Population dynamics of lactococci from industrial, artisanal and non-dairy origins in defined strain starters for Gouda-type cheese
2001
Ayad, E.H.E. | Verheul, A. | Wouters, J.T.M. | Smit, G.
Lactococcal strains from various artisanal and natural niches were studied for the development of defined strain starter (DSS) mesophilic cultures with specific flavour forming characteristics as well as with other properties required for Gouda-type cheese. These 'wild' lactococcal strains were found to be stable up to 50 subcultivations with regard to their morphology, genetic profile, bacteriocin production, proteolytic and acidification activity, bacteriophage resistance, citrate utilizing ability as well as their ability to grow at 4 degrees C and in the presence of 4% NaCl. In addition, the flavour forming abilities of the strains were found to be stable during subcultivation, making them suitable as starter cultures. Different DSS were prepared, each one composed of a limited number of strains for Gouda-type cheese making. These starters included proteolytic, non-proteolytic and citrate utilising strains, as well as a specific flavour-generating wild strain. One of the DSS consisted of nisin-producing and nisin-resistant strains. The characteristics of the strains in DSS were studied in milk cultures as well as in cheese making experiments. The population dynamics revealed that a number of strains were able to grow well together and thus were suitable to be applied in tailor-made starter cultures, whereas other strains could not be maintained during growth in a mixed DSS. The results of population dynamics in the cheese corroborated the results obtained in a milk culture. These results may open new avenues for the construction of tailor-made starters for new types of cheese.
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