Soy whey protein isolate (SWPI) – Fenugreek gum conjugates were developed and their molecular characteristics and emulsifying properties were investigated. SWPI was extracted from soy whey of tofu processing. SWPI exhibited excellent emulsifying properties comparable to soy protein isolate. However, to improve the emulsifying properties of SWPI for some applications, it was conjugated to fenugreek gum. The extent of conjugation was verified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared (FTIR) and High performance size exclusion chromatography (HPSEC). The SDS-PAGE of the conjugates showed polydispersed bands at the top of the separating gel in the conjugates suggesting the formation of high molecular weight products. Refractive index spectrum of HPSEC profiles showed a reduction of protein peak of unconjugated mixture and shifted a peak to higher molecular weight of the conjugates. Ultraviolet spectrum of HPSEC showed an increase of protein peak intensity at polysaccharide region. FTIR spectrum showed an amide band I and II were still observed in the conjugates after the unreacted proteins were removed. 1D NMR spectra showed that fenugreek gum was covalently bound to proteins through interaction between the reducing end of mannose residue and lysine. The protein solubility of SWPI – Fenugreek gum conjugates improved as compared to SWPI and SWPI – Fenugreek gum mixture when assessed in the pH range 3 to 8 at 22oC, especially at isoelectric point of protein (pl). A 1:3 and 1:5 ratio of SWPI – Fenugreek gum gave rise to better emulsion stabilization compared to 1:1 ratio. Particle size analysis revealed that conjugation of SWPI – Fenugreek gum at 60oC for 3 days was enough to produce relatively small droplet sizes in oil-in-water emulsions. SWPI – Unhydrolyzed fenugreek gum conjugates exhibited better emulsifying properties compared to SWPI – Partially hydrolyzed fenugreek gum conjugates. The conjugates improved emulsifying properties of SWPI, particularly around the pl of protein. The emulsifying properties were greatly increased by heating the conjugates before emulsification. The conjugates also improved emulsion stability at high salt concentration compared to SWPI. In summary, incorporation of SWPI into fenugreek gum improved emulsifying properties of SWPI near the pl of protein and at high salt concentration. / No / No

The hypothesis that consumption of whey protein (WP) prior to a meal suppresses short-term food intake and reduces post-meal glycemia by insulin-dependent and -independent mechanisms in healthy young adults was explored in three studies. Study one investigated the effect of solid vs. liquid forms of WP (50 g) and sucrose (75 g) on food intake at 1 h. Whey protein, whether in solid or liquid form, suppressed food intake more than sucrose. Study two examined the effect of WP (10-40 g) consumed 30 min prior to a meal on food intake, and pre- and post-meal blood concentrations of glucose and insulin. Whey protein reduced food intake and post-meal glycemia in a dose-dependent manner without increased blood insulin concentrations. In the third study, glycemic control after WP was compared with glucose, at doses of 10 and 20 g. Both pre-meal WP and glucose consumption reduced post-meal glycemia similarly. However, WP resulted in lower pre-meal blood glucose and delayed gastric emptying, lower pre-and post-meal and overall insulin secretion and concentrations and higher GLP-1 and PYY concentrations compared with glucose. Thus, the results of this research support the hypothesis that consumption of WP prior to a meal suppresses short-term food intake and reduces post-meal glycemia by insulin-dependent and -independent mechanisms in healthy young adults.

The hypothesis that consumption of whey protein (WP) prior to a meal suppresses short-term food intake and reduces post-meal glycemia by insulin-dependent and -independent mechanisms in healthy young adults was explored in three studies. Study one investigated the effect of solid vs. liquid forms of WP (50 g) and sucrose (75 g) on food intake at 1 h. Whey protein, whether in solid or liquid form, suppressed food intake more than sucrose. Study two examined the effect of WP (10-40 g) consumed 30 min prior to a meal on food intake, and pre- and post-meal blood concentrations of glucose and insulin. Whey protein reduced food intake and post-meal glycemia in a dose-dependent manner without increased blood insulin concentrations. In the third study, glycemic control after WP was compared with glucose, at doses of 10 and 20 g. Both pre-meal WP and glucose consumption reduced post-meal glycemia similarly. However, WP resulted in lower pre-meal blood glucose and delayed gastric emptying, lower pre-and post-meal and overall insulin secretion and concentrations and higher GLP-1 and PYY concentrations compared with glucose. Thus, the results of this research support the hypothesis that consumption of WP prior to a meal suppresses short-term food intake and reduces post-meal glycemia by insulin-dependent and -independent mechanisms in healthy young adults.

