Forschungs- & Entwicklungsinformationsdienst der Gemeinschaft - CORDIS

Improved texture and flavour in quarg

Research is being carried out to improve the texture and flavour of existing quargs and to create new quarg-like products. This entails the production of highly concentrated aroma bases; the improvement of quarg texture by the selection of single strains with different textural properties; and the quality control of quarg production. A screening method for diacetyl production has been developed and one strain of Lactobacillus which is able to produce 40 parts per million (ppm) of diacetyl has been selected. The Lactococcus diacetylactis strains can be separated into three groups: those producing 10 to 20 ppm diacetyl, those producing 5 to 10 ppm, and those that do not produce any diacetyl. Optimization of diacetyl production in the bioreactor has been undertaken with these strains. Mutant strains have been selected from Lc. lactis spp. and lactis var. diacetylactis wild type strains and the diacetyl synthesis by the mutants showed a significant increase compared to wild type strains. To-date 50 texture-producing strains of thermophilic streptococci and lactococci have been selected from different products or cultures. Viscosimetric data are not available for most of these but they were characterized as ropy strains by visual methods. The ropy character of the strains does not necessarily correlate with the pH value after 16 h incubation. For some of them the pH value was about 5.4, others had values of 5.1 to 4.9, and the remainder showed acidification down to pH 4.5. A rotational viscosimetric method has been developed to determine the textural properties of the culture of a single strain in skim milk. The data showed that heating the culture milk to 100 C for 10 min gave the best viscosity. The influence of incubation temperature (26-30-34 C) of single 'ropy' strains in milk has shown that viscosity development varies from strain to strain.

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Yoplait SA
10 rue Jean-Jacques Rousseau
94200 Ivry Sur Seine
France
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