INCORPORATION OF ROSEMARY (ROSMARINUS OFFICINALIS) IN FERMENTED MILK AND FRESH CHEESE: IMPACT ON THE PHYSICOCHEMISTRY OF DAIRY PRODUCTS AND THE PHYTOCHEMISTRY OF THE PLANT

Abstract

Rosmarinus officinalis L. leaves can be valorized by their uses in the production of healthy foods. Dry rosemary leaves powder and its lyophilized ethanolic extract at different concentrations (g/100 g) were used for the formulation of fresh cheeses. This study evaluated whether or not this fortification could affect some physicochemical characteristics, phenolic composition and antioxidant capacity of fresh cheeses along storage period at 5°C.The ethanolic extract was obtained under the optimum conditions of microwave-assisted extraction (MAE) using response surface methodology (RSM) coupled with a Box–Behnken design (BBD). The optimum conditions were as follows: ethanol concentration 78.162%, microwave power 351.825W, ratio of solvent to raw material 101.623:1, and extraction time 122.648 s. Results showed that this enrichment did not affect physicochemical parameters (pH, aciity, proteins, fat) of the formulated cheeses while its effect on cheese color parameters was more marked. Moreover, this incorporation has increased substantially values of total phenolic content (TPC) and ABTS scavenging activity during storage period compared to the control cheese. UHPLC-DAD-ESI-MSn analysis revealed the presence of rosmarinic acid (RA), rosmanol (R), carnosic acid (CA), carnosol (C) and methoxy-carnosic acid (MCA) in rosemary extract and enriched cheeses. Principal components analysis (PCA) was performed and results confirmed a strong relationship between antioxidant activity and these phenolic compounds. Additionally, a correlation between physicochemical parameters, antioxidant activity as well as the sensory characteristics was carried out. Cheeses fortified with 0.5%, 0.75% of powder and 0.5% of extract, were most appreciated (60%–80%) by the panelists.In conclusion, the consumers can successfully employ rosemary as dairy supplements as it improves markedly the TPC and the antioxidant activity of cheese as well as a distinctive taste, aroma and acts as flavor enhancer for better acceptability.In this study rosemary extract and whey protein complexation was highlighted by the turbidity test. It was concluded that rosemary phenolic acids were responsible of this complexation as complexes were detectable at 400nm.