Development of Mint-Flavored Probiotic Obushera using Lactobacillus rhamnosus Yoba 2012
Abstract
Mint essential oil is a common flavorant in the food industry. However, the antimicrobial action of oil is undesirable in production of probiotic foods. In addition, the strong mint flavor can deter the sensory acceptability of the product. This study evaluated the effect of mint essential oil on the viability of Lactobacillus rhamnosus Yoba 2012 and consumer acceptability of the mint-flavored Obushera. Obushera is a traditional fermented sorghum-based beverage from Uganda. The beverage was flavored with 0, 1, 2 and 4% mint emulsion and fermented using Lactobacillus rhamnosus Yoba 2012 (LRY) at 24℃ for 24 h. Microbial counts, pH and titratable acidity (TA) were determined at 0 and 24 h of fermentation. Thereafter, consumer acceptability of the Obushera with ≤ 6 log cfu/mL of the probiotic at 24 h of fermentation was done. Although the Obushera was spiked with about 6 log cfu/mL of LRY at 0 h of fermentation, it was noted that counts reduced with increasing mint concentration. The counts were 5.6, 5.3, 4.8 and 4.0 log cfu/mL in the 0, 1, 2 and 4% mint-flavored Obushera, respectively. At 24 h of fermentation, LRY counts 7.9, 7.8, 7.5 and 5.2 log cfu/mL in the 0, 1, 2 and 4% mint-flavored Obushera, respectively. The pH dropped from pH 5.1 to ˂4.5 in 0, 1 and 2% mint-flavored Obushera in 24 h of fermentation. The TA increased from 0.1 to 0.3% in the 0 and 1% Obushera and 0.1 to 0.2% in the 2% mint-flavored one. The pH and TA of the 4% mint remained the same (pH=5, TA=0.1) throughout the fermentation. The consumer acceptability scores of the 0, 1 and 2% mint-flavored Obushera were in the order 7.2, 5.7 and 4.8, respectively. Results implied that an acceptable probiotic Obushera flavored with ≤1% mint emulsion could be made without adversely inhibiting the probiotic.