One of the main problems in using the concepts of elasticities is that you are facing the problematic introduction of time in economics analysis. In short are you dealing with short term elasticities or long term ? 

Renata,

I am not certain if you are asking if the cross price elasticity has a constrained maximum of +1, or if 5.21 is excessive in comparison with what might be expected.

Different scholars use different terminology.  Cross price elesticities (Exy) might be classified something like the following:

• Exy > 1          = strong substitutes
• 0  >  Exy >1  = mild substitutes
• Exy = 0 (or approaching approaching 0) = no relationship
• 0 < Exy < -1 = mild complements
• Exy < -1       = strong complements

Also, you might look at the paper attached in the first link that reports the AIDS cross price elasticities greater than 1.  However, you may note that it is based on Japan and large (absolute) values are uncommon.

The cross price elasticity of 5.21 that you found for beef and pork seems rather high; however, cross price elasticities are highly dependent on culture as well as other options that may, or may not, exist.  For example, in the US where many alternatives for pork exist (e.g., beef, chicken, turkey, shrimp, fish, and many others), a 1 percent increase in the price of pork, might have about a +0.33 percent change in the demand for beef as illustrated in the second link from the United State Department of Agriculture (USDA) in 2015.  In other countries, the answer might be quite different.

Dominque correctly notes that the elasticities differ in the short term and long term. 

I hope this helps.

Rob

http://ageconsearch.umn.edu/bitstream/21755/1/sp00ta02.pdf

http://www.ers.usda.gov/topics/food-choices-health/food-consumption-demand/food-demand-analysis.aspx

 dear colleagues, thanks in advance,my panel data was 10 years, but was very strange for me this high value. interesting fact was, when I changed input data, because in first model I added all foodstuff, but in the next model I added only meat items. and results was appropriate.