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Call number: LD2668 .T4 1985 M375 / Master of Science

Master of Science / Department of Grain Science and Industry / X. Susan Sun / Soybean protein modified with sodium bisulfite behaves like latex adhesives, with adhesive strength comparable to formaldehyde-based adhesives. β-conglycinin and glycinin are two major protein components of the adhesive system. The objective of this research was to investigate the effect of sodium bisulfite on the physicochemical, morphological, and adhesion properties of glycinin and β-conglycinin in order to better understand the function of glycinin and β-conglycinin in the formation of the soy latex adhesive. Sodium bisulfite broke the disulfide bonds that linked acidic and basic polypeptides of glycinin, and the reducing effect was enhanced with increasing sodium bisulfite concentration. Although cleavage of disulfide bonds was expected to destabilize proteins, the thermal stability of glycinin increased as the sodium bisulfite concentration increased. Sodium bisulfite modified glycinin had higher surface hydrophobicity, which facilitated hydrophobic interations between molecules and aggregation of glycinin. The balance between hydrophobic interactions and electrostatic forces makes glycinin form unique chain-like structures. Adhesive performance of glycinin dropped significantly at lower sodium bisulfite concentration and then increased as sodium bisulfite concentration increased up to 24 g/L. Excess sodium bisulfite was detrimental to adhesive strength and water resistance. High-molecular-weight aggregates were observed in unmodified β-conglycinin, but these aggregates were dissociated by sodium bisulfite treatment. Similar to glycinin, the thermal stability of β-conglycinin was improved by the modification. However, the denaturation enthalpy of β-conglycinin decreased significantly at high level of sodium bisulfite (36 g/L). The turbidity at pH 4.8 also dropped extensively at the concentration of 36 g/L. The contact angle of β-conglycinin reached its minimum at 6 g/L sodium bisulfite on cherry wood and 24 g/L on glass. Morphology study proved that sodium bisulfite modification made the β-conglycinin solution more dispersed. At pH 9.5, water resistance of β-conglycinin was improved to a small extent by 6 g/L sodium bisulfite. At pH 4.8, adhesive performance was enhanced by 3 g/L and 6 g/L sodium bisulfite. High level of sodium bisulfite at 36 g/L reduced the adhesive performance of β-conglycinin drastically.

The increasing demand for energy in combination with a greater awareness for our environmental impact have encouraged the development of sustainable energy sources, including materials for energy storage. Latent heat thermal energy storage by the use of phase change material (PCM) have become an area of great interest. It is a reliable and efficient way to reduce energy consumption. PCMs store and release latent heat, which means that the material can absorb the excess of heat energy, save it and release it when needed. By introducing soy wax as a biobased PCM and apply it on textile, one can achieve a thermoregulation material to be used in buildings and smart textiles. By replacing the present most used PCM, paraffin, with soy wax one cannot only decrease the use of fossil fuel, but also achieve a less flammable material. The performance of soy wax PCM applied on a textile fabric have not yet been investigated but can be a step towards a more sustainable energy consumption. The soy wax may also broaden the application for PCM due to its low flammability. The aim is to develop an environmental friendly latent heat thermal energy storage material to be used within numerous application fields.

There is demand for improved security of refrigerated ready-to-eat meats. Antimicrobial edible films and coatings could function as an added barrier against post-processing contamination. Hops and hop extracts are known for their antimicrobial efficacy which is attributed to key antimicrobial components including humulones, lupulones, xanthohumol and various terpenoids. Yet, hop ethanol extract has not been studied as an antimicrobial to incorporate into edible protein films and/or coatings. The overall objective of this research was to evaluate hop ethanol extract as an antimicrobial agent incorporated into edible soy protein isolate (SPI) films and coatings, and the influence on the shelf-life and sensory attributes of bologna. Hop ethanol extract was examined for minimum inhibitory concentration before the extract was incorporated into a 6% SPI solution at 0, 10, and 20% levels to determine antimicrobial efficacy as a cast film and simulated coating via zone of inhibition against Listeria monocytogenes strains ATCC 4644, UKADL and ATCC 49594. The results showed that hop ethanol extract alone was inhibitory of all three strains. Moreover, the hop ethanol extract, when incorporated at 10 and 20% (v/v) into edible soy protein isolate (SPI) films and simulated coatings, exhibited antimicrobial action against all three L. monocytogenes strains. Key antimicrobial components, as mentioned above, were identified in the hop ethanol extract via mass spectrometry. The SPI with 10% incorporated hop ethanol extract (SPI+10%hop) antimicrobial coating was applied to bologna, prepared in lab without L. monocytogenes inhibitors, where it exhibited a significant (P ≤ 0.05) bacteriostatic effect against strain ATCC 4644. The SPI+10% hop coating was then applied to a commercial bologna to examine effects on shelf-life and sensory attributes. Significant differences (P ≤ 0.05) were found in instrumental red and yellow colors, however not in sensory color. There was no significant difference (P > 0.05) found in measured lipid oxidation between the bologna with no coating, SPI coating or SPI+10%hop coating. The incorporation of hop did exhibit a slightly bitter taste. Overall, these findings indicate that the SPI+10%hop antimicrobial coating functioned as an inhibitor of L. monocytogenes while producing minimal effects on shelf-life and sensory attributes of bologna.

