Master of Science / Department of Grain Science and Industry / Jon M. Faubion / Endosperm texture is an important characteristic in determining wheat processing and end-use. The presence of puroindoline proteins on the starch surface is the biochemical marker for wheat hardness. Near-isogenic samples over expressing puroindolines have been used to assess the effect of wheat hardness on final product characteristics. The objective of this study was to determine differences among starch isolated from near-isogenic samples and to investigate the role starch surface components play in pasting. The use of near-isogenic samples over expressing puroindolines combined with the use of two methods of starch isolation (batter and dough) was an effective means to create samples with varied amounts of surface components. Starch thermal properties were characterized and surface proteins and lipids were quantified. Starch isolated from hard wheat cultivars presented more similarities with starch isolated from its soft near-isogenic line when a dough method was used than when a batter method was used. Starch from soft experimental lines isolated using a batter method showed increased MVA peak viscosity, breakdown and swelling power. Increased levels of LysoPC in starch isolated from hard wheat cultivars or soft experimental lines by dough method could have complexed with amylose and restricted granule swelling. Thereby, decreasing peak viscosity, breakdown and swelling power.

The purpose of lactation is for nutrient provision and also importantly for protection from various environmental stressors. Milk polar lipids reduce cholesterol, protect against bacterial infection, reduce inflammation and help maintain gut integrity. Dynamic interactions within dietary fat, lipid metabolism, gut permeability and inflammatory cytokines remain unclear in the context of obesity and systemic inflammation. A rat model and three mouse models were developed to test the hypotheses that dietary milk polar lipids may affect lipid metabolism and intestinal integrity and may protect against systemic inflammation in the context of stressful diet, systemic inflammation, and obesity. The milk polar lipids isolates had complex effects on lipid metabolism and associated gene expression in the rat model. There were complex dynamics in lipid metabolism, gut permeability and systemic inflammation at different time points in all mouse models. The milk phospholipids increased gut permeability in genetic and diet-induced obesity and during the lipopolysaccharide (LPS) -induced inflammation. The phospholipids increased the plasma LPS level in genetic obesity and during the LPS stress. The phospholipids reduced liver mass and liver lipids in genetic obesity and during the LPS-induced inflammation. The phospholipids increased the body fat in the diet-induced obesity model. The milk gangliosides did not significantly affect gut permeability, systemic inflammation, and lipid metabolism in all three mouse models. Current estimate by the Centers for Disease Control is that about 1/3 Americans are obese (body mass index, BMI ≥ 30) and 1/3 Americans are overweight (25 ≤ BMI < 30). More than 25% of Americans today have a fatty liver which could lead to further health problems. The data from this dissertation shed light on the complicated interrelationships between gut permeability, systemic inflammation, and lipid metabolism in obesity. The results contribute to our understanding of the bioactivities of milk polar lipids and provide scientific evidence for the role of milk polar lipids rich materials in affecting biological functions. The study of the influence of milk polar lipids on gut barrier integrity adds new information on understanding the mechanisms of gut leakiness and recovery. The investigation of the impact of milk polar lipids on lipid metabolism reveals new perspectives for the development of diet-induced obesity.

The purpose of lactation is for nutrient provision and also importantly for protection from various environmental stressors. Milk polar lipids reduce cholesterol, protect against bacterial infection, reduce inflammation and help maintain gut integrity. Dynamic interactions within dietary fat, lipid metabolism, gut permeability and inflammatory cytokines remain unclear in the context of obesity and systemic inflammation. A rat model and three mouse models were developed to test the hypotheses that dietary milk polar lipids may affect lipid metabolism and intestinal integrity and may protect against systemic inflammation in the context of stressful diet, systemic inflammation, and obesity. The milk polar lipids isolates had complex effects on lipid metabolism and associated gene expression in the rat model. There were complex dynamics in lipid metabolism, gut permeability and systemic inflammation at different time points in all mouse models. The milk phospholipids increased gut permeability in genetic and diet-induced obesity and during the lipopolysaccharide (LPS) -induced inflammation. The phospholipids increased the plasma LPS level in genetic obesity and during the LPS stress. The phospholipids reduced liver mass and liver lipids in genetic obesity and during the LPS-induced inflammation. The phospholipids increased the body fat in the diet-induced obesity model. The milk gangliosides did not significantly affect gut permeability, systemic inflammation, and lipid metabolism in all three mouse models. Current estimate by the Centers for Disease Control is that about 1/3 Americans are obese (body mass index, BMI ≥ 30) and 1/3 Americans are overweight (25 ≤ BMI < 30). More than 25% of Americans today have a fatty liver which could lead to further health problems. The data from this dissertation shed light on the complicated interrelationships between gut permeability, systemic inflammation, and lipid metabolism in obesity. The results contribute to our understanding of the bioactivities of milk polar lipids and provide scientific evidence for the role of milk polar lipids rich materials in affecting biological functions. The study of the influence of milk polar lipids on gut barrier integrity adds new information on understanding the mechanisms of gut leakiness and recovery. The investigation of the impact of milk polar lipids on lipid metabolism reveals new perspectives for the development of diet-induced obesity.

