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Investigation into the palatability of whole wheat versus intermediate wheat grass (Kernza) flour in choice and no-choice feeding paradigms

Abstract
The perennial grain Kernza (Thinopyrum intermedium) has environmental advantages over annual wheat, e.g., it grows deeper roots that improve soil stability, and water and nutrient retention. Importantly, Kernza has a distinct composition, including higher fibre and protein levels than wheat, suggesting its consumption might convey health benefits. However, composition affects palatability, which calls into question whether Kernza is as palatable as wheat. Hence, this thesis aimed to investigate the acceptance of and preference for Kernza in comparison to whole wheat flour in rats, an established feeding research model. Three variations of diets were used: mash, slurry, and pellets, to account for processing as a factor affecting palatability. Food intake experiments were followed by the analysis of the reward system’s activation (using a neuronal activation marker, c-Fos) in response to a Kernza vs wheat meal. Acceptance was assessed in the no-choice meal paradigms, in which a single diet was offered to the animals. Regardless of whether meals were given either after or without prior food deprivation, and during the day or at nighttime, rats consumed similar amounts of Kernza- and wheat-based diets. Similarly, a sub-chronic 9-day Kernza vs wheat meal exposure, showed no difference in acceptance. In preference paradigms in which two diets were offered simultaneously, rats preferred Kernza over standard chow, but wheat was preferred over Kernza. Both wheat and Kernza were less preferred than hyperpalatable high-fat high-sugar pellets. Finally, the c-Fos immunoreactivity (IR) analysis in animals that have eaten a similar amount of Kernza or wheat (versus unfed controls), showed that regardless of the diet offered, activation of the ventral tegmental area, nucleus accumbens shell (AcbS), and nucleus accumbens core, is higher in response to food intake. However, consumption of wheat produced greater c-Fos IR the AcbS, which is in line with this grain being preferred over Kernza. Overall, I conclude that Kernza is an accepted and palatable flour, however, the preference of wheat over Kernza and the reward system’s activity changes indicate that Kernza is somewhat less palatable than wheat.
Type
Thesis
Type of thesis
Series
Citation
Date
2023
Publisher
The University of Waikato
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