THE CHORLEYWOOD BREAD PROCESS
CONTENTS 1 INTRODUCTION 1 2 BREADMAKING AN OVERVIEW 7 PART I WHEAT AND FLOUR QUALITY 27 3 THE CHEMISTRY AND BIOCHEMISTRY OF WHEAT 28 4 ASSESSING GRAIN QUALITY 69 5 TECHNIQUES FOR ANALYSING WHEAT PROTEINS 95 6 WHEAT PROTEINS AND BREAD QUALITY 119 7 STARCH STRUCTURE AND BREAD QUALITY 145 8 IMPROVING WHEAT QUALITY THE ROLE OF BIOTECHNOLOGY 166 9 ANALYSING WHEAT AND FLOUR 185 10 MILLING AND FLOUR QUALITY 196 11 MODIFYING FLOUR TO IMPROVE FUNCTIONALITY 215 12 THE NUTRITIONAL ENHANCEMENT OF WHEAT FLOUR 247 PART II DOUGH AND BREAD QUALITY 265 13 THE MOLECULAR BASIS OF DOUGH RHEOLOGY 266 14 MOLECULAR MOBILITY IN DOUGH AND BREAD QUALITY 281 15 THE ROLE OF WATER IN DOUGH FORMATION AND BREAD QUALITY 298 16 FOAM FORMATION IN DOUGH AND BREAD QUALITY 312 17 BREAD AERATION 342 18 MEASURING THE RHEOLOGICAL PROPERTIES OF DOUGH 363 19 CONTROLLING DOUGH DEVELOPMENT 389 20 THE USE OF REDOX AGENTS 409 21 WATER CONTROL IN BAKING 431 22 IMPROVING THE TASTE OF BREAD 450 23 HIGH FIBRE BAKING 469 24 MOULD PREVENTION IN BREAD 481 25 DETECTING MYCOTOXIN CONTAMINATION OF CEREALS 495 26 IMPROVING WHEAT QUALITY 515 27 PREVENTING BREAD STALING 541 1 INTRODUCTION MENTION THE WORD QUALITY AND ON A GOOD DAY MY EYES NORMALLY GLAZE OVER AS PICTURES OF DETAILED AND OFTEN MEANINGLESS PROCEDURES APPARENTLY DESIGNED TO ENSURE THE QUALITY OF A PROCESS OR A PRODUCT SPRING TO MIND ON A BAD DAY I MIGHT RUN SCREAMING FROM THE ROOM THE BIG PROBLEM WITH MOST QUALITY SYSTEMS IS THAT THEY FAIL TO TAKE SUFFICIENT ACCOUNT OF THE REAL PURPOSE OF THE PROCEDURE OR PRODUCT CONCERNED THIS IS ESPECIALLY THE CASE IN BREADMAKING WHERE THE PERCEPTION OF PRODUCT QUALITY IS VERY PERSONAL WE ALL HAVE OUR SELECTION OF CRITERIA WHICH CLASSIFY BREAD AS GOOD OR BAD CORRECT OR WRONG AND WHILE THERE ARE SOME COMMON CHARACTERISTICS ON WHICH MANY OF US WOULD AGREE FOR EXAMPLE THE BREAD SHOULD NOT BE MOULDY THE FINAL JUDGEMENT WILL ALWAYS BE HIGHLY PERSONAL IN THE FINAL ANALYSIS IF WE DEFINE QUALITY AS BEING FITNESS FOR PURPOSE THEN FOR THE EACH OF US BREAD QUALITY MAY BE DESCRIBED AS BEING THE SUM OF THOSE QUALITY TRAITS WHICH CONFER THE SENSORY PLEASURES ASSOCIATED WITH SMELL TASTE AND TEXTURE IN SUMMARY WHEN WE TASTE AND EAT THE PRODUCT WE EXPERIENCE PLEASURE OUR INDIVIDUAL PERCEPTION WILL THEN DEPEND ON THE COMBINATION OF THOSE PARAMETERS WHICH CHARACTERISE THE MIX OF PRODUCT APPEARANCE TEXTURE SMELL AND FLAVOUR WHICH BEST SUITS EACH OF US WE MUST ALSO RECOGNISE THAT OUR PERCEPTION OF QUALITY WILL CHANGE WITH THE PASSAGE OF TIME AND PERSONAL CIRCUMSTANCES NOT LEAST OUR HEALTH WHILE THERE