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Determination of pasteurization treatment of liquid whole egg by measuring physical and rheological properties of cake cream

2019-06-30
Uysal, Reyhan S.
BOYACI, İSMAİL HAKKI
Şümnü, Servet Gülüm
The aim of this study is to determine whether liquid whole egg (LWE) is pasteurized by measuring the physical and rheological properties of cake cream. The applicability of the method was demonstrated on the creams prepared using unpasteurized and pasteurized LWE (ranging from 60 to 68 degrees C for 2 and 5 min). Foaming capacities (%) of the LWE samples were measured. Physical (specific gravity) and rheological properties (shear rate-shear stress and shear rate-viscosity) of the creams were measured. A statistically difference (decrease from 740 to 531) was found between the foaming capacity of unpasteurized and other LWE (pasteurized). The specific gravity of the control cream (containing unpasteurized LWE) was statistically found different from the other creams (containing pasteurized LWE) since it had more air bubbles. In addition, consistency index (K, decrease from 12.27 to 3.31 Pa.s(n)) and flow behavior index (n) of the control cream were found significantly different from the other creams due to the formation of less volume. A high correlation (r = .90) between the foaming capacity of LWE and consistency index of the cream was found. The results suggest that proposed method can be used as an alternative procedure to determine pasteurization treatment and foaming ability of LWE. Practical Applications Egg is one of the essential ingredients in cake batter formulation due to its ability to form foam. In recent years, liquid egg product (LEP) is more preferred thanks to its microbial safety and ease of use. On the other hand, LEP may damage the physical structure of bakery products because of the pasteurization treatment in LEP process. Pasteurization process may lead to a disruptive effect on foaming functions of egg proteins, which is ended in less volume of batter. Therefore, a practicable and reliable method is required to determine whether liquid egg is pasteurized or not. In present study, pasteurized liquid whole egg (LWE) could be determined by taking physical and rheological measurements of cake cream. In addition, a rapid and reliable analysis via rheological measurement of the cream can be proposed as an alternative to determine the foaming ability of egg.