Screening and Optical Sorting of Roasted Sesame Seeds

Removing Potential Foreign Materials for Maximum Quality and Safety

Sesame seeds are a key ingredient in many food products such as tahini, halva, bakery goods, and snacks. Roasted sesame seeds are especially valued for their rich aroma and enhanced flavor profile. However, the quality of roasted sesame is not determined only by taste and aroma. Purity and food safety are equally critical.

Even after roasting, sesame seeds may still contain unwanted foreign materials or defective kernels. That is why screening (sieving) and optical sorting (color sorting / Sortex) are essential processing steps in modern sesame production.

What Kind of Foreign Materials Can Be Found in Roasted Sesame?

Sesame seeds pass through many stages from harvesting to final packaging. Even if cleaning is performed before roasting, some impurities may remain or reappear due to handling and processing.

Possible foreign materials found in roasted sesame include:

• Hull residues (shell fragments)

• Stones, sand, and soil particles

• Metal fragments (machine wear-related)

• Dust, fibers, and straw residues

• Burnt or over-roasted seeds

• Black or damaged sesame seeds

• Other crop seeds (cross-contamination)

These unwanted materials can negatively affect not only the appearance and taste, but also the safety and compliance of the final product.

What is Screening (Sieving)?

Screening is a mechanical separation process used to remove impurities based on particle size. It is usually carried out using:

• vibrating screens

• multi-layer sieve systems

• air aspiration systems

What does screening achieve?

Screening helps to:

✅ Remove fine dust and small particles 

✅ Separate larger foreign materials such as straw or stones 

✅ Eliminate broken or undersized seeds 

✅ Improve size uniformity and product consistency

Screening is often the first major cleaning step after roasting and prepares the product for optical sorting.

What is Optical Sorting (Sortex / Color Sorting)?

Optical sorting (commonly called Sortex) is an advanced cleaning technology that separates sesame seeds based on color, shape, and surface defects.

This system uses high-resolution cameras and sensors to detect unwanted materials. Defective kernels and foreign particles are removed instantly by air jets.

What can optical sorting remove?

Optical sorting is highly effective in eliminating:

✅ Burnt or over-roasted seeds 

✅ Black or discolored sesame seeds 

✅ Mold-risk or damaged kernels 

✅ Hull residues 

✅ Seeds from other crops 

✅ Plastic or dark foreign materials

This step is essential for achieving premium quality, especially for tahini-grade sesame seeds.

Why is Optical Sorting Even More Important After Roasting?

Roasting changes the color of sesame seeds and makes defects more visible. During roasting:

• some seeds may burn unevenly

• color variations may occur

• hull residues may become more noticeable

Therefore, optical sorting becomes a critical quality-control stage to ensure consistent appearance and uniform roasting results.

Benefits of Combining Screening + Optical Sorting

Although screening and optical sorting are both powerful processes, their best performance is achieved when they are used together.

Key advantages of this combination:

✅ Higher product purity 

✅ Better visual uniformity 

✅ Improved tahini color consistency 

✅ Reduced foreign material risk 

✅ Stronger customer trust and brand reputation 

✅ Compliance with international food standards

This is especially important for export markets such as Europe, USA, the Middle East, and high-quality industrial food manufacturers.

Importance for Food Safety and Quality Assurance

Roasted sesame is often used directly in food production or processed into tahini. Any foreign material remaining in the product can cause serious issues related to consumer health, legal regulations, and brand reputation.

Screening and optical sorting help:

• increase food safety

• minimize contamination risks

• reduce customer complaints

• prevent costly product recalls

Conclusion: Clean Roasted Sesame Means Premium Quality

In roasted sesame production, flavor is important—but cleanliness, purity, and uniformity are just as essential. Screening and optical sorting are key processes that ensure the final product is safe, visually consistent, and suitable for premium markets.

In short:

The true quality of roasted sesame is revealed after screening and optical sorting.