Nucleation and Expansion During Extrusion and Microwave Heating of Cereal Foods

Characteristics and oil absorption in deep-fat fried batter prepared from ball-milled wheat flour

BACKGROUND

The porous structure generated during frying influences oil absorption and textural qualities. The alteration in physical properties of wheat flour is suspected to affect the structure formation. The present study investigated the effect of physicochemical changes in wheat flour by the ball-milling process on structure formation and consequently oil absorption of a fried wheat flour batter model.

RESULTS

Batter models containing 600 g kg(-1) moisture were made of 0-10 h ball-milled wheat flour and then fried in frying oil at 150 degrees C for 1-7 min. The samples made of milled flour possess larger pores and exhibit lower oil absorption than sample made of 0 h milled flour. The fracture force of a fried sample prepared from 5 and 10 h milled flour is lower than that of a sample prepared from 0 h milled flour.

CONCLUSION

The decrease in glass transition temperature (T(g)) and melting temperature (T(m)) of milled flour affect the microstructure formation in the fried wheat flour batter. The microstructure is responsible for oil absorption and fracturability in fried food. The samples made of flour of longer ball-milling time have lower oil absorption and higher crispness. Ball-milling may be a tool to produce mechanically modified wheat flour which can reduce oil absorption for fried batter.

Characterization of deep-fat frying in a wheat flour-water mixture model using a state diagram

BACKGROUND

Crispness is an important characteristic to be controlled in deep-fat fried products. The physical state of food polymers influences the development of cellular structure and textural qualities of fried food. Glassy state is believed to play an important role in the mechanical properties of low-moisture food. Therefore, an understanding of the physicochemical phenomena in the development of fried food structure using a state diagram of the frying process is discussed.

RESULTS

Wheat flour models containing 400 and 600 g kg(-1) initial moisture content were fried in frying oil at 150 °C for 1-7 min. Thermal properties of wheat flour, structure alteration and textural properties of fried samples were evaluated. The porous structure continuously enlarged when the sample was in the rubbery state. As the frying time was prolonged, the state of the product became glassy due to a decrease in water content, resulting in the ceasing of porous enlargement.

CONCLUSION

The results revealed that physicochemical changes during frying influence the alteration of microstructure and quality of fried food, and the state diagram could be applied to explain the formation of microstructure during the frying process and used as a decision-making tool to choose the proper conditions to provide desirable qualities in fried food. Copyright © 2007 Society of Chemical Industry.