Grain classification at the mill intake is the first stage of quality control in flour production. Before grain enters storage or proceeds to cleaning and conditioning, laboratory technicians measure a defined set of physical and chemical parameters that determine whether a delivery meets purchase specifications and how it should be allocated within the mill's grain inventory. In Poland, these procedures are governed by national standards aligned with EU Regulation No 1308/2013.
Wheat Classification Parameters
Polish wheat (Triticum aestivum) delivered to mills is assessed against the following key parameters at intake:
Test Weight (Hektolitermasa)
Test weight — the mass of one hectolitre of grain in kilograms — is a proxy for kernel density and milling potential. For bread wheat accepted at Polish mills, the minimum standard is 76 kg/hl; premium-grade material typically runs 79–82 kg/hl. Low test weight may indicate immature kernels, excessive broken grain, or high impurity content. The measurement is made using a standardised Schopper-Damm chondrometer following PN-EN ISO 7971-3.
Moisture Content
Accepted grain must have moisture content at or below 14.5% for safe long-term storage. Material at 15–16% moisture can be accepted directly into short-term bins for rapid processing or passed through continuous grain dryers, which are standard equipment at larger Polish mills. NIR (near-infrared) analysers at the intake scale house deliver moisture readings within seconds, allowing immediate routing decisions.
Protein Content
Protein content — measured as nitrogen × 5.7 on a dry matter basis — is the primary quality differentiator for bread wheat. The key thresholds used by Polish mills are:
- Below 11.0%: Suitable for biscuit or cake flour; used in Type 450 and Type 500 production
- 11.0–13.0%: Standard bread flour range; suited to Type 550 and Type 650 production
- Above 13.0%: High-protein milling wheat; used for strong bread flours, Type 750 and above
NIR analysers, calibrated annually against wet chemistry reference values, provide protein readings at intake. The Dumas combustion method (PN-EN ISO 16634-1) is used as the reference method for dispute resolution.
Falling Number
The Hagberg falling number (PN-EN ISO 3093) measures alpha-amylase activity in the grain — a critical indicator of sprout damage. A high falling number (above 250 seconds) indicates low enzyme activity, which is normal for undamaged grain. A falling number below 180 seconds signals excessive alpha-amylase, typically caused by pre-harvest rainfall and sprouting, which would produce sticky bread crumb and gummy dough. Most Polish mill intake specifications require a minimum falling number of 220 seconds for bread wheat.
Impurities and Foreign Matter
Impurity analysis (PN-EN 15587) covers broken kernels, shrivelled kernels, sprouted kernels, foreign seeds, ergot, and mineral impurities. Total impurity limits for EU cereal trade are set at 12% maximum for bread wheat, but commercial contracts between Polish growers and mills are typically stricter, with limits of 3–5% total admixture for the clean grain fraction.
Rye Classification Parameters
Rye (Secale cereale) classification follows a parallel but distinct set of criteria. Rye is naturally higher in pentosans (arabinoxylans) than wheat, which creates viscosity in the dough and requires different test parameters.
Test Weight for Rye
Rye kernels are lighter and less dense than wheat. A minimum test weight of 71 kg/hl is standard for milling-grade rye; material below 68 kg/hl is generally rejected or downgraded to feed use. Polish rye varieties bred for milling — including Dankowskie Złote and Dańkowskie Diament — typically reach 72–74 kg/hl under good growing conditions.
Falling Number for Rye
Rye is significantly more susceptible to pre-harvest sprouting than wheat, and falling number testing is therefore even more critical. Unlike wheat, rye amylase activity is partly native (not exclusively induced by sprouting), so falling number thresholds are interpreted differently. A minimum of 120 seconds is generally the floor for rye accepted at Polish flour mills, though premium rye for pumpernickel or high-quality dark bread can require 140–160 seconds.
Ergot Content
Ergot (Claviceps purpurea) contamination is a food safety concern unique to rye and, to a lesser degree, triticale. EU Regulation 2015/1940 sets a maximum ergot content of 0.05% for grain intended for human consumption. Polish mill intake testing measures ergot as a percentage by weight of the grain sample, and any delivery exceeding 0.03% (the typical contractual limit) is rejected for food use.
Poland ranks among the top three EU rye producers by volume, with the Mazowieckie, Łódzkie, and Kujawsko-Pomorskie regions accounting for the majority of the national crop. Rye flour types from Type 720 to Type 2000 are defined under PN-A-74032.
Grain Intake Grading System
Once measured, grain at Polish mills is typically allocated to one of four internal intake grades:
| Grade | Typical Use | Key Thresholds |
|---|---|---|
| A — Premium milling | White bread flour, Type 550–750 | Protein ≥12.5%, FN ≥240, moisture ≤14% |
| B — Standard milling | Standard bread and all-purpose flour | Protein ≥11.0%, FN ≥220, moisture ≤14.5% |
| C — Lower-grade milling | Biscuit flour, wholemeal blending | Protein 9–11%, FN ≥180 |
| D — Non-food use | Feed, industrial starch, bioethanol | Below food specification on any parameter |