Bread improver is a term, generally used by the bakery industry, for a group of chemical substances natural or synthetic in nature which can improve the mixing properties of dough, product characteristics, and retard staling of the bakery products. Deepak Mudgil and Sheweta Barak discuss about bread improver in detail.
Table of Contents
Nowadays, bakery products have become an important part of our daily diet hence improvement in the quality of bakery products is in great demand. To improve the quality bakery industry often uses certain additives such as stabilizers, emulsifiers, and antistaling agents. Emulsifiers are commonly added to commercial bakery products to improve dough handling characteristics and bread quality. Some commonly used emulsifiers are diacetyl tartaric acid esters of mono-diglycerides and lecithin, which are also known as dough improvers, and monoacylglycerols, which are considered as antistaling agents or crumb softeners (Stampfli 1995).
Stabilizers or food hydrocolloids are biopolymers used as functional ingredients in the bakery industry. In the baked goods, hydrocolloids have been used for retarding the staling and for improving the quality of the fresh products as they can induce structural changes in the main components of the wheat dough system. Hydrocolloids can act as bread improver because they can increase water retention and loaf volume and thus finally decreases the firmness and starch retrogradation which further retarded the staling of bread (Mudgil et al. 2011).
Hydrocolloids are used either alone or in combination to achieve specific synergies between their respective functional properties. They can minimize the negative effects of the freezing and frozen storage due to their hydrophilic nature which prevents the growth of ice crystals during frozen storage of products, and moisture migration from the substrate to the outer surface, which improves the freeze/thaw stability.
The presence of hydrocolloids influenced melting, gelatinization, fragmentation, and retrogradation processes in starch molecules which can affect pasting properties, dough rheological behavior and finally the bread staling. An improvement in wheat dough stability during proofing can be obtained by the addition of sodium alginate, k-carrageenan and xanthan gum. Carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC) and alginate can be added as anti-staling agents that retarded crumb firming (Guarda et al., 2004).
Guar gum as bread improver
It is a galactomannan obtained from the seed of a leguminous plant Cyamopsis tetragonolobus. An aqueous solution of guar gum is highly viscous at low concentration and useful in thickening, stabilization and water-binding applications (Mudgil et al. 2011). In bakery industry, guar gum is used to improve the mixing properties of the dough, to extend the shelf life of bakery products through moisture retention and to prevent syneresis in frozen foods. Ribotta et al. (2001) reported that the addition of guar gum in frozen dough produced bread with a higher volume, a more open crumb structure with a higher percentage of gas cells than those prepared without it. Guar gum may also delay bread staling by softening effect likely due to possible inhibition of the amylopectin retrogradation as it preferentially binds to starch which can be explained by an effect on the formation of amylose network avoiding the spongy matrix creation.
Locust bean gum
Locust bean gum (LBG) is a natural galactomannan extracted from the seeds of the carob tree (Ceratonia siliqua L.). It is composed of galactose and mannose units like guar gum but gives less viscous solutions as compared to guar gum at the same concentration. Its application in bakery products results in higher baked product yields; it improves the final texture and adds viscosity in the dough. Furthermore, it appears effective in lowering serum lipids and in the dietary treatment of diabetics (Mandala et al. 2007).
Gum Acacia as bread improver
It is a hydrocolloid derived from the dried gummy exudates of the stems and branches of Acacia senegal. It is water-soluble in nature and resistant to human digestive tract secretion. It is highly branched in nature which gives rise to compact molecules with a relatively small hydrodynamic volume and as a consequence gum solutions become viscous only at high concentrations. It was demonstrated that the addition of gum acacia increased the loaf volume and bread characteristics via water phase management.
Carrageenan as dough improver
It is a sulphated polymer extracted from certain red algae. When it is used as a dough improver in bakery industry, has an ability to improve the specific volume of the bread due to its interactions with gluten proteins (Leon et al. 2000). The presence of this hydrocolloid in the bread dough increased the moisture content in the final bread.
