Abstract:
Yoghurt is a popular probiotic milk product. Coffee flavoured yoghurt was
developed to enrich the product with functional properties and help enhance
local coffee consumption. The aim of the research was to study potential
interaction of polyphenolic compounds present in coffee extract on the
viability of lactic acid bacteria, yeast and moulds and, functional properties
of coffee flavored yoghurt. Coffee flavoured yoghurt was prepared by adding
coffee flavour extract to the yoghurt in varying amounts; 0.0%, 0.1%, 0.2%,
and 0.3%. Treatment 0.0% was the control. A complete randomized design
(CRD) was used, in which yoghurt was divided into 4 treatments in triplicate
and was randomly assigned to 12 experimental units. The sampling for
analysis was done at intervals of one week for 28 days from day one.
Microbial analysis was done using standard AOAC 2016 method using MRS
and PDA media and results were reported as CFU/ml of the coffee flavored
yoghurt. Functional properties were determined by evaluation of total
polyphenols and antioxidant activity using the Free radical scavenging
activity by DPPH method and Folin ciocateau method. Data was analyzed
by use of ANOVA, means separated by LSD at p<0.05 level of significance.
From the findings, lactic acid bacteria in coffee flavoured yoghurt ranged
between 3.7x107
-1.09x108CFU/ml. Yeast and moulds ranged between
3.6x101
-8.33x100 CFU/ml. TPC between 5.76±0.4-97.89±0.6mgGAE/ml while
Antioxidant properties ranged from 15.82±0.9- 68.55±0.9 % DPPH. There
were significant differences between coffee flavoured yoghurt and the
control on the functional properties. In conclusion, addition of coffee flavour
extract into the yoghurt improved the keeping quality of the yoghurt while
maintaining its probiotic potential. More studies on addition of natural
coffee flavour into other milk products are recommended.