Les bétaïne lipides (BL) sont des lipides polaires qui se distinguent des phospholipides (PL)par l’absence de phosphore (P). La réorientation métabolique induite par une limitation en P chez des microalgues produisant des BL (Tisochrysis lutea et Diacronema lutheri, Haptophytes) ou en produisant peu (Phaeodactylum tricornutum, Bacillariophyte) a été comparée à celle induite par une limitation en azote (N). Le devenir et le flux de carbone dans différentes voies de biosynthèse ont été étudiés par une approche pluridisciplinaire.La limitation nutritive en P ou en N affecte différemment le métabolisme du carbone selon les espèces microalgales. La limitation en P réduit fortement l’activité photosynthétique et la respiration chez P. tricornutum et T. lutea. Par conséquent, l’accumulation de carbone est plus élevée que sous limitation en N chez ces deux espèces. Les deux limitations stimulent en particulier la synthèse des lipides neutres et / ou des glucides. Le remplacement des PL par les BL a été observé chez P. tricornutum en condition de limitation en P. Ce résultat est en accord avec une augmentation de la transcription du gène codant la bétaïne lipide synthase. En revanche, cette limitation ne modifie pas les teneurs en BL rapportées au carbone chez T. lutea et D. lutheri. La composition en acides gras des différentes classes lipidiques est modifiée selon l’espèce microalgale et l’élément nutritif limitant. Une attention particulière a été portée aux acides gras de la série oméga-3, notamment l’acide eicosapentaénoïque (EPA, 20:5 ω3) et l’acide docosahexaénoïque (DHA, 22:6 ω3) dont les proportions varient en fonction de l’élément limitant,de l’espèce et de la classe lipidique. L’augmentation de la production des lipides neutres et / ou des lipides polaires, notamment des bétaïne lipides, riches en DHA et/ou EPA induite par un stress nutritif laisse envisager une valorisation de ces molécules d’intérêt dans différents domaines dont la nutrition et la santé. / Betaine lipids (BL) are P-free polar lipids, conversely to phospholipids (PL). The metabolic reorientation induced by phosphorus (P) limitation in microalgae producing BL (Tisochrysis lutea and Diacronema lutheri, Haptophyta) or producing low levels of BL (Phaeodactylum tricornutum, Bacillariophyta) was compared to that induced by nitrogen (N) limitation. The carbon destiny and flow in different biosynthetic pathways were studied with a multidisciplinary approach. P or N limitation differently affected carbon metabolism according to microalgal species. P limitation highly decreased photosynthetic activity and respiration of P. tricornutum and T. lutea. Consequently, carbon accumulation was higher than under N limitation in these two species. Both limitations stimulated the synthesis of neutral lipids and / or carbohydrates. Replacement of PL by BL was observed in P. tricornutum under P limitation. This result is in agreement with a transcription increase of the gene encoding BL synthase. On the other hand, this limitation did not modify BL contents in reference with carbon in T. lutea or D. lutheri. Fatty acid composition of the different lipid classes was modified according to the microalgal species and the limiting nutrient. Particular attention was paid to the fatty acids of the omega-3 series, notably eicosapentaenoic acid (EPA, 20:5 ω3) and docosahexaenoic acid (DHA, 22:6 ω3), the proportions of which vary according to the limiting element, species and lipid class. The increase in the production of neutral lipids and / or polar lipids, especially betaine lipids, rich in DHA and / or EPA induced by nutritive stress suggests a valorization of these molecules of interest in various areas including nutrition and health.