Alginates
Alginates are a polyuronic saccharides isolated from the cell walls of a number of brown seaweed species. Alginates are used to stabilize bakery toppings and icings, as well as to prevent the sticking of products to wrapping paper. Other bakery applications in which alginates are used include meringues and fruit or chiffon pie fillings. The addition of these compounds provides bakery cream with freeze-thaw stability, reduced syneresis, improves shelf life, and moisture retention in bread and cake mixes.
Xanthan gum
Xanthan gum is an extracellular polysaccharide secreted by the bacterium, Xanthomonas campestris. This hydrocolloid contributes smoothness, air incorporation and retention, and recipe tolerance to batters for cakes, muffins, biscuits and bread mixes. Baked goods have increased volume and moisture, higher crumb strength, less crumbling and greater resistance to transport damage. At low concentrations provides storage stability and water-binding capacity. Its pseudoplastic behavior is important in bakery products during dough preparation, i.e. pumping, kneading, and moulding. It prevents lump formation during kneading and improves dough homogeneity. It induces cooking and cooling stability in wheat flour and improves the freeze/thaw stability of starch-thickened frozen foods (Alvarez et al. 2008). It also improves the cohesion of starch granules, thus providing a structure to these products.
It is used to increase water binding during baking and storage and thus prolongs the shelf life of baked goods and refrigerated dough. The addition of Xanthan gum into a frozen dough formulation can strengthen the dough by forming a strong interaction with the flour proteins. It also increases water absorption and the ability of the dough to retain gas, increasing the specific volume of the final bread and the water activity of the crumb (Selomulyo and Zhou 2007). It can also be used in soft baked goods for the replacement of egg white content without affecting appearance and taste. It is also used in prepared cake mixes to control rheology and gas entrainment and to impart high baking volume.
Hydroxypropyl methylcellulose
HPMC is a water-soluble fiber that has been used in food for decades to enhance the manufacturing process and improve food product qualities. This compound is obtained by the addition of methyl and hydroxypropyl groups to the cellulose chain. The etherification of hydroxyl groups of the cellulose increases its water solubility and also confers some affinity for the non-polar phase in doughs.
Hence, in a multiphase system like bread dough, this bifunctional behaviour allows the dough to retain its uniformity and to protect and maintain the emulsion stability during breadmaking (Selomulyo and Zhou 2007). It was also demonstrated that using HPMC dough improver in breadmaking improves its quality in terms of loaf volume, moisture content, crumb texture, and sensorial properties. In addition, this hydrocolloid is a good antistaling agent for retarding the crumb hardening. Its effect should be attributed to its water retention capacity, and possible inhibition of the amylopectin retrogradation.
Carboxymethyl cellulose
CMC is a cellulose derivative with carboxymethyl groups bound to some of the hydroxyl groups present in the glucopyranose monomers that form cellulose backbone (Selomulyo and Zhou, 2007). CMC is used, as dough improver, in baked goods mostly to retain moisture, to improve the body or mouthfeel of the products, to control sugar and ice crystallization, to protection against leavening losses in cake mixes, to improving volume and uniformity of baked products, and to increase the shelf life of cereal products.
Diacetylated tartaric acid esters of mono- and diglycerides of fatty acids (DATEM)
These are anionic oil-in-water emulsifiers that are used as dough strengtheners. They are the most important emulsifier used for bakery ingredients, for the production of bread and small baked items. When added to the dough, they improve mixing tolerance, gas retention, the resistance of the dough to collapse, improves loaf volume and endow the crumb with a resilient texture, fine grain as well as good slicing properties. It is also reported that DATEM formed hydrogen bonds with starch and glutamine is capable to promote the aggregation of gluten proteins in dough by binding to the protein hydrophobic surface.
This results in baked goods with high volume and good crumb structure which are characteristics of high quality. Added to this, the emulsifier also ensures the machinability of dough during make-up. Moreover, mono-glycerides of fatty acids and starch may form “inclusion compounds” which prevent the recrystallisation of starch (retrogradation) in the finished baked good. This retrogradation is the main cause of staling.
