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Doctor of Philosophy / Department of Grain Science and Industry / Xiuzhi Susan Sun / Soy protein is one of the most promising bio-degradable adhesives as an alternative to synthetic petroleum-based adhesives for wood composite industries. In this study, soy protein was modified to improve adhesion properties and water resistance, which could facilitate the industrialization of soy protein-based adhesives. Furthermore, we attempted to identify a reliable indicator to predict the adhesion properties of soy protein by establishing the correlation of physical and mechanical properties with adhesion properties of soy protein. One of the objectives in this work was to investigate if inorganic calcium silicate hydrate (CSH) hybrids could improve adhesion properties of soy protein-based adhesives. 3-aminopropyltriethoxysilane (APTES) was used as a crosslinking agent between organic soy protein and inorganic CSH phases. APTES helped to form a crosslinked interface between soy protein and CSH, which was confirmed by changes in thermal, rheological, spectroscopic, and morphological properties with aging effect. More entangled structure and reduction of water-sensitive functional groups could lead to improvements in adhesion strength compared to unmodified soy protein-based adhesives. The second objective was to identify reliable indicators to predict shear adhesion properties by building the correlation between physical properties and adhesion properties of enzymatically modified soy protein-based adhesives (ESP). ESP was prepared with three independent variables (X1: trypsin concentration, X2: incubation time, and X3: glutaraldehyde (GA) concentration as a crosslinker) using a response surface methodology (RSM) called a central composite design (CCD). The important physical properties of viscosity (Y1), tacky force (Y2), and water resistance (Y3) were measured and investigated their relationship with adhesion strength. Viscosity, tacky force and water resistance showed solid correlation with adhesion strength of ESP and they were used to predict adhesion performance of soy protein modification system in this work. In addition, we studied the correlation between film strength and adhesion strength of another soy protein system. Because cohesion among protein molecules plays an important role in film and bonding mechanisms, we assumed that the film strength may be a reliable indicator to predict the adhesion strength of soy protein. The mechanical properties of the film and adhesion properties of soy protein on cherry wood were measured in terms of different concentrations of plasticizer (poly (propylene glycol) bis (2-aminopropyl ether) (H2N–PPG–NH2)). The results found out the low correlation between film and adhesion strength of soy protein in the presence of the plasticizer. We believe this might be caused by different curing conditions for film and adhesive applications of soy protein. Curing conditions greatly affect the thermal and curing behavior as well as mechanical properties of final materials. Thus, similar or comparable curing conditions should be required to obtain the information on the relationship between film and adhesion strength of soy protein.

Canola protein isolate (CPI) has tremendous potential as a protein alternative to soy within the global protein ingredient market. The overall goal of this thesis was to compare and contrast the gelling mechanism of CPI with a commercial soy protein isolate (SPI) ingredient. Specifically, the gelation properties of CPI and SPI were evaluated as a function of protein concentration (5.0–9.0%), destabilizing agent [0.1 – 5.0 M urea; 0.1 and 1.0% 2-mercaptoethanol], ionic strength (0.1, 0.5 M NaCl) and pH (3.0, 5.0, 7.0, 9.0). The fractal properties of CPI were evaluated as a function of protein concentration (5.0 – 9.0%) and pH (3.0, 5.0, 7.0, 9.0). In the first study, the gelling properties of CPI and SPI as a function of concentration were evaluated, along with the nature of the interactions within their respective gel networks. Overall, the magnitude of the storage modulus (G') of the gel was found to increase with increasing concentration at pH 7.0, whereas the gelling temperature (Tgel) remained constant at ~88ºC. As the NaCl level was increased from 0.1 to 0.5 M, the zeta potential was found to be reduced from ~-20 to -4 mV, but with little effect on Tgel or network strength. In the presence of 2-mercaptoethanol, networks became weaker, indicating the importance of disulfide bridging within the CPI network. Disulfide bridging, electrostatics and hydrogen bonding are all thought to have a role in CPI gelation. In the case of SPI, the magnitude of the storage modulus (G') and Tgel were found to increase and decrease (~80ºC to 73ºC), respectively, with increasing urea concentration at pH 7.0. Increases in NaCl from 0.1 to 0.5 M reduced the zeta potential from ~-44 to -13 mV and caused a shift in Tgel from ~84ºC to 67ºC, and increased G'. No gels were formed in the presence of 2-mercaptoethanol. In the second study, the effect of pH on the gelling properties of CPI and SPI was evaluated. Surface charge (i.e., zeta potential) measurements as a function of pH found CPI to be positively (+18.6 mV), neutral and negatively (-32 mV) charged at pH 3.0, ~5.6 and 9.0, respectively. On the other hand, SPI was observed to be positively (+35.4 mV), neutral and negatively (-51 mV) charged at pH 3.0, 5.0 and 9.0, respectively. An increases in NaCl concentration from 0 M to 0.1 M resulted in a reduction in surface charge at all pHs for both CPI and SPI. Differential scanning calorimetry was performed to determine the thermal properties of CPI. The gelation temperature was found to be above the onset temperature for denaturation. For CPI, the