Investigation of antimicrobial properties of plant extracts in unripened curd cheese

The aim of this work was to select sensory acceptable concentrations of plant extracts: cinnamon (Cinnamomum cassia), schisandra (Schisandra sphenanthera), rosemary (Rosmarinus officinalis), cryptocaria (Cryptocaria massoia) and to investigate their antimicrobial properties in unripened curd cheese. In total 10 cheeses were produced at temperatures of 40°C and 60°C degrees: 2 control and with each CO2 plant extract (cinnamon, schisandra, rosemary, cryptocaria). Then the sensory acceptability of the cheeses was evaluated (based on the 7-point hedonic scale) and sensory profiling was performed (using a 100 mm non-graded linear scale). The number of aerobic colonies (on Plate Count Agar (PCA)), coliform bacteria (on chromogenic agar (CCA)), yeast and mold (on Yeast Extract Glucose Chloramphenicol (YGC) culture medium) was determined in microbiological studies. The data were processed using Microsoft Excel 2016 and SPSS / w 24.0 packages. It was found that the most acceptable concentration of plant extracts was: cinnamon CO2 – 5 drops (0.25 ml), schisandra CO2 – 12 drops (0.6 ml), cryptocarya and rosemary CO2 3 drops (0.15ml), and the most preferred plant extract was found to be cinnamon CO2. The sensory profiling analysis of the cheeses enriched with plant extracts showed that the highest acceptability of overall appearance (6.8 and 6.5 respectively), overall taste (6.3 and 6.5) and smell (6.4 and 6.8) intensity was found in cheeses with cinnamon extract in 40°C and 60°C temperature. However the consistency of the cheese produced at 40°C with schisandra extract (6.0) and the cheese produced at 40°C with cinnamon extract (6.9) was acceptable the most. Evaluation of microbiological parameters of the cheese with plant extracts determined that the lowest number of aerobic (7.0x104 and 4.0x103 CFU/g respectively) and coliform bacteria (3x102 and 0 CFU/g) were found in cheese with cinnamon extract, however the lowest number of yeast and molds was found in cheeses produced at 40°C with cinnamon extract (8.0x102 CFU/g) and in cheeses produced at 60°C with rosemary extract (1.0x102 CFU/g). Compared to cheeses produced at 40°C and 60°C the differences were statistically significant, p<0.05. Comparing the antimicrobial effect of plant extracts in cheeses produced at 40°C and 60°C, it was found that antimicrobial effects of cinnamon extract on aerobic and coliform bacteria in cheeses produced at 60°C were 15.9 and 100.0 times more potent than in cheeses produced at 40°C (p