Orientador: Valdemiro Carlos Sgarbieri / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-09T15:20:43Z (GMT). No. of bitstreams: 1 Roman_JanescaAlban_D.pdf: 80272858 bytes, checksum: d2c3b69837cbfcc4c22bbdc506291b21 (MD5) Previous issue date: 2007 / Resumo: O isolado protéico de soro de leite bovino (WPI) utilizado nesse trabalho foi obtido em planta piloto através do processo de separação em membrana, ultrafiltração, diafiltração e liofilização. O processo de obtenção do WPI foi realizado na planta piloto do Instituto Nacional de Pesquisa Agronômica (INRA), Rennes¿França. Obteve-se WPI com 96,8% de proteína (base seca) e 2,2% de resíduos minerais em condições microbiológicas adequadas para o consumo, com perfil de aminoácidos apresentando quantidades suficientes de todos os aminoácidos essenciais. O perfil eletroforético e a cromatografia em coluna comprovaram que o WPI é composto principalmente pelas frações b-lactoglobulina (b-Lg) e a-lactalbumina (a-La) além de outras proteínas presentes, como albumina de soro bovino (BSA), imunoglobulinas (Ig) e outras em menores quantidades. A gelatina apresentou-se deficiente em relação a todos os aminoácidos essenciais e ausência de triptofano, apresentando elevadas concentrações dos aminoácidos não essenciais arginina, prolina, glicina e alanina, superiores às do WPI. A desnaturação térmica do WPI, determinada pela análise DSC ocorreu em 75,4ºC e da mistura 60:40% WPI/GB em 75,7ºC, ambas apresentando apenas um pico definido. Para a gelatina a desnaturação ocorreu em 36,1ºC. A solubilidade do WPI, pH entre 2,5 a 7,5, em solução aquosa e 0,1M NaCl foi elevada (87,4 a 97,5%), a gelatina apresentou solubilidade inferior (63%) sendo o valor mais baixo (24%), em pH 6,5. A solubilidade da mistura foi intermediária, na faixa de 58 a 81%. Estudou-se a influência da concentração de proteína (3,2 a 8,8%), da temperatura (51 a 79°C) e do tempo de aquecimento entre 10 e 40 min, na de textura de géis mistos. O gel com as melhores características foi o obtido com 60% WPI:40%GB, pH 6,5, aquecido 30 min a 65ºC, com 6% de proteína. A melhor textura encontrada foi na faixa de 270-310g-força, mastigabilidade e gomosidade próximas a 265 g-força, elasticidade e coesividade elevadas, 0,87-0,96. O gel misto (60WPI:40GB) apresentou capacidade de retenção de água de 48,6% enquanto que a do gel de GB foi 23,2%. O planejamento experimental elaborado permitiu uma boa descrição e previsão do comportamento de geleificação dos géis mistos em função da concentração de proteínas e da temperatura. Amostras de produtos geleificados à base de misturas de proteínas (soro de leite/gelatina) foram degustadas por 65 julgadores não treinados, utilizando-se a Escala Hedônica estruturada de nove pontos. As médias obtidas para os atributos de cor, sabor, aroma e textura, apresentaram-se nas categorias gostei ligeiramente e gostei regularmente. As maiores notas foram atribuídas à consistência, independentemente de formulação. O produto contendo isolado protéico de soro de leite apresentou aceitabilidade acima de 70%, semelhante à gelatina comercial, o que sugere um índice satisfatório de aceitação no mercado consumidor / Abstract: The bovine whey protein (WPI) utilized in the present work was obtained in pilot plant employing membrane ultrafiltration/diafiltration and liofilization. The WPI was obtained at the National Institute of Agronomic Research (INRA) at Rennes, France. WPI with 96.8% protein (dry basis), 2.2% ash, and adequate essential amino acids and microbiological profiles, was obtained. Electrophoretic and chromatographic profiles showed ß-lactoglobulin (ß-Lg), a-lactalbumin (a-La), bovine serum albumin (BSA) and imunoglobulins (Igs) as the major protein components of WPI. Gelatin revealed deficiency in all essential amino acids and absence of tryptofan, presenting elevated concentration of the non essential amino acids arginine, proline, glycine and alanine, which were at higher concentrations than in WPI. Difference Scanning Calorimetry (DSC) showed that WPI denatures at 75.4ºC and the WPI:BG mixture (60:40%) at 75.7ºC, both samples presenting only one defined pike. Gelatin (BG) denaturation occurred at 36.1ºC. The solubility of WPI, pH 2.5 to 7.5, in water or 0.1M NaCl solution was high (87.4 to 97.5%). For gelatin the highest solubility was 63% and the lowest (pH 6.5) 24%. The solubility of the mixture 60:40% was in the 58 to 81% range. The influence of protein concentration (3.2 to 8.8%), temperature (51 to 79ºC) and heating time (10-40min), in the texture of mixed gels, was studied. Best texture was defined in the range 270-310g-force, chewiness and gomosity around 265g-force, high elasticity and coesiviness (0.87-0.96). The 60% WPI:40%BG gel presented 48.6% water holding capacity (WHC) while for BG gel WHC was 23.2% The experimental design used permitted good prevision and description of the behavior of the mixed 60:40% WPI/BG gels, as a function of protein concentration and temperature. Samples of products were tasted by 65 non-trained judges, a non-structured mine point Hedonic Scale. Average scores were obtained for the color, taste, aroma, and texture. The highest scores were attributed to viscosity, independently of the formulation. The product containing 60% WPI and 40% BG presented acceptability above 70%, similar to the commercial gelatin, an index that suggests adequacy for market consumption / Doutorado / Nutrição Experimental e Aplicada à Tecnologia de Alimentos / Doutor em Alimentos e Nutrição

