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

Soy flour was inoculated with Lactobacillus delbrueckii ssp. lattis R0187, and incubated for 8 h, to evaluate the protein hydrolysis and identify peptides generated by this fermentation, and the impact on ACE and trypsin inhibitory activities. Aqueous protein extracts prepared from different fermentation time periods showed a decrease in soluble protein content (from 2.83 to 0.02 mg/mL), while soluble inorganic nitrogen and free amino acid contents increased (from 0.029 to 0.062% w/w, and from 0.75 to 0.90% w/w, respectively). The protein extracts were analyzed by SDS-PAGE; proteolysis was observed after 5 h incubation of inoculated soy flour, suggesting that glycinin, beta-conglycinin, and trypsin inhibitors, were hydrolyzed. Peptides were isolated by tricine-SDS-PAGE, and analyzed by MS/MS; fragments of soy anti-nutritional factors (Kunitz and Bowman-Birk trypsir, inhibitors), as well as of other soybean proteins, were identified, confirming that these proteins were hydrolyzed. The protein extracts at time 0 h and 8 h were analyzed by RP-HPLC; one fraction was analyzed by MS/MS, which identified peptides from Lactobacillus species. Determination of trypsin inhibitory activity showed less inhibition of the enzyme with inoculated soy flour compared to the control (un-inoculated soy flour), confirming the deactivation of trypsin inhibitors by fermentation. Determination of ACE inhibitory activity showed a higher inhibition with the control (86% +/- 3.0) compared to inoculated soy flour (66% +/- 7.6).

No description available.

