Rheological characterization of creams and prediction of stability
(2022) KLGM15 20212Food Technology and Nutrition (M.Sc.)
- Abstract
- The aim of this project was to develop analytical methods for characterizing rheological behavior of creams. The rheological methods of shear ramp, thixotropy, amplitude sweep, and frequency sweep, as well as texture analysis were initially developed at LTH and later transferred to Galenica.
For this project two series of emulsions were formulated and used as test subjects for these methods. One using Cetostearyl alcohol (CSA) (0.2%, 0.5%, 1%, 2.0%) as a thickening agent, which tends to form lamellar bilayers within the microstructure, and one with Xanthan Gum (0.1%, 0.2%, 0.3%, 0.5%), which forms more of a traditional polymer of a five-fold helical structure.
The results showed that the developed rheological and mechanical methods... (More) - The aim of this project was to develop analytical methods for characterizing rheological behavior of creams. The rheological methods of shear ramp, thixotropy, amplitude sweep, and frequency sweep, as well as texture analysis were initially developed at LTH and later transferred to Galenica.
For this project two series of emulsions were formulated and used as test subjects for these methods. One using Cetostearyl alcohol (CSA) (0.2%, 0.5%, 1%, 2.0%) as a thickening agent, which tends to form lamellar bilayers within the microstructure, and one with Xanthan Gum (0.1%, 0.2%, 0.3%, 0.5%), which forms more of a traditional polymer of a five-fold helical structure.
The results showed that the developed rheological and mechanical methods were successfully able to quantify and give an overall picture of the behavior of the microstructure in each sample. This allowed for a differentiation between samples depending on the types or amounts of polymer used. The shear ramp showed an overall comparable viscosity level between the highest and lowest concentration for each thickening agent, despite the different amounts used for the two formulation series. Moreover, the thixotropy measurement resulted in a better recovery property for samples of Xanthan, after exposed to shear stress.
The amplitude sweep test also showed a similar behavior between the two thickening agents, with the elastic modulus (G’) of CSA staying on a slightly higher level compared to Xanthan. Furthermore, the level of the yield stress is increased with the concentration level, with most samples experiencing a break down between 1-10Pa.
The frequency sweep measurements also showed a similar pattern of with all samples showing stability within the frequency range of 0.1-10 Hz. With a slight positive inclination throughout the range, which could be an indication that the polymer has time to untangle themselves at low frequencies but not at higher frequencies, thus leading to a higher elastic modulus.
Further analysis presented a textural difference, where samples with CSA tended to gather into a cohesive lump with increasing concentration, while instead Xanthan samples gravitated more towards a higher stringiness.
Looking to replace viscosity measurements using a Viscometer with a Rheometer were found to be difficult with results between the two instruments deviating from 32 to 215% for ther investigated samples. One reason for this could be the different dimensions of the spindle used for the Viscometer and the geometer used for the Rheometer.
Investigation of the storage stability of the samples as conducted at room temperature and at 40° Celsius pointed to a conclusion that samples that showed a combination of a higher viscosity, elastic modulus and yield stress had better stability and in these formulation, creaming was more efficiently prevented. (Less) - Popular Abstract (Swedish)
- - Kan man förutse en kräms hållbarhetstid utifrån dess tjocklek?
I detta examensarbete har de reologiska- och texturegenskaper undersökts hos två typer av krämer, en med Cetostearylalkohol som förtjockare, och en med ett mer naturligare alternativ som Xanthan Gum, samtidigt som stabiliteten hos dessa två krämer har undersökts under längre tidsperiod.
Att utveckla nya läkemedel är en tidskrävande process som vanligtvis tar mellan 10 och 15 år att genomföra. Under den kliniska- och toxikologiska testperioden undersöks bland annat stabilitetsförmågan hos ett läkemedel. För att försäkra sig om att ett läkemedel behåller sina medicinska och kosmiska egenskaper är det viktigt att undersöka hur lång tid det tar innan det börjar fasseparera... (More) - - Kan man förutse en kräms hållbarhetstid utifrån dess tjocklek?
I detta examensarbete har de reologiska- och texturegenskaper undersökts hos två typer av krämer, en med Cetostearylalkohol som förtjockare, och en med ett mer naturligare alternativ som Xanthan Gum, samtidigt som stabiliteten hos dessa två krämer har undersökts under längre tidsperiod.
Att utveckla nya läkemedel är en tidskrävande process som vanligtvis tar mellan 10 och 15 år att genomföra. Under den kliniska- och toxikologiska testperioden undersöks bland annat stabilitetsförmågan hos ett läkemedel. För att försäkra sig om att ett läkemedel behåller sina medicinska och kosmiska egenskaper är det viktigt att undersöka hur lång tid det tar innan det börjar fasseparera sig. Detta är dock en långvarig och kostsam undersökning. Detta projekt ämnar därför undersöka ifall man skulle kunna förutse hållbarhetsgraden av en kräm utifrån dess rheologiska egenskaper.
