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Effects of water temperature on doughBread making is not just a culinary gift but also science at the same time. There are certainunique requirements of bread making to tickle the taste buds of food connoisseurs. The basicingredients used in the process are flour, fats, eggs, salt, yeast and water. However, thetemperature is an important factor that plays a crucial role as far as making enjoyable bread isconcerned. Experts point out that temperature essentially impacts time management, productconsistency, crust and flavors and shelf life of bread. The dough temperature is kept at 27 degreeCelsius, flour temperature at 15 degree Celsius. Water temperature is calculated as: 2* doughtemperature - flour temperature and it comes out as 39 degree Celsius (Kim and Cornillon,2001). The dough temperature is largely influenced by ambient temperature, flour temperature,water temperature and temperature emanating from the action of kneading or mixing also calledas friction factor (Farahnaky and Hill, 2007 ). Friction, in turn, varies based on manual andmechanical actions as well as how much time does it take. It is generally estimated that the riseof temperature should be 1 degree C per minute for kneading and 2 degree Celsius formechanical mixing. The temperature of the water is used to control and regulate the temperatureof the dough, and it is obtained by using a little bit of calculation.Temperature of water = (Dough temperature * 3) – (room temperature + flour temperature +friction) = 21 degree Celsius.With preferment, Temperature of water = (Dough temperature * 4) – (room temperature + flourtemperature + friction + preferment temperature) = 25 degree Celsius.Friction factor = (dough temperature * 3) – (flour temperature + room temperature + watertemperature) = 12With preferment, Friction factor = (dough temperature * 4) – (flour temperature + roomtemperature + water temperature + preferment temperature) = 14When preferment is included the water temperature thus obtained is 25 degrees Celsius.However, commercial bakers take into account the required water temperature. They try to keepa stable temperature and use ice (chilled water preferably) to keep the temperature in check asthe dough prepared with too hot or too cold water might yield undesirable results and affect thefermentation process (Toyosaki, 2007). A baker’s control on the temperature dependence startsfrom the very beginning of the dough making process, and its importance cannot be neglected.
The role of yeast in bread making is also very important. It metabolizes free sugars (released byenzymes from starch) for producing carbohydrates and carbon dioxide as well as alcohol as a by-product. C6H12O6 → 2C2H5OH + 2 CO2 . So, one molecule of glucose yields two moleculesof alcohol and two molecules of carbon dioxide.Temperature during fermentation and proofingThe minor fluctuations in dough temperature can affect the bulk fermentation and proofing a lot.After adding dried yeast, the optimum temperature is kept just over 27 degree Celsius. If thetemperature is increased further, the activity of yeast declines correspondingly and thetemperatures above 35 degree Celsius make yeast dormant or nearly dead. Whereas, at 34 degreeCelsius, the bacterial activity is at its peak, that is why some bakers choose to ferment the breadat 32 degree Celsius. The activity of yeast is exactly halved at 21 degree Celsius, and it takestwice as long to ferment. The correct temperature is extremely critical variable for the growthand replication of yeast (Winata and Lorenz, 1997). In the given graph, the growth rates ofLactobacillus and Milleri (yeast) are compared. The duration 0 to 7 is a doubling time(generation time) of one hour. If the doubling time at 20 degree Celsius is half of that at 30degree Celsius C, the yeast will grow half as fast at 20 degree Celsius compared to 30 degreeCelsius. So, it comes out that the ratio of growth to growth rate at optimum temperature matters alot (method of producing and baking frozen yeast leavened dough, 1997).
The activity of the ferment is an important factor for dough development during the process ofprimary fermentation. So temperature, again, has to play a crucial role in determining the time ofmaturation with a certain ferment level (Fisher, Strasser and Gutzler, 2000). The fermentquantity and fermentation time are often appropriately adjusted with the rises and fall of ambienttemperature. If at the time of dough making the seasonal temperature is low, then a longerfermentation period is required and vice-versa. Also, the temperatures oscillating between 20 and24 degree Celsius indicate optimal environmental parameters during fermentation. The fact thatdifferent fermentation temperatures give different results, bakers utilizes them according to theirneed. With the change in fermentation temperature, the proportions of lactic acid and acetic acidalso change. As a result of this, different flavors and physical characteristics are achieved. So iffermentation temperature is increased to 27 degree Celsius, there will be a noticeable boost inlactic acid production.The high content of lactic acid in bread makes taste fuller in the mouth as the crust becomesthinner, crispier and more crumbs (Wehrle, Grau and Arendt, 1997). Whereas lower temperatureof 22 degree Celsius, not affecting acidic acid levels, drops lactic acid level and eventuallyastringent, tighter and sharper flavor is achieved. Higher levels of acetic acid, on the other hand,results in tighter crumbs with thicker, less crispy and chewier crust (Seguchi, Hayashi andMatsumoto, 1997).The excessive cool conditions during fermentation and proofing, the dough does not get enoughgassing power and hence dough is rigid, tough and flat. In excessive warm conditions, duringmixing, dough attains its high gassing power and as a result, dough lacks elasticity, becomes dryand breaks on stretching.Pathway of alcohol fermentation by yeast: