Optimization of teff fermentation by Lactobacillus coryniformis starter culture and investigation of sorghum and buckwheat as substitute components in injera batter
Open Access
- Author:
- Strobel, Scott Alan
- Area of Honors:
- Food Science
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Gregory Ray Ziegler, Thesis Supervisor
Robert F Roberts, Thesis Honors Advisor
Ali Demirci, Faculty Reader - Keywords:
- injera
fermentation
starter cultures
teff
buckwheat
sorghum
optimization
modified Gompertz model - Abstract:
- Injera, a flatbread indigenous to Ethiopia, is traditionally made from teff flour fermented in water. The organisms responsible for the process are native to the flour, and the fermentation is traditionally initiated by backslopping a portion of the previous batch. This staple food is typically made in relatively small batches, and scaling up for commercial production offers the potential to produce injera at reduced price to the consumer, which may benefit Ethiopia socially and economically. This two-phase study aims first to optimize the fermentation of teff by using Lactobacillus coryniformis as a starter culture. A bioreactor was used to ferment 2.5 L batches of ivory teff, water, and starter culture with full agitation at 25, 28, 31, 34, 37, 40, and 43 degrees Celsius. Batches with and without starter culture and agitation were performed at ambient temperature. During fermentation, the pH of the batter was monitored for up to 72 h. Kinetic parameters (lag duration and maximum acidification rate) relevant to the modified Gompertz model were determined to characterize the change in pH. The time to reach pH 3.8 was used to assess the time to complete the fermentation. Acidification to pH 3.8 is accomplished in the least time (5.9 h) when using L. coryniformis starter culture, 300 rpm impeller speed for agitation, and temperature control at 37C. The second phase of the project assessed how flour composition influences fermentation kinetic parameters. Inoculated injera batters were fermented at 37 degrees Celsius under agitation, with the flour composition varying between teff, sorghum, buckwheat, and their mixtures. Teff and a teff-sorghum composite fermented in the least time. A higher fraction of buckwheat in the batter arrested the fermentation at a higher pH. The results of this study are used to make recommendations for scaling up the teff fermentation process.