Ali Sheibani

Melbourne, Victoria University, Australia
Title : Extent of proteolysis during ripening of reduced-salt Cheddar cheese as affected by process modifications

Abstract

Reducing salt content in Cheddar cheese may require optimization of process parameters in order to produce cheese of appropriate quality. Effects of change in pH at drainage, rennet concentration and casein to fat ratio on proteolytic characteristics of salt-reduced Cheddar cheese were thus investigated. Cheeses made from milk of different C/F ratios (0.60, 0.70, and 0.80), pH (6.2, 5.9, and 5.6) and rennet concentrations (0.1 and 0.3 mL rennet/L of milk) were made and analyzed for chemical composition, LAB count and proteolysis. At the same drainage pH, cheeses made with C/F ratio 0.6 had significantly higher moisture content compared other ratios. Ash content was greater in cheeses made with milk with a C/F ratio of 0.6 compared with other cheeses. The pH values of all cheeses decreased significantly from day 0 to day 120 and then remained constant. Total LAB growth in cheeses made with rennet level of 0.3 ml rennet /L was higher at the same C/F ratio and pH 6.2. TPC growths at day 180 were significantly higher compared with day 0. At the same pH, C/F ratio and storage time, WSN contents in cheeses made with 0.3 ml/L rennet were higher compared with 0.1 ml/L. TFAA and TCA-SN content increased significantly during storage. More hydrophobic peaks appeared as the rennet concentration increased from 0.1 to 0.3 ml/L. The percentages of the extra-hydrophobic peptides at day 0 in cheeses made with pH 5.6 were higher compared with cheeses with higher pH value. Increase in C/F ratio and rennet concentration, especially at low pH, showed similar proteolysis as normal cheese containing normal salt concentration of 2.5-3%. 

Keywords:  Low-salt Cheddar cheese, proteolysis, casein-to-fat ratio, pH at drainage, rennet

Biography

I graduated from Victoria university. My thesis focused on application of probiotics in dairy products and especially cheese. After graduation, I worked as lecturer assistant, quality assurance manager, and scientific advisor at food manufacturing companies. Dairy technology, food microbiology, probiotics, proteins, salt reduction, sugar reduction, flavors, and ready to eat foods are my expertise.