ARE MANY FACTORS WHICH CHARACTERISE THE QUALITY OF BREAD PRODUCTS THAT CAN BE EASILY DEFINED AND MEASURED E G LOAF HEIGHT AND VOLUME THERE ARE MANY OTHERS WHICH ARE EPHEMERAL IN NATURE AND THEREFORE MORE DIFFICULT TO DEFINE E G SMELL AND FLAVOUR IN DEFINING QUALITY THE TERM CONSISTENCY IS OFTEN USED AS FREQUENTLY AS FITNESS FOR END USE CONSISTENCY IS INDEED A DESIRABLE QUALITY TRAIT WITH MOST PRODUCTS BUT FOR THE HIGHLY INDIVIDUAL PERCEPTION OF BREAD QUALITY EVEN THIS SIMPLE QUALITY TRAIT IS DIFFICULT TO APPLY WITH ABSOLUTE CERTAINTY IF YOU ARE A SANDWICH MAKER THEN YOU CERTAINLY WANT CONSISTENCY OF VOLUME SHAPE AND CELL STRUCTURE BUT IN A CRAFT BAKERY CONTEXT CUSTOMERS MAY STILL WANT TO CHOOSE BETWEEN LIGHT AND DARK CRUST COLOURED PRODUCTS THE VARIABILITY IN BREAD QUALITIES SOUGHT BY CONSUMERS DEMANDS THAT BAKERS BE ABLE TO MEET ALL OF THE QUALITY REQUIREMENTS CONCERNED ALL IN ALL BREADMAKING REQUIRES A DEEP UNDERSTANDING OF THE MANY COMPLEX RAW MATERIAL AND PROCESS INTERACTIONS THAT ALL PLAY A PART IN DETERMINING FINAL PRODUCT QUALITY 1 1 1 WHEAT AND ITS SPECIAL PROPERTIES ALMOST EVERY DISCUSSION OF BREAD AND ITS QUALITY WILL START WITH A REFERENCE TO THE SPECIAL NATURE OF WHEAT GIVEN THAT WHEAT FLOUR IS THE LARGEST INGREDIENT IN DOUGH AND BREAD FORMULATIONS IT IS HARDLY SURPRISING IN THE CONTRIBUTIONS WHICH FOLLOW MUCH WILL BE MADE OF THE SPECIAL PROPERTIES OF WHEAT FLOUR PROTEINS TO FORM GLUTEN AFTER HYDRATION AND DURING MIXING DOUGH MIXING IS THE PROCESS WHICH STARTS DOUGH AERATION AS THE GLUTEN FORMS A NETWORK WHICH TRAPS AND RETAINS BUBBLES OF AIR FOR INFLATION BY CARBON DIOXIDE GAS FROM YEAST FERMENTATION IT IS BECAUSE OF THE SPECIAL PROPERTIES OF WHEAT PROTEINS THAT MUCH RESEARCH HAS BEEN DEVOTED TO THEM CHAPTER 3 PROVIDES A COMPREHENSIVE INSIGHT TO THE MANY DIFFERENT ASPECTS OF WHEAT CHEMISTRY AND BIOCHEMISTRY AND THIS THEME IS CONTINUED IN CHAPTERS 6 AND 26 IMPROVEMENTS IN WHEAT QUALITY TO MAKE IT BETTER SUITED TO ITS END USES ARE CONSIDERED IN CHAPTERS 8 AND 11 ALONG WITH OPPORTUNITIES FOR FUTURE DEVELOPMENT THE KEY ROLE OF THE GLUTEN FORMING PROTEINS RIGHTLY RECEIVES CONSIDERABLE ATTENTION IN SEVERAL CHAPTERS BUT TO ADDRESS THE BALANCE THE ROLE OF STARCH IS CONSIDERED IN CHAPTER 7 FUNDAMENTAL TO ACHIEVING A GIVEN BREAD QUALITY IS THE ABILITY TO MEASURE WHEAT QUALITY AND PREDICT THE LIKELY BREADMAKING PERFORMANCE OF ANY GIVEN WHEAT SAMPLE THIS HAS BEEN THE HOLY GRAIL FOR FARMERS MILLERS AND BAKERS FOR CENTURIES CEREAL SCIENCE HAS DEVELOPED MANY TECHNIQUES AND TOOLS TO HELP BUT THE COMPLEXITY OF THOSE LITTLE WHEAT GRAINS AND THE IMPACT OF