Lecture 2: Cleaning Seeds, Threshing, and Separating the Kernels from the Hulls�

CREATOR : Bekhzod Kuramboev, assistant teacher, 2 nd year PhD student, Urgench State University

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Introduction

• The Foundation of Quality: Mastering Seed Preparation in Oil Processing

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STEPS OF OIL-SEED PROCESSING :

• Cleaning, (TOZALASH)

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• Threshing (Dehulling),(CHAQISH)

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• Separating Kernels from Hulls.(MAG’IZNI QOBIQDAN AJRATISH)

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1. Cleaning: The First and Non-Negotiable Step

• Purpose:�The primary goal of cleaning is to remove all foreign materials (FM) that are not the desired oilseed. This includes:
• Physical Contaminants: Stones, clods, sticks, and metal pieces.
• Biological Contaminants: Leaves, stems, weed seeds, and other crop seeds.
• Other: Sand, dust, and any other extraneous matter.

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• Why is it so Critical?
• Equipment Protection: Stones and metal can cause sparks, excessive wear, and catastrophic damage to expensive machinery like flakers and expeller presses.
• Oil Quality: Foreign materials can impart off-flavors, unusual colors, and increase the impurity load (increasing the Free Fatty Acid content), which makes the subsequent refining process more difficult and costly.
• Yield and Safety: Contaminants can absorb valuable oil, reducing overall yield. Furthermore, dust and fine organic matter pose a significant dust explosion hazard.

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• Pre-Cleaning (Scalping)
• Screening
• Aspiration
• Magnetic Separation
• Destoning

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The Cleaning Process: A Multi-Stage Attack

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2. Threshing & Dehulling: Breaking the Protective Barrier�

• The Hull (or Shell/Husk)

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• The Kernel

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• Threshing vs. Dehulling: A Technical Clarification

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• The Purpose of Dehulling:

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• Increase Oil Yield

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• Improve Meal Quality

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• Protect Equipment

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• Enhance Oil Quality

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3. Separating the Kernels from the Hulls: The Art of Separation�

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• The Science of Separation
• Size
• Density
• Aerodynamic Properties

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• Separation Technologies:
• Aspiration (Winnowing): The lightweight hulls are carried away by the air stream, while the heavier kernels fall through the chamber. This is a highly efficient way to remove the bulk of the hulls.
• Screening (Sieving): After aspiration, the kernel-rich stream is passed over a series of vibrating screens. These screens are designed to separate based on size:
• A screen with the right aperture size allows the smaller broken kernels and fine hull fragments to pass through while retaining the desirable whole and large kernel pieces.
• Another screen might be used to separate any remaining large, unhulled seeds for re-circulation back to the dehuller.

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• Thanks for your attention and spent time girls !!!!!!!!

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