A process which incorporates whey sol ids, primarily protein, into cheese to increase cheese yield and eliminate whey handling problems was evaluated. Whey was concentrated by ultrafiltration to levels of 9.8 to 20.3 percent total solids (4.3 to 7.1 percent protein), heated at 70 C for 30 minutes and added to cheese milk with the coagulating enzyme. Increase in cheese yield, on the basis of 39 percent moisture, for 10 pairs of samples was 4.0 ± 2.8 (S.D.) percent. This increase was significant at alpha less than 0.001. Moisture and protein content increased while fat content decreased. Setting time and pH also decreased. Body/texture evaluation showed no change, but flavor scores decreased. Specific defects responsible for changes in flavor and body/texture were identified.

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ABSTRACT Effects of Filtration Temperature and Heat Treatment on Composition and Rheological Properties of Whole Milk Ultrafiltration Retentates John William Montella For the first part of my thesis, the effects of filtration temperature and heat treatment on the compositional properties of whole milk Ultrafiltration retentate (UF) were studied. Ultrafiltration is primarily run at temperatures in the range of 50-55°C but more and more plants are starting to filter at refrigeration temperatures. In the ultrafiltration of milk, filtration temperature can affect the composition of the retentate by affecting the chemistry of milk components. The application of a pasteurization step can also affect the chemistry of milk components. There were two filtration temperatures used: 10°C and 50°C. The effect of stage in the filtration process in which the pasteurization step is applied (before UF vs. after UF) is also studied. The heat treatment used was a batch pasteurization treatment of 63°C for 30 minutes. The milk was concentrated to a Volume Concentration Ratio (VCR) of 3X through a 10,000 Molecular Weight Cut Off polysulfone membrane. Compositional analysis was performed on permeate and retentate. According to my results, there were significant treatment effects on the retention of true protein (both casein and whey protein nitrogen), total protein, non-casein nitrogen, minerals (including Ca) and pH of the retentate. The chemistry of the milk components were considered as possible reasons for these differences. The week of processing did not affect the results. For the second part, the effect of composition of the retentate on their viscosity and flow properties was observed. Rheological properties are very important in process design and for consumer acceptability. Flow and viscosity data was collected using a dynamic stress rheometer. Three analytical temperatures were used during the rheological measurements: 10°C, 40°C, and 70°C. A shear rate of 500 s-1 was used for viscosity analysis. Flow properties were also observed using the same three temperatures. According to the results, all the retentate displayed shear thinning behavior and this behavior became more pronounced as the testing temperature increased. As the shear rate increased, there was a shear thickening effect that became more pronounced as temperature increased. There was a significant effect of treatment on the viscosities of the retentate. Compositional differences in the retentate are possible contributors to observed results. The week of processing had no effect on the results. For the final part, the effect of filtration temperature and heat treatment on rennet coagulation time of retentate was observed. A 22μl aliquot of chymosin was added to 100 ml of retentate heated to 30°C prior to analysis. Rennet coagulation time was monitored using a dynamic stress rheometer. The rennet coagulation time was recorded as the time at which the G’ value reached 1 Pa. There was a significant effect of filtration temperature and heat treatment on the rennet coagulation time of the retentate. Compositional differences are all possible contributors to these differences. From the observations from all three studies, the following conclusions can be made: (1) There were significant differences observed with respect to filtration temperature and heat treatments on chemical composition of the retentate; (2) The retentate displayed a shear thinning behavior and the chemical composition of the retentate could be a contributing factor as well as the sample testing temperature. There was also a significant treatment effect on the viscosity of the retentate; and (3) Significant differences in rennet coagulation times were observed, possibly due to compositional differences of retentate. Processing week did not have a significant effect on my results.

