Abstract:
Probiotics are important in enhancing food quality, reducing incidences of diarrhoea and
promoting good health. A fruit jam is an ideal food to deliver probiotics because it is
easy to produce, a good source of sugar, and most rural population consume it. A
probiotic jam was developed using an underutilised fruit, U. kirkiana, to benefit the
resource-poor population in southern Africa. U. kirkiana fruit is found abundant in most
semi-dry rural areas of Zimbabwe. Ripe U. kirkiana fruits were obtained from preferred
domesticated trees by households residing in semi-dry rural areas of Zimbabwe. The
fruits were pulped by removing seeds, mashing and sieving through an 800 μM sieve.
Pectin content of the pulp was determined. A probiotic jam was developed using the
formulation 55 % (wt/vol) pulp, 43 % (wt/vol) sugar, 1.5 % (wt/vol) pectin, and 0.5 %
(wt/vol) citric acid. The fruit pulp was mixed with sugar in a stainless steel pot and
cooked at 110 °C. Citric acid was added and stirred whilst cooking until it reached 55 o
Brix. Pectin was added and the jam was continuously stirred until it reached 68 o
Brix.
The jam was inoculated with 0.25 % L. rhamnosus yoba and left to propagate for 24
hours, while bacterial growth was monitored. The physicochemical and functional
properties (pH, total soluble solids, sugars, total titratable acidity, iron content, zinc
content, and vitamin C), and L. rhamnosus yoba viability in the probiotic jam was
analysed. The probiotic jam had vitamin C, total titratable acidity, total soluble solids,
and moisture content of 0.34 ±0.02 mg /100 g FW, 2.2 ± 0.11 g / L FW, 68.5 ± 0.2 %
FW, and 34.8 ± 1.2 % FW, respectively; iron and zinc content of 4.13 ± 0.52 mg /100 g
FW and 0.36 ± 0.02 mg /100 g FW, respectively; high fructose and sucrose content of
12.84 ± 0.21 g /100 g FW and 24.61 ± 0.12 g /100 g FW, respectively; and a total
titratable acidity content of 2.2 g / L at day 0 (after production), 2.37 ± 0.01 g / L FW at
day 4, and 2.48 ± 0.02 g / L FW at day 7 of storage (25 °C). The probiotic jam had 6.2 ±
0.2 Log CFU / mL viable cells on point of consumption. U. kirkiana fruit jam can
potentially deliver live L. rhamnosus yoba cells as a probiotic food
