Effect of starter cultures with a genetically modified peptidolytic or lytic system on Cheddar cheese ripening
2001
Guldfeldt, L.U. | Sorensen, K.I. | Stroman, P. | Behrndt, H. | Williams, D. | Johansen, E.
Using a food-grade vector system, a derivative of the laboratory strain Lactococcus lactis subsp. cremoris MG1363 was modified to over-express the genes pepC, pepN, pepO, pepV or the lysin gene of bacteriophage phivML3. In addition, the pepN gene of the commercial strain of L. lactis subsp. lactis CHCC377 was either deleted or replaced by the corresponding and more active pepN gene of L. lactis subsp. cremoris Wg2. The cheeses produced with strains over-expressing pepN or pepC were characterised by good scores in flavour preference and low bitterness and, consequently, were clearly preferred by the sensory panel. The cheeses produced with strains over-expressing pepO or pepV, and the cheeses produced with the modified commercial strain were indistinguishable from the control. Partial least square (PLS) regression revealed a positive relationship between the level of lysine, aspartic acid and glutamic acid, and the sensoric quality of cheese.
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