Advances in Heat Transfer Unit Operations

Baking and Freezing in Bread Making

Georgina Calderon-Dominguez, Gustavo F. Gutierrez-Lopez, Keshavan Niranjan, Georgina Calderon-Dominguez, Gustavo F. Gutierrez-Lopez, Keshavan Niranjan

• Publisher: CRC Press
• Year: 2016
• Print ISBN:
  9781466504677
• eBook ISBN:
  9781315356938
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

Advances in Heat Transfer Unit Operations: Baking and Freezing in Bread Making explains the latest understanding of heat transfer phenomena involved in the baking and freezing of bread and describes the most recent advanced techniques used to produce higher quality bread with a longer shelf life. Heat transfer phenomena occur during key bread-making stages (cold storage, resting, and fermentation) in which temperature and amount of heat transfer must be carefully controlled. This book combines the engineering and technological aspects of heat transfer operations and discusses how these operations interact with the bread making process; the book also discusses how baking and freezing influence the product quality.

Divided into fourteen chapters, the book covers the basics of heat and mass transfer, fluid dynamics, and surface phenomena in bread-making industrial operations, mathematical modelling in porous systems, the estimation of thermo-physical properties related to bread making, design of equipment, and industrial applications.

1	Heat Transfer Operations in Bread Making Introduction Ma. De la Paz Salgado-Cruz and Georgina Calderón-Domínguez

CONTENTS

1.1  Introduction

References

1.1  INTRODUCTION

Bread is known worldwide and consumed in many different forms; besides, it is the main source of protein and energy in many countries. To produce bread, many different formulas and procedures can be used. However, in all cases, wheat flour and water are the main ingredients, and mixing and baking are two common stages.

Mixing involves the combining and blending of the formula ingredients and, depending on the type of bread, the physical development of gluten; and independently of the mixing degree, the momentum transfer is the base of this unit operation.

Regarding baking, it has been defined as the process where a piece of dough is transformed into bread by the action of heat, under controlled conditions of temperature, time, and humidity. Generally, the process conditions are a function of the type of bread baked, its size, and the formulation employed to produce it, varying the level of temperature from 180°C to 250°C for large dough loaves with low moisture content (Treuillé and Ferrigno 1998) or higher temperatures and shorter baking times (450°C, 35 s) for some type of flat breads (Maleki and Daghir 1967; Qarooni 1990, 1996).

Baking is considered a very complex process, due to the physical and chemical changes occurring simultaneously in the dough, which have been reported to be dependent on temperature (Mondal and Datta 2008) and to occur throughout three stages: (1) the expansion of dough, (2) the transformation of the dough from a foam structure into an elastic structure, and (3) the setting of the sponge structure (Bloksma 1990; Chevallier et al. 2002; Scanlon and Zghal 2001; Singh and Bhattacharya 2005; Sommier et al. 2005).

The first step, also described as the expansion stage or the ovenspring, takes place during the first minutes of baking (Hoseney 1994; Sommier et al. 2005). This dough expansion has been attributed to three processes: the release of CO₂ (He and Hoseney, 1991), the growth of bubbles in the dough (Singh and Bhattacharya 2005), and the reduction of dough density (Chevallier et al. 2002). The study of the changes in the dough structure that occurred during this first baking stage has been limited by the fact that dough is a very fragile system that easily collapses and by the lack of instruments and techniques that allow the evaluation of this complex structure.

In the second baking stage, the transformation of the structure of the dough into an elastic crumb sponge begins at 65°C. During this stage, the gelatinization of starch promotes an increase in both dough viscosity (He and Hoseney 1991) and dough elasticity, as well as a decrease in dough extensibility, resulting in larger gas pressure and larger tensile stress inside the cells (Lostie et al. 2002; Mitchell et al. 1999; Scanlon and Zghal 2001; Sommier et al. 2005). During the third stage of baking, the dough temperature achieves a steady value at the crumb center, the moisture loss rate gets a constant value, the volume decreases, and the crust is set and achieves its golden brown color, all enhanced by the high surface temperature, the extensive protein coagulation, and the Maillard browning reactions. At the same time, the water in the dough reaches its boiling point and the evaporation contributes to the dough stiffening.

