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Thermodynamic Interactions of Micellar Casein and Oat ß-Glucan in a Model Food System

Sarantis, Stylianos
http://rave.ohiolink.edu/etdc/view?acc_num=osu1531829793743745

Abstract Details

2018, Master of Science, Ohio State University, Food Science and Technology.
Consumers’ demand for “clean label” foods has motivated food manufacturers to develop natural ingredient alternatives to replace commonly used additives that are unfamiliar to the general public. Oat ß-glucan, a soluble dietary fiber, is an attractive natural alternative. Its consumption is associated with the reduction of coronary heart disease risk (21 CFR 101.81) and its use alters the texture and mouthfeel of food products. Therefore, it could be used as a stabilizer or thickening agent in value-added food products. Dairy products are a suitable carrier to deliver ß-glucan’s health benefits to consumers since they are widely consumed and have high nutritional value. However, adding ß-glucan in dairy formulations often causes phase separation because of the thermodynamic incompatibility of micellar casein and ß-glucan. The objectives of this study are to investigate the micellar casein - ß-glucan interaction mechanism and study the effect that biopolymer concentrations, thermal treatment and dispersion medium ionic strength have on these interactions. Ten binary mixtures were created with concentrations ranging from 0.5% to 2% ß-glucan and from 0.75% to 6% casein. The mixtures were processed under three thermal conditions, namely pasteurization at 73°C for 15 seconds, retort sterilization at 121°C for 5 minutes and control (not treated). To investigate the dispersion medium ionic strength effect, three media were used: 5 mM potassium phosphate buffer, 171 mM sodium chloride in phosphate buffer and milk permeate. After mixing and processing, the samples were kept for 5 days at 4°C and after storage it was visually determined whether they exhibited phase separation or not. Next the composition of the two phases was determined and the phase diagram was constructed to identify the critical biopolymer concentrations for phase separation. The stability of the samples was calculated as the percentage of the total volume occupied by the upper phase. Dynamic light scattering (DLS) was applied to measure the particle size distribution and ¿-potential. The apparent viscosity of the samples was measured at a shear rate range of 10 – 279 s-1. Isothermal titration calorimetry (ITC) was used to detect enthalpic interactions while titrating micellar casein into a ß-glucan solution. Confocal laser scanning microscopy (CLSM) images were obtained to examine the microstructure of the mixtures. The results showed that both thermal treatments significantly increased the biopolymer compatibility and the stability of the samples. The thermally treated formulations exhibited smaller particle sizes, which explains the higher stability. Increasing the medium ionic strength decreased the biopolymer compatibility and stability of formulations, and the particle sizes appeared to increase. The results obtained from ITC analysis confirmed that the nature of the studied interactions is entropic since the heat of binding was insignificant. The CLSM images illustrated the immiscibility of the two biopolymers showing the formation of two phases even on samples that had not yet exhibited macroscopic separation.
Valente Alvarez, Dr. (Advisor)
Rafael Jimenez-Flores, Dr. (Committee Member)
Emmanuel Hatzakis, Dr. (Committee Member)
134 p.
Food Science
micellar casein; beta-glucan; interaction; biopolymer

Recommended Citations

Citations

  • Sarantis, S. (2018). Thermodynamic Interactions of Micellar Casein and Oat ß-Glucan in a Model Food System [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1531829793743745

    APA Style (7th edition)

  • Sarantis, Stylianos. Thermodynamic Interactions of Micellar Casein and Oat ß-Glucan in a Model Food System. 2018. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1531829793743745.

    MLA Style (8th edition)

  • Sarantis, Stylianos. "Thermodynamic Interactions of Micellar Casein and Oat ß-Glucan in a Model Food System." Master's thesis, Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1531829793743745

    Chicago Manual of Style (17th edition)

osu1531829793743745
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This open access ETD is published by The Ohio State University and OhioLINK.