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Panna Agrawal

Document Type

Thesis - University Access Only

Award Date

2006

Degree Name

Master of Science (MS)

Department / School

Dairy Science

First Advisor

Ashraf N. Hassan

Abstract

The texture of reduced-fat Cheddar cheese is typically rubbery, dry and grainy. In previous studies (Awad et al., 2005a; b; Hassan et al., 2005), an exopolysaccharide-(EPS) producing culture improved textural, melting and viscoelastic properties of reduced-fat Cheddar cheese. However, this EPS-positive cheese developed bitterness after 2 to 3 months of ripening due to increased residual chymosin activity. We hypothesized that the reduced amount of chymosin needed to coagulate ultrafiltered (UF) milk might result in reduced residual chymosin activity and bitterness in cheese. The objectives of this study were to improve the texture and flavor of reduced-fat Cheddar cheese using a combination of EPS-producing culture and UF. Reduced-fat Cheddar cheeses were manufactured with EPS-producing and non-producing cultures using skim milk or UF skim milk (1.2x) adjusted to a casein: fat ratio of 1.35. The EPS-producing culture increased yield, moisture in nonfat substance, and residual chymosin activity in reduced-fat Cheddar cheese. In addition, EPS-positive cheese was softer, and less gummy and rubbery than the EPS-negative cheese. The viscoelastic moduli were higher in 1 day old EPS-negative reduced-fat cheese than in the EPS-positive cheese. During ripening, whereas the viscoelastic moduli increased in the EPS-positive cheese, they decreased in the EPS-negative one. At day 1, the creep/recovery test showed that EPS-positive cheese was less rigid and more deformable than EPS-negative cheese. Lower (P≤0.05) residual chymosin activity was found in cheese made from UF milk than that in cheese made from control milk. The low UF concentration level (1.2x) did not affect the textural characteristics of cheese. Panelists reported that UF-EPS-positive cheese was less (P≤ 0.05) bitter than EPS-positive cheese made from control milk. Using an EPS-producing culture improved the texture and UF milk (1.2x) reduced bitterness in reduced-fat Cheddar cheese, which has beneficial commercial implications in the manufacture of this type of cheese.

Library of Congress Subject Headings

Cheddar cheese
Cheese -- Microbiology
Microbial exopolysaccharides
Ultrafiltration

Description

Includes bibliographical references (pages 51-63)

Format

application/pdf

Number of Pages

95

Publisher

South Dakota State University

Rights

In Copyright - Non-Commercial Use Permitted
http://rightsstatements.org/vocab/InC-NC/1.0/

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