Principles of Fruit Preservation: Jam Making, Canning and Drying

This book has behind it nine years of research and factory experience in the fruit-preserving industry and five years research on the special problems of fruit canning. As the title indicates, it deals with the scientific principles and control of the various processes involved in the manufacture of jams and fruit jellies, fruit canning and fruit drying. For an understanding of these it has been necessary to give some account of the composition of fruits, especially in regard to their contents of acids sugars and pectin. The various methods of preserving fruits for jam-making and canning out of season are also described, and there is an account of the control of the actual manufacturing processes by the works chemist. In the section on fruit canning considerable space has been allotted to the problems of can-corrosion, a major source of trouble with certain products, especially in warm climates. The various stages of the canning process are also described and discussed in their proper sequence, and there are chapters on the standardization and examination of canned products and on fruit bottling. The section on fruit drying deals with recent researchers in the U.S.A., Australia and South Africa, both in connection with sun-drying and with artificial dehydration. Space is also given to the subject of prune-drying in France and the drying of grapes in Australia. There are also discussions of the problems connected with the storage and packing of dried fruits and of the general considerations in constructing and working a dehydrating plant. At the end of the book there are two chapters on subjects common to all the sections. One of these deals with the nature of fruit colours and their behaviour towards metallic salts and other agents of discoloration; the other with the effects of the various manufacturing processes on the vitamins in fruits. Although the book is mainly designed to assist the chemist and the technical expert, it is hoped that it will also prove useful to the engineer, since for a good many process the broad outlines of factory requirements are laid down, and, in any case, and understanding of the principles underlying a process can scarcely fail to inspire and guide the construction of the plant necessary for commercial production.