FARMING PRACTICES ON GRAIN QUALITY MEANS THAT THE GOAL STILL REMAINS LARGELY UNATTAINED MUCH PROGRESS HAS BEEN MADE AND IS CONSIDERED IN SEVERAL OF THE CHAPTERS WHICH FOLLOW HOWEVER IF YOU READ ON EXPECTING TO ENCOUNTER A SINGLE TEST TO MAKE THE PERFECT PREDICTION YOU WILL BE DISAPPOINTED IT REMAINS UNLIKELY THAT THERE WILL BE A SINGLE TEST WHICH WILL PREDICT BREAD QUALITY WITH CERTAINTY AND THAT IS HARDLY SURPRISING GIVEN THAT THERE ARE MANY DIFFERENT TYPES OF BREAD AND BREADMAKING PROCESSES EACH REQUIRING A DEGREE OF VARIATION IN THE QUALITY PREDICTORS FOR THE MOMENT WE WILL HAVE TO CONTENT OURSELVES WITH USING A RANGE OF ANALYTICAL TECHNIQUES BUT I HOPE THAT THE CHAPTERS FOR EXAMPLE 4 5 AND 9 WHICH ADDRESS THIS GENERAL ASPECT WILL ENABLE YOU TO DECIDE WHICH COMBINATION BEST SUIT YOUR PARTICULAR NEEDS CEREALS AND CEREAL BASED PRODUCTS ARE AMONGST THE SAFEST OF FOODS THAT WE HAVE AVAILABLE HOWEVER GROWING AND PROCESSING GRAIN IS NOT WITHOUT ITS HAZARDS SOME OF THE MOST DEADLY TOXINS ARE THOSE WHICH OCCUR NATURALLY IN CEREALS SUCH UNWANTED MATERIALS MAY COME IN THE FORM OF MYCOTOXINS WITH THE WIDESPREAD TRANSPORT AND LONGER TERM STORAGE OF CEREAL PRODUCTS ISSUES OF FOOD SAFETY HAVE BECOME INCREASINGLY IMPORTANT AND FOR THESE REASONS THE DETECTION AND CONTROL OF MYCOTOXINS MATERIALS ARE THE SUBJECT OF CHAPTER 25 1 2 CONVERTING WHEAT TO FLOUR IN ORDER TO MAKE AN AERATED BREAD STRUCTURE IT IS NECESSARY TO PROCESS THE WHEAT GRAINS INTO ANOTHER MORE SUITABLE FORM OVER THE CENTURIES TECHNIQUES HAVE EVOLVED WHICH PERMIT THE SEPARATION OF THE WHITE ENDOSPERM FROM THE DARKER COLOURED BRAN SKINS AND GERM THE PROGRESSION TOWARDS GREATER AVAILABILITY OF WHITE FLOUR HAS SPAWNED THE LARGE NUMBER OF BREAD PRODUCTS THAT WE SEE IN BAKERIES TODAY THERE ARE A NUMBER OF FACTORS WHICH HAVE THE CHORLEYWOOD BREAD PROCESS 2 DRIVEN THE MOVE TO WHITE FLOURS NOT LEAST THE GREATER GLUTEN FORMING POTENTIAL OF THE WHEAT PROTEINS IN THE STARCHY ENDOSPERM AS DISCUSSED IN CHAPTER 10 THE FLOUR MILLING PROCESS HAS EVOLVED INTO A SOPHISTICATED PROCESS BUT ITS EFFICIENCY AND ECONOMIC VIABILITY STILL DEPEND ON THE QUALITY OF THE RAW MATERIAL ENTERING THE FLOUR MILL BECAUSE OF THIS FLOUR MILLERS REMAIN ACUTELY AWARE OF THE NEED TO ASSESS WHEAT QUALITY AND LINK ITS QUALITIES WITH THE FINAL PRODUCT FOR WHICH IT IS DESTINED FLOUR MILLERS THEREFORE CONTINUE TO USE A RANGE OF TESTS TO ASSESS BOTH THE RELIABILITY AND CONSISTENCY OF THEIR OWN OPERATIONS AS DISCUSSED IN CHAPTER 9 SINCE THE NUTRITIONAL PROPERTIES OF THE WHEAT GRAIN ARE NOT HOMOGENEOUSLY DISTRIBUTED THROUGHOUT THE WHEAT GRAIN THE