Dry heat treatment of flour: addressing quality and safety implications

Keppler, Silvia (2017). Dry heat treatment of flour: addressing quality and safety implications. University of Birmingham. Ph.D.

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Abstract

High ratio cake formulations such as sponges and cupcakes are well appreciated by the market due to their favourable attributes like sweet taste, moist mouthfeel, and tender texture. To bake a successful cake of such kind, it is necessary to change flour functionality. This can be done by dry heat treatment. The aim of this work was to investigate the dry heat treatment of flour and to implement it on a novel thermal processing equipment, the Revtech system, for the production of high ratio cake flour.
For this purpose, flour was heat treated in lab-scale experiments at accurately controlled time-temperature conditions. The effect of heat on flour functionality was evaluated with a variety of analytical methods, e.g. the Rapid-Visco-Analyser (RVA) or the rheometer.
The Revtech system is presented for the continuous heat treatment of flour. Particles are conveyed through helical pipes by vibrations and the pipe walls are heated by resistive heating. Residence time distributions were determined depending on process parameters and shown to be narrow. The residence time was generally found to increase during extended periods of operation, which was related to the deposition of a powder layer inside the pipe. Temperature distributions of pipe and flour flow were characterised. After flour heat treatment in the Revtech equipment, high ratio cakes were baked and analysed. A method was developed to compare the results to lab-scale experiments. The time-temperature history of flour was described in terms of equivalent, constant treatment times and temperatures, which may be correlated to cake quality attributes. The approach is industrially relevant for the development of a cake flour specification and the facilitation of process validation.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):