NORTH-SOUTH CENTRE - ETH - North-South Centre North-South ...

Camel milk products of high hygienic
quality and safety
Camel milk is consumed in East Africa as untreated fresh
milk or fermented milk product known as “suusac”. Pathogenic
microorganisms (MO) in suusac represent health risks
for consumers. We assume that these MO develop in uncontrolled,
spontaneous fermentations due to unhygienic
processes and raw material of low quality. The objective
of this project is to improve existing camel milk products.
Through investigation of the microbiota of camel milk, we
aim at (i) developing starter cultures for the production of
improved fermented milk, and (ii) reducing risk-MO, which
might have a negative impact on human health.
We collected more than 1500 bacterial and fungal isolates
of over 130 milk product samples from Kenya and Somalia.
At first, we focused our search on lactic acid bacteria (LAB),
which might be responsible for acidification, proteolysis
and aroma forming during spontaneous milk fermentation.
A promising selection of potential starter culture candidates
were identified and comprised species such as Streptococcus
thermophilus, Lactococcus lactis subsp. lactis and
Lactobacillus spp. In addition, predominant pathogenic
species such as Streptococcus agalaticae (raw milk) and
Streptococcus infantarius (suusac) indicating the potential
health risk were also isolated. First fermentation trials were
successfully performed. In these trials we used potential
starter cultures in order to investigate acidification rate,
symbiotic interactions, metabolite production, and antimicrobial
activity. We also included the first lab-scale
production of suusac. For safety reasons, we assessed
antibiotic resistances in pathogenic MO such as Enterobacteriaceae
and Staphylococci. Worrying resistances to a
number of antibiotics were detected. These findings coupled
with our extended diversity analysis of pathogens imply
that improved hygiene practice at all levels in the production
and marketing chain are needed.
Therefore, a first set of potential starter culture strains are
about to be tested in small-scale pilot plant experiments
at the University of Nairobi. Simultaneously, further experiments
with the goal to optimise starter culture composition,
to analyse fermentation kinetics and to produce
the starter culture will continue at the ETH Zurich.
Coordinating lab-scale, pilot-plant and field experiments
in Kenya and Switzerland should allow for a fast and
high quality development of an adapted and safe suusac
starter culture.
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Project leaders
Christophe Lacroix
Leo Meile
Zakaria Farah
Research collaboration
Livestock systems research
Contact persons
Christoph Jans, ETH Zurich
Patrick Njage, University of Nairobi, Kenya
Collaborators
Jakob Zinsstag, Swiss Tropical Institute, Basel, Switzerland;
John Wangoh, University of Nairobi, Kenya;
Mario Younan, KARI, Nairobi, Kenya
Duration
June 2007 – June 2010
Thematic cluster
Food quality and public health
Patrick Njage, Christoph Jans and Mulwa Dasel working on bacteria
isolated from camel milk products at Analabs, Nairobi, Kenya