Effect of Starter Culture Types on Textural, Rheological, and Melting Properties of Spreadable Processed Cheese Made from UF Milk Retentate

Abstract

Starter cultures types have a substantial effect on the structural characteristics of spreadable processed cheese made from Ultra filtered (UF) milk retentate and can minimize the final product cost. In this study, the effect of starter culture type which had been used on the meltability, firmness and rheological properties of the processed spreadable cheese manufactured from UF milk retentate was investigated. Standardized UF processed cheese was inoculated with three starter cultures (ABT-8, CHN-22 and FRC-60). Half of the inoculated starter cultures samples were incubated at 25°C for 24h while the other half was incubated at 25°C for 72h. The control treatment was prepared without adding any starter cultures. Rheological modelling, firmness and meltability of UF processed cheese properties were examined through the period of 3 months of storage at 6±2°C. Significant differences in flow behaviour indexes were shown as a result of adding various starter cultures during storage and PC22-3 had the highest value. The highest decrease in consistency coefficient (k-values) was found with PC8-1 and PC60-1 throughout the storage period. Viscosity of processed cheese decreased corresponding to the increase in shear rate in all treatments. Furthermore, all the tested samples displayed the typical Herschel-Bulkley model having shear-thinning Pseudoplastic, while the flow curves lacked a linear characteristic. The cheese structure was rapidly broken down after the initial shearing. However, the breakdown rate decreased at the higher shear rate. Additionally, the treatments fermented with starter cultures (PC8-1, PC22-1 and PC60-1) for 24h had lower firmness than control and other treatments. Good meltability for all starter cultures treatments was obtained corresponding to the two factors, fermentation time and storage period.