Sentence:  <WSD>Pink slime</WSD> is a real and continuing problem in many paper mills. Once established it may be difficult to ... Holmes (15, 16) and Sanborn (24) stated that yeasts or yeast-like fungi were often the cause of <WSD>pink slime</WSD>. 
Meaning of the word marked with <WSD> tags:  An undesirable pink-colored microbial mass occurring in the slurry used in making paper. (from 1951)