Egg grading is clearly a topic of great importance to free range producers. Maximising the number of Class A eggs they are paid for by a packer or can sell to their customers is key to profitability. It is therefore of interest to them to understand how their eggs are graded and what makes a Class A egg; in order to minimise seconds. BFREPA and sponsors are planning to fund a study looking at the current level of seconds and how this can be reduced. The research will look at where and how seconds occur in the production chain.
Why grade eggs?
The purpose of defining Class A eggs is to fix the quality characteristics to guarantee that consumers are buying a high quality eggs. Regulations exist to quantify those criteria, these are set out in EU law and enforced by individual countries. The authorities in each country will check compliance with the regulation through inspections. In the UK this is the responsibility of the Egg Marketing Inspectorate (EMI), who are part of the Animal and Plant Health Agency (APHA), an executive agency of DEFRA.
Producers who market their own eggs, in the most part, have to meet the same standards for egg grading as a large packer, buying eggs from a number of producers. All packing stations should be registered with the EMI, have a packing code and gain approval. They are required to have the following machinery to accurately grade eggs:
• Automatic or manual candling
• Devices for measuring the height of the air space
• Equipment for grading eggs by weight, included one or more approved balances
• Equipment for marking eggs
Most of those supplying packers will screen eggs to remove obvious seconds including; dirty eggs, soft shells and those with highly visible cracks. However, it is then the packer’s responsibility to ensure that it sells only Class A eggs into retail. They will evaluate the internal and external quality of the eggs by using an automatic grading machine.
What it takes to be a Class A egg
Eggs should be graded, marked and packed within 10 days of laying or 4 days if marketed as Extra/Extra Fresh. Class A eggs cannot not be washed or cleaned, before or after grading. The regulations on the quality grading & storage of eggs states that Class A eggs shall have the following quality characteristics:
• Shell and cuticle: normal shape, clean and undamaged
• Air space/cell: height not exceeding 6 mm, stationary or 4 mm if marketed as extra fresh
• Yolk: visible on candling as a shadow only, without clearly discernible outline, slightly mobile upon turning the egg, and returning to a central position
• White: clear translucent
• Germ: imperceptible development
• Foreign matter: not permissible
• Foreign smell: not permissible
Class A eggs, sold in packs, which meet more stringent standards may be marketed as extra or extra fresh until the ninth day after lay. Although not commonly found on the supermarket shelves, eggs labeled at Extra Fresh are sold at farmers markets or local shops. The size of the air space or cell is an indicator of freshness and therefore will increase with time after laying. If eggs are packed within a couple of days of being laid then exceeding maximum air space height is unlikely to be a problem.
Rules on tolerance levels
Just as the quality characteristics for Class A eggs are set out in EU legislation so are their associated tolerance levels. The regulations state that certain tolerances should be allowed when checking compliance with the marketing standards.?The following tolerances are be allowed when checking batches of Class A eggs:
• at the packing centre, just before dispatch: 5 % of eggs with quality defects
• at the other marketing stages (after packing but before purchase from a wholesaler or retailer: 7 % of eggs with quality defects.
This means that although every egg must be checked by the packer to ensure it meets the quality criteria; up to five percent that don’t, are allowed through. Where the batch checked contains fewer than 180 eggs, the percentage tolerances given above can be doubled. And no tolerances are allowed if eggs are marketed as Extra or Extra Fresh.
So how to packers make sure that they are not exceeding these tolerance levels?
Egg graders and packers
All large packers will be using highly sophisticated automatic grading machine, which have throughputs of 120,000 - 180,000 eggs an hour. The technology used by this kind of equipment is constantly evolving, with accuracy and gentle handling improving all the time. A popular example is the Omnia grader from MOBA, which works in the following manner.
1. A vision module detects any eggs that are leaking and removes them so that they don’t contaminate the rest of the batch. It is sensitive enough to tell the difference between damp or sweating eggs and those with actual albumin leaking from them.
