Milling
Processing - Preparation
a) Storing
As wheat arrives at the mill each load is sampled and tested for its quality. It is then passed through a pre-cleaning process to remove coarse impurities such as wood and stones, and is then binned according to its quality, which is determined predominantly by its variety and protein content. When the wheat is required it is drawn off from the bins and passed through the cleaning system.
b) Cleaning
The cleaning operation begins with screening to remove coarse and fine materials before whole, pure wheat, is passed into the conditioning bins.
For Durum milling the wheat must be as clean as possible; this requires extra cleaning passages to remove all unwanted seeds and grains which could affect the appearance of the finished product.
c) Conditioning
Before wheat can be milled it is necessary for the wheat to be in the best possible condition this is termed as reaching a uniform degree of mellowness and reasonably uniform moisture content throughout. Correct conditioning limits the break-up of the bran during milling and improves its separation from the endosperm. This is done by adding water to the cleaned wheat and leaving it to stand in holding bins for up to 15 hours. Incorrect conditioning means that the miller cannot properly control the way that the wheat and semolina breaks up on the mill, with resultant imbalance of the mill and bran speck contamination.
For semolina milling double conditioning enables a more efficient separation of bran and semolina, contributing to the quality and appearance of the product.
d) Gristing
For semolina milling, gristing is the careful selection of Durum wheats of the quality required for the semolina functionality and to give the specified colour and cleanliness of semolina. These varieties of wheat are then blended and cleaned.
Wheat is gristed similiary for flour milling to acheive flour functionality that the customer has requested.
Cleaning & Conditioning System