All these changes are necessary to get a bread with the typical porous structure that bakers consider as a good quality factor, and all are related to the momentum (viscosity changes, bubble expansion, and coalescence), heat (gases expansion and water evaporation), and mass (water evaporation and crust drying) transfer phenomena simultaneously occurring inside the dough during the baking process.

Bread products have a short shelf life. They start to change from the moment they are removed from the oven, due to the staling process and the microbiological contamination. Good manufacture practices help to increase the shelf life of baked breads until 2 weeks, but after this time, they are not acceptable anymore. Hence, different technological alternatives have been proposed to delay the staling of the product. One of these approaches is the production of frozen bread products such as doughs, prefermented doughs, full-baked breads, cookies, cakes, and prebaked breads.

The use of low-temperature processes has shown several advantages. For example, the reduction of equipment and staff requirements, the increase in the shelf life of the product, and the delay of the staling rate (Hamdami et al. 2007). However, a detrimental effect on textural (firmness) and quality properties (specific volume and moisture content) during subzero temperature storage have been reported (Gómez et al. 2011; Jia et al. 2014), related to the growth of ice crystals and their recrystallization, as well as to starch retrogradation (Berglund et al. 1990, 1991; Polaki et al. 2010).

The freezing of bread can be achieved in a variety of ways, but in all cases, the temperature and the velocity of the air will affect the freezing rates and, as a consequence, the size of the ice crystals formed inside the product. In this regard, it has been published (Baier-Schenk et al. 2005) that the growth of ice crystals leads to a redistribution of water in the dough in the form of ice, which affects the properties of its polymeric compounds (starch and proteins) and reduces the baking performance of prefermented frozen doughs. Similar results have been reported by other researchers (Berglund et al. 1991; Eckardt et al. 2013; Yi and Kerr 2009).

Since dough and/or bread showed very important modifications during baking and freezing or in frozen storage, and most of these changes are related with the phenomena of heat and mass transport, the study of these operations, along with the study of the changes on the physical and biochemical properties of dough and breads during this thermal operations, will be useful to understand the phenomena that take place.

REFERENCES

Baier-Schenk, A., Handschin, S., and Conde-Petit, B. 2005. Ice in prefermented frozen bread dough—An investigation based on calorimetry and microscopy. Cereal Chemistry 82, 251–255.

Berglund, P. T., Shelton, D. R., and Freeman, T. P. 1990. Comparison of two sample preparation procedures for low-temperature scanning electron microscopy of frozen bread dough. Cereal Chemistry 67, 139–140.

Berglund, P. T., Shelton, D. R., and Freeman, T. P. 1991. Frozen bread dough ultrastructure as affected by duration of frozen storage and freeze-thaw cycles. Cereal Chemistry 68, 105–107.

Bloksma, A. H. 1990. Rheology of the breadmaking process. Cereal Foods World 35(2), 228–236.

Chevallier, S., Della Valle, G., Colonna, P., Broyart, B., and Trystram, G. 2002. Structural and chemical modifications of short dough during baking. Journal of Cereal Science 35, 1–10.

Eckardt, J., Öhgren, C., Alp, A. et al. 2013. Long-term frozen storage of wheat bread and dough—Effect of time, temperature and fibre on sensory quality, microstructure and state of water. Journal of Cereal Science 57, 125–133.

Gómez, M., Ruiz, E., and Oliete, B. 2011. Effect of batter freezing conditions and resting time on cake quality. LWT-Food Science and Technology 44, 911–916.

Hamdami, N., Tuam, P. Q., Le-Bail, A., and Monteau, J. 2007. Two stage freezing of part baked breads: Application and Optimization. Journal of Food Engineering 82, 418–426.

