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Modelling the steaming of whole wheat grains

Modelling the steaming of whole wheat grains
Modelling the steaming of whole wheat grains
The heat and moisture treatment of starch is important to food manufacture. In cereal processing, grains must be boiled or steamed for the starch to gelatinise and be digestible. NMR imaging has shown that the moisture content distributions of steamed wheat grains are uniform. Thus, gravimetric data are sufficient to enable the time evolution of the moisture content to be analysed. When steam is taken up by the grain it is ultimately absorbed as liquid water. Since this involves a phase change, the accompanying liberation of latent heat will raise the grain temperature. Thermocouple measurements confirm that the grain temperature is slightly higher than the surrounding steam temperature. A model for the mass and heat transfer is proposed which takes account of the experimental observations. The simplest model predicts the temperature difference between the grain and the surrounding steam to be a linear function of grain moisture content, with the moisture content varying exponentially with time. The model predictions are compared with experimental data, and the values of water activity coefficient, heat and mass transfer coefficients are extracted and compared to values in the literature where available.
starch, water activity, moisture content, heat transfer, mass transfer, cereal grains
0009-2509
965-975
Stapley, A.G.F.
1fe66044-beb4-4a7c-8537-8d7fcfcf72ee
Landham, K.A.
b4f7e523-4e64-4a82-9503-98415a344ea3
Please, C.P.
118dffe7-4b38-4787-a972-9feec535839e
Fryer, P.J.
d11bb1a0-1812-411b-baf2-8dcc29732ada
Stapley, A.G.F.
1fe66044-beb4-4a7c-8537-8d7fcfcf72ee
Landham, K.A.
b4f7e523-4e64-4a82-9503-98415a344ea3
Please, C.P.
118dffe7-4b38-4787-a972-9feec535839e
Fryer, P.J.
d11bb1a0-1812-411b-baf2-8dcc29732ada

Stapley, A.G.F., Landham, K.A., Please, C.P. and Fryer, P.J. (1999) Modelling the steaming of whole wheat grains. Chemical Engineering Science, 54 (8), 965-975. (doi:10.1016/S0009-2509(98)00404-7).

Record type: Article

Abstract

The heat and moisture treatment of starch is important to food manufacture. In cereal processing, grains must be boiled or steamed for the starch to gelatinise and be digestible. NMR imaging has shown that the moisture content distributions of steamed wheat grains are uniform. Thus, gravimetric data are sufficient to enable the time evolution of the moisture content to be analysed. When steam is taken up by the grain it is ultimately absorbed as liquid water. Since this involves a phase change, the accompanying liberation of latent heat will raise the grain temperature. Thermocouple measurements confirm that the grain temperature is slightly higher than the surrounding steam temperature. A model for the mass and heat transfer is proposed which takes account of the experimental observations. The simplest model predicts the temperature difference between the grain and the surrounding steam to be a linear function of grain moisture content, with the moisture content varying exponentially with time. The model predictions are compared with experimental data, and the values of water activity coefficient, heat and mass transfer coefficients are extracted and compared to values in the literature where available.

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More information

Published date: 1999
Keywords: starch, water activity, moisture content, heat transfer, mass transfer, cereal grains

Identifiers

Local EPrints ID: 29243
URI: http://eprints.soton.ac.uk/id/eprint/29243
ISSN: 0009-2509
PURE UUID: cf45934c-d1f2-4ffe-8852-8c7748467a78

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Date deposited: 06 Feb 2007
Last modified: 08 Jan 2022 06:53

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Contributors

Author: A.G.F. Stapley
Author: K.A. Landham
Author: C.P. Please
Author: P.J. Fryer

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