Response of lactic acid bacteria to milk fortification with dietary zinc salts

Zinc is essential for many basic physiological functions in humans. The human body has a limited zinc storage capacity; zinc deficiency can develop rapidly when intakes are low. Food fortification is a successful strategy to control zinc deficiency. Very little information is available about the response of lactic acid bacteria (LAB) to milk fortified with different zinc salts. In this study, the acidifying activity of 98 LAB cultures in reconstituted skim milk fortified with zinc aspartate, zinc sulphate or zinc gluconate was assessed. Based on the overall results, a strain-dependent response was seen irrespective of the zinc source. The cultures with the best performance in terms of acidification rate and acidification extent were used for the formulation of multi-strain starters destined for the manufacture of two zinc-reinforced Italian cheeses (Squacquerone and Caciotta). The cheese-making trials showed that zinc fortification had no impact on the main properties of the cheeses.