Grain Vitreousness: How to Test It, Why It Matters and How It Affects Price

What is vitreousness?

Vitreousness is an external and internal characteristic of grain structure that shows how densely and evenly starch and proteins are packed in the kernel. A vitreous kernel looks translucent and dense, with a glossy fracture surface. A mealy kernel is loose and pale, with a matt surface.

Example: durum wheat with 80-100% vitreousness commands a higher price because it produces flour with better baking properties.

Why vitreousness matters

Vitreousness affects:

• Wheat class under GOST 9353-2016: this determines whether the grain can be used for food;
• Flour yield and quality: vitreous grain yields more semolina (middlings) and less feed flour;
• Moisture behaviour: vitreous grain absorbs moisture less readily and keeps longer in storage;
• Processing value: a high proportion of vitreous kernels is important for pasta, bread and bakery products;
• Purchase price: grain with vitreousness below 20% may be downgraded to the feed category.

Under GOST 10842-89, grain with vitreousness below 50% cannot be classified as class 1 or class 2.

How is vitreousness measured?

The official method is set out in GOST 10842-89 and includes:

1. Sampling: 100 kernels with no visible damage, selected by hand;
2. Breaking the kernels: each kernel is broken with tweezers or a knife;
3. Visual assessment: the percentages of vitreous, partly vitreous and mealy kernels are determined under a magnifying glass or against a light background;
4. Result: the percentage of vitreous kernels in the total is calculated.

Important: there are no automatic instruments for measuring vitreousness. It is a manual procedure that requires skill and experience.

What affects vitreousness?

• Weather: a dry summer increases vitreousness, while a wet, cold one reduces it;
• Varietal traits: durum wheat is always more vitreous than common wheat;
• Ripening and harvest conditions: early harvesting or improper drying lowers vitreousness;
• Nitrogen nutrition: excess nitrogen in the soil promotes vitreousness but may reduce gluten.

Where is vitreousness used as an indicator?

• In grain classification under GOST 9353-2016;
• In supply contracts, both export and domestic;
• In quality control by surveyors at elevators, in ports and during transhipment;
• In laboratory testing of grain crops;
• In assessing whether raw grain is suitable for processing.

Grain vitreousness is an indicator that can bring the price down or lift a lot into a higher grade. It is a quality indicator that reflects the biochemical processes inside the kernel.
Understanding vitreousness and knowing how to test it is a professional skill that comes with experience. The final price, suitability for processing and the security of the contract all depend on it.

Types of grain vitreousness

Vitreousness falls into three categories:

1. Full vitreousness: the kernel is dense and its fracture surface is translucent, glossy and yellowish-amber. A sign of maturity and high endosperm density.

2. Partial vitreousness: partial translucency, with a mealy area in the centre or at the edges. A transitional form, often linked to ripening conditions.

3. Mealiness: the kernel is opaque, with a matt, white fracture surface. The structure is loose and porous. A sign of immaturity or weather damage.

Threshold values under GOST 10842-89:

• ≥80% vitreous kernels: a good lot;
• 50-79%: satisfactory;
• <50%: a lot with reduced processing value.

Consequences of low vitreousness

• A lower class under GOST 9353-2016: vitreousness is used as a classification criterion;
• A lower selling price: processors pay less for mealy grain;
• Rejection by processing plants: at values <40%;
• Risk of spoilage in storage: mealy grain stores less well, heats up and becomes infested with pests;
• Nonconformity findings in export: deviation from the contract specifications;
• Processing problems: higher feed flour yield, weaker gluten, inconsistent product quality.

The price difference between vitreous and mealy grain can range from RUB 500 to RUB 2,500 per tonne, depending on:

• the region (for example, Stavropol Territory, the Volga region, Altai);
• market conditions;
• the season and yields;
• buyer requirements (processor, exporter, public procurement).

Examples of price differences:

Documents and regulatory references

• GOST 10842-89: the main document governing the manual method for determining grain vitreousness.
• GOST 9353-2016: uses vitreousness as one of the criteria for assigning wheat classes.
• GOST 13586.3-83: describes methods for preparing grain for the determination of physical characteristics.
• GOST 13586.1-68: sampling rules.

Legal significance of test results

• Can be used as evidence of quality in disputes over price, nonconformity or returns;
• Accepted in court, provided the report is prepared in accordance with GOST and bears signatures, stamps and company details;
• Provides grounds for filing a claim or rejecting the goods;
• Required for certification of a lot and for preparing export documents;
• Taken into account by insurers when handling an insured event (for example, if a lot is found nonconforming and is insured on CIF or FOB terms).

Errors that affect the result

• The sample does not comply with GOST 13586.1: it may not be representative;
• Poor break: the kernel is split incorrectly;
• The examination is not carried out under controlled lighting: visual distortion;
• Counting errors: when there is no double check or photo record;
• No test report: the result has no legal force.

TopFrame can help you assess grain quality across many parameters, including vitreousness

In our own certified laboratories we:

• Determine vitreousness manually in accordance with GOST 10842-89;
• Test lots at acceptance and shipment;
• Issue reports recognised by insurers, courts and government authorities;
• Help establish the exact grain class and avoid losses on sale.

TopFrame carries out testing in its own laboratories (Moscow, Saint Petersburg, Novorossiysk, Rostov-on-Don, Stavropol, Samara, Voronezh, Novosibirsk, Vladivostok, Astana, Kokshetau, Vitebsk, Tehran), issues expert reports and handles the documentation for grain shipment, acceptance and export.

TopFrame laboratories meet GAFTA, FOSFA and GOST/ISO 17025 standards. We guarantee independent and prompt testing and provide detailed, high-quality reports. All work is carried out by certified specialists with many years of experience.

Our company operates throughout Russia and in 30 countries, so we can carry out inspections and sampling at every stage of the route. We work with all modes of freight transport and promptly provide detailed reports, including photo and video records.
Our portfolio includes more than 150 leading exporters, among them major market players such as Avgust Agro, Skopa, KTI Sibir, Grain Gates, Aston, Grain Service, MZK, GAP Resource, Rostov Grain Terminal, Novosibirsk Food Corporation, Yug Rusi and others.

Submit a request on our website and our specialists will contact you to give detailed advice and find the best solution for your needs.