Falling Number

The number of cases ( engl.: Falling Number) is a simple and fast method for testing the baking quality of cereal flour.

The case number is the time in seconds it takes for a standard rod to pass through a starch paste of flour and water falling through (including 60 s mixing time ). Has Sprouted damaged the strength, the number of cases is too small. For rye bread they must be higher than 75 s, baking wheat values ​​are optimal at 200-250 s; less than 150 s, the flour auswuchsgeschädigt.

The Falling Number method ( Hagberg ) determines the alpha -amylase activity using the strength of the sample as a substrate. The method is based on the rapid gelatinization of an aqueous suspension of flour or meal in the boiling water and the subsequent measurement of liquefaction of the starch by alpha -amylase in the sample.

Amylase is an enzyme present in the cereals. While poor growth conditions ( too cold or too moist during the growth phase) reinforced -amylase is formed. Wheat flours with medium number of cases ( 230-280 ) produce normal, elastic, gutgeporte crumb and have a sufficient driving force. Flours with low numbers (< 220 s ) are inelastic and the Gebäckkrume is wet (moist backend). Furthermore, these have an increased driving force. Wheat flours with high number of cases ( > 300 s ), however, give a dry Gebäckkrume (dry backend) and a low baking volume. They also have a low driving force, this requires the addition of fermentable sugars (eg malt flour ) and / or enzyme-containing baking agents.

Briefly, the number of cases is information on:

  • The resistance of gelatinized starch to degradation by enzymes
  • The activity of starch- degrading enzymes ( amylases ) and the degree of a possible Auswuchsschädigung

Effect of amylase

The starch in the flour leads to a " gelatinization " of the dough, it binds to and from is tough. -Amylase stops this process and make it undone; the dough is so thin and its processing is difficult if not impossible.

Preparation

A sufficiently large sample ( at least 300 grams) grain is taken and mixed well. The grain is milled with a cross beater mill and mix again. One of the moisture content of the flour -dependent amount ( default: 7 grams at 14% moisture ) is placed in a Fallkörperviskosimeter, followed by 25 ml of distilled water was added. The viscometer tube is closed with a rubber stopper and shaken vigorously 40 times, more often if necessary, to obtain a klümpchenfreie suspension. The plug is removed, the water attached to the tube walls with the powder is pushed into the liquid Rührviskosimeter.

Implementation

Start of the timing. The tube comes in a hot water bath 95 ° C. After five seconds, the stirring begins, while the measuring rod is vertically reciprocated. After 60 seconds, the dipstick is pulled and released upwards, which takes another two seconds. Because of its weight of the dipstick is now pulled down, the toughness of the verkleisteren suspension sets him doing a resistance. Is the dipstick once on the ground, the time is stopped. The depth reading time in seconds ( stirring time settling time ) is the number of cases. At the time, only whole seconds are taken into account.

The investigation is internationally standardized:

  • ICC No. 107/1
  • AACC No. 56- 81B
  • No. ISO ISO / DIS 3093
  • ASBC Barley 12-A

Evaluation

  • The greater the amylase activity, the thinner and less resistance is the suspension and the smaller the number of cases.
  • The smaller the amylase activity, the more viscous, the dough, and the greater the number of cases.
  • Caused by the measurement process case numbers are always greater than 62 seconds.

Low case numbers mean poor baking quality. The baking result is best when sample sizes of 250-300 s ( wheat flour) and 150-180 s ( rye flour). Are the number of cases is too high ( > 400 s ), the baking result is also bad, because the dough is too tough and too little gas production capacity ( fermentable sugars ) has to let him go up ( by yeast or other leavening agent ).

Liquefaction number

It is amazing that you can not mix after falling number values ​​flours. Example: If you mix two flours with 200 and 300 s number of cases equally, come into the mix not remove a sample size of 250 s. Therefore you have the number of cases before in liquefaction numbers (English Liquefaction Number, LN ) convert. Liquefaction number = 6000 ( case number - 50). With their help, you can mixing ratios are calculated, with which the desired sample size is achieved in the mixture.

The latest findings

The strength of nature depends on many factors.

  • So criticism is that in the case of payment method after ICC 107 the starch excess of water and simultaneously high enzyme activity is performed. Such starch liquefaction is in doughs with limited water availability but only in visible outgrowth possible.
  • Reserve proteins and Nichtstärkekohlehydrate regulate the vulnerability and the hydration of the starch.
  • Polar lipids counteract a low number of cases. In particular, the heat in 2010 resulted in an increase.
  • The heat in July 2010 caused a Stärkestrukturhärtung (annealing ).

Investigations revealed that even well loosened Small wheat biscuits were achieved with sample sizes of less than 100 seconds.

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