Thesis
Physicochemical and structural changes in potato French fries during processing
Washington State University
Master of Science (MS), Washington State University
2014
Handle:
https://hdl.handle.net/2376/101243
Abstract
French fries are one of the most popular foods in the United States. Producing French fries on the commercial level generally involves the following major unit operations: peeling, preheating, cutting, blanching, drying, par frying, freezing and finish frying. Even though there is a tremendous amount of research available in the literature, gaps still exist in understanding the physicochemical and structural changes occurring in the French fries during the complete frying process. Thus, the objectives of this study were to elucidate the physicochemical and structural changes occurring in French fries during each processing step and to find relationships between these properties and the frying oil temperatures. The impact of frying oil temperatures of 335°F, 355°F and 375°F was evaluated in 10 second time intervals during par frying for a total of 60 seconds and in 20 second time intervals during the finish frying processes for a total of 160 seconds. French fries were analyzed for their moisture and oil contents, color, cross-sectional density profiles, texture, structure (through non-invasive micro-CT scanning), thermal transition range, thermal degradation, pasting properties and starch changes. Results showed that at all frying oil temperatures tested, moisture content decreased during both par and finish frying. The highest oil content was found in French fries fried at 355°F, while frying at 375°F led to French fries with lowest amount of oil. Micro-CT scanning results showed similar trends. Micro-CT scanning also revealed an increase in crust thickness with an increase in frying time. This translated into a harder French fry with increased frying time, at all temperatures, also shown through texture analysis. The color of French fries darkened during the progression of frying at all temperatures tested, with the darkest fries resulting from the frying oil temperature of 375°F. The pasting profiles revealed that the longer the French fries are cooked, peak viscosity decreased due to degradation of the starch molecules. The degradation of the amylopectin starch molecule contributing to the amylose fraction was shown through intermediate pressure size exclusion chromatography. Thermally decomposing the French fries showed similar results with decomposition of high molecular weight molecules into smaller ones. With a goal of achieving the crispiest and lowest fat containing French fry, the frying oil temperature of 375°F was found to be optimal. Thoroughly understanding the changes that French fries undergo during processing will help to control the process effectively and to develop French fries with desired properties.
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Details
- Title
- Physicochemical and structural changes in potato French fries during processing
- Creators
- Trent Millin
- Contributors
- Girish Ganjyal (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Food Science, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525063901842
- Language
- English
- Resource Type
- Thesis