The concentrated protein fractions of soyabeans, known as soya protein isolate, was produced by three different methods from the same raw material namely defatted soya flakes. Extraction of the soluble fraction of the raw material is common to all three methods. A study was therefore undertaken to optimise the extraction process conditions in terms of time, temperature, pH, extraction time, extraction volume and raw material particle size, thereby maximising yields of soluble material. The three different methods, namely isoelectric precipitation, ultrafiltration and swollen gel technology were then used to separate the soluble and non-soluble protein fractions. Both the isoelectric and ultrafiltration methods gave good yields of finished product, with the ultrafiltration process giving the better overall yield, but the swollen gel method gave disappointing results and was not feasible in practice. Functional properties of the products from the isoelectric and ultrafiltration methods were compared and found to be broadly similar although different in certain respects from those of commercial soya isolates. Levels of the anti-nutritional factors trypsin inhibitor and phytate in products from the three processes were determined and the substantial differences observed in trypsin inhibitor levels were further investigated. Determination of lysinoalanine levels was also attempted but the results obtained were unsatisfactory. Amino acid composition and polyacrylamide gel electrophoresis were used to compare the chemical composition of products from the three processes. The comparative economics of the isoelectric and ultrafiltration processes for large scale production of soya protein isolates were evaluated, taking into account the comparative efficiencies of the two processes as determined during the study. It was established that, while the isoelectric process initially appears more economical, it may be possible to modify the ultrafiltration process in such a manner as to make it more economical than the isoelectric process. Overall figures however indicate that the manufacture of soya protein isolate in South Africa is not currently a viable economic proposition, due to high raw material costs. / Thesis (M.Sc.)-University of Natal, 1995.

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Doctor of Philosophy / Department of Grain Science and Industry / Praveen V. Vadlani / Soy meal (SM) is the main protein source for monogastric animals. Anti-nutritional factors in SM limited its usage for young monogastric animals. Aspergillus was investigated to degrade these factors and to enhance its nutritional value via solid state fermentation. Galacto-oligosaccharides were totally degraded from the initial 9.48 mmol/100 g, and trypsin inhibitor decreased from 10.7 TIU/mg to a non-detectable level after 36 hr fermentation. Structural polysaccharides decreased by 59% (w/w) and the degree of hydrolysis of SM protein increased from 0.9% to 7% (w/w) through the 7 d fermentation. Fermentation also modified nutritional factors. Protein content increased from 50.47% (w/w) to 58.93% (w/w) after 36 hr fermentation. Amino acid profile was significantly enhanced. Two - stage temperature-induced fermentation protocol was developed to increase the degradation rate of phytic acid by A. oryzae (ATCC 9362) and by A. ficuum (ATCC 66876). The first stage maximized phytase production with fermentation parameters obtained by central composite design. The second stage achieved maximum enzymatic degradation with parameters obtained by studying the phytase temperature characteristics. While using A. oryzae, 57% of phytic acid in SM was degraded by the two stage protocol compared to 39% degradation from single stage fermentation. For A. ficuum, the two-stage temperature fermentation protocol achieved a 98% degradation level of phytic acid degradation compared with the single stage process. Two-stage temperature-induced co-fermentation of A. oryzae and A. ficuum was investigated to simultaneously degrade phytic acid and soy protein with high efficiency. Co-fermentation of A. oryzae and A. ficuum resulted in higher phytic acid degradation than A. oryzae fermentation and superior protein hydrolysis compared to A. ficuum fermentation. Sterilization distorted the results of fermentation effect on soy allergens and soy protein degradation. Virginiamycin is a kind of bacterisin. It was added to A. oryzae solid state fermentation, to exclude the necessity of SM sterilization. Nonsterile, solid state fermentation using A. oryzae and virginiamycin showed the complete degradation of α and α’ subunits of β-conglycinin and decreased immunoreactivity of soy protein. The modified SM after microbial bioprocessing created an innovative product with enhanced characteristics with potential wider applications for feed industry.