onset of denaturation was found to occur at ~68ºC and then increased to ~78-79ºC at pH 7.0-9.0. With respect to rheological properties, SPI did not gel at pH 9.0, and G' declined as pH increased from 3.0 to 7.0. CPI did not gel at pH 3.0, however the network formed at pH 5.0 became stronger (higher G') as pH increased. The SPI gelling temperature at pH 3.0, 5.0 and 7.0 was observed to be ~85.6, ~46 and ~81ºC, respectively. SPI gels formed at pH 5.0 earlier due to increased protein aggregation near its isoelectric point (pI). The gelation temperature for CPI at pH 5.0 and 7.0 were similar (~88ºC), then declined at pH 9.0 (~82ºC). Network structure of CPI as a function of pH also was investigated using confocal scanning light microscopy (CSLM). As the pH became more alkaline from pH 7.0 to pH 9.0, there was a decrease in lacunarity (~0.41->~0.25). However, the fractal dimension was found to increase (from ~1.54 to ~1.82) showing that increasing the pH resulted in a more compacted CPI network. In summary, protein-protein aggregation induced either by increasing concentration or changing the pH resulted in network formation for both CPI and SPI, where both networks were thought to be stabilized by disulfide bridging and hydrogen bonding. SPI underwent protein aggregation earlier than CPI near its pI value, whereas CPI gels formed the strongest networks away from its pI under alkaline conditions. In all cases, CPI grew in diffusion-limited cluster-cluster aggregation to from the gel network.

Every year, accidents, falls, sport injuries and other incidents cause thousands of people to suffer spinal cord injury (SCI). In the United States alone, it is estimated that the number of Americans that live with SCI is around 259,000, with 12,000 new cases that happen annually (1). These injuries lead to spinal cord damages expressed by massive nerve tract degeneration followed by neurological loss, paralysis and disabilities. Therapy of SCI patients with non-steroidal anti-inflammatory drugs (NSAIDs) help in diminishing secondary injury and lessen pain and swelling. However these drugs do not promote tissue repair. Therefore there is an unmet clinical need to develop technologies and therapeutic strategies that compensate loss of neuronal tissue, support and facilitate reestablishment of nerve tracks connectivity in the injured spinal cord. Recent progress in nerve regeneration indicates that a tissue engineering approach using soft tissue scaffolds, stem cells and neurotrophins, can lead to a partial therapy in animal models of SCI. Bioengineered scaffolds prepared by freeze casting technology provide an experimental tool for guidance of regenerating neuronal tracts and/or axons and therefore are useful for regeneration of injured spinal cord. In this engineering approach for scaffold preparation, temperature controlled directional solidification of an aqueous polymer(s) solution creates channels of different diameters that can direct axonal outgrowth of neurons populating the scaffold. In a previous study from our laboratory, such scaffolds promoted differentiation of neurons, a process facilitated by co-population of the scaffold’s channels with endothelial cells. “Green” plant proteins, such as soybean proteins, are becoming an attractive alternative source of natural polymers for a variety of biomedical applications including scaffold fabrication for neuronal tissue regeneration. In the present study, we developed a second generation of improved, microchanneled composite scaffolds from gelatin and soy protein isolate cross-linked with genipin (2 w/v %, 0.5 w/v %, 1 w/v %, respectively). The fabrication of these scaffolds by a controlled freeze drying technique, their mechanical properties (stiffness, ~3-4 kPa) as well as their uniform longitudinal channels of a diameter of ~30-55 µm is described. Preliminary biocompatibility experiments in 2D and 3D using the above mentioned scaffolds populated with either undifferentiated PC12 cells or nerve growth factor differentiated PC12 cells indicated partial biocompatibility of the scaffolds for neuronal growth. Improving the biocompatibility of these composite scaffolds is under investigation in our laboratory. / Bioengineering

Many sources of protein have been investigated to reduce the use of fish meal (FM) in aquaculture feeds, including soybean meal (SBM). However, FM replacement in feeds for carnivorous species is limited by problems with feed intake, growth rate, and overall health associated with reduced digestibility and anti-nutritional factors found in SBM. However, soy processing strategies can reduce the effects of anti-nutritional factors and improve utilization. Therefore, we examined the possibility of further FM replacement in SBM maximized feeds for hybrid striped bass using refined soy products, soy protein concentrate (SPC) and soy protein isolate (SPI). Results indicate that further FM sparing is possible, beyond what can be achieved with SBM. For example, it is possible to reduce dietary FM content as low as 5% using SPC, and though this negatively affects growth rate, this effect may be reversed by the addition of a betaine-based attractant. Replacement with SPI resulted in such a degree of feeding reluctance that starvation and cannibalization became issues during the trial. Reducing FM content below 5-10% resulted in more variable production performance and, when using SPI, increased incidence of cannibalism. No differences in stress tolerance were observed during the trials; however, there was a trend of increasing handling mortality in fish fed the SPC diets. Refined soy proteins can be used in conjunction with SBM to spare FM, but the cost of these products, along with their acceptability to aquatic livestock, will determine the extent of their utilization in aquafeeds.

