Application of gluten testing line
In the cereal and flour industry, especially in Polish conditions, determination of gluten quantity and quality are very important operations in every laboratory. Gluten is a protein substance, mainly consisting of:
- gliadin (prolamins)
- glutenin (glutelins)
Both proteins are present in wheat; therefore, the quality parameter should always be included in grain classification. In commercial traffic, apart from proper quality parameters, the content of gluten in wheat is often low, and its spread is very high, which means that the wheat is of poor quality. Gluten, depending on its rheological properties, can be strong, normal and weak. Weak glutens reduce volume which results in deterioration of the general quality of bread.
The result of gluten quantity and quality determined according to the applicable code of practice is influenced by many factors; in particular, method of dough preparation, fermentation time before washing, temperature, and even the chemical constitution of the water used both for dough preparation, fermentation and washing. The dough washing method and method of forming "washed out” gluten are also very important.
There are different techniques of gluten treatment and washing, which provide different results. Some are based on mechanical dough preparation and gluten washing, some on partially mechanical operations with manual washing under a tap. The present PN-A/74943 standard, equivalent to the ISO 5531 standard, recommends the use of mechanical equipment and 2% salt water solution for dough preparation and washing.
In Poland the manual system for both dough preparation (in a mortar using 25 g of flour) and gluten washing (under a tap) following dough fermentation in water for 20 minutes used to be predominant. This method is very inconvenient and burdened with errors. With the use of mechanical instruments, repeatable results are obtained and determination of gluten is faster eliminating disadvantages of the manual method, as documented and confirmed in hundreds of laboratories using Polish instruments, which are systematically modernized and adapted to society's needs and modern trends. Therefore, in practice the following two different ways for the determination of both gluten quantity and quality are used:
1 – traditional mechanical sets adapted to preparation of dough from 25 g of flour and washing with normal water in a double chamber gluten washer following 20-minute fermentation of the dough ball in water,
2 – general-purpose mechanical sets adapted both to traditional methods and requirements according to the ISO standard, recommended preparation of dough from 10 g of flour with distilled water containing 2 % of table salt, which immediately allows the washing of the dough ball.