There is an increasing awareness in the food industry about the role that proper nutrition plays in maintaining health and preventing disease. Women especially have always been interested in nutrition and its impact on their well-being. This awareness has placed more pressure on the food industry to provide a greater variety of nutritious and wholesome products which has led to the development of a new field in the food industry, called functional foods. These are food products that apart from the micro- and macronutrients that it already provides have additional important physiologically active functions that enhance health. These active components, called phytochemicals (from plant sources) and zoochemicals (from animal sources) have changed the role of diet in health. Functional foods can, by nature or design, bridge the traditional gap between food and medicine and thereby provide consumers with the opportunity to become involved in their own health care. One of these functional foods that have been receiving increased attention and research is soy. Apart from other health benefits of soy, such as cholesterol reduction and bone strengthening, scientific evidence has shown that soy can be used as an alternative for hormone replacement therapy (HRT). The increased interest in the latter can be ascribed to the changed attitude of women, as well as evidence of the side effects of conventional hormone replacement therapies. Consumer research in the nutraceutical area is, however, still in its infancy stage. Objective: The main objective of this study was thus to assess South African consumers' opinion of the potential health benefits of soy and soy products as an alternative for HRT. To attain this main objective, the following specific objectives were stated: To determine, by means of a consumer questionnaire, the percentage of South African consumers who are aware of soy. To determine, by means of an attitude scale, the attitudinal disposition of South African consumers towards the potential health benefits of soy and soy products as an alternative for HRT. To determine South African consumers' opinions regarding the menopausal related health benefits of soy. To determine whether there is a relation between respondents who Eat/drink soy and their opinion of the potential health benefits of soy. To determine whether there is a relation between respondents who never use soy and their opinion of the bone strengthening benefit of soy. To determine whether there is a relation between respondents' opinion of the health benefits of soy and their opinions of soy as an alternative for HRT and reliever of menopausal symptoms, respectively. Methods: In this study, consumers' opinion regarding the health benefits of soy was evaluated using a questionnaire. Respondents were randomly selected from nine metropolitan, as well as rural areas in South Africa, representing the four main race groups, namely whites, blacks, coloureds and Indians. The total sample size of the metropolitan and rural subjects was 3001. A sub-dataset was created which included female respondents that have heard of soy before and were premenopausal (35-44 years) and post-menopausal (50-59 years) of age. Thus, the total number of respondents used for further statistical analyses was 825. The respondents expressed their opinions of the health benefits of soy on a five-point hedonic (Likert) scale which was adapted to a three-point scale for easier interpretation of the tables. Results: 1. Of the 3 001 respondents, 2 437 (80%) were aware of soy. 2. A mean attitudinal disposition score of 2.47 on a three-point scale indicated a neutral to positive attitudinal disposition of the South African consumer population towards the potential health benefits of soy and soy products as alternative for HRT. No practically significant differences were found between the mean values of each statement, which indicated that no specifically strong opinions were expressed between different races or between different age groups. 3. Of all the consumers surveyed and those who did express a specific opinion, 72% agreed that soy has many health benefits compared to only 7% who disagreed. Although 34% of South Africans expressed a positive opinion when asked if soy can be used as alternative for HRT, the majority (46%) of the population had a neutral opinion. Forty-two percent of the consumers who held an opinion regarding soy as reliever of menopausal symptoms were positive, 35% had a neutral opinion and 23% of South Africans did not agree that soy can relieve menopausal symptoms. 4. A relation, although not of practical significance, was found between respondents who eat/drink soy and their opinion of the health benefits of soy. Of the respondents who indicated that they eat/drink soy, the majority agreed that soy has many health benefits. The respondents who disagreed when asked if they eat/drink soy, still expressed an overall positive opinion when asked whether soy has many health benefits. 5. A relation, although not of practical significance, was found between respondents who never use soy and their opinion of the bone strengthening benefit of soy. Of those who indicated that they use soy, the majority agreed that soy has a bone strengthening benefit. On the contrary, only 43% of those who agreed that they never use soy were positive about the bone strengthening benefit of soy, whereas 37% held a neutral opinion and 20% expressed a negative opinion. 6. The relation between respondents' opinion of the overall health benefits of soy and their opinion of soy as alternative for HRT and reliever of menopausal symptoms was of practical significance. Of the respondents who did not agree that soy has many health benefits, the majority expressed a negative opinion of soy as an alternative for HRT. Of those who agreed that soy has many health benefits, 45% expressed a neutral opinion and 44% a positive opinion of soy as alternative for HRT. Almost half (47%) of the respondents who agreed that soy does have many health benefits, expressed a neutral opinion when asked if soy can relieve menopausal symptoms, whereas only 30% had a positive opinion in this regard. The majority (86%) of the respondents who disagreed that soy has many health benefits, also expressed a negative opinion of soy as reliever for menopausal symptoms Conclusion: The results of this study indicate that 80% of the South African consumer population are aware of soy and that South African consumers have a neutral to positive attitudinal disposition towards the potential health benefits of soy. Respondents did not express a particularly strong opinion regarding several health benefits of soy. It may be hypothesized that they are not informed well enough on the health benefits of soy as to take a stand and to form a definite opinion. Neither different race groups, nor pre- or post-menopausal women differ significantly in the frequency of their opinions, indicating that in this study, race and age did not have a practical significant influence on opinion of the health benefits of soy. Of all those surveyed and who did express a specific opinion, 72% agreed that soy has many health benefits, which is almost the same percentage (74%) as American consumers who perceive soy products as healthy as according to the United Soybean Board (USB) National Report (2003-2004:4). A survey by Adams (2001:433) reported that 71% of American consumers believed that plant-derived HRT have fewer risks and can thus be used as a safe alterative for conventional HRT. According to the results of the present study only 34% of South African consumers expressed a positive opinion when asked if soy can be used as an alternative for HRT. Insufficient evidence on the safety and efficacy of the potential health benefits of soy, as well as a lack of consumer education in South Africa, could be the reason for this uncertainty among XIV South African consumers. While only 26% of American consumers are aware that soy might relieve menopausal symptoms (USB National Report, 2003- 2004:4), results of the current study found that 42% of South Africans were of opinion that soy can relieve menopausal symptoms. A relation, although not of practical significance, was found between respondents who eat/drink soy and their opinion of the health benefits of soy. This can be an indication that whether or not the South African consumer population consume soy doesn't have an influence on their opinion of soy's health benefits in practice. The relation found between respondents who never use soy and their opinion of the bone strengthening benefit of soy were not of practical significance. This can be an indication that whether or not South Africans use soy does not influence their opinion of the bone strengthening benefit of soy in practice. Furthermore, a practically significant relation was found between respondents' opinion of the overall health benefits of soy and their opinion of soy as alternative for HRT and reliever of menopausal symptoms, respectively. Interestingly, respondents who expressed a positive opinion regarding the health benefits of soy did not have a convincingly positive opinion of soy as alternative for HRT and as reliever of menopausal symptoms. They expressed a more neutral opinion. As expected, consumers that were not of opinion that soy has certain health benefits, also disagreed when asked if soy can be used as an alternative for HRT or as reliever of menopausal symptoms. Although the causes for the respondents' opinion or uncertainty were not determined in this study, it can be hypothesised that it may be due to lack of standardisation of evidence on the safety and efficacy of alternative hormone replacement therapies. Further studies are still needed to determine the contributing factors which influence consumers' opinion or lack of opinion on soy. If consumers are not educated about the benefits and disadvantages of soy as alternative for HRT, they cannot make intelligent decisions and choices as to whether or not to use soy as alternative for HRT. / Thesis (M. Consumer Science)--North-West University, Potchefstroom Campus, 2004.

