The laws of kashrut require the extraction and drainage of all blood from beef or fowl within 72 hours of slaughtering. This is accomplished through a unique soaking and salting process-or, in some instances, through broiling. The reddish liquid that remains inside the meat after this procedure is not halachically considered blood; it is the meat's "juice," and is 100% kosher. Reference: www.chabad.org/library/article_cdo/aid/682641/jewish/Is-a-medium-rare-steak-kosher.htm