Sentence:  Stew no longer than the meat is thoroughly done to eat, and you will obtain excellent broth, without depriving the meat of its nutritious succulence : to boil it to rags, as is the common practice, will not enrich your broths, but make them thick and <WSD>grouty</WSD>. 
Meaning of the word marked with <WSD> tags:  Full of grout(s), that is, sediment.