Wheat Processing

Wheat processing is the process of removing impurities from wheat, followed by blending, moisture adjustment, crushing, bran removal, purification, grinding, and sieving to produce wheat flour with minimal bran content. The processing method is a key factor affecting the technical performance and final product quality of wheat flour.

Intake and Pre-cleaning

The first step in wheat processing is intake and pre-cleaning, aimed at removing large impurities, light debris, and dust from the raw grain, creating favorable conditions for subsequent cleaning processes.

Raw Wheat Receiving

After wheat arrives at the flour mill from various regions, it enters the receiving system. The receiving process includes:

• Automatic weighing: Recording the quantity of wheat entering the mill
• Initial inspection: Testing basic indicators such as moisture, bulk density, and impurity content
• Temporary storage: Storing in raw wheat bins according to quality classification

Pre-cleaning

Pre-cleaning primarily removes large impurities and light debris from wheat:

• Screening: Using vibrating sifters or planar rotary sifters to remove impurities larger than wheat (such as straw, soil clumps)
• Air separation: Using airflow to separate light debris (such as husks, dust)
• Magnetic separation: Removing magnetic metal impurities

Cleaning and Conditioning

Cleaning and conditioning is the most critical preparation process before wheat milling, directly affecting flour quality and extraction rate.

Wet Cleaning

Washing machine is the core equipment for wet cleaning, with main functions:

• Soaking wheat to soften surface impurities
• Removing stones (sand and gravel similar in size to wheat grains)
• Adjusting wheat moisture
• Killing some microorganisms

Dry Cleaning

• Wheat scourer: Removing dust, microorganisms, and embedded impurities from the grain surface through impact
• Gravity separator: Removing different grain varieties such as buckwheat and wild peas based on seed length differences
• Wheat brush: Cleaning impurities from wheat grooves

Moisture Conditioning

Water adder is used to precisely control wheat moisture:

• Adding appropriate water based on original wheat moisture and target flour moisture
• Winter water temperature generally controlled at 35-45°C to promote moisture penetration
• After water addition, wheat needs to rest for 6-8 hours for moisture to evenly penetrate the grain interior

Blending

Wheat from different origins and varieties has significant quality differences, requiring blending:

• Adjusting protein content to ensure stable flour quality
• Balancing gluten quality and ash content
• Optimizing costs and improving economic benefits

Milling

Milling is the core环节 of wheat processing, using physical methods to separate and grind various parts of the grain into flour.

Cleaning Process

1. Break system: Handling the separation of bran and endosperm
2. Reduction system: Fine grinding of endosperm to obtain fine white flour
3. Grinding system: Handling wheat middlings to further extract endosperm
4. Tail system: Handling end materials of bran to extract remaining endosperm

Main Equipment

Equipment	Function
Roller mill	Using roller extrusion and shearing to grind endosperm into flour
Plansifter	Sieving flour and bran of different particle sizes
Purifier	Using airflow and sieving to purify middlings, improving flour quality
Bran finisher	Separating flour adhering to bran

Grinding System

Modern milling uses multi-pass grinding processes, typically including:

• 4-5 breaks
• 6-8 reductions
• 2-3 grindings
• 1-2 tail passes

Each grinding pass requires sieving and classification to achieve proper material distribution.

Flour Post-treatment

Flour Blending

According to different usage requirements, flour from various systems is precisely blended:

• Adjusting protein content and quality
• Controlling ash indicators
• Optimizing whiteness and gluten strength

Aging

Freshly milled flour needs resting and aging:

• Allowing gluten proteins to fully oxidize, improving dough rheological properties
• Promoting stability of enzyme activity
• Improving flour baking performance

Aging time is typically 1-3 days, with temperature controlled at 20-25°C.

Storage

Flour storage conditions require:

• Temperature: Controlled below 20°C to prevent insect infestation and mold
• Humidity: Relative humidity not exceeding 70% to prevent caking
• Ventilation: Maintaining air circulation to avoid odor absorption
• Light protection: Preventing light-induced pigment oxidation and discoloration

Packaging

Graded packaging according to different market demands:

• Retail packaging: 1kg, 2.5kg, 5kg small packages
• Wholesale packaging: 10kg, 25kg woven bags
• Bulk: Direct delivery to food processing plants

The packaging process must strictly control metal detection and weight inspection.

By-product Processing

Various by-products are generated during wheat processing:

• Bran: The outer epidermis of wheat, rich in dietary fiber and B vitamins, mainly used as feed
• Middlings: The transitional product between bran and flour, can be used for feed or food additives
• Germ: The embryonic part of wheat, high nutritional value, can be extracted for germ oil or used as food raw material