036: Impact of Composition and Extent of Proteolysis on Rheological and Tribological Properties and Their Relationship With Machineability of Cheddar Cheese

Introduction

High-speed processing operations are used to convert cheese blocks into value added and convenient forms of cheese e.g. shreds and slices. Machineability of cheese is an important criterion for evaluating cheese block for its ability to covert into different forms. Poor machinability will cause significant mass losses due to either crumbliness or stickiness. The objective of this study was to find out the influence of composition, extent of proteolysis on the material properties related to the machineability of Cheddar cheese such as wear behavior, tackiness, and textural properties.

Methods

Ten commercial Cheddar cheese samples were subjected to moisture, protein, fat, salt, pH analysis. Extent of proteolysis was analyzed by performing pH 4.6 soluble nitrogen analysis and reported as intact casein (IC). Wear Behavior and Tack behavior were performed on Anton Paar MCR302 Rheometer using Pin in Disk (PID/44) and PP50 geometries respectively on a 5 mm thick slice of cheese and reported as penetration depth (PD), rate of wear and mass loss. The texture profile analysis (2-bite compression test) was performed on cheese cubes of 2x2x2 cm3 using TA.XT plus Texture Analyzer. All of analytical tests were performed at 5℃ and at least in triplicate.

Results

Compositional parameters and material properties, total protein to moisture ratio (P/M), intact casein to moisture ratio (IC/M) and fat content (FC) had strong correlations (r>0.70) with the tested material properties. Samples with higher P/M and IC/M exhibited higher hardness, less tackiness, PD and mass loss, indicating softer and aged cheese is more prone to sticking to the rotating blade and causing more material loss. Hardness increased, tackiness and PD decreased with higher fat content suggesting that fat at low temperature (5oC) reinforced the cheese matrix, causing less stickiness to the blade and mass loss.

Significance

Loss of material due to sticking and production of fines during high-speed processing of cheese block can be predicted using material properties, provided influencing factors are identified and a relationship between these factors and mass loss is established. This study will help predict slicing/shredding behavior of cheese by the cheese industry.