεϊνών γάλακτος, καθώς και των συνθηκών ομογενοποίησης (πίεση ομογενοποίησης 200 έως 600bar) του γαλακτώματος. Επίσης, μελετήθηκε η επίδραση της συγκέντρωσης γαλακτωματοποιητών εμπορίου (Tween 80) στη σταθερότητα των γαλακτωμάτων. Επιπρόσθετα, έγινε κινητική μελέτη συσσωμάτωσης των γαλακτωμάτων από πρωτεΐνες γάλακτος και στη συνέχεια μελετήθηκαν πιο συγκεκριμένα τα γαλακτώματα καζεϊνών, με σκοπό τον προσδιορισμό της σταθεράς ταχύτητας της συσσωμάτωσης των λιποσφαιριδίων σε θερμοκρασίες 30,5 και 80 ᵒC. Αυξάνοντας την πίεση ομογενοποίησης του γαλακτώματος παρατηρήθηκε μείωση της διαμέτρου των λιποσφαιριδίων. Τα γαλακτώματα που ομογενοποιήθηκαν σε πίεση μεγαλύτερη των 500 bar παρουσίασαν ευρύτερη κατανομή μεγέθους, λόγω της υψηλής θερμοκρασίας που αναπτύχθηκε κατά τη διάρκεια της ομογενοποίησης. Η πρωτεϊνική συγκέντρωση έχει σημαντικές επιπτώσεις στις φυσικοχημικές ιδιότητες του γαλακτώματος (λάδι σε νερό). Αυξανόμενης της συγκέντρωσης των πρωτεϊνών γάλακτος, μειώθηκε αισθητά η διάμετρος των λιποσφαιριδίων του γαλακτώματος και σε χαμηλές συγκεντρώσεις πρωτεϊνών (<1%κ.β.) παρατηρήθηκε σχηματισμός συσσωματωμάτων. Παρατηρήθηκε μικρή μεταβολή της διαμέτρου των λιποσφαιριδίων των γαλακτωμάτων που σχηματίστηκαν με διαφορετικές αναλογίες κλασμάτων πρωτεϊνών ορού/καζεϊνών. Οι δύο τύποι των πρωτεϊνών του γάλακτος παρουσίασαν πολύ καλή γαλακτωματοποιητική δράση και τα γαλακτώματα που σχηματίστηκαν ήταν πολύ σταθερά. Παρατηρήθηκε ότι, αυξάνοντας τη συγκέντρωση των πρωτεϊνών του ορού γάλακτος και ταυτόχρονα μειώνοντας τη συγκέντρωση των καζεϊνών, μειώθηκε η διάμετρος των λιποσφαιριδίων του γαλακτώματος. Η σταθερότητα των γαλακτωμάτων σε σχέση με τον χρόνο οφείλεται στη δομή των μορίων των πρωτεϊνών που σταθεροποιούν τα γαλακτώματα αυτά. Κατά συνέπεια, τα μόρια των καζεϊνών και των πρωτεϊνών ορού, προσδίδουν διαφορετικές ιδιότητες στα γαλακτώματα λόγω της διαφορετικής δομής τους. Τα γαλακτώματα που σχηματίστηκαν με καζεΐνες ήταν πιο ανθεκτικά στην θερμοκρασία και παρουσίασαν μακροπρόθεσμη σταθερότητα σε σχέση με τα γαλακτώματα που περιείχαν μόνο πρωτεΐνες ορού. Η υπολογισθείσα φαινόμενη σταθερά συσσωμάτωσης των γαλακτωμάτων καζεϊνών στη θερμοκρασία των 30,5 ᵒC βρέθηκε να είναι σχεδόν 14 φορές μικρότερη από αυτή των γαλακτωμάτων που συσσωματώθηκαν στη θερμοκρασία 80,0 ᵒC. Επομένως, η διαδικασία της συσσωμάτωσης συμβαίνει ταχύτερα σε πιο υψηλές θερμοκρασίες θέρμανσης για τα γαλακτώματα καζεϊνών, ωστόσο έφτασαν στο μέγιστο βαθμό συσσωμάτωσης σε ίδιο χρονικό διάστημα. / In the food industry, when referring to an oil-in-water emulsion, is usually described in which oil is dispersed in the form of small spherical droplets in the continuous phase. Food emulsions are thermodynamically unstable. Nevertheless, food scientists are able to slow down the above physicochemical mechanisms responsible for emulsion instability and thus, extend the self-life of such products by a relatively simple and well studied process, termed emulsification. Surface active materials termed emulsifiers, such as proteins help produce small droplets and contribute to the stability of the emulsion. Emulsifiers decrease the interfacial tension between the oil and water phases through rapid adsorption to the surface of the newly formed oil droplets. Milk proteins (caseins and whey proteins) are well known surfactants and hence are used as ingredients in a wide range of food emulsions. One of the important parameters affecting the quality, appearance and taste of the final food products is the particle size of the ingredients included. For example, particle size of fat globules plays predominant role in the stability of the milk-protein stabilized emulsion. Milk protein-stabilized model emulsions were formed using high-pressure homogenization and the effect of homogenization pressure during emulsification, protein concentration, type of milk proteins (casein and whey proteins) and the effect of the surfactant Tween-80 were studied. The kinetic of milk protein emulsions aggregation was also studied and moreover, the apparent rate constant was calculated for the aggregation of caseinate stabilized emulsions in different temperatures (30,5 and 80,0 ᵒC). Sedimentation field flow fractionation was employed for the size characterization of oil droplets and the results obtained are consistent with those of other studies. Increasing protein content results in significant reduction in emulsion particle size for the concentration range (0.5 – 3.0 % w/w) employed in this study. Low protein content (<1%) may be correlated with bridging flocculation leading to increased particle size, as indicated by optical microscopy. Similarly, increasing pressure during the homogenization process results in decreasing significantly the particle size of the oil-in-water emulsions, for the pressure range (200 – 600 bar) utilized in this study. Increased heating associated with high levels of pressure during the homogenization process, can result in changes in the oil or protein structure, which in turn may have an impact on the physicochemical properties of the oil-in-water emulsions on a long-term basis. The two types of milk proteins appeared to be both good emulsifiers and the formed emulsions were very stable. Increasing whey protein content and together decreasing the casein content, results in small reduction in emulsion particle size. Different proteins depending on their composition and structure posses’ properties, which render them, better emulsifiers than others. Caseinate stabilized emulsions were more resistant in heating time than whey stabilized emulsions. The calculated apparent rate constant for the aggregation of caseinate stabilized emulsions at the temperature of 30,5 ᵒC was found to be fourteen times smaller than the one at the temperature of 80,0 ᵒC. Therefore, the aggregation process is faster in high temperatures for caseinate stabilized emulsions, although the maximum of aggregation point is attained at the same time in both temperatures.