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Research efforts pertaining to natural organic material (NOM) have focused primarily on the dissolved portion of NOM since it is the most prevalent fraction. Numerous procedures have been developed to separate dissolved organic material (DOM) into fractions but methods were not fully refined in the areas of quantitative analysis, DOM recovery, and DOM isolation. This research chemically and physically characterized DOM using synthetic resin adsorption and ultrafiltration, respectively. A 0.45 μm filter separated the NOM into particulate and nonparticulate fractions prior to characterization. The DOM of two natural waters were fractionated into six separate organic fractions (hydrophobic bases, acids, neutrals and hydrophilic bases, acids, neutrals). Apparent molecular weight distributions were performed on the two natural waters and six organic fractions via ultrafiltration. The effects of pH on coagulation removal efficiency were investigated on four of the organic fractions (acidic and neutral). A procedure was developed to investigate the synergistic/antagonistic effects of the hydrophobic acid fraction and the hydrophobic neutral fraction on each other during coagulation. Ultrafilters (30K and 100K nominal molecular weight cutoff) were utilized to analyze the phase-change behavior of DOM during coagulation. Results indicated the coagulation pH affected the removal of the organic acidic fractions but not the neutral fractions. A further study showed poorer removal of the hydrophobic neutral fraction resulting from the greater presence of the hydrophobic acid fraction in a solution composed of the two fractions and vice versa. At less than enhanced doses of both alum and ferric chloride there existed the presence of colloidal metal bound organic material. This colloidal fraction can be effectively removed by the addition of a nonionic polymer, providing a cost effective alternative to the higher coagulant doses often required to achieve enhanced coagulation of surface waters. / Master of Science

Tableau d'honneur de la Faculté des études supérieures et postdorales, 2015-2016 / La microfiltration (MF) est un procédé membranaire permettant de séparer les micelles de caséines (CN) des protéines sériques (PS) du lait grâce à des pores ayant un diamètre de 0,1 μm. Le rétentat obtenu est enrichi en CN, tandis que le perméat contient des PS sous forme native. La membrane céramique à gradient de perméabilité (GP) a été développée récemment dans le but de réduire l’encrassement à long terme, ce qui permet des flux de perméation élevés et une meilleure séparation des protéines. À ce jour, les conditions opératoires les plus efficientes pour réaliser la MF du lait n’ont pas été déterminées pour ce type de membrane. L’objectif de cette étude était donc de caractériser l’effet de différentes pressions transmembranaires (PTM), différents facteurs de concentration volumique (FCV) et de la diafiltration (DF) sur l’efficience du procédé. Un bilan de matière a été réalisé à la suite du dosage des solides totaux, ainsi que de l’azote total, non caséique et non protéique. La consommation énergétique du système de MF a également été mesurée in situ. Les résultats obtenus démontrent qu’un FCV de 1,5X permet d’obtenir la meilleure séparation des protéines, tout en ayant un flux de perméation plus élevé et une plus faible consommation énergétique. Lorsque le FCV est plus élevé, les pertes totales de CN dans le perméat et la consommation énergétique deviennent plus importantes, ce qui réduit la rentabilité du procédé. Les étapes de DF réduisent l’efficience du procédé en augmentant la durée de filtration et la quantité de perméat généré de façon considérable, sans permettre d’obtenir une quantité satisfaisante de PS supplémentaires dans le perméat. Les résultats obtenus pourront bénéficier aux transformateurs laitiers lors de la prise de décision quant à la pertinence d’effectuer la MF du lait avec la membrane céramique GP. / Microfiltration (MF) is a membrane process used to separate casein (CN) micelles from serum proteins (SP) of milk using 0.1 μm pore diameter membranes. The resulting retentate is enriched in CN, while the permeate contains native SP. The graded permeability (GP) ceramic membrane has been recently developed to reduce long-term fouling, which improves permeation flux and protein separation. To date, the most efficient operating conditions to achieve MF of milk have not been determined for this type of membrane. The objective of this study was to characterize the effect of different transmembrane pressures (TMP), volumetric concentration factors (VCF) and diafiltration (DF) on the process efficiency. Mass balance measurements were carried out following the determination of total solids, total nitrogen, non-casein nitrogen and non-protein nitrogen. The in situ energy consumption of the MF system was also measured. Results obtained showed that a VCF of 1.5X provided the best separation of proteins, while allowing the highest permeation flux and the lowest energy consumption. When the VCF was higher, the total losses of CN in the permeate increased, as well as energy consumption, which reduces the process profitability. DF steps reduced the process efficiency by increasing the filtration time and the amount of permeate generated, without increasing significantly the transmission of additional SP in the permeate. Results will benefit dairy processors in decision making about the potential of MF of skim milk with GP membrane.

