Microbial changes during the fermentation of baobab (Adansoniadigitata) fruit pulp yoghurt

Abstract

This study was conducted to assess the microbial changes during the fermentation of Baobab (Adansoniadigitata)fruit pulp yoghurt. The Baobab fruit pulp yoghurt was prepared in the Laboratory using the conventional method. Lactobacillus bulgaricus and Streptococcus thermophilus were used as starter cultures while a control was produced without the starter cultures. de Man Rogosa Sharpe (MRS) agar was used to culture lactic acid bacteria. The microbialload, succession and percentage occurrences were determined using standard methods. The total aerobic bacterial count wasfound to be within the range of 1.9x10³ - 1.4x10⁵ cfu/ml. The Lactic acid bacteria and fungal count ranges were 4.5 x 10³  - 7.5 x 10³  cfu/ml and 8.0 x 10¹ – 2.8 x 10⁴  cfu/ml respectively. At the end of fermentation time, there was significant difference between the test and control Baobab yoghurt at P<0.05.  Lactic acid bacteria recorded the highest count of 6.2 x 10⁴  and 7.5 x 10³ cfu/ml in the test and control respectively. Bacillus species , Staphylococcus aureus, Lactobacillus bulgaricus,Streptococcus thermophilus and Micrococcus species were the bacteria isolated while the fungal isolates were Saccharomyces cerevisiae and Hansenula species. Lacbacillusbulgaricus, Streptococcus thermophilus, Bacillus species and Saccharomyces cerevisiae were the only microorganisms found at the end of fermentation time. The study obtained low microbial count and isolated less number and type of microorganisms from Baobab fruit pulp yoghurt because of the antimicrobial effect of baobab pulp and pasteurization treatment.Based on the results of this study, Baobab fruit pulp yoghurt can be said to be of good microbiologicalquality for human consumption. The industrial use of Baobab fruit pulp in the production of yoghurt is recommended.