Lecithins
These are a group of naturally occurring, complex phospholipids. They have been reported to reduce staling and to have the advantage of being amenable to modification for specific applications. They are also used in baguette and other crusty bread to improve dough gas retention to a degree and contribute to crust formation. The main commercial source of lecithin is plant seed especially soybean. Soya lecithin hydrolysate form complex effectively with starch amylose and retarded wheat starch crystallization due to its content of lysophospho-lipids. In addition, lecithins slow down the amylopectin crystallization because of their high content in lysophospholipids. This may explain why the effect brought about by enriched lecithins in lysophospholipids presented a better antistaling capacity (Azizi et al. 2003).
Monoacylgly-cerols
These are the most widely used fat-based emulsifiers in bread and other food systems. These substances can be applied to delay staling and as crumb softeners in bakery products. The generally accepted theory about the mechanism by which crumb softeners retard the firming process is based on the ability of monoglycerides to form complexes with amylose. It is reported that this amylose monoglycerol inclusion complex is insoluble in water. Therefore, the part of the amylose which is complexed by the monoglycerides does not participate in the gel formation which normally occurs with the starch in the dough during baking. Therefore, upon cooling, the complexed amylose will not recrystallize and will not contribute to the staling of the bread crumb (Stampfli 1995).
Glycerol mono-stearate (GMS)
It is best used in the hydrated form but can be added as a powder. It does not greatly contribute to dough gas retention of bread volume but does act as a crumb softener through its proven anti-staling effect. It was also reported that did not alter the water absorption capacity significantly, but marginally improved the stability of the dough (Maga & Ponte, 1975).
References
1 Alvarez, M. D., Fernández, C., & Canet, W. (2010). Oscillatory rheological properties of fresh and frozen/thawed mashed potatoes as modified by different cryoprotectants. Food and Bioprocess Technology, 3(1), 55-70.
2 Azizi, M. H., Rajabzadeh, N., & Riahi, E. (2003). Effect of mono-diglyceride and lecithin on dough rheological characteristics and quality of flat bread. LWT-Food Science and Technology, 36(2), 189-193.
3 Brownlee, I. A., Allen, A., Pearson, J. P., Dettmar, P. W., Havler, M. E., Atherton, M. R., & Onsøyen, E. (2005). Alginate as a source of dietary fiber. Critical reviews in food science and nutrition, 45(6), 497-510.
4 Guarda, A., Rosell, C. M., Benedito, C., & Galotto, M. J. (2004). Different hydrocolloids as bread improvers and antistaling agents. Food Hydrocolloids, 18(2), 241-247.
5 León, A. E., Ribotta, P. D., Ausar, S. F., Fernández, C., Landa, C. A., & Beltramo, D. M. (2000). Interactions of different carrageenan isoforms and flour components in breadmaking. Journal of agricultural and food chemistry, 48(7), 2634-2638.
6 Maga, J. A., & Ponte, J. G. (1975). Bread staling. Critical Reviews in Food Science & Nutrition, 5(4), 443-486.
7 Mandala, I., Karabela, D., & Kostaropoulos, A. (2007). Physical properties of breads containing hydrocolloids stored at low temperature. I. Effect of chilling. Food Hydrocolloids, 21(8), 1397-1406.
8 Mudgil, D., Barak, S., & Khatkar, B. S. (2011). Guar gum: processing, properties and food applications–A Review. Journal of Food Science and Technology, doi 10.1007/s13197-011-0522-x
9 Ribotta, P.D., Leon, A.E., and Añon, M.C. 2001. Effect of freezing and frozen storage of doughs on bread quality. J. Agric. Food Chem. 49:913–918.
10 Ribotta, P. D., Perez, G. T., Leon, A. E., & Anon, M. C. (2004). Effect of emulsifier and guar gum on micro structural, rheological and baking performance of frozen bread dough. Food Hydrocolloids, 18(2), 305-313.
11 Selomulyo, V. O., & Zhou, W. (2007). Frozen bread dough: Effects of freezing storage and dough improvers. Journal of Cereal Science, 45(1), 1-17.
12 Sidhu, J. P. S., & Bawa, A. S. (2004). Effect of gum acacia incorporation on the bread-making performance of Punjab wheat. International Journal of Food Properties, 7(2), 175-183.
13 Stampfli, L., & Nersten, B. (1995). Emulsifiers in bread making. Food Chemistry, 52(4), 353-360.
