Semester of Graduation

Spring 2022


Master of Science (MS)


Nutrition and Food Sciences

Document Type



Orange peel (OP) is a major byproduct from orange juice production, and is a good source of fiber and flavonoids, particularly nobiletin. Nobiletin has been reported to exhibit pharmacological activities including anti-inflammation and antioxidation. Incorporating orange peel into food products would harness economic benefit of this industrial byproduct and support a sustainable food chain. This study was performed to evaluate consumer perception of gluten-free oat-based snack bars (GFOSBs) containing orange peel.

In the first study three GFOSBs were formulated to contain 17%, 20%, and 23% orange peel by weight. Consumers (N=103) evaluated GFOSBs for sensory liking (9-point hedonic scale) and determined purchase intent (PI; yes/maybe/no) before and after a health-related statement was informed to consumers. Consumers selected evoked emotions after tasting GFOSBs using a check-all-that-apply format. Orange flavor was evaluated by a just-about-right scale (JAR). Data were analyzed using ANOVA for sensory liking data, Stuart Maxwell and McNemar’s tests for PI, and penalty analysis for JAR data.

All GFOSBs were not significantly different in terms of liking scores for visual-quality, surface-color, aroma, crispiness, chewiness, and overall-texture. However, liking scores for orange-flavor, overall-flavor, and overall-liking of GFOSB containing 23% orange peel were significantly lower than those containing 17% and 20% orange peel (5.32-5.57 vs. 5.93-6.05). This was attributed to the “too-much-orange-flavor” JAR response rated by 48.5% of the participating consumers. Most of the emotions elicited by GFOSBs were positive being ‘good’ and ‘interested’ the highest percentage among participants. The health-related statement was efficient to increase PI.

In the second study, sensory rejection was evaluated for attributes like appearance, color, aroma, texture, orange flavor, overall flavor, and overall. Consumers (N= 111) evaluated GFOSBs with five OP concentrations, 14%, 17%, 20%, 23%, and 26%. The analysis was made based on the probit analysis for rejection tolerance threshold (RTT) at 25% and rejection range (RR) with fiducial limits at 95% of confidence using SAS 9.4. The results concluded that overall acceptance of the product with a RTT25% was 18.16% of OP.

Finally, making use of OP, would add value to this byproduct from orange juice production while reducing agricultural and environmental problems.

Committee Chair

Witoon Prinyawiwatkul