ABSTRACT

Studies on the full-fat traditionally fermented milk product (kindirmo) were carried out using survey, physicochemical, microbial and sensory techniques. Study objectives were to' find out the indigenous methods of kindirmo handling and processing, evaluate of market samples and investigate effects of processing factors on kindirmo quality. Others were to find out the level of substitution of cow milk with soymilk for kindirmo production and ascertain the microorganisms associated with of kindirmo. Temperature sensitivity of Lactic Acid Bacteria and its effect on the quality and shelf-stability of kindirmo were also investigated. One Lactic acid bacteria (LAB) isolate involved in kindirmo fermentation was fully characterized at the molecular level. Predictive modeling was used to ascertain the relationship between kindirmo quality and selected process variables. Results showed the same principles and techniques of production for yoghurt and kindirmo. They however differ in inoculation, fermentation temperature as well as the crude and unsanitary processing and handling practices for kindirmo. The pH of market samples of kindirmo ranged from 3.3 —3.8, as opposed to that of yoghurt, which was 4.2 --4.8. It was observed that 70% substitution of cow milk with soymilk significantly affected the organoleptic appeal of kindirmo. Processing factors such as fermentation time, starter culture type and age, milk type, inoculation temperature and inoculum volume, affected the physicochemical and organoleptic acceptability of kindirmo. Shelf-stability of market sample of kindirmo was 48h at room temperature (32°C). Use of kindirmo as starter culture produced kindirmo of better sensory and physical and chemical quality than that produced with the commercial starter culture (DVI) containing Lactobacillus bulgaricus and Streptococcus thermophilus. Fungi isolated from milk were Rhodotorula sp., Cephalosporium sp, Mucor sp and Cladosporium sp. While probable bacteria isolates were Streptococcus sp, Bacillus sp and Micrococcus sp. LAB isolated were L. hilgardi, L. cásei, L. plantarium and L. bfidium. Most of the LAB isolates produced acids and gas from sugars when placed to ferment various sugars. The LAB isolates varied from season to season. During the period between March and April, only one LAB isolate was always present. But as from September to December, several LAB isolates (five) were present. The single LAB isolate obtained during the months of March and April produced kindirmo that was viscous, sweet smelling and of very desirable quality when compared to kindirnio produced with other starter cultures. Its molecular characterization showed it is closely related in characteristics (95% match in gene sequence) to Bacillus asahii that was isolated from soil in Japan in 2004. Further comparison showed that though both of them had good flavour producing characteristics, nevertheless they are unlikely the same microorganism. Most of the LAB isolates produced during the months of September to December had no bacteriocin activity. The LAB isolates had different temperature sensitivities that ranged from 15 — 45°C. Starter culture inoculation at a defined temperature gave products of much more uniform quality. Process temperature combinations (Inoculation & fermentation temperatures) used in the research includes I420C — F320C; I38°C — F27°C & I3s°C — F27°C. The linear regression model was developed to predict kindirmo quality such as p1-I and titrable acidity from fermentation time. The model was found to be a better predictor of pH than titrable acidity. Weak positive levels of relationships existed between sensory qualities of the kindirmo with fermentation time, pH or titrable acidity.