Doctor of Philosophy / Department of Grain Science and Industry / Xiuzhi Susan Sun / Soy protein is one of the most promising bio-degradable adhesives, with great potential as alternatives synthetic petroleum based adhesives for wood composite industries. However, its intrinsic drawbacks such as low water resistance, high viscosity, and short shelf life still limit its broad application. In this research, soy protein was further modified and characterized to improve adhesion properties, flow-ability, water resistance, and long shelf life, which could facilitate the industrialization of soy protein based adhesives. In this study, we exploited the in situ sodium bisulfite (NaHSO3) modification on soy protein in soy flour-water extracts, and then the modified soy protein was obtained through acid precipitation. First, different concentrations of NaHSO3 were used to modify soy flour slurry, then glycinin-rich and β-conglycinin-rich fractions were precipitated at pH 5.4 (SP 5.4) and pH 4.5 (SP 4.5), respectively. Unmodified sample SP 5.4 and SP 4.5 showed clay-like properties and viscoelastic properties, respectively; whereas with addition of NaHSO3 in range of 2-8 g/L, both SP 5.4 and SP 4.5 had the viscous cohesive phase with good handability and flow-ability. The overall adhesion performance of SP 4.5 was better than SP 5.4; the wet strength of these two fractions was in the range of 2.5-3.2 MPa compared to 1.6 MPa of control soy protein isolate. Then soy protein with various β-conglycinin/glycinin (7S/11S) ratios were extracted from soy flour slurry and characterized for adhesion properties based on the different solubility of 7S and 11S globulins. Seven glycinin-rich soy protein fractions and six β- conglycinin-rich soy protein fractions were obtained. According to the morphology, viscosity, and particle size results, we proposed that proper protein-protein interaction, hydration capacity (glycinin-rich fractions), and certain 7S/11S ratios (β-conglycinin-rich fractions) in modified soy protein are crucial to continuous protein phase formation. The viscous cohesive samples were stable for up to several months without phase separation at room temperature, with the wet adhesion strength of 2.0-2.8 MPa. The soy protein modified with NaHSO3 showed good compatibility with commercial glues applied on plywood and paper labeling fields. The modified soy protein made some functional groups, carboxylic (-COOH), hydroxyl (-OH) and amino groups (-NH2) available, which cross-linked with hydroxymethyl groups (-CH2-OH) from urea formaldehyde (UF) wood glue. The modified soy protein (MSP) with pH 4.8 also acted as an acidic catalyst for the self-polymerization of UF based resin. The wet adhesion strength of MSP/UF blends (40/60) was 6.4 MPa with 100% wood cohesive failure, as compared to 4.66 MPa of UF. As to the paper labeling application, peel strength of MSP on glass substrate increased rapidly, with curing time much shorter than commercial polyvinyl acetate based adhesives (PVAc). And the MSP/ PVAc blends showed shorter curing time, higher water resistance and lower viscosity than pure PVAc. Chemical modification could also enhance the adhesion strength of MSP. 2-octen-1- ylsuccinic anhydride (OSA) was proved to be grafted on soy protein through reaction between amine, hydroxyl groups of protein and anhydride groups. The oily nature and hydrophobic long alkyl chains of OSA mainly contributed to the significant water resistance improvement of MSP.

