Manufacture of zinc-fortified dairy products with selected multi- and mixed-strain starter cultures

Zinc is the second most abundant d-block metal in the human body after iron. It is necessary for numerous physiological processes. Zinc deficiency may develop rapidly if intakes are low since the human body has a limited capacity of storing zinc. Consumption of zinc-fortified foods substantially increases zinc intake. The main aim of the present study was to manufacture zinc-fortified dairy products, namely yogurt and two traditional Italian fresh cheeses, Squacquerone and Caciotta with selected multi- and mixed-strain starter cultures. Yogurt is an ideal vehicle for zinc supplementation due to its widespread consumer acceptance, whereas Squacquerone and Caciotta are attractive products for risk groups who typically consume fresh cheeses. In order to achieve our goal, three zinc salts, namely Zn-gluconate, Zn-sulphate and Zn-aspartate and starter cultures including selected strains of Streptococcus thermophilus, Lactobacillus delbrueckii ssp. bulgaricus and Lb. helveticus were used for cheese-making trials. The first two zinc salts are allowed for food supplementation by Regulation (CE) N. 1925/2006, whereas the latter is not allowed yet, although its dietary supplementation at the proposed use level of 50 mg/day and 0.8 mg/Kg bw/day is not of safety concern according to the European Food Safety Authority (EFSA). Both the experimental zinc-fortified batches and the control dairy products were subjected to physico-chemical, compositional, microbiological and sensory analyses. The experimental results were finally analyzed statistically by ANOVA, in order to establish significant (P >0.05) differences between control and Zn-reinforced dairy products.