Document Type

Dissertation - University Access Only

Award Date

2003

Degree Name

Doctor of Philosophy (PhD)

Department / School

Dairy Science

First Advisor

Vikram V. Mistry

Abstract

The objective of this study was to compare the effects of vacuum condensed and ultrafiltered milk on chemical composition and selected functional properties of Cheddar and pasteurized Process cheese. Two level of concentrations - 4.5% protein and 6.0% protein were used for both vacuum condensing and ultrafiltration, along with a 3.2% protein control. Raw whole milk was separated to approximately 0.4% fat, pasteurized and split in 3 parts. One part (175 kg) was vacuum condensed to 11-12% protein (CM) and another (175 kg) was ultrafiltered to 15-16% protein (UF). The third part, pasteurized cream and CM or UF were blended to casein to fat ratio of 0.7 and protein of 4.5% (UFl and CMl) and 6.0% (UF2 and CM2). No concentrate was added to the control (C), 3.2% protein. Cheddar cheeses (6 replicates) were made using frozen concentrated starter (7g/kg protein in cheese milk) and rennet (9 ml/45.4 kg milk for C and 6 ml/45.4 kg milk for the concentrates). At 1 wk, the moisture content of Cheddar cheeses ranged from 39.2 (C) to 36.5% (UF2). The fat content ranged from 31.5 to 32.4% with no significant differences between treatments, and salt from 1.38 to 1.83% with significant differences. Calcium content was higher in UF cheeses than CM cheeses followed by control and it increased with protein content in cheese milk. UF milk produced cheese with higher protein content than CM milk. The soluble protein content of all cheeses increased during 30 wk of ripening. Control cheeses exhibited the highest extent of proteolysis followed by CM cheeses and UF cheeses. Control cheeses exhibited highest meltability followed by 4.5% and 6.0% protein concentrates. There were no significant differences in counts of lactic acid bacteria and non-starter lactic acid bacteria among the treatments. Pasteurized Process cheeses were manufactured using a 1: 1 blend of shredded 18-week and 30-week Cheddar cheese, butter oil and disodium phosphate (3%), heated and pasteurized at 74° C with direct steam injection. The moisture content of the resulting Process cheeses ranged from 39.3 to 40.2%. Fat and protein contents were influenced by both level and method of concentration of cheese milk. Fat content was the highest in C (35.0%) and the lowest in UF2 (31.6%), whereas, protein content was the lowest in C (19.6%) and the highest in UF2 (22.46%). Ash content increased with increase in level of concentration of cheese milk with no effect of method of concentration. Meltability of Process cheeses decreased with increase in level of concentration and was higher in control than the concentrates. Hardness was highest in UF cheeses followed by CM cheeses and control. Viscosity of molten cheese at 80 ° C was higher in 6.0% protein treatments than in 4.5% protein treatments and in control. Free oil in Process cheeses was influenced by both level and method of concentration with C (14.3%) being the lowest and CM2 (18.9%) the highest. Overall flavor, body and texture, and acceptability were significantly higher for Process cheeses made with the concentrates compared to control. The experiments to alter meltability of Cheddar cheeses from 6.0% protein ultrafiltered milk indicated that calcium, salt and moisture content influences meltability in decreasing order. It was concluded that i) both vacuum condensing and ultrafiltration could be valuable tools in altering composition and some functional properties of Cheddar and Process cheese as desired, ii) reduction in calcium content of cheese was the most effective way of increasing meltability of Cheddar cheese, and iii) acidification of skim milk prior to ultrafiltration was effective in lowering the calcium content of resulting Cheddar cheese.

Library of Congress Subject Headings

Cheddar cheese.
Process cheese.
Condensed milk.
Ultrafiltration.

Publisher

South Dakota State University

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Rights Statement

In Copyright