Master of Science / Department of Grain Science & Industry / Xiuzhi Susan Sun / Bio-based protein adhesives derived from renewable resources, especially soy protein are becoming more significant due to the concerns about environment and health related issues and the limit of petroleum recourses. However, the relatively poor water resistance of soy-based protein adhesives limits its wide applications. The goal of this study was to improve the water resistance performance of soy-based protein adhesives by chemical modification. The specific objectives are 1) to modify soy protein with calcium carbonate (CaCO[subscript]3) and sodium bisulfite (NaHSO[subscript]3) as the denaturing agents; 2) to investigate the effects of calcium carbonate (CaCO[subscript]3) concentrations, curing time and curing temperatures on adhesion performance of the modified soy-based protein adhesives. In this study, the co-effects of NaHSO[subscript]3 and CaCO[subscript]3 on adhesion properties of soy protein adhesives were investigated. NaHSO[subscript]3 was added to soy flour slurry at constant concentration 6g/L, while concentration of CaCO[subscript]3 was chosen in the range of 0 to 23g/L. Soy protein adhesives modified with 4g/L and 16g/L CaCO[subscript]3 were selected to characterize the adhesion performance on 3 ply yellow pine plywood using the Response Surface Method (RSM). The effects of curing temperature and curing time on the adhesion properties were also studied. The major findings are 1) 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 modified soy protein adhesives (MSPA) had better adhesion performance (both dry and wet) than 16g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA; 2) Higher temperature (170°C) resulted in higher wet shear adhesion strengths; 3) Longer hot press time had positive impact on wet adhesion shear strength; and 4) 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA showed better adhesion shear strength after 2 weeks storage than 16g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA. In general, 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA, under longer hot press time and higher temperature would lead to a better adhesion performance.

Oxidation plays an important role in the basic processes of life, such as the production of energy and phagocytosis employed by the immune system. However, when an imbalance between oxidants and antioxidants exists in vivo, oxidation can become uncontrolled and result in diseases such as arthritis, cancer, artherosclerosis, and Alzheimer’s Disease. Dietary antioxidants including polyphenolic compounds, proteins, and peptides have been identified as being physiologically functional foods capable of contributing to the restoration of this oxidant-antioxidant balance. The objective of this study was to explore the production of antioxidant soy peptides from a commercially available soy protein isolate (SPI) by enzymatic hydrolysis in a process similar to that occurring in the human digestive tract. In this study Archer-Daniels Midland SPI PRO-FAM 974 was used as a raw material for the production of antioxidant soy peptides. The digestion consisted of enzymatic digestion of the SPI (3.12 wt %) with pepsin (37ºC, pH 1.5) and/or pancreatin (40ºC, pH 7.8) either individually or sequentially. The enzyme concentration and digestion time for each enzyme was optimized using a 2^4 factorial experimental design to produce the greatest concentration of peptides quantified in PheGly equivalents by the OPA assay. A maximum peptide concentration of approximately 65 mM PheGly equivalents was achieved in the follow-up digests resulting from this factorial design model, using pepsin (0.15 g/L, 15 minutes) and pancreatin (4.5 g/L, 120 minutes) sequentially to digest the SPI. Fractionation of the peptides by sequential dead-end membrane ultrafiltration with molecular weight cut-offs (MWCO) of 3 kDa and 1 kDa was performed to produce peptide fractions with increased antioxidant capacity. The permeate flux as a function of time was fit to empirical models, revealing that the membrane fouling resulting in the permeate flux decline is largely reversible and most likely the result of cake filtration. Antioxidant capacity was quantified by the DPPH, FCR, and ORAC assays to determine the electron-donating and proton-donating capacities of the soy peptides. The electron-donating DPPH assay was not suitable to quantify the antioxidant capacity of the soy peptides due to poor peptide solubility in the assay media and sensitivity. The electron-donating FCR assay and the proton-donating ORAC assay were used to distinguish between the ultrafiltration and digestion conditions employed to produce