Development of a direct observation method and the influence of formulation parameter on frozen ice cream microstructure

Abstract

Ice cream microstructure is influenced by the ingredients used and processes conducted during production. The equipment required to observe the microstructure of this temperature-sensitive material is very expensive and might not be affordable for most small-scale ice cream business entrepreneurs. This study aimed to develop an economical and affordable device setup and method to capture images of ice cream microstructure in sub-freezing conditions. The arrangement comprises a portable Dino-Lite microscope placed in a freezer with a surrounding temperature of-21.5oC. The commissioning of the setup was conducted by viewing the microstructure of ice cream made with different percentages of oil content i.e., 0%, 4%, 5%, and 6% at 500× magnification. Several analyses were conducted to correlate the microstructure with the physical quality of ice cream i.e., overrun and melting rate. It was found that ice cream with higher fat content had smaller air cell sizes and well-distributed microstructural components. The air cell radius (r) decreased from 0.089 mm (0% oil) to 0.056 mm (6% oil). Ice cream with lower fat content had higher overruns and vice versa. Overrun of ice cream with 0% and 6% oil were 55.12% to 33.38%, respectively. The overrun decreased linearly with fat content (R2 = 0.9859). The melting rate of ice cream with 0% and 6% oil contents were 1.82 g/min and 1.66 g/min, respectively. Ice cream with higher fat content melts slower and decreased linearly with oil content (R2 = 0.9413). The device and method developed are reliable in characterizing the size of the microstructure of ice cream, which provides a fundamental understanding of the relationship between the ingredients used with the microstructure of ice cream for small-scale ice cream business entrepreneurs and even researchers.