Cetostearylalkohol och Xanthan Gum tenderar att bilda olika typer av mikrostrukturer, vilket reflekteras i undersökningen. Samtliga tester tyder på att prover med innehållande Xanthan Gum gav jämförbara eller i vissa fall bättre egenskaper som förtjockare jämfört med deras motsvarande Cetostearylprover, trots att en mindre mängd Xanthan Gum användes. Bland annat kunde en högre viskositet påvisas under bred skjuthastighetsräckvidd. Dessutom kunde man även notera att prover med Xanthan Gum även tenderade att ha en bättre återhämtningsförmåga, då krämen utsätts för deformation. När man å andra sidan studerade vidare på skillnaden på texturen mellan de två olika förtjockarna kunde man fastställa att Cetostearylalkohol tenderade till att bli mer klumpig vid högre halter, medan Xanthan Gum i stället blev klibbigare.
Stabilitetsundersökning utfördes på prover som förvarats i både rumstemperatur och 40 graders Celsius. Resultatet tydde på att prover med låg koncentration av förtjockare visade en tydligare separationsgrad än resterande prover, vilket korresponderade med låga reologiska egenskaper.
Från en praktisk synvinkel kan det vara fördelaktigt att utnyttja Xanthan Gum då det krävs betydligt mer Cetostearylalkohol för att uppnå samma kvalitet som med Xanthan Gum. Stabiliteten har kunnat knutit samman med karakteristiska reologiska drag hos krämer. Men det finns fortfarande rum kvar att forska vidare på, specifikt att kunna kvantifiera resultaten genom att relatera hållbarheten utifrån en specifik tjocklek för varje förtjockare. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9082638
- author
- Huynh, Tony LU
- supervisor
- organization
- course
- KLGM15 20212
- year
- 2022
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Rheology, Stability, Cream, Pharmaceutical Technology
- language
- English
- id
- 9082638
- date added to LUP
- 2022-06-17 12:04:21
- date last changed
- 2022-06-17 12:04:21
@misc{9082638,
abstract = {{The aim of this project was to develop analytical methods for characterizing rheological behavior of creams. The rheological methods of shear ramp, thixotropy, amplitude sweep, and frequency sweep, as well as texture analysis were initially developed at LTH and later transferred to Galenica.
For this project two series of emulsions were formulated and used as test subjects for these methods. One using Cetostearyl alcohol (CSA) (0.2%, 0.5%, 1%, 2.0%) as a thickening agent, which tends to form lamellar bilayers within the microstructure, and one with Xanthan Gum (0.1%, 0.2%, 0.3%, 0.5%), which forms more of a traditional polymer of a five-fold helical structure.
The results showed that the developed rheological and mechanical methods were successfully able to quantify and give an overall picture of the behavior of the microstructure in each sample. This allowed for a differentiation between samples depending on the types or amounts of polymer used. The shear ramp showed an overall comparable viscosity level between the highest and lowest concentration for each thickening agent, despite the different amounts used for the two formulation series. Moreover, the thixotropy measurement resulted in a better recovery property for samples of Xanthan, after exposed to shear stress.
The amplitude sweep test also showed a similar behavior between the two thickening agents, with the elastic modulus (G’) of CSA staying on a slightly higher level compared to Xanthan. Furthermore, the level of the yield stress is increased with the concentration level, with most samples experiencing a break down between 1-10Pa.
The frequency sweep measurements also showed a similar pattern of with all samples showing stability within the frequency range of 0.1-10 Hz. With a slight positive inclination throughout the range, which could be an indication that the polymer has time to untangle themselves at low frequencies but not at higher frequencies, thus leading to a higher elastic modulus.
Further analysis presented a textural difference, where samples with CSA tended to gather into a cohesive lump with increasing concentration, while instead Xanthan samples gravitated more towards a higher stringiness.
Looking to replace viscosity measurements using a Viscometer with a Rheometer were found to be difficult with results between the two instruments deviating from 32 to 215% for ther investigated samples. One reason for this could be the different dimensions of the spindle used for the Viscometer and the geometer used for the Rheometer.
Investigation of the storage stability of the samples as conducted at room temperature and at 40° Celsius pointed to a conclusion that samples that showed a combination of a higher viscosity, elastic modulus and yield stress had better stability and in these formulation, creaming was more efficiently prevented.}},
author = {{Huynh, Tony}},
language = {{eng}},
note = {{Student Paper}},
title = {{Rheological characterization of creams and prediction of stability}},
year = {{2022}},
}