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Food Storage > Equipment > Heat (Impulse) Sealers

Heat Impulse Sealers.

Introduction. Heat sealing is accomplished by applying pressure and heat to melt films and bond them together, providing a safe environment for the contents of food inside the package that is sealed.[i]

When working with foil pouches, heat impulse sealers should be used.  One theory of heat sealing is to use an iron to seal a package instead of a heat impulse sealer.  However, using an iron will not seal the package properly, especially for powdered products.[ii] 

Where can heat impulse sealers be found?  They are available at most home storage centers.

Critical Factors in Sealing. Critical factors in heat sealing include the seal bar temperature, the pressure put on the seal by the sealing bars, and the time seal bar pressure is applied on the seal.[iii] Increasing seal pressure above the amount required will not improve the sealing and may result in thinning of films at the seal.[iv]^,[v]  Instructions provided with the sealing unit should be followed.    

It is also very important to make sure that the seal area is not contaminated with food, grease, moisture or some other contaminant that may weaken or prevent the seal.  The sealing surface should be smooth, parallel, wrinkle and contaminant free.  

Testing Seals.ⁱⁱ  After the process of sealing, look over seams to make sure they are adequate and don’t have burn spots. If seams are burned, decrease the sealing setting by ¼ step.   You should not be able to pull the seam apart.  If seam can be pulled apart, the seam area of the machine may need to be cleaned or the pouch may be too full. If needed, the sealing setting may be increased by ¼ step and then reseal the pouch.  Pressing on the package should not cause leaks.

References.

[i] Kun-xiu, D., Sheng-hai, H., et al. Parallel Horizontal Sealing Mechanism Design and Experimental Research about Heat Sealing Parameters. Key Engineering Materials. 419-420: 241-244. Available online at: http://www.scientific.net/KEM.419-420.241

[ii] The Church of Jesus Christ of Latter-Day Saints. (2007). Foil Pouches for Longer-Term Food Storage. Available online at: http://providentliving.org/pfw/multimedia/files/pfw/pdf/92987_FoilPouchStorageInstructionsv3_pdf.pdf

[iii] U.S. Food and Drug Administration. (2009). Guide to Inspections of Low Acid Canned Food Manufacturers: Part 3. Available online at: http://www.fda.gov/ICECI/Inspections/InspectionGuides/ucm109763.htm

[iv] Baer, E., Capaccio, G., Hiltner, A., Mueller, C. (1998) Heat Sealing of LLDPE” Relationships to Melting and Interdiffusion. Department of Macromolecular Science and Center for Applied Polymer Research.

[v] Kropf, D.H. (2004). Packaging: Technology and Films. Encyclopedia of Meat Sciences. Available online at: http://www.sciencedirect.com/science/article/pii/B012464970X001379#hit16.