Le lactosérum, co-produit de la transformation fromagère, peut être valorisé en concentrant ses protéines par ultrafiltration (UF). Le principal inconvénient de l’UF est le colmatage des membranes, notamment par les protéines et le phosphate de calcium, qui entraîne une réduction des performances du procédé. Depuis quelques années, il est reconnu que les membranes peuvent être colmatées par des cellules bactériennes et des biofilms lors de l’UF du lactosérum. De nombreux auteurs ont souligné la présence de biofilms sur les membranes et investigué différents paramètres régissant la diversité bactérienne de ces biofilms. Toutefois, aucune étude n’a encore démontré l’impact concret du colmatage bactérien sur les performances de l’UF du lactosérum. L’objectif général de cette étude était donc de quantifier les baisses de performance causées par le dépôt de cellules bactériennes et la formation de biofilms lors du l’UF du lactosérum. Le premier objectif a démontré que le dépôt de cellules bactériennes pouvait exacerber les baisses de flux causées par le colmatage des protéines sériques en UF frontale, alors qu’il avait peu d’effet sur le colmatage minéral. Une neutralisation partielle des charges électrostatiques entre les bactéries et les protéines réduirait les répulsions et entraînerait la formation d’un gâteau de particules plus compact sur la membrane. Les résultats du deuxième objectif ont permis de confirmer, en UF tangentielle de lactosérum doux, que le colmatage bactérien provenant de la microflore intrinsèque du système de filtration pouvait diminuer les flux de perméation après 18 h de filtration. Le colmatage bactérien a augmenté la résistance hydraulique des membranes, permettant le calcul de résistances spécifiques au colmatage bactérien (Rbio) qui représentaient de 31 à 44% de la résistance totale de la couche de colmatage. Ces résultats démontrent que le colmatage bactérien peut influencer négativement les performances de l’UF du lactosérum et soulignent l’importance de développer des solutions pour mitiger ce colmatage. / Whey, the main co-product of cheese manufacturing, can be valorized through protein concentration by ultrafiltration (UF). The main drawback of UF is fouling, mainly by protein and calcium phosphate, which lowers the process performance. It has recently been acknowledged that membranes can also be fouled by bacterial cells and biofilms during whey UF. Numerous authors have demonstrated the presence of biofilms on membranes and investigated many parameters that can modulate the bacterial diversity of these biofilms. However, the impact of biofouling on the performance of whey UF is still unknown. The general objective of this study was therefore to quantify the loss of performance caused by bacterial cell deposition and biofilm formation during whey UF. The first objective demonstrated that bacterial cell deposition could increase the flux drop caused by whey protein fouling during dead-end UF, while it had minor effects on mineral fouling. Partial neutralization of bacterial cells and protein electrostatic charges may have reduced repulsions led to the formation of a more compact cake. The results of the second objective confirmed, during crossflow UF of sweet whey, that biofouling from the intrinsic microflora of the filtration system could lower permeation fluxes after 18 h of filtration. Biofouling also increased membrane hydraulic resistances, allowing the calculation of biofouling-specific resistances (Rbio), which accounted for 31 to 44% of the total fouling layer resistances. These results demonstrate that biofouling can negatively affect the performance of whey processing by UF and highlight the need for solutions to mitigate biofouling.

La lactoferrine est une protéine du lactosérum, capable de lier le fer. Elle a des propriétés biologiques importantes lui conférant de l'intérêt comme ingrédient dans les aliments fonctionnels et les nutraceutiques. Le but de ce travail était d'étudier la capacité du procédé d'électrodialyse avec membrane d'ultrafiltration (EDUF) à séparer la lactoferrine bovine à partir du lactosérum. Pour ce faire, la mobilité électrophorétique de la lactoferrine a été étudiée en fonction du pH. La mobilité électrophorétique de la LF a été optimale à pH3. Ensuite, nous avons démontré la faisabilité de la séparation de la lactoferrine par EDUF à partir d'une solution modèle: un taux de migration de 46% a été obtenu. Finalement, l'EDUF a été appliquée sur du lactosérum enrichi, en testant les pH 3, 4 et 5. Le plus haut taux de migration de la lactoferrine a été obtenu à pH3 avec 15% de migration.

