BREAD: Its ingredients, making process and recent innovations

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Authors – N Sai Prasanna


Bread is the most important stable food in the human diet all around the world since from years. Bread provides basic nutrients, such as carbohydrates, protein, dietary fibre, vitamins, micronutrients, and antioxidants, essential for human nutrition. Bread formed due to several complex reactions and its organoleptic characteristics (taste, flavour, aroma and texture) which are particularly influenced by ingredients used, technology applied and baking conditions. The basic ingredients used in bread are wheat flour, yeast, water, shortenings, salt, sugars, etc. leavening agents.

Role of ingredients in bread making
Wheat flour: Three principal types of wheat are Triticum vulgare (or aestivum), T. durum, and T. compactum. T. vulgare used to produce flour (milled) for bread making. Hard wheat with high quantity of protein (approximately 12–15%) mainly in the form of gluten provides excellent flour for bread – making. Soft wheat that has low protein quantity (8 – 11 %) results in less attractive and smaller bread crumb structure¹. Wheat flour is responsible for unique behaviour and advanced mouth feel. Wheat flour contains two proteins – gliadin (sticky and inelastic in nature that forms viscous dough) and glutenin (more elastic in nature that provides rubbery strength) are most responsible for viscoelastic properties of wheat dough. Both these proteins get mixed when added water and the resulting mixture is known as gluten which gets wetted during the preparation of dough and forms cohesive and elastic network. Gluten gives dough its ability to form thin sheets that will stretch and hold gas in baking process. The water holding capacity of wheat dough mainly depends on wheat flour type, origin and other properties. Properly stored flour has better water holding capacity than freshly milled flour.

Water: The bread crumb and texture and crumb mainly depend on wheat flour and water. Water is necessary for formation and flow ability of dough, sucrose hydrolysis and starch gelatinization during bread baking. Water activates enzymes and binds together the insoluble proteins of wheat flour which form gluten. Water alters the rheological properties of dough. Water provides the required nutrients for the yeast growth during proofing step. Water gets vaporized during baking process and contributes to oven spring rise of bread. Right amount (approximately 50%) of water addition makes the bread crumb structure non – sticky and pleasing. Most artisan bread formulas contain about 60 – 75% of water. Optimum amount of water to be added in bread making was determined using a farinograph instrument.

Leavening agents: Leavening agents responsible for dough expansion, breakdown of sugars, flavour development and alcohol synthesis during fermentation. Saccharomyces cerevisiae (baker’s yeast) is the most common yeast used as leavening agents in bread making. In bread making, Yeast cells metabolize fermentable sugars (glucose, fructose, sucrose and maltose) under anaerobic conditions producing gases like carbon dioxide that helps in rise of dough volume. Depending on the yeast types, active dry yeast has a long shelf-life at room temperature but needed to be hydrated before incorporating with other ingredients. In contrast, instant yeast can be incorporated with flour and other ingredients without prior hydration. 

Salt: Salt strengthens the gluten, controls loaf volume, improves flavour and aids the action of amylases to maintain maltose supply for yeast. Salt inhibits the action of flour proteases which might depolymerize proteins of the gluten complex. Yeast dough without salt is sticky and difficult to manipulate.

Sugars: Sugars are normally used by yeast during the early stages of fermentation. Sugars sweeten the bread, increases gas production and improves crust colour. Sugars also act as an anti-plasticizers and anti – staling ingredients inhibiting starch recrystallization. Sugar alternatives like honey could serve as an alternative to sucrose in the bread making process. Honey has high in sugars such as fructose and glucose (80-90%) can improve crust browning. 

Shortenings were added to increase the machinability or specifically slicability, increases  loaf volume, improves crumb uniformity, Edible fats and oils containing dough conditioners and emulsifiers (Calcium stearoyl-2-lactylate, sodium stearoyl-2-lactylate, ghee or margarine), Mono and diglycerides, Polysorbate 60, Succinylated monoglycerides, Ethoxylated monoglycerides, Sucrose esters) can be used for shortening purpose.

