Date of Award
Master of Science
Food Science and Technology
The purpose of this study was to develop a sweet potato product (sweet potato leather) and to evaluate certain quality factors including chemical composition, physical and sensory attributes, and caloric content of the product.
Two types of sweet potato leather were prepared using two cultivars of sweet potato (L3-151 and Travis): recipes were designated basic sweet potato leather and basic sweet potato leather with apple. Drying rate curves were determined for the basic sweet potato leathers of both cultivars. 'Travis' basic sweet potato leather initially contained more moisture than 'L3-151' basic sweet potato leather and, consequently, after drying contained more moisture.
Proximate composition of sweet potato leathers was determined. Basic sweet potato leathers had a slightly higher moisture content than the basic sweet potato leathers with apple. In general, the addition of apple to the sweet potato leathers did not affect the composition. Caloric values also remained the same with the addition of apple.
Thickness measurements were determined for sweet potato leathers and basic sweet potato leathers prepared with apple were thinner than leathers prepared with the basic recipe. Apple contributed to the thinness of the leathers.
Hunter color measurements showed that leathers prepared with the L3-151 cultivar of sweet potato were darker, redder, and less yellow than samples prepared from 'Travis'. This was due to color differences in sweet potato cultivars. Basic recipe leather samples were lighter, redder, and more yellow than basic recipe leathers containing apple. Addition of apple produced a darker leather.
The pH of the leathers were close to each other but the leathers prepared from the basic with apple recipes had a slightly lower pH than basic recipe leathers. Tensile strength of the leathers was measured and basic recipe leathers were tougher than basic with apple leathers. No microbial counts were higher than log10 2.3 for any leathers over 60 days storage period.
The leathers were evaluated by a sensory panel for flavor, texture, and overall acceptability. Included in the taste panel evaluation samples were leathers prepared from the basic recipe and dried in a kitchen oven and a solar dryer. Also included in the taste panel evaluation were leathers prepared from the basic recipe but containing 55% and 90% high fructose corn syrup instead of honey.
Leathers dried in a forced air dehydrator were rated tougher and chewier than those dried in a solar dryer and those sweetened with 55% and 90% high fructose corn syrup. 'L3-151' leathers were chewier than 'Travis' leathers. Dehydrator-dried leathers were rated stickier than those leathers dried in a solar dryer. Basic sweet potato leathers prepared with 55% high fructose corn syrup were rated stickier than those prepared with 90% high fructose corn syrup.
This study shows that acceptable sweet potato leathers can be prepared by various drying methods and recipes. Ease of preparation and storage indicate that additional studies could be conducted to produce a marketable sweet potato product.
Washam-Hutsell, Linda Jayne, "Evaluation of sweet potato leather as a food product. " Master's Thesis, University of Tennessee, 1983.