Honors Theses

Date of Award

Spring 5-6-2022

Document Type

Undergraduate Thesis

Department

Biology

First Advisor

Erik Hom

Second Advisor

Georgianna Mann

Third Advisor

Tiffany Bensen

Relational Format

Dissertation/Thesis

Abstract

Water kefir is traditionally fermented using dark brown sugar due to a fast growth rate, however the use of other sweeteners, such as honey, is relatively unexplored. This paper describes the investigation of using alternative mediums made with honey, agave nectar, Truvia/stevia, and monk fruit sweetener, each supplemented with dark brown sugar on the biomass growth of water kefir grains (WKGs). Growth in these alternative mediums was compared to WKG growth in the standard medium prepared using only dark brown sugar. Two trials were conducted, each with three replicates for each experimental medium as well as three replicates of dark brown sugar medium controls. WKG biomass growth was measured every other day and recorded, and the culture medium was changed every other day to ensure adequate nutrients. Due to the higher vitamin content in honey and agave nectar (Cronometer, a nutrition analysis website was used to find this information), it was hypothesized that these two alternative mediums will have an increase in net biomass growth over the control. Because of the lack of vitamin supplementation in Truvia and monk fruit sweetener, it was hypothesized that these two mediums would have a decrease in net WKG mass compared to the control. I found that of the alternative mediums, agave nectar, Truvia, and honey did not support WKG growth as well as the control, with all of them recording a lower net increase of kefir grain biomass over time. Monk fruit recorded a slight increase of kefir biomass growth, although it was very modest. Monk fruit recorded an average of 1.02% more biomass increase than the control, Truvia with 5% less increase in biomass compared to the control, agave nectar biomass increase was 5% less than the control, and honey with 11.6% less biomass increase compared to the control. While the monk fruit supplemented medium resulted in WKG growth closest to that of dark brown sugar medium, the observed growth was only a small percentage more than the control, and was not consistent with the hypothesized effect. These results suggest the notion that agave nectar, Truvia, and honey are either less nutritious or inhibitory to the growth of WKGs relative to the standard dark brown sugar medium, and monk fruit could be an adequate alternative with more research. It remains to be determined if WKGs could be adapted to grow better with these alternative sweeteners.

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