Stages in bread making
The general stages involved in bread baking and respective changes caused in each are as mentioned below:

Milling: The two predominant methods used in wheat milling are stone milling and roller milling. The selected milling technique significantly influences wheat flour quality, dough rheological properties and bread characteristics. The optimal milling conditions and specific strategies to improve these milling techniques is very much crucial to maintain these desired physicochemical and functional properties of wheat flour, dough and bread¹.

Dough Mixing: The straight dough method, modified straight dough method and sponge method are the three mixing methods for combining ingredients for bread dough. Dough is produced by mixing of all the ingredients in required quantity and in desirable sequence for a certain period of time. The main functions of mixing are to blend the ingredients into a quasi-homogeneous mixture, to develop gluten matrix in wheat dough and to incorporate air. In mixing step, first the proteins are hydrated and then they interact with each other during the mixing process. Other flour components like lipids, salts, non-starch polysaccharides and starch also mixed to gluten matrix.

Dough Kneading: Kneading bread dough is an important process to developing a gluten structure which strengthens the bread. It also creates a more even crumb for the final product and improves the flavour of the bread. The mixed ingredients of the bread dough are kneaded thoroughly either in kneading machines using a dough hook or by hand. Knead the dough until it is smooth and elastic. Correct kneading time helps to avoid over and under – mixing, warming, excessive weakening and over-softening of bread dough. Kneading helps to obtain optimal dough rheology and consistency, correct dough temperature and mixing speed, correct water temperature, water absorption, correct dough aeration. It also ensures proper oven spring during baking and optimal bread crumb. Kneading process improved through strategies using alternative refrigerants like CO2 snow to maintain low dough temperature, measuring the kneading progress in real time, delay the addition of bran and middlings during whole wheat dough kneading and by adding organic acids, sourdough, emulsifiers, hydrocolloids, enzymes, and salt substitutes. Concerning to kneading machines, machine type, kneading element, total element revolutions, kneading time and other important parameters should be thoroughly optimized for pleasant bread making².

Fermentation/ Leavening: After kneading, the dough is allowed to rest for fermentation before baking. In this step, wheat flour, water, salt and yeast are bound together and transform into bread. Here yeast will begin to feed on the starches in wheat flour and sugars added in the dough, gets fermented because of available moisture. This process release CO2 gas and substances that affect the flavour and aroma of the baked bread. Leavening is done by that CO2 produced from yeast fermentation. The dough volume rises during this resting period in the presence of living yeast also known as proofing. Proofing and fermentation can be carried either at room temperature or specified humidity conditions. Properly proofed dough causes optimum balance of extensibility, elasticity and rheological properties as well as good machinability and produces bread with desirable volume and crumb characteristics. As water vapour and CO2 expands, they act as insulating agents and help to prevent high temperature rise of bread crumb, possibility of excessive moisture evaporation from bread surface, develops texture and flavour of the bread in baking. After fermentation, the dough is shaped into rolls, loaves or other shapes using desired moulds.

Baking: Baking of dough in electric or baking ovens is the most vital step in bread making process. It results in a series of physical, chemical and biochemical changes in bread loaf like volume expansion, evaporation of water, formation of porous structure, protein (gluten) denaturation, starch gelatinization, crust formation and browning reaction, protein crosslinking, melting of fat crystals and their incorporation into the surface of air cells, rupture of gas cells, expansion of gas cells into an open network of pores at microscopic level. The baking process alters the sensory properties, improves palatability, destroys enzymes and microorganisms, and enhances tastes, aromas and texture of bread formed. The formation of the brown crust due to Maillard-type browning reaction and caramelization is the primary factor responsible for final bread characteristics such as flavour, crust colour and crispiness. The optimum baking process depends on the type of bread to be baked and the desired bread characteristics. 

