Abstract #179

# 179
Minimizing moisture migration in large 291-kg blocks of Cheddar cheese.
C. E. Collins*1, M. E. Johnson2, S. Govindasamy-Lucey2, J. J. Jaeggi2, J. A. Lucey1,2, 1University of Wisconsin-Madison, Madison, WI, 2Wisconsin Center for Dairy Research, Madison, WI.

In the industry, 291-kg blocks (known as 640-blocks) of Cheddar cheese are manufactured for ease of handling and reducing trim loss during conversion. Significant moisture (MC) migration occurs within blocks due to temperature gradients during cooling. Some manufacturers also concentrate cheese milk, resulting in higher amounts of casein and thus higher amounts of colloidal calcium phosphate (CCP). To reduce MC variation within 640-blocks, we explored the impact of pre-acidifying milk to solubilize some CCP and varying cooling rates after pressing to reduce temperature gradients. Four replicate 640-blocks of stirred curd Cheddar cheese were manufactured at a commercial facility. Milk was ultrafiltered to 14.8 ± 0.6% solids and 3.2 ± 0.1% casein. Vats were pre-acidified to pH levels (no pre-acidification, pH 6.35, 6.20) using lactic acid. Blocks were stored in different coolers for 15 d (4 or 21°C for 2 d followed by 4°C). All blocks were transferred to a 1°C warehouse at 15 d. After 30 d, 640-blocks were cut into sixteen 40-lb portions. Inner core and outer samples were cut from four 40-lb blocks. Inside of 640-blocks was lower in MC than outside, as expected. Treatments reduced MC variability between inside and outside less than expected, likely due to low pH (<5.0) observed in pre-acidified samples. Slow cooling resulted in lowered pH. Functionality was monitored by texture profile analysis and small amplitude oscillatory rheology. Cheese hardness was higher in inside of the 640-blocks compared with outside, but slightly less variation was observed with pre-acidification and slow cooling. Higher temperatures for maximum loss tangent (an index of meltability) were observed in inside samples compared with its outside. Less variation between inside and outside samples was observed in melting point (LT = 1) for pre-acidified and slow cooled cheeses. A split-split plot design was used for statistical analysis, and a comparison of means was carried out (P < 0.05). Pre-acidifying cheese milk and slowing the cooling rate appeared to reduce some functionality variation in 640-blocks of Cheddar cheese, but more control is needed over final cheese pH to reduce MC migration.

Key Words: pre-acidification, cooling, moisture