Séminaire

Mardi 11 Septembre 2018 à 11h00.

Utilization of Ultrasound Spectroscopy for Studying on the gelation of Food Proteins

''Ultrasound spectroscopy has been previously employed to observe heat-induced changes in whey proteins (Corredig et al. 2004). In this seminar, I would like to introduce three topics as follows.
1. The analysis for the gelation in food proteins with fatty acid salts at ambient temperature using ultrasonic spectroscopy
2. The mechanism for the gelation of -lactoglobulin in the presence of cysteine using ultrasonic spectroscopy
3. The analysis for the gelation in the mixed food proteins with different heat stability using ultrasonic spectroscopy
Previously, we reported that several kinds of food protein form transparent and high water-holding gels by the addition of fatty acid salts which have more than ten carbon atoms without heating 1, 2). In the first topic, I will show that ultrasonic spectroscopy is a very useful method for investigating the changes of macromolecular structures in a fluid system consisted from -lactoglobulin, sodium captrate and sodium chloride in situ and real time, even with small changes of velocity and attenuation in the system 3, 4). In the second topic, I introduce the role of cysteine addition in the gelation of -lactoglobulin 5). Namely, we investigated the effect of cysteine on -lactoglobulin interactions, and found that -lactoglobulin with cysteine showed that earlier changes in velocity, which tended to increase the compressibility resulting in a greater attenuation of the colloid system than for -lactoglobulin. In the last topic, I would like to talk about the analysis for the gelation in the mixed food proteins with different heat stability 6, 7). We used -lactoglobulin which is one kinds of heat-coagulable protein and ovomucoid from egg white as a heat-stable protein. Addition of ovomucoid caused a -lactoglobulin solution to softer gel. Ovomucoid interacted with -lactoglobulin, and resulted in aggregates intermediate in size between those of 5% and 10% -lactoglobulin gels. Using ultrasonic spectroscopy, we found that ovomucoid will be able to interact with other type of proteins resulting in new textured materials.

References
1) Yuno-Ohta N, Toryu H, Higasa T, Maeda H, Okada M, Ohta H (1996) Gelation properties of ovalbumin as affected by fatty acid salts. J. Food Sci., 61: 906-910 & 920.
2) Yuno-Ohta N (2006) Mechanism for formation of ovalbumin-fatty acid mixed gels. Food Hydrocoll., 20: 357-360.
3) Yuno-Ohta N and Corredig M (2007) Characterization of -lactoglobulin A gelation in the presence of sodium caprate by ultrasound spectroscopy and electron microscopy. Biomacromolecules, 8: 2542-2548.
4) Yuno-Ohta N and Corredig M (2011) -casein aids in the formation of a sodium caprate-induced -lactoglobulin B gel. Colloids Surf B: Biointerfaces 84: 442-446.
5) Yuno-Ohta N (2009) Use of ultrasound spectroscopy to examine the effect of cysteine on -lactoglobulin interactions. Colloid Polym Sci., 287: 1487-1491
6) Yuno-Ohta N, Endo M, Sawaki M, Kishikawa M (2014) Effects of -casein and sodium caprate on the formation of heat-induced ovalbumin gels. Nippon Shokuhin Kagaku Kogaku Kaishi 61: 183-191.
7) Role of ovomucoid in the gelation of a -lactoglobulin-ovomucoid mixture. Colloid Polym Sci., 294: 1065-1073
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