the soy peptides and the antioxidant capacity was quantified in equivalence to the standard antioxidant Trolox. The soy peptide fraction with the greatest antioxidant capacity was produced by enzymatic digestion with pancreatin (4.5 g/L, 120 minutes) alone and had a molecular weight cut-off of between 3 kDa and 1 kDa. This fraction had an equivalent antioxidant capacity of approximately 190 mg Trolox/g sample in the ORAC assay and approximately 180 mg Trolox/g sample in the FCR assay. A preliminary linear model for the optimum digestion and ultrafiltration conditions for the production of antioxidant peptides with the greatest ORAC antioxidant capacity was also developed. The model includes a positive pancreatin digestion time term and a negative pepsin digestion time term. No ultrafiltration terms were found to be significant in this preliminary model, but a large constant term persisted. In conclusion, the enzymatic digestion of commercially available SPI with pancreatin and fractionated by ultrafiltration successfully produced a soy peptide fraction with increased antioxidant capacity.

Oxidation plays an important role in the basic processes of life, such as the production of energy and phagocytosis employed by the immune system. However, when an imbalance between oxidants and antioxidants exists in vivo, oxidation can become uncontrolled and result in diseases such as arthritis, cancer, artherosclerosis, and Alzheimer’s Disease. Dietary antioxidants including polyphenolic compounds, proteins, and peptides have been identified as being physiologically functional foods capable of contributing to the restoration of this oxidant-antioxidant balance. The objective of this study was to explore the production of antioxidant soy peptides from a commercially available soy protein isolate (SPI) by enzymatic hydrolysis in a process similar to that occurring in the human digestive tract. In this study Archer-Daniels Midland SPI PRO-FAM 974 was used as a raw material for the production of antioxidant soy peptides. The digestion consisted of enzymatic digestion of the SPI (3.12 wt %) with pepsin (37ºC, pH 1.5) and/or pancreatin (40ºC, pH 7.8) either individually or sequentially. The enzyme concentration and digestion time for each enzyme was optimized using a 2^4 factorial experimental design to produce the greatest concentration of peptides quantified in PheGly equivalents by the OPA assay. A maximum peptide concentration of approximately 65 mM PheGly equivalents was achieved in the follow-up digests resulting from this factorial design model, using pepsin (0.15 g/L, 15 minutes) and pancreatin (4.5 g/L, 120 minutes) sequentially to digest the SPI. Fractionation of the peptides by sequential dead-end membrane ultrafiltration with molecular weight cut-offs (MWCO) of 3 kDa and 1 kDa was performed to produce peptide fractions with increased antioxidant capacity. The permeate flux as a function of time was fit to empirical models, revealing that the membrane fouling resulting in the permeate flux decline is largely reversible and most likely the result of cake filtration. Antioxidant capacity was quantified by the DPPH, FCR, and ORAC assays to determine the electron-donating and proton-donating capacities of the soy peptides. The electron-donating DPPH assay was not suitable to quantify the antioxidant capacity of the soy peptides due to poor peptide solubility in the assay media and sensitivity. The electron-donating FCR assay and the proton-donating ORAC assay were used to distinguish between the ultrafiltration and digestion conditions employed to produce the soy peptides and the antioxidant capacity was quantified in equivalence to the standard antioxidant Trolox. The soy peptide fraction with the greatest antioxidant capacity was produced by enzymatic digestion with pancreatin (4.5 g/L, 120 minutes) alone and had a molecular weight cut-off of between 3 kDa and 1 kDa. This fraction had an equivalent antioxidant capacity of approximately 190 mg Trolox/g sample in the ORAC assay and approximately 180 mg Trolox/g sample in the FCR assay. A preliminary linear model for the optimum digestion and ultrafiltration conditions for the production of antioxidant peptides with the greatest ORAC antioxidant capacity was also developed. The model includes a positive pancreatin digestion time term and a negative pepsin digestion time term. No ultrafiltration terms were found to be significant in this preliminary model, but a large constant term persisted. In conclusion, the enzymatic digestion of commercially available SPI with pancreatin and fractionated by ultrafiltration successfully produced a soy peptide fraction with increased antioxidant capacity.

