Explainer · Defects and grading
How to identify a star crack in an egg
A star crack is several short lines radiating from one point, usually an impact on the shell. If the shell membranes are intact and the contents do not leak, it counts as a check (7 CFR 57.1), not a leaker. A surface camera sees the longer, deeper branches, but fine branches can be missed, so candling is still needed.
Updated · 4 min read
What is a star crack?
A star crack is a pattern in which several short lines radiate from one point, as from a blow. It differs from an ordinary crack, which is a single elongated line. For grading, what matters is the membrane: an intact shell membrane keeps the egg in the cracked category.
Under the US definition, a check is an egg with a broken or cracked shell whose membranes are intact and whose contents are not leaking (7 CFR 57.1). A star crack that keeps the membrane fits that definition. If the membranes break and the contents are exposed or exuding, the egg becomes a leaker.
Is a star crack a cracked egg or unfit?
It depends on the membrane and on dirt. With no leak and a clean shell, the egg goes to industrial processing as quickly as possible (RIISPOA, art. 227). With a dirty, broken shell, it is unfit for human consumption (RIISPOA, art. 500, VI).
| Situation | Destination | Basis |
|---|---|---|
| Shell broken in a star, shell clean, membrane intact | Industrial processing, as quickly as possible | RIISPOA, art. 227 |
| Shell broken in a star and dirty | Unfit for human consumption | RIISPOA, art. 500, VI |
| Membrane broken and contents exposed | Unfit for human consumption (leaker) | RIISPOA, art. 500, VII |
In every case the shell is no longer Class A, because art. 225, I requires an intact shell.
Why is a star crack hard to measure from an image?
Vigiovo measures cracks as lines. A line counts as a crack if it is at least 5 times longer than wide, reaches at least 0.35 of the radius r, and runs at least 0.4 r into the shell instead of following the rim. The egg is cracked if the total crack length reaches 0.8 r. These values are Vigiovo configuration settings, not legal standards.
A star has short branches, so each branch can fail the length or depth test even when it is part of a real defect. The public description of the rules speaks of lines and does not detail how the branches of one star are grouped. So the behaviour with stars should be confirmed on labelled eggs from your own line, during calibration.
How do you recognise the impact that caused a star crack?
In practice, the centre the lines radiate from shows where the shell took the blow. That point helps explain the source of the damage during collection and transport, but it does not change the destination, which depends on the membrane and on dirt.
Fine, short branches can also be invisible under normal light. When a star has hairline branches, a camera sees the centre and the stronger branches, and candling completes the picture, as with hairline cracks.
What should you do with a star crack on the line?
Treat a star crack as a check until the membrane is confirmed. The steps below keep the egg out of Class A and set its correct destination.
- Separate the star-cracked egg from the Class A flow.
- Confirm on candling that the membrane is intact and that the contents do not exude.
- Check whether the shell is dirty, because that changes the destination.
- Send the egg to industrial processing if the shell is clean and the membrane intact, or treat it as unfit if the shell is dirty or the membrane is broken.
- Record how many star-cracked eggs were separated, to follow the source of the damage on the line.
Frequently asked questions
Is a star crack a real crack?
- Yes. It is a crack in the shell, so the egg cannot be Class A (RIISPOA, art. 225, I). If the membrane is intact and the contents do not exude, it is a check under the 7 CFR 57.1 definition.
Does every star crack make the egg leak?
- No. A star crack becomes a leaker only when the shell and membrane break and the contents are exposed or exude (7 CFR 57.1). With the membrane intact, the egg is still a check and can go to industrial processing if the shell is clean (RIISPOA, art. 227).
Can a camera see a star crack?
- Partly. A camera sees the longer, deeper and more elongated lines that meet its image rules. Short, fine branches may not count on their own, and only candling reveals the finest lines. So the camera should be calibrated with star-cracked eggs labelled from your own line.
Sources
- Decreto nº 9.013/2017 (RIISPOA), Presidência da República (Brasil)
- 7 CFR § 57.1 Definitions (Inspection of Eggs), U.S. Electronic Code of Federal Regulations
How Vigiovo helps
Vigiovo grades eggs on the conveyor as clean, dirty, cracked or unverified, in real time, with deterministic computer vision: every decision comes with the measurements behind it, on an ordinary CPU.