VOLUME 3 /NUMBER 7 Reducing Agents Practical technology from Lallemand Inc. Dough A Guide to Reducing Agents Reduction Chemistry EDUCING AGENTS (like L-cysteine) improve machinability, and improve loaf are a type of dough conditioner volume. Frozen bread dough is a spe cial Cysteine is unique among the protein R used to reduce mix time and case where short mix time is especially amino acids because it has a sulfhydryl improve extensibility. They are used in important because it helps improve yeast group at the end of the molecule. Cysteine bread to increase bakery throughput and stability. is important to dough reduction chemistry to adjust for flour variation and in a num - Extensibility is important in other yeast because it occurs in the gluten protein ber of other yeast and chemically leavened and chemically leavened applications from flour, in the tripeptide glutathione applications. including pizza, tortillas, cookies, saltines, from yeast, and in free amino acid form as and other crackers. Reducing agents a synthetic reducing agent. FUNCTIONALITY decrease the elasticity that can cause During mixing, the gluten in the flour is shrinkage or curling after these products O stretched and pulled apart so that it can be are formed. || reformed during proofing and baking to HSCH 2CHCOH | provide the needed strength and structure. CHARACTERISTICS NH 2 Reducing agents act like mixing to Protein-based reducing agents include L-cysteine reversibly break down gluten so that once cysteine, glutathione, and yeast. Cysteine O O they have been used up the gluten reforms. is the most commonly used reducing agent || || This mechanism is the opposite of oxidiz - in bread. It is an amino acid that is usually HSCH 2CH C–NHCH 2COH ing agents, which build up gluten. produced synthetically as L-cysteine hydro- | O NH Reducing and oxidizing agents can be chloride, is usually added at the mixer, and || | used separately, or a reducing agent can be acts quickly. Glutathione is a peptide that HOCCHCH 2CH 2C used with a slow oxidizing agent (like contains cysteine but is not generally ||| potassium bromate) to increase gluten available in its pure form. It functions simi- NH 2 O Glutathione breakdown early in the process and gluten larly to L-cysteine but is potentially more reformation later in the process. When effective because it can react more times. The significance of cysteine’s sulfhydryl reducing agents are used with fast oxidiz - Yeast is a natural source of glutathione. group is that two of them from different ing agents (like iodate or azodicar - Special nonleavening yeasts are used as proteins can be oxidized to one molecule bonamide), they counteract each other. reducing agents in the same applications as of cystine, with the creation of a disulfide Bread dough requires a combination L-cysteine. bond between them. When gluten mole - of strength, extensibility, and tolerance Sulfites are commonly used reducing cules become linked (oxidized) during that depends mostly on flour quality, water agents in cookies and crackers. Their breadmaking, the dough strength increases absorption, and mixing conditions. Reduc- active ingredient is the bisulfite ion that is but its extensibility decreases. During mix - ing agents are used especially with high- obtained from sulfur dioxide or from one of ing, these linkages are broken mechanical - strength flour and high-speed processes to its salts, such as sodium bisulfite. Sulfites ly to provide the extensibility needed for reduce mix time, lower energy input, Continued moulding. The process is reversible, and the gluten matrix reforms during the later stages of proofing and baking. REDUCING AGENTS AND MIX-TIME REDUCERS COMPOUND USE LEVEL CONSIDERATIONS L-cysteine 10–90 ppm Most-common reducing agent Glutathione Not commercially available Nonleavening yeast 0.0 5–1.0% Natural source of glutathione The disulfide bonds in gluten that are Bisulfite 20–100 ppm May require finished product labeling broken mechanically during mixing can also be broken chemically by a series of Ascorbic acid 100–200 ppm For closed system continuous mix reactions with cysteine or glutathione Sorbic and fumaric acids 10–90 ppm Limited use as reducing agent Protease Not a true reducing agent Continued International Persp ect ive: A Guide to Reducing Agents (Continued) FRENCH BREAD AND MODERN FL OUR destroy the vitamin thiamine, are inhibi- Parts of the French baking industry have modernized rapidly since the 1970s, with tory to yeast, cause sensitivity reactions in increased production of pan bread and frozen dough on high-speed lines with short some people, and require special label processes. In response, French wheat growers and flour millers have selected wheat declarations if used in the U.S. at levels in varieties for increased strength. But the increase in strength has come at the expense of the finished product above 10 parts per extensibility and has made optimum mixing and moulding more difficult to achieve. million. The problem of decreased extensibility