Paper Number
PO109
Session
Poster Session
Title
Rheology of starch gelation using a new pressurized pasting cell
Presentation Date and Time
October 23, 2019 (Wednesday) 6:30
Track / Room
Poster Session / Ballroom C on 4th floor
Authors
- Adhia, Yash (TA instruments - Waters llc, Applications)
- Ahuja, Amit (TA Instruments)
- Lee, Reginald (TA Instruments)
- Latshaw, Alina (TA Instruments)
- Foster, Peter (TA Instruments)
Author and Affiliation Lines
Yash Adhia, Amit Ahuja, Reginald Lee, Alina Latshaw, and Peter Foster
TA Instruments, New Castle, DE 19720
Speaker / Presenter
Adhia, Yash
Text of Abstract
Characterizing processing behaviors are vital for the successful production of food products. In the food industry, many food products experience extreme processing conditions of high temperature and high stresses. The measurements of sample behavior for water-based formulations above 100 °C is extremely challenging due to changes in material composition from the boiling of volatile ingredients. We have developed a high-sensitivity, pressurized starch pasting configuration (up to 5 bar) which utilizes a design free of mechanical bearings and seals, resulting in an order-of-magnitude improvement in torque sensitivity (1 µN.m in oscillatory and 10 µN.m in shear flows) compared to traditional rheometer pressure cells. A pressurized atmosphere suppresses boiling of the volatile components, allowing us to characterize the structure-property relationships of the sample over a range of testing conditions (-5 to 150 °C). In this work, the in-situ gelatinization of starch dispersions of varying starch particle weight fractions was studied as they were subjected to elevated temperature (120 °C) at a fixed shear rate. We determined typical parameters associated during gelatinization such as onset and peak temperature along with peak viscosity to probe the impact of high temperature on the gelation process and the rheological properties of the final starch paste. Additionally, yield stresses of the final paste, measured at 120 °C, were examined for varying particle weight fractions through traditional flow and oscillatory methods. The yield stress and the viscosity rapidly increase with increasing particle concentrations above a critical fraction of 0.04. Yield stresses at 120 °C ranged from 0.25 – 6.5 Pa for weight fractions between 0.05 and 0.15 following a power-law dependence, with 0.05 being the minimum starch weight fraction for which there was any measurable yield stress. The starch pastes were found to exhibit shear-thinning and significant thixotropic behavior.