This discussion will involve an informal explanation for the problems which have occurred in baked products. It is only a brief discussion utilizing current slides which are available. Sugar has been roles and functions in baked products. In a yeast-leavened product it not only affects the color and volume of the product but affects structure stability. Sucrose is hydrolyzed by the yeast organism and produces not only carbon dioxide but also acids, alcohols and a number of other compounds. Sugars, particularly reducing sugars or hydrolyzable sugars with a reducing sugar component, are an important component in the Maillard reaction. Sugar inhibits and delays both starch gelatinization and protein denaturation. The appropriate balance of sugar in a product is, thus, important. This is readily important in a product, such as cinnamon rolls. In attempting to get a "sweeter" product a large amount of sugar may he used. Occasionally, not only will fermentation and thus leavening be inhibited, but the product will be moist and gummy. This is due to a great extent to the greatly increased gelatinization point of the starch and inhibition of protein denaturation of the gluten proteins in the structure.
The effect of a moderate increase in sugar on a loaf of yeast bread is shown. Note the much darker color of the bread with two times as much sugar when compared to the standard. If a standard bread is permitted to overferment note the considerably lighter color. In overfermentation yeast utilizes much of the sugar. Since sugar is the component of both leavening and color, it is influenced by its type. For example, the reducing sugar, lactose, does not serve as a yeast food yet is a very effective agent for the Gaillard Reaction. Glucose and malt sugar are effective, efficient yeast food sources. In addition to color, there are other reactions inititated by the fermentation metabolic reaction of yeast. This slide shows two loaves of bread with a difference in break and shred. In addition to break and shred being influenced by gluten quality, it is also influenced by the oven spring. Technically, according to the American Association of Cereal Chemists standards, a good break and shred is an indication of good wheat flour and a quality loaf of bread. A considerable portion of the oven-spring occurs due to the volatilization of ethanol produced during fermentation. The ballooning of the right loaf of bread is likely due to over fermentation and proofing. Extremes of fermentation also. If two extremes on overfermented and then a loaf of bread that likely was either obtained from green flour, flour that had a lot of dead yeast cells or flour that had a reducing agent such as glutithion added to it. Under fermentation shows sharp corners and this is an indication that the protein, the gluten forming protein, the gliadin and glutenin has not been oxidized enough in to disulfide bonds and you get what they call a tight structure. Overfermented bread, of course, shows the more rounded corners that vnil net more likely when you have proper fermentation. A loaf of bread made of whole wheat flour has a very poor break and shred. Very likely you either had too low of an oven temperature or more likely, in order to try to keep the dough from being sticky, possibly due to the flour brand, too much flour was added and the dough was too stiff for proper rising. With different types of flours we do get the different type of product, different degree of leavenings because of the presence either of the reducing agents that are normally found in the flour brand, such as here with bran flour, or less gluten formation because of either the replacement of part of the gluten by volume with bran and germ. Other flours may be used in breads; however, as noted here, if the flour has no gluten forming proteins it may formulate a poor quality product. These products made with varying amounts of corn flour show an increasing decrease in quality with corn flour substitute.
If you have a steam leavened oroduct you must have the proper oven temperature. If you have the improper oven temnerature steam will not be produced adequately while the structure of protein starch is still elastic and so you will not qet a nice popped product. These slides and a popover show the need of a correct oven temperature. The amount of baking powder as well as the type of baking powder may influence the color of a baked product. In these biscuits, on the far right, a single fast acting baking powder such as tartrate in the middle a normal standard product made out of sodium aluminum sulfate acid portion of the leavening powder and then on the far left, a biscuit with too much baking soda added. These comparisons permit one to see the effect of pH upon color. Generally speaking, with all factors held steady as you have a more acid type of product you are going to get a lighter type of product. This is due to the effect of pH on the maillard reaction. In biscuits, with overkneading the gluten is developed to too great of an extent for the natural leavening action of the baking powder to allow it to rise equally. What happens is pressure builds up and suddenly and the carbon dioxide will usually escape from the side at that point where the gluten structure is the weakest. The effect of mixing, as well as influencing biscuit, bread, and cake quality, is veny influencial in ultimate quality of muffins. This slide shows you the effect, from left to right, of mixing muffins where undermixed you have a rough type surface, very little peaking. As you proceed with increased mixing you not only get a smoother surface but you may even get bubbling as we see on the second from the right. With this "bubbling" tunnels are usually formed.
With cakes we sometimes may get a sunkened structure either due to improper temperature, length of cooking time, or possibly because too much tenderizing agent, such as fat or sugar. Here we see the sunken cakes. In this particular instance the reason for the second appearance was not because of increased tenderizers such as sugar to inhibit gelatinization of starch and gluten denaturation. It was not due to improper cooking. It is not due to under baking and/or baking at too low of a temperature. Rather the reason for the sunken appearance that is shown is simply because an unbleached cake flour was used. Unbleached cake flour, and the causative factors are not completely elucidated, will not make proper structure in a cake. Some type of counterbalance or added agent.for structure improvement must be added. This next cake is sunken in appearance. It is a sour cream chocolate cake. Instead of using sour cream, the experimenters used synthetic or artificial sour cream. In some manner it changed the structure. Possibly the effect is on qluten strength.
There has been some work done with elaidic acid. Now with elaidic acid you do get a difference in the structure or the texture of a shortened cake. As you may recall, elaidic acid is aleic acid in the trans form, whereas, aleic acid is in the cis form. This makes a considerable difference in the solidity of the fat with elaidic acid having over a two times higher melting point. This next slide shows the effect of quadrupling the amount of sugar in the shortened cake. Again you need to revert back and think about the roles and function of sugar in shortened cakes. If you add too much sugar you, of course, are going to have an increased gelatinization point. Also, the point of denaturation of the cake is going to be increased. Cake possibly shows the results of either enough of tenderizer, or overmixinq. Otherwise, it is tough even though it may have initially had enough tenderize. The result could be due to improper cooking with too slow of an oven temperature so that the outer side structure would set and the interior batter would still be fluid producing carbon dioxide and leavening. As a result, a tunneling effect would occur. These next slides are just other perspectives. This particular slide shows you, the effect of differences in the proportion of the batter or the amount of batter in a cake pan or possibly improper leavening. With the rectangle cake we quite often will get the curved and split top. Again, because of the method of heat transfer the setting of structure on the outer edge and the fluid interior will eventually cause cracking. If the proportion of ingredients happens to be improper aquick bread which was very tough and rubbery because not enough tenderizer was present and in order to incorporate the ingredients a considerable amount of stirring took Dlace and developed the gluten. With different types of fats, with different proportions of ingredients, and with different oven temperatures the difference in spreading of cookies can be seen in this particular slide. There are many other factors which influence quality of flour mixture.
