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Development of protein-polysaccharide complex for stabilization of oil-in-water emulsions

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dc.contributor.advisor Goff, Douglas
dc.contributor.advisor Cui, Steve W.
dc.contributor.author Kasran, Madzlan
dc.date.accessioned 2013-02-05T20:53:01Z
dc.date.available 2013-02-05T20:53:01Z
dc.date.copyright 2013-01
dc.date.created 2013-01-21
dc.date.issued 2013-02-05
dc.identifier.uri http://hdl.handle.net/10214/5445
dc.description No en_US
dc.description.abstract 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. en_US
dc.description.sponsorship No en_US
dc.language.iso en en_US
dc.subject Protein-polysaccharide conjugates en_US
dc.subject Soy whey protein en_US
dc.subject Fenugreek gum en_US
dc.subject Emulsions en_US
dc.subject NMR en_US
dc.title Development of protein-polysaccharide complex for stabilization of oil-in-water emulsions en_US
dc.type Thesis en_US
dc.degree.programme Food Science en_US
dc.degree.name Doctor of Philosophy en_US
dc.degree.department Department of Food Science en_US


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