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Basic Manufacturing of Bacon

By Ana Elia Rocha

Manufacturing bacon is a simple process that usually involves injection followed by a short massaging process and cooking along with smoking and chilling.  Nevertheless, there are factors in each step that require consistency to obtain a high-quality product.  Good Manufacturing practices are essential as well.

Pork production and quality has improved in the last 25 to 30 years in the United States.  All the genetic science applied to pork production has yielded leaner, meatier animals.  Thus, fat and meat portions of pork bellies are different now.

Still, about 60% of most pork bellies are fatty tissue, and research has shown that this fat portion can be affected by the animal’s genetics and sex.  Leaner pigs tend to yield softer fat because of a lower percentage of saturated fatty acids.  Softer pork fat also presents an even lower melting point than normal pork fat.  This presents a challenge for processors when slicing bacon, since fat with lower melting point is more sensitive to increases in temperature and melts easily.

Raw Material and Preparation

Pork bellies should be sorted by size and fat percentage at the plant.  Sorting the raw material will reduce variability throughout the process and will yield more consistent bacon in the end.  Try to compile smaller batches to reduce variability as well.  If you receive in combos, work with your supplier to ensure the bellies are well packed and do not present wrinkles.  Folding the bellies sometimes leads to separation of lean and fat when frozen, and this can be a quality issue in the finished product. Also check for bellies that present PSE characteristics.

Once bellies have been sorted and classified, they must be trimmed to specification, and to a rectangular or square shape.  Again, this will reduce the variablity throughout the process, and will increase slicing yields at the end.

If you receive skin-on bellies, pay special attention to the skinning step, as this will have a great impact on yield.

Brine and Injection

Traditional ingredients in bacon manufacturing are water, salt, sugars, nitrate and/or nitrite, sodium erythorbate and/or ascorbate and phosphates.  Spices and flavorings are added to specialty bacon.  Salt content in the range if 1.5% to 2% is common in bacon.  Nitrite is limited to 120 ppm, and sodium erythorbate-a cure accelerator – to 550 ppm by regulation in bacon brined by injection or immersion.  The recommendation for phosphate is 0.3% to 0.4% in the finished product.  Levels higher than 0.5% can lead to soapy flavor.  For sugars a level of 0.1% is recommended to avoid extreme caramelization on the slabs surface during cooking.  Brine shoud be made at a temperature of about 40°F, and mixing of ingredients is important, starting with phosphates and followed by salt and curing ingredients.

It is important to make sure you add ingredients in adequate amounts.

When doing your calculations consider the following:

  • Measure water by weight not volume.  Consider that water weight changes with temperature.  Always weigh water at 40°F.
  • Add phosphates first, and only add salt once they are completely dissolved.
  • Every ingredient should be added slowly to assure good solubility.
  • Know the purity of your ingredients, and calculate based on the percentage of the active ingredient.
  • Always prepare a new batch of brine, and avoid using brine from the day before, as most ingredients deactivate as time progresses

Partially frozen raw material does not allow for ingredients to be evenly distributed when brine-injected, so make sure bellies are properly and completely thawed and at about 40°F (4°C to avoid food safety issues.

The amount of the ingredients in the formulation is based on the percentage of injection, and so it is critical to aim for that percentage when injecting.  Otherwise, you will end up with a higher or lower concentration of ingredients in the final product, which will lead to quality and consistency problems and perhaps regulatory issues.

Recommended pumping levels are between 14% and 16%, which will allow you to stay within the regulated 1% weight gain after thermal processing.  Also, keep in mind that too much pressure applied will likely create “pickle pockets” between fat and muscle, which can lead to separation of these two when bacon is being sliced.

When injecting pork bellies, consider the following:

  • Check that the injection level is being achieved by running several bellies and obtaining the average.  Repeat this at several intervals during the process for a more consistent product.
  • Place bellies lean side up as they enter the injector’s conveyor belt to reduce the incidence of fat-plugged needles.
  • Keep brine temperature no higher than 40°F (4°C).

Curing

Pork bellies need to rest for curing to take place.  The characteristic color of bacon is developed during curing.  Injected bellies’ curing period can go from one to five hours, whereas for immersed bellies the time is much longer, from two to seven days.

Vacuum tumbling could be applied to injected bellies to assure a better ingredient distribution – accelerating the cure – and less pickle pockets.  Some experts suggest that the protein extracted during this step gives bacon a more attractive appearance after smoking.  However, tumbling time should not be excessive, or connective tissue can be damaged, resulting in decreased quality.  Vacuum tumbling should be done at 30°F to 40°F  (-1°C to 4°C), and at slow speed.

Thermal Processing

This is the step where pork bellies turn into bacon.  Pork bellies must be hung using bacon combs, which should be pushed into the belly on the lean side, making sure the Cutaneous Trunci Muscle (or CT Muscle) has been penetrated.  Proper combing is important to produce slabs that are more regular in shape, which ultimately results in higher slicing yeilds.  Bellies are then hung from tree racks or trucks and taken into the smokehouse.

Bellies should be cooked and smoked until they reach an internal temperature of 124°F to 132°F (51°C to 55°C).  The cooking and smoking process usually results in a 10% to 12% cooking loss.  Depending on the type of product desired, cooking cycles can go from one to two hours to a day and a half, especially for artisan bacon.

Depending on the smokehouse being used, smoking can be natural from bruning wood, or liquid applied by spraying.  Smoking gives bacon the traditional aroma, and also stabilizes and sets traditional color, both in the lean portion and the outer surface.

Chilling and Pressing

The way bacon slabs are chilled and tempered will influence the pressing and slicing steps.  Bacon slabs are quickly shower-chilled right after the thermal process and taken to a refrigerated area, where they shoud reach an internal temperature of 40°F (4°C) in 24 hours, and chilled to 10°F (-12°C) afterwards.  Then they need to be tempered in another refrigerated area in preparation for pressing.  Some experts recommend tempering to about 18°F (-8°C), while others mention a range of 22°F to 26°F (-5.5°C to -3.3°C).

During pressing, bacon slabs should be at a temperature ranging from 28°F to 30°F (-2°C to -1°C). This will facilitate a better shape that eventually results in better slicing and increased slicing yeilds.

Slicing

During slicing, bacon slabs should be at a temperature between 23°F and 25°F (-5°C and -4°C).  Slice breakage or fat smearing can occur if bacon slabs are too cold or too warm, respectively.  Another quality problem related to temperature in this step is possible lean and fat layer seperation.