is worsened by traditional product types and Ascorbic acid (vitamin C) is used as a legal restrictions. Baguettes must be long and regular in shape with well-defined top reducing agent only in certain closed con - cuts. Croissants and brioches require thin dough laminations without tearing. For these tinuous mix applications. In the presence of and other products, French regulations prohibit most reducing agents, including oxygen it functions as an oxidizing agent, L-cysteine, sulfites, and sorbic acid. Techniques such as decreased dough temperature but in the absence of oxygen, as a reducing and reduced proofing time help somewhat by slowing oxidation reactions but create agent. It can be used in coated form for other problems. increased stability as a component of bread Since 1990, French bakers have begun using increasing amounts of nonleavening improvers and dough conditioners. yeast as a dough conditioner for high-strength/low-extensibility flour. The products Other acids that have been suggested have a high glutathione content so that they act as reducing agents and are permitted as reducing agents, but are not commonly under French regulations as “deactivated fermentative agents.” Versions are available used, include sorbic acid and fumaric acid. for artisanal and industrial applications and for a range of products including bread, They are part of a group of “activated pastry, puff pastry, and retarded dough. The same products are used in other European double-bond compounds” and are more countries with similar flour/product/regulatory requirements and in the U.S. and commonly used as preservatives. These Canada for bromate replacement and other applications. acids are inhibitory to yeast and less eco - nomical than other synthetic reducing Dough Reduction Chemistry (Continued) agents. Proteases are used to decrease mix known as disulfide interchange. The reac - glutathione molecules added and are re- time and increase elasticity but are not tions are shown here, with R and R' repre - versible so that the degree of relaxation can reducing agents. They are natural enzymes senting the two gluten molecules and with be controlled. The reaction is similar with that break down gluten irreversibly and cysteine as the reducing agent: either cysteine or glutathione, except that must be used with careful attention to with glutathione less is required. This is dose, time, and temperature to avoid over - R–S–S–R' + cys–SH R–S–S –cys + R' –SH because an enzyme present in flour converts conversion. R–S–S–cys + cys–SH cys–S– S–cys + R –SH glutathione disulfide into two glutathiones with free SH groups that can parti cipate in These reactions reduce the number of further disulfide reactions. Because no anal - cross-links between the gluten subunits ogous enzyme exists for cysteine sulfide, proportional to the number of cysteine or each cysteine SH can be used only once. Fermaid ® Dough Relaxers ERMAID ® DOUGH RELAXERS are Finished volume is high and uniform, with nonleavening yeast products that a fine, uniform internal structure. Using Freduce mix time and improve dough Fermaid ® dough relaxers to optimize mix extensibility. They are natural replace - time minimizes the effect of flour changes, Lallemand Baking Update is produced by Lallemand Inc. to provide bakers with a ments for L-cysteine hydrochloride, sulfites, improves machinability, and avoids both source of practical technology for solving and other chemical reducing agents in “bucky,” undermixed doughs and sticky, problems. You can find the latest issues breads, rolls, pizza, pretzels, tortillas, and overmixed doughs. online at www.lallemandbaking.com. crackers. Fermaid ® dough relaxers are Fermaid ® dough relaxers are available If you have questions or comments, processed to maximize available gluta- in versions for a range of products and please contact us at: thione—a naturally occurring yeast pep - applications. Those with lower glutathione LALLEMAND Inc. tide that acts as a reducing agent. They levels are used at higher doses so that they 1620 Préfontaine function similarly to L-cysteine but with also contribute flavor and crust color. Montréal, QC H1W 2 N8 Canada tel: (800) 840-4047 ( 514) 522- 2133 the added benefit of being label-friendly. Those with higher glutathione levels are email: solution s@ lallemand.com For breads and rolls, Fermaid ® dough used at lower doses to provide dough relax - www.lallemand.com relaxers can be used to reduce the mix ation without contributing taste or flavor. To the best of our knowledge, the information in time required for high-strength flour or Formulations with other dough conditioner Lallemand Baking Update is true and accurate. How- ever, any recommendations or suggestions are made high water absorption. They give a dough ingredients are optimized for specific appli - without warranty or guarantee. that is smoother and easier to handle at cations including pizza, pies, crackers, tor - the moulder, with good flow in the pan. tillas, and wraps. © 2018 Lallemand Inc..