No presente trabalho foi estudado o efeito do consumo de soja geneticamente modificada e de sua parental em parâmetros nutricionais e hematológicos em ratos em crescimento. Farinha de soja, desengordurada e autoclavada, foi incorporada em rações experimentais: 12% de proteína para o 1° ensaio e 10% para 2° ensaio. As rações com soja foram suplementadas com aminoácidos essenciais (Ieucina, lisina, metionina e vali na) no 2° ensaio, devido a menor concentração desses aminoácidos nas rações do 1° ensaio quando comparadas ao grupo controle, perfil confirmado pelo aminograma. Ratos Wistar (n=64) foram alimentados, ad libitum, com rações controle (AIN-93G) e rações com a farinha de soja por 28 (1° ensaio) e 32 dias (2° ensaio). Para avaliação do aproveitamento biológico da proteína da dieta e da qualidade protéica, foram realizadas análises de nitrogênio na carcaça dos animais, nas fezes e na urina que foram coletadas ao longo de 2 períodos de balanço de 6 dias cada ensaio. Os parâmetros nutricionais avaliados foram : Coeficiente de eficácia alimentar (CEA), Coeficiente de eficácia protéica (PER), Coeficiente de eficiência líquida da proteína (NPR), Valor biológico da proteína (BV), Coeficiente de utilização líquida da proteína (NPU), digestibilidade protéica e o \"Escore químico corrigido pela digestibilidade real da proteína\". Para avaliação do estado nutricional foram avaliadas as concentrações de albumina, proteínas totais e IGF-1 no plasma. Como parâmetros hematológicos, foram avaliados o hemograma completo, mielograma e esplenograma. Os resultados obtidos demonstraram que animais alimentados com soja GM e sua parental apresentaram desenvolvimento semelhante ao grupo controle (caseína). Os valores de CEP e NPR encontrados nos 2 ensaios mostram que a proteína de soja é nutricionalmente adequada. A oferta protéica de 10% com suplementação com aminoácidos essenciais favoreceu no desenvolvimento dos animais, visto que foi observado aumento de peso em média de 50g, PER e NPR melhores quando comparados com a oferta protéica de 12% sem suplementação. Nos dois ensaios, os valores de digestibilidade dos grupos alimentados com soja foram inferiores aos do grupo controle, resultado evidenciado pela maior dificuldade das enzimas digestivas em digerirem a proteína vegetal, maior perda de aminoácidos endógenos e quantidade de fibra insolúvel presente na soja. O valor de POCAA de 85% demonstra bom aproveitamento dos grupos com soja. Não houve diferença estatística nos parâmetros plasmáticos estudados, bem como nos resultados hematológicos sugerindo que o consumo de soja, convencional ou GM, não altera o estado nutricional dos animais. / In the present work, the effects of genetically modified (GM) soybean and its parental on nutritional and hematological parameters in growing rats were studied. Autoclaved, fat-free soybean flour was added to experimental diets: 12% protein in the first assay and 10% in the second assay. The soybean diets were supplemented with essential amino acids (Ieucine, Iysine, methionine and valine) in the second assay, since such amino acids presented a lower concentration in the diets of the first experiment, as confirmed by the aminogram. Wistar rats (n= 64) were fed a control diet (AIN-93G) and diets supplemented with soybean flour (parental and GM) ad libitum over 28 days (1st experiment) and 32 days (2nd experiment). For evaluating the biological utilization of dietary protein and protein quality, nitrogen analyses were carried out on the animal carcasses, feces and urine. Feces and urine were collected along two 6-day periods within each assay. The following nutritional parameters were evaluated: feed efficiency ratio (FER), protein efficiency ratio (PER), net protein ratio (NPR), biological value (BV), net protein utilization (NPU), protein digestibility and protein digestibility corrected by amino acid (POCM) score. For evaluating the nutritional status, plasma albumin, total proteins and IGF-1 were analysed. Complete hemogram, myelogram and splenogram were used as hematological parameters. The results indicate that animals fed the GM soybean and its parental showed a similar growth rate to the control group (casein). PER and NPR values found in both assays show that soybean protein is nutritionally adequate. A diet containing 10% protein supplemented with essential amino acids favored the growth of the animals in comparison to a diet containing 12% protein without amino acid supplementation. In both assays, the protein digestibility in soybean-fed groups was lower than in the control group, a result evidenced by a greater difficulty of enzymes in digesting vegetal proteins, a greater loss of endogenous amino acids and the presence of insoluble dietary fiber in the soybean. A POCM value of 85% showed a good protein utilization in the soybean-fed groups. No statistically significant differences were observed in the plasmatic and hematological parameters among the groups, suggesting that consumption of soybean (either GM or parental) does not alter the nutritional status of the animals.