Characterization of ice cream structure by direct optical microscopy. Influence of freezing parameters

• Published in: Food science & technology Vol. 36; no. 8; pp. 743 - 749
• Main Authors: Caillet, Alexandre, Cogné, Claudia, Andrieu, Julien, Laurent, Pierre, Rivoire, Alain
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-01-2003; Elsevier
• Subjects: Air porosity; Biological and medical sciences; Chemical and Process Engineering; Engineering Sciences; Food engineering; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; Ice cream structure; Ice crystal size; Milk and cheese industries. Ice creams; Reflexion photonic microscopy; Air porosity; Ice cream structure; Ice crystal size; Reflexion photonic microscopy; Particle size; Crystallization; Dairy product; Freezing; Operating conditions; Optical microscopy; Frozen product; Porosity; Microstructure; Ice cream
• ISSN: 0023-6438; 1096-1127
• DOI: 10.1016/S0023-6438(03)00094-X

The main objective of this study was to develop and to set up a new optical direct microscopy method, based on the reflected light flux differences, with episcopic axial lighting to characterize the different phases structure of commercial overrun ice creams. Firstly, the results obtained have been validated by two others methods, a destructive method by dispersion and observation by light microscopy and, an indirect method, by scanning electron microscopy after freeze-drying sample. It was observed that the three methods were in agreement and led to the same conclusions concerning the main freezing parameters influence.
So, this technique has been principally used to investigate the effects of the freezing conditions on the ice crystal structure. One of the most important parameters is the freezing rate that governs not only the size, but also the ice crystals texture of the ice cream. The air introduction (overrun) tends to limit the ice crystal growth. Besides, by this method, it was also possible to observe and to quantify the air bubbles size distribution. This direct microscopy method could be extended to other frozen food structure analysis.