Off-campus South Dakota State University users: To download campus access theses, please use the following link to log into our proxy server with your South Dakota State University ID and password.

Non-South Dakota State University users: Please talk to your librarian about requesting this thesis through interlibrary loan.

Kartik Shah

Document Type

Thesis - University Access Only

Award Date

2012

Degree Name

Master of Science (MS)

Department / School

Dairy Science

First Advisor

Lloyd E. Metzger

Abstract

Nonfat yogurt is a popular fermented product available in various forms. In the US, the Code of Federal Regulations (CFR) requires >8.25% milk solids in the yogurt base. NDM is a common ingredient utilized to provide milk solids in yogurt produced in the US. However, in International markets, Skim Milk Powder (SMP), Milk Protein Concentrate (MPC), and De-Proteinized Whey (DPW) are also utilized in yogurt formulations. The protein content, Total Solids (TS), source of milk protein, and seasonal variation in yogurt formulations may have an impact on the functionality of yogurt. Additionally, physicochemical changes during storage of powders can result in variation of the functional properties of powders as well as of the product in which they are used. The first objective of this study was to evaluate the effects of Milk Solids Not Fat (MSNF) based fortification of yogurt formulations with various milk powders (SMP, NDM, MPC40, and MPC70) on the functionality of nonfat stirred yogurts. Required amounts of powder were added to produce yogurts containing 8.5% MSNF. The second objective of this study was to evaluate the effects of storage of various milk powders (SMP, NFDM, MPC40, and MPC70) on their functional properties and on the functionality of nonfat yogurts at three different protein and TS levels. Three different lots of SMP, NDM, MPC40 and MPC70 were collected from US manufacturers and each lot was divided into 3 portions. A portion was analyzed after 3, 9, and 15 months of storage at 25°C. At each storage time, yogurt formulations with %protein/%TS of 4/12.5, 4.5/13.5 and 505.5 were produced from each lot of SMP, NDM, MPC40, and MPC70. The third objective of this study was to evaluate the effects of seasonal variation of powder manufacture (SMP and NDM) on their functional properties and on the functionality of nonfat yogurt at three different %protein/% TS ratios ( 4/12.5, 4.5/13.5 and 5/15.5). Skim milk powder and NDM were collected from US manufacturers during summer (May'09 - August'09) and winter (Nov'09- Feb' 10) season for yogurt manufacture. A Rapid Visco Analyzer (RVA) method was utilized to produce yogurt for all objectives. At each storage time, yogurt formulations with three different · %protein/%TS (4/12.5, 4.5/13.5 and 5/15.5) were produced from each lot of SMP, NDM, MPC40, and MPC70. Varying amount of DPW was included to standardize the protein and TS content. Functional properties such as solubility, Emulsification Ability Index (EAI), foaming, and hydrophobicity of each powder lot was evaluated at 3, 9, and l 5months of storage. The data were analyzed by split plot design using PROC Mixed in SAS. Functional properties of yogurts (standardized at 8.5% MSNF) improved with an increase in the protein content in the formulation. Powders storage time did not have a significant effect (p>0.05) on the functional properties of yogurts fortified with NDM, MPC40, and MPC70 at all protein/TS ratio (protein:TS). Viscosity of both MPC40 and MPC70 yogurts was significantly (p0.05) effect on their functional properties such as solubility, EAI and hydrophobicity. In conclusion, the storage of milk powders has an impact on their functional properties but has a minimal influence on the functional properties of nonfat yogurt, whereas the use of MPC had a substantial impact on the functionality of nonfat yogurt. Furthermore, the season of powder manufacture also has an impact on the functional properties of yogurts.

Library of Congress Subject Headings

Yogurt
Functional foods
Proteins in human nutrition

Description

Includes bibliographical references (pages 69-93)

Format

application/pdf

Number of Pages

142

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

Download

Share

COinS