| Food chain - Number 19 - November 1996 |
In the third of our regular features following on from tests that can be made on flours, we look at more simple methods for use in a small bakery. In this issue a further two methods for assessing starch gelatinisation quality and water absorption are described. The author, Dr Peter Fellows, would like to acknowledge the information contained in a recent FAO Publication: Quality Assurance for Rural Food Industries, FAO Technical Bulletin No 117, available from FAO Publications, FAO, Rome.
STARCH GELATINISATION MEASUREMENT (MODIFIED 'FALLING NUMBER' METHOD)
The ability of starch to gelatine (to thicken when heated with water) is a major concern especially when preparing batters for cakes, as this will determine the structure and volume of the cake. This simple method can he routinely used in a bakery.
1. 100g of flour is mixed with 900g of hot water in a pot
2. The pot is heated until the flour mixture has gelatinised.
3. The mixture is poured into 1 litre measuring vessel such as a graduated glass cylinder.
4. The measuring vessel is stood in hot water.
5. A steel ball is dropped into the mixture and the time to drop 200ml recorded.
6. The time (in seconds) is compared against the standard batch.
It should he noted that this method relies on comparison of results between different batches using the same measuring cylinder. It cannot be used to compare results from different cylinders unless they are identical.
WATER ABSORPTION MEASUREMENT (FLOUR)
The amount of water absorbed by flour is one of the most important factors affecting the structure and texture of all baked goods, including breads, biscuits and cakes. In this method a burette is required to accurately measure added water. This equipment can usually be obtained from a scientific suppliers in the capital city, hut could also be made locally by carefully calibrating a glass tube to indicate exactly the volume of water contained (see Figure).
1. 100g of flour is weighed into a small mixer or mixed by hand.
2. Water is slowly added from a burette until a standard dough is made. This is judged by the processor by adding water until it feels right.
3. The amount of water added is recorded.
New batches of flour are tested alongside the existing material. This can be used as a comparative test to indicate a wrong grade of flour.