Microorganisms have traditionally been selected for fermentation of milk on their ability to grow in milk. However nowadays the trend is towards including probiotic bacteria, i.e. those bacteria that have been suggested to provide additional health benefits to the consumer. Probiotic microorganisms have beneficial effects when ingested such as lowered incidence of colon cancer, the suppression of putrefactive and pathogenic bacteria by competitive exclusion and the production of organic acids, diacetyl and bacteriocins and a hypocholesterolemic effect, to mention but a few. To be more effective, the proposed microorganisms must be of human origin. Lactobacillus acidophilus and Bifidobacterium bifidum, which are two of the most successful probiotic bacteria used commercially, are normal inhabitants of the intestine of many animals including humans. They must however maintain their viability and activity in the bio-product in which they are formulated to be available at the right level at the time of consumption. A number of factors affect their viability, including low pH, the type of culture used and availability of essential amino acids. The choice of ingredients in the mix is crucial since it affects a number of mix properties such as pH and availability of nutrients. The demand for low fat products is a very strong driving force on the market place. However, reducing the fat content of such complex products as frozen dairy desserts is very difficult, since fat forms an integral part of the product. Removing fat poses a number of challenges as to which other ingredients to add in its place. Microparticulated whey protein concentrates have been formulated by food technologists to mimic the functionalities of fat especially as far as creaminess is concerned. Little information is available on fat replacement in frozen yoghurt, in terms of both its effects on the survival of probiotic bacteria and on some important quality parameters. Likewise, little research, if any, has been done on the perception of strawberry flavour in fat-free ice-creams and similar products. The purpose of the present study was thus to provide information on fat replacement by a microparticulated whey protein concentrate (Simplesse® 500) in frozen yoghurts and its influence on the survival of 1. acidophilus and B. bifidum. Several quality parameters of the frozen yoghurts were also evaluated. Frozen yoghurts were prepared by inoculating the mix with an ABT (acidophilus, bifidum and thermophilus) culture. Four mixes were formulated to contain 10% (m/m) milk fat, 5% (m/m) milk fat, 5% (m/m) of the microparticulated whey protein concentrate (WPC) and 3.4% (m/m) of the microparticulated WPC respectively. Decreasing milk fat from 10% to 5%, together with the addition of more milk solids-not-fat, did not lead to a significant increase (p > 0.05) in the acidity of the mix. Likewise the buffering capacity in both alkaline and acidic conditions were not significantly different (p > 0.05). Substituting fat with Simplesse® 500 at 3.4% levelled to a significant decrease in the pH of the mix (p < 0.05), which was due to the presence of more weak acids. The addition of the microparticulated WPC also led to an increase in the buffering capacity of the mix, which was due to an increase in weak acids and other buffer systems present in milk such as the citrate and phosphate systems. The addition of more Simplesse® 500 did not result in a significantly higher acidity (p > 0.05) since whey proteins are only weak acids. The viability of all three the bacteria types present in the ABT culture did not seem to be related to the presence or absence of the microparticulated WPC. The numbers of Streptococcus salivarius subsp. thermophilus, 1. acidophilus and of B. bifidum did not differ significantly (p > 0.05) between the four yoghurt mixes after incubation, ageing, whipping and freezing and three weeks of storage. However, only S. salivarius subsp. thermophilus and 1. acidophilus increased in numbers during fermentation in all the yoghurt mixes and only S. salivarius subsp. thermophilus increased significantly (p < 0.05) as a result of ageing in all the yoghurt mixes. Although the addition of the microparticulated WPC led to an increase in the acidity of the yoghurt mixes it also led to an increase in the buffer capacity, which thus helped to maintain the numbers of S. salivarius subsp. thermophilus and 1. acidophilus