SEPARATION OF THE ENDOSPERM FROM THE OTHER COMPONENTS TO YIELD WHITE FLOUR IS NOT WITHOUT ITS PENALTIES IN THOSE CIRCUMSTANCES WHERE NUTRITION IS AT A PREMIUM THE FORTIFICATION OF FLOUR AND WHEAT BASED PRODUCTS HAS BECOME A POLITICAL AND HUMANITARIAN ISSUE THE ROLE OF FORTIFICATION AND THE MEANS BY WHICH IT MAY BE ACHIEVED ARE DISCUSSED IN CHAPTER 12 AND THEY PROVIDE AN INSIGHT TO ANOTHER IMPORTANT ASPECT OF BREAD QUALITY THE NUTRITIONAL QUALITY LINK IS ALSO COVERED IN CHAPTER 23 WHERE THE ROLE FOR INCREASING FIBRE LEVELS IN BREAD ARE DISCUSSED IT IS SOMEWHAT IRONIC THAT THE WESTERN WORLD APPROACH TO BREADMAKING WHICH HAS BECOME DOMINATED BY WHITE FLOUR BASED PRODUCTS SHOULD BE ADVOCATING A RETURN TO HIGHER EXTRACTION FLOURS THE CONVERSION OF ALL OF THE WHEAT GRAIN TO FLOUR HAS ALWAYS BEEN WITH US BUT THE QUALITY ATTRIBUTES OF WHOLEMEAL OR WHOLEWHEAT BREAD HAVE NOT HAD SUFFICIENT APPEAL FOR THE MASS MARKET IN THE UK WHEN THE TECHNOLOGY FOR MAKING WHOLEMEAL AND SIMILAR BREADS AS LARGE AND SIMILAR IN SOFTNESS TO WHITE BREAD WERE DEVELOPED SALES ROSE FROM 2 TO 20 OF BREADS SOLD THIS INCREASE IN SALES WAS TRULY QUALITY DRIVEN SINCE THE FIBRE HYPOTHESIS HAD BEEN AROUND FOR QUITE SOME YEARS WITH LITTLE IMPACT ON THE DIETARY HABITS OF THE AVERAGE UK CONSUMER 1 3 MAKING BREAD BREADMAKING IS A CENTURIES OLD TRADITIONAL CRAFT PRACTISED IN ANY COUNTRY CAPABLE OF GROWING OR IMPORTING WHEAT THIS HAS MEANT THE EVOLUTION OF A DIVERSE RANGE OF BREADMAKING PROCESSES DESIGNED TO ACHIEVE A WIDE RANGE OF BREAD PRODUCTS THERE ARE A NUMBER OF CENTRAL THEMES WHICH ARE COMMON TO ALL BREAD PRODUCTS AND BREADMAKING PROCESSES THEY ARE THE MIXING OF WHEAT FLOUR WATER YEAST AND OTHER FUNCTIONAL INGREDIENTS AND THE EXPANSION OF THE DOUGH MASS THROUGH THE GENERATION OF CARBON DIOXIDE GAS IN THE TECHNOLOGY OF BREADMAKING CAUVAIN AND YOUNG 1998 2002 IT HAS BEEN STATED THAT FOR NO TIME DOUGHMAKING PROCESSES THAT ABOUT 90 OF FINAL BREAD QUALITY IS DECIDED BY WHAT BAKERS CHOSE TO DO IN THE MIXER THIS ASPECT OF QUALITY EMBRACES THE CHOICE OF RAW MATERIALS AND FORMULATION AS WELL AS DECISIONS ON HOW TO MIX AND DEVELOP THE GLUTEN STRUCTURE IN THE DOUGH THE RELATIONSHIP BETWEEN MIXING AND DOUGH DEVELOPMENT IS STILL NOT FULLY UNDERSTOOD THIS IS A THEME WHICH IS VISITED IN MANY OF THE CHAPTERS IN THIS BOOK IT IS WELL KNOWN THAT SIMPLY BLENDING THE BREAD RECIPE INGREDIENTS IS NOT ENOUGH TO INITIATE THE DEVELOPMENT OF THE GLUTEN STRUCTURE THE TECHNOLOGICAL ASPECTS ASSOCIATED WITH GLUTEN DEVELOPMENT AND THEIR PLACE IN THE DIFFERENT BREADMAKING PROCESSES ARE DISCUSSED THE CHORLEYWOOD BREAD PROCESS 3