Cross-linking in soy proteins is hypothesised to have an impact on the texture of tofu. In vitro incubation showed soy proteins and its two fractions, glycinin and β-conglycinin, were cross-linked using glutaraldehyde, formaldehyde, glyceraldehyde and transglutaminase (TGA). Increasing concentration of these carbonyl compounds and TGA, and temperature of the carbonyl compounds treatment, increased the reactivity of cross-linking. Glutaraldehyde was the most reactive in forming aggregated proteins, followed by formaldehyde and glyceraldehyde. Both carbonyl moieties of glutaraldehyde are believed to be essential for the rapid cross-linking reaction. In the unfractionated soy proteins, β-conglycinin had a higher reactivity than glycinin. In in vitro incubation using TGA, soy proteins served as good substrates for TGA, in which β-conglycinin was more susceptible to TGA than glycinin in the unfractionated soy proteins. The addition of TGA, and 1 and 2 mM glutaraldehyde prior to soymilk boiling in situ resulted in a small number of cross-linked proteins, which correspond to an increase in fracture force. The addition of glutaraldehyde after soymilk boiling resulted in a slight decrease in fracture force compared to the control. At higher concentrations of glutaraldehyde (15 and 30 mM), soy proteins were mostly cross-linked, regardless of addition before or after soymilk boiling. Highly cross-linked proteins resulted in a significant decrease in the fracture force. For TGA treatment, the fracture force was increased with increasing TGA concentration from 1000 to 5000 ppm, added either before or after soymilk boiling. However, the TGA treatment showed only a small quantity of cross-linking. It is hypothesised that TGA hydrolysed glutamine of proteins to glutamate and changed the functional properties of proteins. Upon examination of the microstructure, it was found that the TGA treatment resulted in a fine-stranded network, compact structure and less porosity. These characteristics resulted in a higher fracture force. In contrast, in the glutaraldehyde treatment, the network consisted of a higher porosity, loose network and diffuse structure, which gave lower fracture force. Thus, it appears that substrate modification to the structure of the soy proteins may have a greater impact than the number of cross-links. These findings are likely to have implications for production of soy products with a wide range of textures by manipulating the soy protein properties.

Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on January 16, 2008) Includes bibliographical references.

Thesis (Ph.D.). / Written for the Dept. of Bioresource Engineering. Title from title page of PDF (viewed 2009/06/11). Includes bibliographical references.

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on September 10, 2009). Thesis advisor: Joseph Parcell. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 162-178).

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references.