La phosvitine (45 kDa) de la granule du jaune d’oeuf est une phosphoprotéine reconnue pour ses propriétés émulsifiantes. Un traitement de la granule par hautes pressions hydrostatiques (HPH) a récemment permis le transfert de la phosvitine vers le plasma, la fraction soluble diluée. Ainsi, ce projet avait pour objectif d’évaluer les performances du procédé d’ultrafiltration (UF) lors de la concentration du plasma enrichi en phosvitine afin de générer un ingrédient aux propriétés émulsifiantes améliorées. Une pressurisation (400 MPa, 5min) a été appliquée sur une granule (G1) (10 % m/m), afin d’obtenir après centrifugation, une deuxième granule (G2) et un plasma (P2). Le P2 a été ultrafiltré sur une membrane en polyéthersulfone de 10 kDa pour concentrer la phosvitine. La phosvitine a été identifiée et caractérisée dans le P2 pressurisé (1,73 % m/m) et son rétentat d’UF (26,00 % m/m), validant sa rétention totale par la membrane d’UF. Des flux de perméation similaires ont été obtenus durant l’UF, et ce peu importe les conditions, démontrant que la présence de phosvitine n’impacte pas les performances du procédé. Par conséquent, la combinaison des HPH et de l’UF s’est avérée efficace pour la récupération sélective de la phosvitine et sa concentration. Les propriétés émulsifiantes des rétentats (témoin et pressurisé) ont été évaluées. L’émulsion préparée avec le rétentat enrichi en phosvitine était plus stable à la floculation et au crémage. La microscopie confocale à balayage laser a montré un réseau de protéines agrégées dans lequel sont encapsulées les gouttelettes d’huile, dans l’émulsion avec le rétentat enrichi en phosvitine. Le profil protéique de la crème a montré la présence de plusieurs protéines dont la β-phosvitine, suggérant un effet positif de la β-phosvitine sur les propriétés émulsifiantes du rétentat d’UF enrichi en phosvitine par pressurisation et centrifugation de la granule du jaune d’oeuf. / Phosvitin (45 kDa) from egg yolk granule is a phosphoprotein known for its emulsifying properties. Recently, a high hydrostatic pressure (HHP) treatment on the egg yolk granule, has induced the transfer of phosvitin to the soluble plasma fraction. This project aimed to evaluate the performance of ultrafiltration (UF) treatment for the generation of a fraction enriched in phosvitin, to produce an ingredient with improved emulsifying properties. An HHP treatment (400 MPa during 5 min) was applied to the granule (G1) (10 % w/w), in order to obtain a second granule (G2) and a plasma (P2) after centrifugation. The P2 fraction was ultrafiltered on a 10 kDa-polyethersulfone membrane to concentrate phosvitin. Phosvitin was identified and characterized in pressure-treated fraction P2 (1.73 ± 0.07% w/w) as well as in its corresponding UF retentate (26.00 ± 4.12% w/w) validating its total retention by the membrane. Similar permeation fluxes were obtained during UF, regardless of the conditions, demonstrating that the presence of phosvitin does not affect the performance of the process. Therefore, the combination of HHP and UF represents an interesting processing for the recovery and the concentration of phosvitin. The emulsifying properties of both retentates (control and pressure-treated) were evaluated. The emulsion prepared with the phosvitin-enriched retentate was more stable to flocculation and creaming. Confocal laser scanning microscopy showed a network of aggregated protein similar to a gel, which encapsulated oil droplets in emulsion made with UF retentate of pressure-treated plasma. SDS-PAGE profiles of the proteins recovered in the washed cream fraction showed the presence of several proteins, including β-phosvitin. Overall, the phosvitin enriched UF concentrate obtained from the plasma of pressurized egg yolk granule show better emulsifying properties than the plasma control suggesting a positive effect of β-phosvitin on the emulsifying properties.