Understanding the Relationship between Microstructure and Physicochemical Properties of Ultrafiltered Feta-Type Cheese Containing Saturea bachtiarica Leaf Extract

Microwave-assisted extraction was optimized to prepare Satureja bachtiarica leaf (SBL) extract based on antimicrobial (IZD) and antioxidant activities (DPPH) and extraction yield (EY). At optimum condition, i.e., 800 W power and 8 min, the best extraction results with EY = 16%, IZD = 73.56 mm, and DPPH = 24.2% were obtained. To develop a novel Feta-cheese, the influence of SBL extract, rennet, and starter concentrations were evaluated in terms of rheological, textural, and sensorial properties. At the optimized condition, the acceptance, taste, the strength of the network (A), and the distance between sequential cross-linking points (ξ) were 8.13, 8.07, 34,036.12 Pa·s^1/z, and 5.41 nm, respectively. At the 60th day of storage time, the lowest z value (the network extensity parameter) of the cheese samples was observed. SEM image texture indices showed a good correlation with the studied instrumental texture parameters during 60 days of storage. The mold and yeast counts and their growth rate in the SBL extract-added cheese were lower than those for control one; whereas, the former cheese showed a greater LAB population between the 80th and 120th days. The antimicrobial and antioxidant qualities of SBL extract showed a significant influence on cheese properties.

Quality improvement of spreadable processed cheese made from ultrafiltered milk retentates using commercial starter cultures

This study was undertaken to evaluate the feasibility of using commercial starter cultures for quality improvement of spreadable processed cheese manufactured from ultrafiltered milk retentates. Compared to control, six samples of ultrafiltered milk retentate were incubated at 25 ℃ with starter cultures CHN-22, FRC-60, and ABT-8. Three samples were incubated for 24 h and the others were incubated for 72 h. Physicochemical, microbiological, and organoleptic characteristics in all treatments during the 90-day cold storage (6 ± 2 ℃) period were determined. The results showed that protein content of all treatments was significantly lower than the control. Utilization of starter cultures in ultrafiltered processed cheese production increased titratable acidity, where titratable acidity of the treatments (PC_22-3, PC_60-3, and PC_8-3) was significantly higher than the other treatments and the control. PC_8-1, PC_60-1, and PC_22-1 treatments were the highest penetrometer readings and with low firmness. All treatments had higher water soluble nitrogen/total nitrogen%, total bacterial viable and lactic acid bacterial counts especially PC_22-3, PC_60-3, and PC_8-3 compared to the control. The results revealed that PC_60-1 and PC_22-3 treatments gained the highest acceptability scores than PC_60-3, PC_22-1, and the control.

Physicochemical, microbiological and spoilage analysis of probiotic processed cheese analogues with reduced emulsifying salts during refrigerated storage

Microbial quality of low-salt processed cheeses supplemented with Bacillus coagulans spores (10(7)-10(8) CFU/g) relying on their physicochemical characteristics during 60 day-cold storage was evaluated. A reduction in moisture content, water activity and pH value and a significant enhancement in proteolytic index of control and probiotic samples were obtained by prolonging storage time. Survival rate of the probiotic cells significantly decreased up to day 30, while total count of the viable cells increased by increasing storage time. A 20 and 67 % increase in total counts of coliforms and mold-yeast of the control sample were respectively observed after 60 days of cold storage. A considerable decrease in the total counts of coliforms and mold-yeast was also found in the processed cheeses containing probiotic supplement. According to the macroscopic and sensory assessment, off-odors and off-flavors in the control sample were diagnosed after day 1 of cold-storage. Noticeably, the resistance to spoilage was more prominent in samples containing the probiotic cells.