Can undigested food proteins enter the bloodstream?
Sort of.

Proteins can enter the body through the intestines by exploiting a few transport mechanisms, They are not truly crossing the cell membrane but are transported across the cell in vesicles. Though not into the bloodstream but into the lymph system.

M cells in particular will move antigens across the intestinal wall, a few more durable proteins (like prions) have been shown to piggyback on this system to cross in tiny quantities. Some viruses also exploit it. Collagen definitely does not enter this way but there are likely egg antigens that may. 

Note this is very rare for non-antigens, the vast majority of food you eat will not contain anything that can exploit this although they may contain antigens that get passed to the immune system. 

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