at the same level as in the mixes containing milk fat. While S. salivarius subsp. thermophilus and 1. acidophilus grew to numbers greater than 107 cfu/g, B. bifidum did not grow at all in any of the yoghurt mixes and the results suggest that they might not be available at the right level to have any therapeutic benefits to the consumers. Decreasing fat content led to an obvious increase in coarseness of frozen yoghurts (p < 0.05). The increasing perceived coarseness could be related to the amount of ice nuclei formed during whipping and freezing. The addition of the microparticulated whey protein concentrate could have resulted in a decrease in the freezing point, low enough to lead to a decrease in the amount of ice nuclei formed as a result of whipping and freezing. Therefore, the amount of unfrozen water available to freeze during hardening increased, thereby leading to an increase in the size of ice crystals. Fat is also known to decrease the size of ice crystals and the presence of more fat could also have led to an increased perception of smoothness. Increasing fat content led to a decrease in the perception of strawberry flavour and an increased perception of an aftertaste (p < 0.05). Fat is known to bind lipophilic compounds as well as decrease the melting rate and mass transfer, both of which will decrease the release of flavour compounds. / Dissertation (MSc (Food Science))--University of Pretoria, 2006. / Food Science / unrestricted

Made available in DSpace on 2014-06-12T23:01:59Z (GMT). No. of bitstreams: 2 arquivo4019_1.pdf: 511958 bytes, checksum: 744297095eb58a54dd383184bf6e315b (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2008 / Este trabalho teve como objetivo: estudar, em ratos jovens, os efeitos da ingestão de Nutri Whey Protein® sobre alguns metabólitos e na composição corporal dos animais, como também em substituição à proteína convencional. A dissertação inclui dois artigos: um de revisão da literatura e outro original. O primeiro, composto por uma revisão sistemática da literatura, em periódicos especializados impressos e eletrônicos, onde identificou-se que é idéia corrente entre os praticantes de exercício físicos que é necessário consumir mais nutrientes do que o recomendado sendo destacado o consumo do whey protein. No segundo artigo, 108 ratos, com 60 dias de idade foram alimentados com três dietas: padrão (com 17% de proteínas) e suplementadas com 5 e 10% de whey protein (ambas com 22% de proteínas); e submetidos ou não ao exercício (sedentários, natação sem e com carga), divididos em nove grupos (n=12): S, sedentário-dieta padrão; E, exercitado-dieta padrão; EC, exercitado com carga-dieta padrão; S-5, sedentário-dieta suplementada com 5% de whey protein; E-5, exercitado-dieta suplementada com 5% de whey protein; EC-5, exercitado com carga-dieta suplementada com 5% de whey protein; S-10, sedentário-dieta suplementada com 10% de whey protein; E-10, exercitado-dieta suplementada com 10% de whey protein; EC-10, exercitado com carga-dieta suplementada com 10% de whey protein. Determinou-se: ganho de peso, ingestão alimentar, gordura da carcaça, uréia, creatinina, alanina (ALT) e aspartato aminotransferase (AST). Resultados: Tanto o exercício quanto a suplementação promoveram aumento significativo no consumo alimentar sendo mais pronunciado nos grupos exercitados com carga. Houve alteração nos pesos dos exercitados com carga (EC, EC5 e EC10), que se apresentaram significativamente menores que os demais grupos. Ocorreu interação entre a dieta e o exercício no sentido de diminuição no ganho de peso. No caso da gordura coporal os grupos E, E5 e E10, apresentaram aumento significativo, independentemente da dieta consumida. EC5 e EC10 apresentaram uma elevação significativa na concentração sérica da uréia (U) quando comparados ao grupo S, onde exercício e dieta interferiram significativamente no aumento da uréia. Quanto à creatinina (CR) foi verificado que as dietas suplementadas (5% e 10%) promoveram aumento significativo neste metabólito, independentemente da intensidade do exercício executado. A AST apresentou aumento significativo em todos os grupos submetidos ao exercício com carga (EC, EC5 e EC10), intensificado pela suplementação de 10% do whey protein. No caso da ALT, o comportamento em relação ao exercício físico foi semelhante nas três dietas, verificando-se aumento significativo nos grupos exercitados com carga (EC, EC5 e EC10) em comparação aos demais. Os resultados levam a concluir que: é de suma importância, para praticantes de atividades físicas, a ingestão de uma alimentação adequada; faz-se necessária a revisão do conceito de suplementos, como também alertar sobre os que apresentam risco ou ineficiência, devendo-se respeitar uma ingestão até 2,0g de proteína/kg de peso corporal/dia. É imprescindível a fiscalização, regulação da comercialização e publicidade dos suplementos pelo Ministério da Saúde, bem como a intervenção do nutricionista na prescrição e acompanhamento do seu uso. O whey protein foi pouco efetivo na melhoria da composição corporal, sendo contra-indicado para sedentários. Quanto aos parâmetros bioquímicos, tanto a suplementação quanto o exercício podem ter promovido um desequilíbrio no metabolismo, podendo causar danos à saúde

