DOMINANT LACTIC ACID BACTERIA FROM FERMENTED MILK AND
PRODUCTION OF ORGANIC COMPOUNDS IN ZIMBABWE
A. N. Mutukumira1*, J. A. Narvhus2, A. Marzin3, S. B. Feresu4 and R. K.
Abrahamsen2
ABSTRACT
In rural Zimbabwe and in some small-scale milk collection centres,
fermented milks are produced by natural fermentation. The products are
characterised by inconsistent quality as the producers do not use starter
cultures, and the methods are not standardised. The objective of this study
was to identify strains of lactic acid bacteria (LAB) isolated from naturally
fermented milk in Zimbabwe and to assess their potential to serve as
starter cultures for fermented types of milk. Isolates of LAB were
identified using standard tests, and representative LAB strains were
examined for their ability to coagulate milk and/or to produce volatile
organic compounds and organic acids in reconstituted non-fat dry milk. Of
the 200 isolates, the predominant genera found in the samples were
Lactococcus (L.), Lactobacillus (Lb.), Enterococcus (E.) and Leuconostoc
(Leuc.). Of the representative strains, 21 were identified to species level
using the API 50 CH system. The representative strains belonged to L.
lactis subsp. lactis, L. lactis subsp. lactis biovar. Diacetylactis; Lb. casei
subsp. casei, Lb. plantarum, Lb. acidophilus; Leuc. mesenteroides subsp.
mesenteroides, E. faecium and E. faecalis. Strain L. lactis subsp. lactis
biovar. diacetylactis C1 produced the highest amount of lactic acid and
coagulated milk within 12 hours. This strain produced the highest
amounts of desirable flavour compounds and fermented milk. The genus,
Lactococcus, was predominant with the isolates identified as L. lactis
subsp. lactis and L. lactis subsp. lactis biovar. diacetylactis. Milk
fermented by L. lactis subsp. lactis biovar. diacetylactis C1 strain
contained appreciable amounts of flavour compounds. It is concluded that
the L. lactis subsp. lactis biovar. diacetylactis strains might be of interest
to the dairy industry. It is recommended that due to their fermentation
potential in milk, the Lactococcus strains should be further studied and
developed into lactic starter cultures.
1*Institute
of Food Nutrition and Human Health, Massey University Albany Campus,
North Shore Mail Centre 0745, Auckland, New Zealand. Email address:
tony.mutukumira@gmail.com
2Norwegian University of Life Sciences, Dept of Chemistry, Biotechnology & Food
Science, P.O. Box 5036, N-1432 Ås, Norway.
3Formerly with the Institut National Superieur de Formation Agro-Alimentaire (INSFA),
65 rue de Saint-Brieuc, 35042 Rennes Cédex, France.
4Institute of Environmental Sciences, University of Zimbabwe, P.O. Box MP167, Mount
Pleasant, Harare, Zimbabwe.