2. The same module picks up any dirt on the outside of the egg and also grades them as seconds
3. The crack detector uses an acoustic device to measure the egg and then taps it in several places. The resulting resonance indicates the size and position of any cracks. If those cracks would be visible then the egg will be down graded
4. Next a UV module disinfects the eggs and the rollers
5. A weighing bridge picks up each individual egg and weighs it, improving accuracy and reducing contamination
6. The blood detector uses a UV light source to pick up any haemoglobin in the egg and will down grade any eggs with blood spots, which would be visible
7. Finally the eggs are printed with their code
If this kind of machine is set up correctly, properly maintained and calibrated, then accuracy should be 100 %. The packer is responsible for this, although the manufacturers provide guidance and can carry out servicing. In order to check everything is working as expected the packers will take samples of eggs from each batch and test them in their own lab. At this point they will measure air space height and Haugh units etc. as well as manually checking for quality defects to ensure that don’t exceed tolerance levels.
Automatic graders can be set to vary the percentage of eggs that get through, dependant on the type of defect. So whilst they mustn’t exceed the five percent tolerance limit they may accept a certain level. This will vary on the specification of the customers they are going to or market conditions. Another example is that very fine cracks may be accepted in eggs from younger flocks but not from older birds, as the thinner shells increases the risk of breakages. However, from the EMI’s point of view they do find non-compliance, where packers have perhaps pushed tolerance limit too far.
Quality Checks
The EMI as previously stated is responsible for the enforcement of the EC Egg Marketing Regulations, at all marketing stages, excluding retailer level. Through inspections they will check that packers are meeting requirements and not exceeding tolerance levels on grading criteria. The frequency of visits is based on a risk assessment and is dependant on nature/size of the business, as well as compliance history. Most inspections will be unannounced to get a true picture of how each business operates.
The inspectors visit packer armed with a variety of manual egg grading equipment: candling lamp, weighing machine and air cell measuring device. A UV light source is also used to check the condition of the cuticle and look for signs that eggs have been cleaned. They select a batch of eggs and then take a sample of boxes to check for any that don’t meet the quality criteria. If that number is over five percent then the packer will not be able to market the eggs. Issues will have to be proved to have been rectified, follow up visits made and if persistent non-conformance is found then prosecution will be sought. The inspectors will also check the packer’s records to ensure the traceability of eggs.
Size matters
In terms of returns for producers, egg weight is also important. Their contract may specify a size range required or min and max of small or large. Therefore, if eggs fall outside these parameters, they may not get the price they expected. Class A eggs must be sold according to weight, or in minimum weight, mixed-size packs. Just as for the measures of quality, the grading machines will be set up and calibrated for EU egg sizes as below:
• XL - VERY LARGE eggs weighing 73g or more
• L - LARGE 63g up to (but not including) 73g?
• M - MEDIUM 53g up to (but not including) 63g
• S - SMALL below 53g
There are also tolerance levels for Class A egg weights. Batches may contain not more than 10% of eggs at the higher weight grade and not more than 5% of the lower weight grade. Where batches contain fewer than 180 eggs, the percentages can be doubled. Automatic graders are highly accurate at weighing but these tolerance levels allow for any sorting errors.
The bottom line
If eggs are not graded Class A, they are considered Class B or ‘seconds’. These eggs will be sent for processing but will only we worth approximately a third of the value of a Class A egg. If a producer were able to reduce the level of seconds by just one percent, it would have a significant effect an annual income. By law egg packers are required to keep full and accurate records of the eggs they grade. This includes details of numbers of Class B eggs and the number of Class A eggs by weight. These records should be traceable back to the producer as well as recording who they were sold to.
Clearly the packers have a lot of information but getting it to producers in a meaningful format is not always achieved. However, when speaking to producers at the BFREPA conference, many mentioned their desire to have more details. It would be useful to them to know what was the main reason for down grading a batch of eggs; cracked, dirty etc. In fact software has been developed to capture data from the grading and packing machines to enable producers to have feedback on their eggs quicker. Producers would then be able to work solve problems – the more information they have the better the decision making process.
Transparency
For both producers and packers every Class A egg counts as both will receive higher payments. Minimising seconds is clearly a priority for everyone and one that the previously mention study hopes to address. This why packers buy the latest grading and packing technology, which claims to reduce seconds by up to two percent. Such an increase in Class A eggs for either producer or packer could make the difference between profit or loss. Some packers encourage their producers to visiting the station and see the grading machines in action. It is these kinds of initiative, which will help improve transparency in this area.