Whey proteins have restricted use in many food applications because of limited functional properties. Whey proteins' relatively high content of disulfide bonds may be responsible for their lack of functionality, especially in extrusion applications. To determine the effect of disulfide bond content on functional properties and extrudate performance, whey protein concentrate was treated with sodium sulfite to achieve four levels of disulfide bond sulfonation (0, 31, 54, and 71%). Sulfonated whey protein functional properties, extrusion-expanded snack properties (32% total protein), and extrusion-textured fibrous product properties (48% protein) were determined. Correlation analysis was performed to determine relationships between functional properties and extrudate performance. Sulfonation of whey protein concentrate (80% protein) increased foaming and emulsion properties and decreased melt temperatures. These changes were largely attributed to increased protein unfolding and flexibility. Sulfonation decreased gel strength and increased resolubilization after heat treatment. These changes were likely the result of increased electric charge on the proteins, limiting protein-protein interactions during heating. Snack products extruded from the 31 and 71% sulfonated samples were less expanded and released less protein and carbohydrate during extrudate solubilization. Sulfonation may have promoted protein unfolding, thereby exposing interaction sites and increasing the formation of insoluble protein-starch aggregates . In support of this suggestion, negative correlation s were found between extrusion performance and protein functional properties related to flexibility , including emulsification activity index, foam stability, and melt onset temperature. The anomalous behavior of the 54% sulfonated sample may be the result of significant structural and functional changes of a-Lb that are predicted to occur at approximately 50% sulfonation. Although the textured extrudate produced from all levels of sulfonation (including the control) did not possess typical fibrous texture, sulfonation at 31% and higher decreased stability after hydration . Decreased stability and fibrous texture may have resulted from decreased protein-protein interactions caused by the repulsion of electric charges contributed by sulfite groups. In conclusion, sulfonated whey protein functional and extrudate properties were influenced by disulfide bond content. Changes in these properties were attributed primarily to increased protein unfolding and flexibility. Increased electric charge on proteins also played a role where protein-protein interactions were important.

The effects of altering pH and calcium level during whey protein extrusion were assessed by measuring the protein solubility and WHC of the textured whey protein (TWP). TWP samples were produced by extruding dry mixtures of 2/3 WPC 80 (80% protein) and 1/3 cornstarch using screw speed of 200 rpms, feed rate of 23 g/min, water flow rate of 11 g/min, and product temperature of 150°C. The levels of acid and base were adjusted by adding concentrated HCl or NaOH, respectively, to the water source. Calcium was added to the raw mix in the form of calcium chloride dihydrate before extrusion at levels of 0.4%, 0.88%, and 1.69% calcium per protein (w/w). It was shown that WHC of TWP was increased (p < 0.05) by extrusion with water. WHC was further promoted by extruding with increased levels of base. Solubility of whey protein in water was reduced by extrusion, especially when extruded with added acid or calcium. The practicality of using hydrated TWP in beef patties was determined using sensory, physical, and instrumental analysis. An open consumer panel was conducted on six beef patty samples: 1) 100% beef, 2) 30% TWP extruded with 0.2 M NaOH (TWP0.2MNaOH), 3) 30% TWP extruded with 1.69% calcium (w/w protein) added (TWP1.69%Ca2+), 4) 30% TWP extruded with water (TWPH2O) , 5) 30% TWP extruded with 0.1 M HCl (TWP0.1MHCl), and 6) 30% textured soy protein (TSP). It was found that patties containing 30% TWP0.2MNaoH were equal (p < 0.05) to 100% beef patties in tenderness, juiciness, texture, flavor, and overall acceptability, and well above the scores for patties with 30% TSP. TWP0.2MNaoH was then tested by sensory, physical, and instrumental analysis at three usage levels, 30, 40, and 50%, against 100% beef patties. Patties with up to 40% TWP0.2MNaOH were well accepted (p < 0.05) by consumers, and had higher cook yield, less diameter reduction, and less change in thickness than 100% beef patties. These results suggest great potential for the use of textured whey protein as a meat extender.

