Assessment of wild non-dairy lactococcal strains for flavour diversification in a mini-Gouda type cheese model

Wild lactococci possess enhanced metabolic capabilities in comparison to industrial dairy strains, including increased amino acid-converting enzyme activities. A bank of Lactococcus lactis strains isolated from different non-dairy environments exhibited wider carbohydrate fermentation profiles in comparison to dairy lactococcal strains. In addition, these non-dairy lactococci had the ability to ferment lactose and produce diverse aroma profiles when grown in milk. Based on volatile analysis, five of these non-dairy strains were selected and investigated as adjuncts to diversify cheese flavour using a mini-Gouda cheesemaking process model and compared to a cheese manufactured with a commercial adjunct. In total, 8 different cheeses were evaluated in duplicate and ripened for 14 days at 12 °C, followed by 8 °C for 84 days thereafter. Physicochemical analysis of cheeses was performed at day 14 and sensory evaluation at day 84. Viable counts, intracellular enzyme activity and indices of proteolysis were monitored over ripening. The ability of the non-dairy strains to survive, lyse, and release intracellular enzymes and alter proteolysis was strain dependent. Some strains performed as well as the commercial adjunct in terms of secondary proteolysis although others were associated with bitterness and development of off-flavours and off-aromas. Attenuation of DPC6853 positively reduced its association with bitterness during ripening. It is evident that non-dairy strains have potential as adjuncts in semi-hard type cheeses, and could be harnessed to diversify flavour profiles in semi-hard cheese varieties.