Three-dimensional measurement of internal structure in frozen food materials by cryogenic microtome spectral imaging system

Abstract

The objective of this work was to establish a three-dimensional measuring method for the size, morphology and distribution of internal structure such as ice crystals, bubbles and solids content within an ice cream sample by using a cryogenic microtome spectral imaging system (CMtSIS). The 3-D images of ice crystals, bubbles and milk solids were recognized by reconstructing the circles in 2-D images into 3-D spheres; and the Overrun by Volume (ORV) was obtained by incorporating the area of bubbles on integrated image and the volume of bubbles in the 3-D image. Keywords: Ice crystal, Bubble, Internal structure, Spectral imaging, Micro- to macro-scale, Freeze-Drying

Shrinkage in frozen desserts

“…A number of studies have used electron microscopy to study the air phase in frozen desserts, but recent advancements in imaging may allow for a more complete study of air phase evolution during storage. The air phase can be visualized within the frozen dessert nondestructively using x-ray microtomography (Pinzer et al, 2012), synchrotron x-ray tomography (Guo et al, 2017(Guo et al, , 2018Mo et al, 2018Mo et al, , 2019, cryogenic microtome spectral imaging system (Do et al, 2018(Do et al, , 2020, and focused beam reflectance measurement (Hernández Parra et al, 2018a). The 2D crosssectional images are computed to 3D renderings that can distinguish high-contrast phase boundaries, which is particularly useful to visualizing ice and air phases within the frozen product.…”

“…Advancements in imaging technologies have produced detailed renderings of coalescence and disproportionation of air cells, and particularly of note is how well 3D imaging can be used to quantify channeling of air cells (Do et al, 2018;Guo et al, 2017Guo et al, , 2018Mo et al, 2018Mo et al, , 2019Pinzer et al, 2012). Chang and Hartel (2002c) visualized channeling using optical microscopy and cryo-SEM and hypothesized that channel formation was a result of partial coalescence of air cells.…”

Determining the Internal Structure of Ice Cream Using Cryogenic Microtome Imaging and X-ray Computed Tomography

“…A CMtSIS technique similar to that used by Do et al [20] was adapted for this study. The CMtSIS instrument consisted of a microtome unit, an automatic high-precision XY stage, an image acquisition unit (visible, fluorescence, and spectroscopic), and a 3-D image processor.…”

“…Bubbles, ice crystals, and milk solids in the ice cream sample were identified from the CMtSIS images using the microscale to macroscale measurement method previously reported by Do et al [20]. Bubbles in an ice cream sample were identified as defocused spots in twodimensional (2D) CMtSIS images due to the difference in the focal distance created by the vacant spaces.…”

“…X-ray computed tomography (CT) has been applied to twoand three-X-ray images generated by differences in X-ray attenuation due to variations in the density of the material within a sample. Also, food materials containing water are freeze-dried to improve the density contrast for X-ray CT. Do et al [20] evaluated bubbles, ice crystals, and milk solids in commercial ice cream samples from microscale to macroscale using CMtSIS images. Sato et al [11] applied X-ray CT using synchrotron radiation to observe the structure of ice crystals in frozen food.…”