Cooling: Bread removed from the oven after being baked, it undergoes various changes that impact its taste during cooling. Rapid cooling causes alcohol vapours, carbon dioxide and water vapour to diffuse through the crust of the bread, later replaced by ambient air. Proper cooling is very much essential to obtain optimum diffusion of aromas from the crust towards the crumb structure and pleasing texture and taste.

Recent Innovative and Challenges in bread production

  • Major focus is healthy bread preparation technologies that include gluten free, protein rich, fibre rich, sprouted and clean – label ingredients. Wheat flours enriched with a particular vitamin or minerals are also being used for baking bread. However, partially amount of gluten is still imitating in bread production5. 
  • The demand for alternative technologies in bread production is to expel the inclusion of additives in bread production. Reduction of food additives will reduce the raw material costs and also can avoid the entry of allergens in the bread product4.
  • In sourdough technology, addition of exopolysaccharides such as lactic acids and acetic acids during fermentation produces soft bread and increases protein stability. Metabolites like carbon dioxide, ethanol, fungicide, fatty acids produces in the fermentation step further helps in the preservation and keeping quality of bread4.
  • In recent times, breads are being developed without yeast as a leavening agent, other agents like bicarbonates and phosphates can reduce the sour taste of the bread and reduces proofing time5. 
  • Sugar in bread making has been replaced with natural sweeteners like stevia, honey, date syrup, jaggery, etc., and has zero calories5. 
  • Enzymes (particularly, amylases, asparaginase, glucose oxidase and lipase) used in industrial bread making improves dough strength, the formation of protein networks in dough that affect bread volume, crumb structure and bread texture, improves shelf life and reduce toxic acrylamide formation during baking6.
  • Modern machines are able to process the bread starter prepared with natural yeast to give the final product characteristics such as the crunchy crust and the soft and fragrant interior.
  • All the steps of modern bread baking lines are automated and adjustable, and can be modified according to the recipes. All modern baking technologies have the ability to prevent weather conditions that affect the final baked product.
  • In modern bakeries, rotary ovens characterized by vertical and horizontal baking chambers with trolleys of baking trays with the bread to be baked and allows for fairly rapid baking. The bread obtained through overlapping horizontal chambers has an intense colour, better taste and fragrance.
  • Many of the electric ovens are thermally insulated to prevent heat loss for controlling energy losses and efficient working. A ventilation system also equipped to facilitate a homogeneous heat distribution and to prevent dehydration. Modern baking technologies prevent that weather conditions affect the final result of the baked product.
  • The infrared technology installed on ovens to reduce the energy required during the cooking process by 20 – 40% and saves up to 70% of the time³.
  • At the ending note, since bread is the foremost essential constituent of the human diet of all age group people. New trends are much needed to develop bread making technologies using different functional ingredients to satisfy consumers’ taste and preferences related to healthy diet. Also with existing conventional and innovative processing techniques like(high – pressure treatment, pulsed electric field, ohmic treatment, radiofrequency treatment), more focus to be done on microbial (mold) inhibition, quality degradation (staling process retardation) and active packaging techniques to prolong the shelf-life of bread at respective storing conditions.
References
  1. Cappelli, A., Oliva, N., & Cini, E. (2020). Stone milling versus roller milling: A systematic review of the effects on wheat flour quality, dough rheology, and bread characteristics. Trends in Food Science & Technology, 97, 147-155.
  2. Venturi, M., Cappelli, A., Pini, N., Galli, V., Lupori, L., Granchi, L., & Cini, E. (2022). Effects of kneading machine type and total element revolutions on dough rheology and bread characteristics: A focus on straight dough and indirect (biga) methods. LWT, 153, 112500.
  3. https://www.italianfoodtech.com/useful-technologies-for-the-production-of-bread/
  4. https://www.foodresearchlab.com/blog/new-product-development/technological-innovations-in-bread-production/
  5. http://www.fnbnews.com/Bakery-Biscuits/emerging-trends-in-bakery-industry-in-india-64827
  6. https://www.newfoodmagazine.com/article/91957/bakery-trends/