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Approaches for improving the rheological characterization of fermented dairy products

Muhammad, Abdulrahman LU (2020) KLTM05 20192
Food Technology and Nutrition (M.Sc.)
Abstract
Fermented dairy products are wildly consumable products in today societies, and these products are known for their unique rheological properties due to the complex structural systems they possess. The simplest rheological model for describing yogurt behavior is the Power Law model, but this model parameters are not sufficient for describing the complex behavior during flow and filling. Therefore, it is important to utilize more sophisticated models that can capture other properties of the products such as the yield stress and the time dependency.
Another challenge is to define a standard measuring protocol that can produce reliable and repeatable results, and at the same time can overcome the challenges associated with the thixotropic... (More)
Fermented dairy products are wildly consumable products in today societies, and these products are known for their unique rheological properties due to the complex structural systems they possess. The simplest rheological model for describing yogurt behavior is the Power Law model, but this model parameters are not sufficient for describing the complex behavior during flow and filling. Therefore, it is important to utilize more sophisticated models that can capture other properties of the products such as the yield stress and the time dependency.
Another challenge is to define a standard measuring protocol that can produce reliable and repeatable results, and at the same time can overcome the challenges associated with the thixotropic and viscoelastic behavior of the samples.
This investigation includes a review of the possible regression methods that can be utilized using EXCEL sheets, and recommend the more suitable method for analyzing rheological measurements. This study also compares the behavior of several yogurt products (Vanilla, Naturell and Långfil) using different models with and without including the yield stress. The investigation includes an attempt to measure the zero- shear viscosity and infinite- shear viscosity which are important parameters for further CFD simulations.
The thixotropic behavior of the three products was also described qualitatively and improved the understanding of the break down and build- up of the studied samples, and to what extent thixotropy can affect the rheological measurements. The study also recommends several methods for eliminating the time effect to improve the measurements of the studied products, which can also be applied to other types of samples.
Elongation tests were performed using two different methods, and even though the results are difficult to interrupt, it was possible to qualitatively estimate the elasticity difference between the studied samples. (Less)
Popular Abstract
One of the most consumed products in the world are fermented dairy products, these products have been developed through time, and the most popular one these days is yogurt with its different forms (stirred, set, drinking, and frozen types). The quality, texture and composition of yogurt products varies depending on where it is produced, and the processes needed for production.
Tetra Pak is manufacturing and developing yogurt processing lines and packages and filling machines, but the challenges that comes with this complex line of products need to be understood, because of the problems caused often by the complex behavior they possess, which is caused by their gel structures and complex composition which can be different from product to... (More)
One of the most consumed products in the world are fermented dairy products, these products have been developed through time, and the most popular one these days is yogurt with its different forms (stirred, set, drinking, and frozen types). The quality, texture and composition of yogurt products varies depending on where it is produced, and the processes needed for production.
Tetra Pak is manufacturing and developing yogurt processing lines and packages and filling machines, but the challenges that comes with this complex line of products need to be understood, because of the problems caused often by the complex behavior they possess, which is caused by their gel structures and complex composition which can be different from product to product based on how it was made and the bacterial culture used.
These issues can appear all over the production line, from an unpredicted pressure drop over the heat exchangers to dripping and splashing (causing a need for more frequent cleaning) during filling under given conditions.
In order to anticipate these issues and understand the reason behind them, a better understanding of the rheology of yogurt products must be developed. To achieve that, it is important to define and measure the relevant properties and it is suspected that the rheological models available now are not enough to give a clear picture of the yogurt properties.
This study is a completion of previous work, and is a part of a bigger project at Tetra Pak aimed to measure the right fluid properties that can best describe yogurt behavior during flow and filling, and to present the required data and parameters for applying Computational Fluid Dynamics (CFD), which is used to present a model for yogurt behavior during different flow conditions. This is done to correlate the validation data to predict yogurt behavior during flow and filling.
The simplest rheological model for describing yogurt behavior is the Power Law model, but this model parameters are not sufficient for describing the complex behavior during flow and filling. Therefore, it is important to utilize more sophisticated models that can capture other properties of the products such as the yield stress and the thixotropy. The yield stress is the amount of shear required to allow the product to flow, and the thixotropy is a property that allow the products to regain their structure after a resting period.
Another challenge is to define a standard measuring protocol that can produce reliable and repeatable results, and at the same time can overcome the challenges associated with the thixotropic and viscoelastic behavior of the samples.
This study also includes a review of the possible regression methods for the data analysis of the results, that can be utilized using EXCEL sheets, and recommend the more suitable method for analyzing rheological measurements. This study also compares the behavior of several yogurt products (Vanilla, Naturell and Långfil) using different models with and without including the yield stress. The investigation includes an attempt to measure the zero- shear viscosity (viscosity at very low shear) and infinite- shear viscosity (viscosity at very high shear) which are important parameters for further CFD simulations.
The thixotropic behavior of the three products was also described qualitatively and improved the understanding of the break down and build- up of the studied samples, and to what extent thixotropy can affect the rheological measurements. The study also recommends several methods for eliminating the time effect to improve the measurements of the studied products, which can also be applied to other types of samples.
Elongation tests were performed using two different methods, and even though the results are difficult to interrupt, it was possible to qualitatively estimate the elasticity difference between the studied samples. (Less)
Please use this url to cite or link to this publication:
author
Muhammad, Abdulrahman LU
supervisor
organization
course
KLTM05 20192
year
type
H2 - Master's Degree (Two Years)
subject
keywords
food engineering, livsmedelsteknik
language
English
id
9006179
date added to LUP
2020-03-26 08:52:45
date last changed
2020-03-26 08:52:45
@misc{9006179,
  abstract     = {Fermented dairy products are wildly consumable products in today societies, and these products are known for their unique rheological properties due to the complex structural systems they possess. The simplest rheological model for describing yogurt behavior is the Power Law model, but this model parameters are not sufficient for describing the complex behavior during flow and filling. Therefore, it is important to utilize more sophisticated models that can capture other properties of the products such as the yield stress and the time dependency. 
Another challenge is to define a standard measuring protocol that can produce reliable and repeatable results, and at the same time can overcome the challenges associated with the thixotropic and viscoelastic behavior of the samples. 
This investigation includes a review of the possible regression methods that can be utilized using EXCEL sheets, and recommend the more suitable method for analyzing rheological measurements. This study also compares the behavior of several yogurt products (Vanilla, Naturell and Långfil) using different models with and without including the yield stress. The investigation includes an attempt to measure the zero- shear viscosity and infinite- shear viscosity which are important parameters for further CFD simulations. 
The thixotropic behavior of the three products was also described qualitatively and improved the understanding of the break down and build- up of the studied samples, and to what extent thixotropy can affect the rheological measurements. The study also recommends several methods for eliminating the time effect to improve the measurements of the studied products, which can also be applied to other types of samples. 
Elongation tests were performed using two different methods, and even though the results are difficult to interrupt, it was possible to qualitatively estimate the elasticity difference between the studied samples.},
  author       = {Muhammad, Abdulrahman},
  keyword      = {food engineering,livsmedelsteknik},
  language     = {eng},
  note         = {Student Paper},
  title        = {Approaches for improving the rheological characterization of fermented dairy products},
  year         = {2020},
}