The design of a three strain starter system for Cheddar cheese manufacture exploiting bacteriocin-induced starter lysis

A three strain starter system was developed for increasing the level of starter cell lysis during cheese manufacture and ripening. The composition of this starter combination includes a bacteriocin (lactococcin A, B and M) producer which causes the lysis of a second strain (sensitive to bacteriocin activity) during cheese manufacture, and a third strain resistant to bacteriocin activity. The latter strain plays an essential role in ensuring acid production during cheese manufacture. Cheeses manufactured at pilot-scale (450L vats), with the three strain starter combination were assessed for levels of the intracellular enzyme, lactate dehydrogenase, released into the cheese matrix during ripening. Experimental cheeses, manufactured with the bacteriocin-producing adjunct, exhibited higher levels of free amino acids and greater release of intracellular LDH than control cheeses manufactured in its absence. Cheese was subject to sensory analysis which revealed that experimental cheese showed a decrease in bitterness over cheeses manufactured without the bacteriocin-producing adjunct. Thus, this three strain system offers manufacturers a reliable starter system exhibiting increased lysis with concomitant improvements in cheese flavour.