He, H., and Hoseney, R. C. 1991. Gas retention in bread dough during baking. Cereal Chemistry 68(5), 526–530.

Hoseney, R. C. 1994. Principles of cereal science and technology. AACC, Second Edition. St. Paul, MN.

Jia, C., Huang, W., Ji, L., Zhang, L., Li, N., and Li, Y. 2014. Improvement of hydrocolloid characteristics added to angel food cake by modifying the thermal and physical properties of frozen batter. Food Hydrocolloids 41, 227–232.

Lostie, M., Peczalski, R., Andrieu, J., and Lauret, M. 2002. Study of sponge cake batter baking process: Part I: Experimental data. Journal of Food Engineering 51, 131–137.

Maleki, M., and Daghir, S. 1967. Effect of baking on retention of thiamine, riboflavin and niacin in Arabic bread. Cereal Chemistry 44, 483–487.

Mitchell, J. R., Fan, J.-T., and Blanshard, J. M. V. 1999. Simulation of bubble growth in heat processed cereal system. In Campbell, G. M., Webb, C., Pandiella, S. S., and Niranjan, K. (Eds.), Bubbles in Food (pp. 107–112). American Association of Cereal Chemists, St. Paul, MN.

Mondal, A., and Datta, A. K. 2008. Bread baking—A review. Journal of Food Engineering 86, 465–474.

Polaki, A., Xasapis, P., Fasseas, C., Yanniotis, S., and Mandala, I. 2010. Fiber and hydrocolloid content affect the microstructural and sensory characteristics of fresh and frozen stored bread. Journal of Food Engineering 97, 1–7.

Qarooni, J. 1990. Flat breads. AIB Research Department Technical Bulletin 12(12), 1–6.

Qarooni, J. 1996. Flat Bread Technology. Chapman & Hall, New York.

Scanlon, M. G., and Zghal, M. C. 2001. Bread properties and crumb structure. Food Research International 34, 841–864.

Singh, A. P., and Bhattacharya, M. 2005. Development of dynamic modulus and cell opening of dough during baking. Journal of Texture Studies 36, 44–67.

Sommier, A., Chiron, H., Colona, P., Della Valle, G., and Rouillé, J. 2005. An instrumented pilot scale oven for the study of French bread baking. Journal of Food Engineering 69(1), 97–106.

Treuillé, E., and Ferrigno, U. 1998. El libro del pan. Vergara, J (Ed.). Dorling Kindersley, London.

Yi, J., and Kerr, W. L. 2009. Combined effects of freezing rate, storage temperature and time on bread dough and baking properties. LWT—Food Science and Technology 42, 1474–1483.

2	Steady-State Heat Transfer Julio C. Fuentes-Gutiérrez, Hugo E. Romero-Campos, Melissa E. Morales-Tovar, Georgina Calderón-Domínguez, Gustavo F. Gutiérrez-López, and Keshavan Niranjan

CONTENTS

2....

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Series Preface
• Series Editor
• Preface
• Acknowledgments
• Editors
• Contributors
• Chapter 1 Heat Transfer Operations in Bread Making: Introduction
• Chapter 2 Steady-State Heat Transfer
• Chapter 3 Nonsteady-State Heat Transfer
• Chapter 4 Principles of Mass Transfer by Molecular Diffusion
• Chapter 5 Thermophysical and Transport Properties of Bread Products during Baking and Freezing
• Chapter 6 Heat and Mass Transfer during Baking
• Chapter 7 Effect of Baking in Product Quality and Baking Ovens
• Chapter 8 Baking Oven Design
• Chapter 9 Heat and Mass Transfer during Bread Freezing
• Chapter 10 Freezing Time Calculations
• Chapter 11 Effect of Freezing Conditions on Bread Quality
• Chapter 12 Cryoprotective Effect of Ingredients on Bread Quality
• Chapter 13 Changes in Dough and Bread Structure as a Result of the Freezing Process
• Chapter 14 Modeling and Simulation of the Freezing Process
• Index