Oil Uptake in French Fries
reduction in oil content measured by bulk analysis. Soxhlet extraction indicated that the uncoated French fries contained 11.8 wt% oil; whereas, the coated fries contained 8.0 wt%, representing a 32% decrease in oil absorption during frying due to the coating. T e microscopy image analysis method is not meant to replace or be an alternative to bulk analysis methods such as Soxhlet extraction. Bulk analysis methods are more representative of the sample as a whole. T e microscopy method, however, provides insight into the distribution of oil within the sample and the depth of penetration of oil from the sample surface, information not available from bulk techniques.
Conclusion
Using osmium staining, thick-section cross-sectioning, and light microscope imaging, qualitative differences in oil distribution in deep-fried food are readily discernible at adequate resolution. The method was used on French fries with and without a methyl cellulose coating applied before frying. Results showed that the coated fries displayed a substantial decrease in the penetration of oil into the food. This is consistent with bulk oil analysis techniques that show a substantial decrease in overall fat content of French fries when methyl cellulose coatings are applied before frying. The microscopy method described here met the goals of our efforts in that it is quick and easy to accomplish using materials and equipment readily available in microscopy and biology laboratories.
Acknowledgments
Keegan Yaroch prepared the batter, coated and fried the potatoes, and performed the bulk oil analysis.
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