Date of Award:

1998

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition and Food Sciences

Advisor/Chair:

Donald J. McMahon

Abstract

Three serious problems have been experienced in the manufacture of low moisture cheese using ultrafiltration (UF)- high fat-loss, excessive moisture retention, and poor cheese texture. In this work the causes of these problems were identified, and means of overcoming them were developed.

Coagulation and cheese-making experiments indicated that UF concentration of milk shifts the control of rennet coagulation toward the casein micelle collision rate and away from rennet activity, resulting in formation of a rough-textured curd structure that resists syneresis. Use of 4x whole milk retentate, instead of 5x, improved rennet curd structure, syneresis, and UF cheese texture without reducing protein retention in the cheese. Use of increased rennet and reduced set temperature (26°C) also improved curd structure, syneresis, and cheese texture. Washing of the rennet curd prepared from 4x milk retentate during cheese-making, instead of diafiltration of retentate, was found to improve cheese texture, and cheese moisture below 39% was achieved.

UF retentate was inconsistent as a starter medium because it offered no protection against bacteriophage proliferation, and the growth of some strains of Lactococcus lactis was impaired in UF retentate. Commercial, internally-buffered pH-controlled starter media were more consistent than fermented retentate starter when used for making cheese from 4x retentate.

Low-pressure homogenization of milk at a temperature between 37°C and 45°C increased fat recovery in UF cheese made from 4x ultrafiltration concentrated milk with minimal damage to cheese texture and syneresis. A procedure was developed for the manufacture of quality, high-yield, low-moisture cheese from 4 times ultrafiltration concentrated whole milk. Fat retention in the cheese was 95% and protein retention was 85%

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