CONTENTS. 



Page. 



Introduction 7 



Process of manufacture 8 



Selection and preparation of stock 9 



Pulping 9 



Cooking and seasoning 10 



Evaporation and finishing 11 



Bottling 11 



Processing 11 



Character of products 12 



First-class products 12 



Inferior products from "trimming stock" ]3 



Labels 14 



Manufacturing experiments without the use of preservatives 15 



Outline of experiments 15 



Discussion of results 17 



Spoilage of ketchup after opening 17 



Spoilage of unopened ketchup 20 



Spoilage of market brands 20 



Sterility of ketchup 21 



Experiments with preservatives 22 



Sodium bcnzoate 22 



Salt 23 



Sugar 23 



Spices 24 



Water infusions 24 



Acetic acid extracts . 25 



Oil extracts 25 



Vinegar and acetic acid 26 



Oil 27 



Study, of Penicillium in ketchup 28 



Development 29 



Reproduction 29 



Growth in ketchup 30 



Temperature tests 31 



Histological structure of ketchup 33 



Microscopical examination of some commercial brands 34 



Summary 35 



5 