Vanderghem Caroline. (2009). La membrane du globule gras du lait : études physico-chimiques et sa valorisation technofonctionnelle dans les babeurres (Thèse de doctorat en Anglais). Gembloux, Belgique, Faculté Universitaire des Sciences Agronomiques de Gembloux. 198p., 14 tabl., 59 fig. Résumé La membrane du globule gras du lait (MGGL) est une structure complexe qui enveloppe, protège et délivre des composants bioactifs et des nutriments dune façon efficace au nouveau-né. Sa structure est unique par rapport à dautres systèmes biologiques de transport de lipides. Lobjectif général de ce travail a été de contribuer à augmenter les connaissances et la compréhension de cet émulsifiant naturel. La première partie de cette thèse concerne létude de la structure de la MGGL. Limportance des protéines membranaires concernant la stabilité et leur disposition dans la MGGL ont été étudiés. Les protéines de la MGGL sont présentes en petite quantité dans le lait et une technique de pré-fractionnement simpose afin de les isoler par rapport aux autres protéines du lait (caséines et protéines du lactosérum). Une technique dextraction qui a été développée dans notre laboratoire a été testée afin disoler la MGGL de la crème laitière. Une analyse détaillée a révélé que cette procédure est très bien adaptée pour lélimination dun maximum de protéines du lait écrémé. Une approche protéomique a été établie et a permis lidentification de protéines majeures de la MFGM ainsi que dautres protéines mineures (GTP-binding proteins, annexins, actin) afin de compléter le protéome. Par la suite, différentes protéases ont été testées en vue dobtenir différents degrés et/ou sélectivité dhydrolyse des protéines de la MGGL. La distribution asymétrique des protéines de la MGGL a été étudiée par une approche basée sur lattaque protéolytique du globule gras natif. Sur base de nos résultats et des données bibliographiques récentes, un nouveau modèle de la structure de la MGGL est proposé. La deuxième partie de cette thèse est consacrée à évaluer les propriétés technofonctionnelles de la MGGL dans les babeurres. Les propriétés interfaciales, moussantes et émulsifiantes du babeurre sont comparées à dautres ingrédients laitiers comme le lait écrémé et le concentré protéique de lactosérum. Nos résultats montrent le bon pouvoir émulsifiant du babeurre en comparaison des autres ingrédients laitiers. Dans les émulsions recombinées, la stabilité envers le crémage a été améliorée et les membranes ont présenté une meilleure résistance face à la coalescence. Les résultats sur la tension interfaciale et les propriétés rhéologiques interfaciales ont été mis en relation avec certaines propriétés des mousses et des émulsions. Vanderghem Caroline. (2009). The milk fat globule membrane: physico-chemical studies and its techno-functional valorisation in buttermilk (Thèse de doctorat). Gembloux, Belgium, Gembloux Agricultural University, 198p., 14 tabl., 59 fig. Summary The milk fat globule membrane (MFGM) is a complex structure that surrounds, protects and delivers bioactive compounds and nutrients in an efficient manner to the neonate. Its structure is unique in relation with any other biological lipid transport system. The overall aim of this work was to contribute to increase the knowledge and comprehension of this natural emulsifier. The first part of this thesis concerned the study of the structure of the MFGM. Membrane proteins were targeted and their importance regarding stability and disposition in the MFGM was studied. MFGM proteins are present at low concentrations in milk and a pre-fractionation of the sample is required in order of MFGM proteins to be visible among other milk proteins (caseins and whey proteins). A mild procedure developed in our laboratory was tested in order to isolate MFGM from cream. Detailed analysis revealed that this procedure is very well suited for the elimination of a maximum of skim milk proteins. A proteomic approach was established and allowed the identification of the most important MFGM proteins and additional minor MFGM proteins for additional completion of the proteome (GTP-binding proteins, annexins, actin). Subsequently, different proteases were screened in an attempt to obtain different degrees and/or selective proteolysis of MFGM proteins. Asymmetric arrangement of MFGM proteins was studied with an approach based on the proteolytic attack on the native fat globule. Based on our results and recent bibliographic data, an updated model of the MFGM structure was proposed. The second part of this thesis was devoted to assess the techno-functional properties of the MFGM in buttermilks. Interfacial, foaming and emulsifying properties of buttermilk were assessed and compared to classic milk ingredients such as skim milk and whey protein concentrate. Our results highlighted that buttermilk possesses good emulsifying power compared to other milk ingredients. In buttermilk recombined emulsions stability towards creaming was improved and the recombined membrane presented a great resistance to coalescence. Results of the interfacial pressure and the interfacial rheological properties were related to some foams and emulsions properties.