Potatoes for Human Health: Effects of Cultivar and Processing on Nutritional Composition of White- and Color-fleshed Potatoes
Open Access
- Author:
- Markham, Laura Elise
- Graduate Program:
- Food Science
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- June 18, 2015
- Committee Members:
- Jairam Kp Vanamala, Thesis Advisor/Co-Advisor
Gregory Ray Ziegler, Thesis Advisor/Co-Advisor - Keywords:
- potato
nutrition
phytochemical
metabolomics
farm to fork - Abstract:
- Potatoes are one of the most important sources of nutrition worldwide, providing energy, essential vitamins and minerals, as well as important dietary phytochemicals. Rising incidence of chronic disease has been associated with the Western diet and lifestyle, and improving the health-benefitting potential of our food supply is one way to address this epidemic. Given the popularity and availability of potatoes and potato products, improving their nutritional profiles with the aim of chronic disease prevention has great potential to improve human health. In pursuit of this effort, it is important to understand how factors from farm to fork affect potato nutritional composition. We investigated effects of two main factors, cultivar and processing, on several health-related constituents of potatoes including starch (macronutrient), vitamin C (micronutrient), metabolite profiles and select phytochemicals, glycoalkaloids (endogenous toxins) and acrylamide (processing-induced toxin). Because colored-fleshed potatoes have demonstrated greater health benefits and are becoming more popular, we used two white-, two red-, and two purple-fleshed varieties to look at cultivar differences. Potatoes are almost always cooked before consumption, so we compared effects of six common processing techniques: raw, steamed, microwaved, baked, French-fried, and potato chips. Overall, processing had the greatest effect on the potato nutritional components investigated, though cultivar and interaction effects were also significant. Moist heat processing methods generally resulted in greater in vitro starch digestibility compared to dry heat processing methods; however, chips and French fries contribute more dietary glucose per unit weight due to greater total starch (TS) content. Colored-fleshed potatoes showed similar in vitro starch digestibility to white-fleshed potatoes across processing methods indicating polyphenol content did not significantly affect starch digestibility. Vitamin C was significantly reduced after processing; steamed, microwaved, and baked samples had similar vitamin C contents, while chips and French fries had the lowest vitamin C contents. Our use of metabolomics was a powerful compliment to the targeted analyses of single compounds; we were able to see overall changes in global metabolite profiles, which included over 15,000 compounds. Overall metabolite profiles were affected similarly to vitamin C; steamed, microwaved, and baked metabolite profiles were more similar to each other, while chips and French fries demonstrated greater differences. Glycoalkaloid levels were lowest in French fries, chips, and steamed potatoes, likely due to leaching in water and oil, and acrylamide was only formed by the dry heat processing methods; both toxins were within acceptable ranges. Colored-fleshed potatoes had overall greater health rankings than white-fleshed potatoes. Significant cultivar and interaction effects suggest some cultivar processing method combinations may be better suited for specific desired outcomes. Together, these findings contribute to our understanding of farm-to-fork factors affecting the health- benefitting potential of potatoes. This type of holistic perspective can inform individuals at every level of the food system, from breeders and producers to consumers, enabling more effective improvements in the healthfulness of potatoes and potato products.