This section is from the book "Experimental Cookery From The Chemical And Physical Standpoint", by Belle Lowe. Also available from Amazon: Experimental cookery.
The principal function of this volume is to present our newer knowledge of food preparation and cookery processes from a chemical and physical basis, particularly that of colloid chemistry. In doing this, many results secured from experimental work along these lines at Iowa State College have been included. A condensed arrangement of the data on cookery, which are found in widely scattered sources, has been included also.
Many of the sciences serve as a foundation or basis for food preparation. Inorganic, organic, physical, and plant chemistry, as well as physics and other sciences, are necessary for an adequate understanding of many processes in food preparation. But the subject matter herein covered is perhaps more closely related to physical chemistry and the branch of physical chemistry known as colloid chemistry. In fact, so many of the ingredients used in food preparation are colloidal in nature that food preparation may be classed as one field of applied colloid chemistry. As a phase of colloid chemistry it offers a vast field for exploration, for although commercially prepared foods have been studied extensively the problems in connection with their preparation are far from completed. Work along other lines of cookery has hardly started. Some of the older work on cookery needs to be repeated and explained in the light of newer interpretations of science.
Because the majority of home economics students have had no opportunity to take even an elementary course in physical or colloid chemistry, it becomes necessary to present a simple outline and explanation of colloid chemistry in its relation to food preparation. Since this is the foundation material for this treatise it seems logical to present it first. But to many persons this is the newest and perhaps the most difficult subject matter in relation to food preparation. Therefore, it is probably better for the student to commence with the chapters on sugar cookery, freezing, and fruits and vegetables, referring only to the few paragraphs in Chapter I (The Relation Of Cookery To Colloid Chemistry) needed to understand some of the factors of sugar cookery and freezing. A fundamental understanding of sugar cookery and freezing preparation processes is based largely upon the portion of physical chemistry dealing with solutions, vapor pressure, the boiling point, and the freezing point. This material is outlined in these chapters. But to present the material on colloid chemistry in such a manner in every chapter would lead to many repetitions and make the book unduly long. Hence this material is summarized in Chapter I, although the author realized that it would probably be necessary to review or to present portions of this chapter in connection with subsequent ones.
Many contradictory observations are often made in cookery. This is to be expected, particularly when the materials used are in a colloidal state. Unless the constituents of food products are present in the same amount, and, even if present in the same proportion, if the colloidal particles are not the same size, if the previous treatment, including the thermal and mechanical treatment and the time element, is not exactly duplicated, then even an elementary knowledge of colloid chemistry leads one to expect different results in finished products, because of variation of these different factors. It is not possible to control all these factors. For instance, the variation in ash content of flour, eggs, milk, meat, fruits, and vegetables is nearly always beyond our control. But the necessity for a detailed description of the technic and method followed in reporting results is obvious. Detailed directions in writing the laboratory outline are essential or the technics followed may vary so much that the results are worthless for comparisons. It is of course understood that adequate explanations cannot be offered for all cookery processes. In some instances it is necessary to determine the results time after time and let the theory fit the laboratory facts. In other cases the explanations offered will need to be changed, modified, or replaced by data obtained from future investigations.
In starting the laboratory work the author asks her students to assume the attitude that every result obtained is right. If it is not as expected, what are the reasons? For example, a burned, charred product results from certain procedures. If, when students have used the same proportions, the same ingredients, and tried to follow the same technic, the individual results differ, what are the possible interpretations for the divergence? In the same manner the reported results of other investigators are taken as correct. If the students' laboratory results do not always agree with reported results, interest comes in comparing methods used, the ingredients used, their proportion, and the technic followed, to find explanations for agreement or disagreement.
It is hoped that this volume will fill a need for a textbook for discussion material for food-preparation courses in colleges and as a reference work for teachers of secondary schools. It is also hoped that the reference to and summary of articles in the literature will create an interest on the part of the student to read and interpret them for herself.
Food-preparation study in colleges may include courses designated as experimental cookery. The material in this book may be given in such courses. The manual "Food Preparation Studies" by Child-Niles-Kolshorn will also be an aid in these courses.
To some the term experimental cookery implies only a method of presenting material. Such is not the use of the expression in this volume. It is used to designate a certain field of subject matter relating to food preparation. The laboratory outline included in this volume is arranged to present this subject matter as far as possible.
What constitutes or should constitute experimental-cookery courses cannot be answered fully at the present time. They are of necessity rapidly developing and changing. The author believes that eventually they will have the same relation to food-preparation courses that those in animal feeding have to nutrition courses.
The author takes this opportunity to acknowledge with appreciation the comments of Dr. P. Mabel Nelson, Florence Busse Smith, Alma Plagge, Viola M. Bell, and the other members of the Foods and Nutrition staff of Iowa State College. The aid of Dr. Amy Le Vesconte for many pH determinations is also acknowledged.
To Dr. E. A. Benbrook and Margaret Sloss of the Veterinary Department the author is indebted for aid in taking photo-micrographs.
For reading portions of the manuscript and for the suggestions they have offered, the author is also indebted to Dr. E. I. Fulmer (the chapter on the Relation of Cookery to Colloid Chemistry); to Prof. M. Mortensen and Prof. C. E. Iverson (the chapter on Freezing); to Dr. R. M. Hixon (the chapter on Fruits and Vegetables); to Dr. Paul E. Howe and Prof. M. D. Helser (the chapter on Meat); to Prof. M. Mortensen, Dr. E. W. Bird, and Dr. B. W. Hammer (the chapter on Milk); and to Ethan E. Hoovler (the entire book).
To the many students in her "Experimental Foods" classes who through their interest and enthusiasm have always been a stimulus to further work, the author wishes to express her most grateful appreciation.