Post-harvest grain quality is not just a reflection of how the growing season has gone. It plays a fundamental role in determining whether grain will meet contract specifications, comply with import regulations, and retain its value throughout storage, handling, and trade.

Grain that appears clean and sound at first glance can still carry defects that affect its marketability or safety. This is why experienced producers and traders prioritise early quality assessments.

Below, we explore five key quality parameters that you should be assessing post-harvest, along with the issues that can arise when they are not properly measured.

Moisture Content

Moisture content remains one of the most influential parameters affecting grain storage, handling, and marketability. Elevated levels increase the risk of biological activity, including mould proliferation and insect infestation, while also accelerating respiration and the risk of self-heating within silos.

Acceptable thresholds vary by commodity and end-use specification, but for most cereals, values above 14–14.5% will trigger drying requirements. Once moisture rises above 16%, deterioration accelerates sharply, making even short-term storage a risk factor. At this point, segregating high-moisture lots is critical to avoid cross-contamination or condensation damage in storage.

Early determination enables timely intervention, informing decisions regarding artificial drying, aeration rates, and storage duration.

Grading and Grain Quality 

Visual defects such as broken grains or sprouting provide an immediate indication of post-harvest handling efficiency and crop condition at intake. These defects can reduce grade, affect processing performance, and could result in contract downgrades.

Adverse weather during harvest can result in grain with higher screenings, while mechanical damage from combine settings or rough handling may increase breakage. Sprouting, particularly in barley and wheat, compromises processing performance and may lead to downgrading.

Carrying out a detailed grading profile at harvest enables:

• Segregation of non-conforming material before it enters storage
• Identification of potential market routes (feed vs milling/malting)
• Early estimation of cleaning and conditioning requirements

Failure to address these issues early increases the risk of grain quality loss and commercial disputes.

Protein and Nutrient Levels

For products such as milling wheat, durum, or malting barley, protein content is a key quality and classification factor. Inconsistencies can result from varietal choice, nitrogen availability, and in-season climatic factors.

Accurate protein data enables producers and traders to align loads with appropriate end-uses (e.g., breadmaking, feed, or bioethanol production), blend strategically to meet contract specifications, and avoid the risk of falling below minimum thresholds in export markets.

In wheat, for example, protein levels below 13% may be excluded from Group 1 milling contracts, while excessively high protein can be detrimental in some feed or brewing applications.

Laboratory analysis is essential to guide post-harvest segregation and maximise value.

Contaminants

Chemical and microbiological contaminants represent one of the most significant risks to grain marketability, particularly in international trade. Mycotoxins, such as vomitoxin or aflatoxin, are influenced by pre-harvest conditions and storage environment and are undetectable to the naked eye.

Additionally, other contaminants may result in rejection at intake or port, these may include:

• Residual pesticide compounds
• Herbicide carryover
• Heavy metals

Rapid screening at harvest helps to:

• Identify affected lots for remedial action or alternative routing
• Reduce the risk of cross-contamination in bulk storage
• Assure buyers on compliance with regulatory thresholds (e.g., EU MRLs, CODEX)

With ever-tightening controls in many jurisdictions, early detection and documentation are critical to avoid costly disruptions later in the supply chain.

GMO Screening

Where markets demand non-GMO assurance, especially in maize, soya, or rapeseed, routine verification is non-negotiable. Even minimal contamination can compromise entire supply chains, particularly in EU and Asian markets with zero-tolerance policies for unauthorised events.

PCR-based screening at harvest supports traceability under identity-preserved programmes, compliance with segregation protocols during transport and storage, and risk management in high-sensitivity export contracts.

For traders handling mixed-origin material, early screening allows for strategic blending or redirection to avoid regulatory breach or reputational damage.

How Alfred H Knight Can Help Determine Grain Quality

Alfred H Knight helps producers, traders, and processors verify grain quality at every stage of the supply chain. From field sampling to laboratory testing, our experts support you in meeting contractual requirements, maintaining food safety standards, and protecting your assets.

We analyse moisture, quality, nutritional content, mycotoxins, pesticide residues and GMO status using internationally recognised methods, conducted by GAFTA (Grain and Feed Trade Association) accredited analysts and superintendents, with a truly global reach.

Speak with an Expert on Grain Quality

Before trading or storing this harvest’s grain, ensure you have the insight needed to protect value and meet specifications. Contact our Grain Experts today via our contact page. For full details on our services, visit our Grains page.