Fat globule size distribution in commercial ice cream determined through ideal application of the laser diffraction technique

Authors: Garcia, Rafael; Olszewski, Faith; Plumier, Benjamin

Submitted to: Applied Food Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2025
Publication Date: 5/30/2025
Citation: Garcia, R.A., Olszewski, F., Plumier, B.M. 2025. Fat globule size distribution in commercial ice cream determined through ideal application of the laser diffraction technique. Applied Food Research. 5:101007. https://doi.org/10.1016/j.afres.2025.101007.
DOI: https://doi.org/10.1016/j.afres.2025.101007

Interpretive Summary: The fat in ice cream exists as tiny globules. When ice cream manufacturing plants produce ice cream that does not meet their specifications, it is disposed of. Recovering the butterfat from waste ice cream could benefit the manufacturer economically and minimize the food loss. In order to design a process for fat recovery, the size of the fat globules must be measured. A method involving the scattering of laser light exists for making this measurement, but this method will give misleading results if not used correctly. In this study, the technique was adapted to produce good results when taking measurements on ice cream. This work will benefit the larger effort towards waste ice cream fat recovery, and should also benefit other dairy product research areas.

Technical Abstract: Design of systems for recovering fat from waste ice cream requires knowledge of the fat globule size distribution. Laser diffraction has often been used to measure this distribution, but it has almost always been done using laboratory-made ice cream. Past reports very often contain indications of serious methodological flaws. This study demonstrates a careful selection of analysis parameters and methodology choices, in order to prevent known sources of error in particle size distribution (PSD) results, and to use the laser diffraction instrument to its best advantage. It is shown that simply loading ice cream into the instrument using a pipette can introduce major errors. Additionally, a value given in the literature as a recommendation for extinction coefficient may be wrong by a factor of 100. Using the methodology developed in the present study, 26 varieties of commercial vanilla ice cream were analyzed for their PSD. A small size mode, sometimes reported in the literature and attributed to free casein micelles, was absent from the PSD of all ice cream varieties. Further, a large size mode, rarely reported in the literature, was found in about half of the ice cream varieties tested. Overall, the results demonstrate that the laser diffraction technique must be used with care, and that understanding of nature of the sample material is crucial.