Orientadores: Lireny Aparecida Guaraldo Gonçalves, Priscila Efraim / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-18T18:52:26Z (GMT). No. of bitstreams: 1 Stroppa_ValterLuisZuliani_M.pdf: 1829992 bytes, checksum: 1eb19d94141314569616332614683d54 (MD5) Previous issue date: 2011 / Resumo: Chocolates são produtos compostos por uma fase lipídica com predominância de manteiga de cacau, e que contem liquor, açúcar emulsificantes e eventualmente leite em pó (ou derivados lácteos) e aromas. As características físicas dos chocolates como brilho, dureza, fusão a temperaturas da boca e estabilidade térmica são conseqüências da estruturação cristalina induzida na manteiga de cacau. Os triacilgliceróis presentes na manteiga de cacau podem-se organizar em até seis formas polimórficas sendo que apenas duas são estáveis e geram produtos de melhor qualidade. A adição de emulsificantes ao chocolate visa melhorar o comportamento reológico durante o processamento diminuindo as tensões interfaciais entre a fase gordurosa e as partículas sólidas. Os emulsificantes promovem o recobrimento das partículas sólidas com a fase oleosa lubrificando as interfaces que, desta maneira, poderão servir de elementos ativos para a nucleação. Este trabalho avaliou o efeito da adição dos dois emulsificantes mais utilizados na indústria, lecitina de soja e PGPR (poliglicerol poliricinoleato), no processo de estruturação cristalina de chocolate amargo. Foram produzidos chocolates com diferentes teores de emulsificantes conforme um planejamento fatorial completo 2² rotacionado. O nível de lecitina variou de 0,08 a 0,92% e o de PGPR de 0,02 a 0,58%. Para caracterizar esta influência foram utilizadas técnicas de reometria (determinação das propriedades de escoamento), ressonância magnética nuclear (acompanhamento da cinética de cristalização), Índice de temperagem (quantificação da pré-cristalização), e ensaios de ruptura (avaliação da resistência estrutural). Os valores de viscosidade plástica de Casson do chocolate medidos a 40ºC variaram de 1,4 a 5,9 Pa.s enquanto que o limite de escoamento variou de zero a 34Pa. Os parâmetros cinéticos avaliados de isotermas de cristalização a 15ºC ajustadas ao Modelo de Avrami resultaram no expoente n variando de 2,598 a 2,956 e o parâmetro k entre 5,15.10-6 e 2,85.10-5 min-n para os diferentes teores de emulsificantes. Estes efeitos foram associados à capacidade da lecitina em aumentar o volume cristalino e ao potencial nucleador do PGPR / Abstract: Chocolates are confectionary products composed by a lipid phase based mainly on cocoa butter that contains cocoa mass, sugar, emulsifiers and eventually milk solids and aromas. Physical characteristics of chocolates like gloss, hardness, melting at mouth temperature and thermal stability result from the crystalline structuration accomplished by the fat phase. The triacylglycerols in cocoa butter can be organized in up to six different polymorphs but only two of them are stable and therefore yield better quality products. The addition of emulsifiers to chocolates intends to improve the rheological behavior during processing by the reduction of the interfacial tension between the fat phase and the solid particles. The emulsifiers promote the coating of the solid particles by an oily layer, lubricating the interfaces that then can serve as active elements for nucleation. This work examines the effects of the addition of the two most used emulsifiers in chocolate, namely soy lecithin and PGPR (polyglycerol polyricinolate) in the crystalline structuration of chocolates. Chocolates with different contents of the two emulsifiers were produced, following a 22 complete factorial rotational design. The lecithin level varied from 0.08 to 0.92% and the PRPG content from 0.02 to 0.58%. The influence of the additives was characterized by rheometry (determination of the flowing parameters), nuclear magnetic resonance (monitoring the crystallization kinetics), Temperindex (pre-crystallization level quantification), and snap test (structural resistance). The values of Casson's plastic viscosity of the chocolates, measured at 40ºC, varied from 1.4 to 5.9 Pa.s while the yield value ranged between zero to 34 Pa. The kinetic parameters evaluated from crystallization isotherms at 15ºC modeled by the Avrami equation resulted in the exponent n varying from 2.598 to 2.956 and k parameters between 5.15 10-5 min-n and 2.85 10-5 min-n when the different amount of emulsifiers were used. These effects are associated to the ability of lecithin to enlarge the crystal volume and to the nucleating potential of PGPR / Mestrado / Engenharia de Processos / Mestre em Engenharia Química