The purpose of this research was to determine the effects of heating (including heating to ultra-high temperatures) homogenized ultrafiltered whole and skim milks on whey protein denaturation and milk's subsequent rennet coagulation properties: coagulation time, curd firmness, and microstructure. Whole and skim milk samples were ultrafiltered using a spiral wound ultrafiltration membrane system. Samples were preheated to 72°C for 58 s, held for 8 s then heated to 72, 89, 106, 123, or 140°C for more than 97 sand held for 4 s. The milk was then cooled to 60°C and homogenized, further cooled to 30°C, packaged into 120 ml sterile containers, and refrigerated overnight. Rennet coagulation time and curd firmness were monitored using a Formagraph . Milk and gel samples were fixed in 2.5% glutaraldehyde solution and examined by electron microscopy. Whey protein denaturation was determined by precipitating casein at pH 4.6 with .lN HCl and measuring protein content in the filtrate by the Kjeldahl procedure. Rennet coagulation time of milk increased as processing temperature was increased. Gel strength decreased with an increase in processing temperature. Ultrafiltration shortened rennet coagulation time and increased gel firmness. Ultra-high- temperature- heated whole and skim milks did not coagulate upon addition of rennet, but their concentrated counterparts did. Rennet coagulation of the concentrated milks was delayed by heating. Samples treated with ultra-high-temperature formed only a weak gel. The casein micelles in milk increased in size as a function of increasing processing temperature and concentration by ultrafiltration. Additional protein material adhered to the casein micelles after high-temperature processing and was especially noticeable in the samples treated with ultra-high-temperature. Whey protein denaturation increased as a function of increased heating temperature. The heated concentrated milks had higher levels of protein denaturation than the heated unconcentrated ones.

The purpose of this study was to evaluate the effectiveness of a whey protein isolate (WPI), a reported glutathione (GSH) booster, on exercise performance, immune function, and antioxidant status during weight maintenance and energy restriction in humans. Twenty well-trained, college age, male cyclists performed a cycling exercise test for 45 min, the first 7 min at 70% of VO2peak and the remaining 38 min at 55% VO₂peak immediately followed by a performance test set at 90% VO2peak until exhaustion. Blood samples were collected prior to the exercise test, after 45 min of exercise, within 5 min of exhaustion, and 1 h after exercise. Blood samples were analyzed for GSH, GSH/GSSG ratio, glutathione peroxidase (GPx), lipid hydroperoxides (LPO), phagocytosis, oxidative burst, peripheral blood mononuclear cell (PBMC) proliferation, and PBMC phenotyping. Subjects consumed 40g/day of WPI or casein placebo (P) along with their normal diet for 2 wk, repeated the exercise test, and then began a low energy period continuing the same supplementation for 4 d before the final exercise test. WPI was not associated with superior exercise performance or antioxidant status following exercise or weight loss. WPI supplementation did result in 33% greater lymphocyte proliferation capacity following exercise. Following exhaustive exercise for all trials, tGSH and GPx increased 7% and 11%, respectively, while WBCGSH decreased 13%. For WPI, GPx activity was 10% lower than P following exhaustive exercise for all trials combined. Weight loss (2.67 ± 0.26 kg) resulted in increases in phagocytosis (65%), white blood cell (WBC) GSH (40%), and GPx (35%) while decreasing the GSH/GSSG ratio (55%) and LPO (16%). Exhaustive exercise caused a 28% increase in CD8+ PBMCs and decreased CD4+ (34%), CD3+ (15%), the CD4+/8+ ratio (45%), and phagocytosis (8%) with all values returning to baseline after 1 h recovery. Supplementation with WPI did not enhance GSH status or exercise performance in trained cyclists, during weight maintenance or energy restriction. Following exercise, WPI is associated with greater lymphocyte proliferation of PBMCs which may help maintain an athlete's health during heavy training or competition. / Ph. D.