Impact of air humidity in industrial heating processes on selected quality attributes of bread rolls

The object of this research was to study the real time percent humidity of the air and consequently to analyze this humidity influences on bread rolls. An industrial baking process was visualised by the use of a high-temperature humidity sensor to measure the level of percent humidity of the air (V% H2O) in relation to the different H2O-steam amounts (SA). In this study H2O-SA from 0 to 3.256 L(H2O) m(-3) of the oven volume were used. After steaming the results of gas moisture without product (GMWoP) showed a higher maximum (approx. 5%) of the percent humidity of the air than the gas moisture with product (GMWP). The trials reveal that the presence of products (bread rolls) is a factor in attaining an increase in the percent humidity of the air which influences product quality. Baking with adequate percent humidity of the air bread roll volume increased by 20% compared to trials without steam. New methods were used to quantify product parameters like crust thickness, compression-force and crispness and to find out correlations with the area under the GMWP curve (auc). Strongest correlations with auc GMWP were found for mean and maximum compression-force. Furthermore, it was shown that the increase in crust thickness, lightness and colour change is mutually dependent on an increase change in the total GMWP. (C) 2011 Elsevier Ltd. All rights reserved.