INFLUENCE OF COOKING PROCEDURE UPON RETENTION OF VITAMINS AND MINERALS IN VEGETABLES¹

Abstract

The nev-er developments in the field of nutrition have indicated that some of the most important elements in our diets, invisible and undetectible by the senses of taste and smell, are lost during the cooking of foods. These are the vitamins and the essential minerals. Prior to these newer developments, the primary function of cooking was to prepare foods in an edible form. In order to preserve the nutritive value of foods, the cook must now look to the nutritionist to ascertain what effects the various operations in the preparation and cooking of foods may have upon the retention of the vitamins and minerals and how these procedures can be so modified as to retain these essential nutrients to the maximum without sacrifice of palatability and appearance.Most of the studies in this field have been concerned solely with vitamin C losses. This v-as due to the availability of a chemical method for ascorbic acid analysis while the laborious, costly, and less precise biological procedures were required for the assay of the other vitamins. With the advent of rapid and inexpensive chemical and microbiological test methods, attention was directed toward evaluating the fate of nutrients other than ascorbic acid in cooked foods. These studies, reviewed by Kohman (19421, were confined to a limited number of factors in one or two different typesThe present study was undertaken to determine the difference in degree of retention of vitamins and minerals as affected by variations in culinary methods. Analyses were conducted for the carotene, thiamin, ascorbic acid, riboflavin, nicotinic acid, iron, calcium, and phosphorus contents of four representative vegetables before and after cooking.The typical vegetables selected were peas, potatoes, carrots, and broccoli representing, respectively, legumes, tubers, roots, and in the last case, leaves, stems, and flowers. Purchases mere made in the open market of the freshest vegetables obtainable during the midsummer season. The cooking experiments were conducted on the same mornings that the purchases were made.Two cooking methods were used, one concerned simply with the preparation of the vegetables in edible form, the other based on a procedure designed also to favor retention of the essential nutrients without sacrifice of palatability. For convenience, the first will be referred to in the present study as the "old-fashioned" procedure and the other as the "new-improved'' method of cooking. In the case of the old-fashioned method large proportions of water v-ere used to show the results obtained when no care is observed in the direction of preserying the nutritive elements, as in the of foods.'This study is one of a series, sponsored by the Westinghouse Electric and Manufacturing Company, Mansfield, Ohio, as part of its Health for Victory Club program. 115

Retention of Vitamins in Fresh and Frozen Broccoli Prepared by Different Cooking Methods

“…Steamed fresh samples retained the full amount of thiamine. Generally these results agree with those of Collings (1946) and Oser et al (1943) who reported 87% to 100% retention of thiamine depending on proportions of water used and cooking pressures. Since thiamine in our samples were in the lower reported ranges (under 80 pg/lOO g), it is possible that retention characteristics of this vitamin are different at the lower concentrations.…”

“…Oser et al (1943) reported a generally high retention (83%) of riboflavin by cooking. Our results showed significant losses from boiling, but full retention in steamed and microwaved fresh samples.…”

VITAMIN RETENTION AND ACCEPTABILITY OF FRESH VEGETABLES COOKED BY FOUR HOUSEHOLD METHODS AND BY AN INSTITUTIONAL METHOD123

“…For all four methods summarized together the retentions in the cabbage, shredded or cut in small pieces, were one-fourth to all of the ascorbic acid ; in spinach, without stems in one study, one-fourth to threefifths of the ascorbic acid, one-half to four-fifths of the thiamin, and one-half to four-fifths of the riboflavin; in peas one-half to four-fifths of the ascorbic acid, one-half to almost all of the thiamin, and two-thirds to almost all of the riboflavin. These values were taken from reports by Halliday and Noble (1936) ; Wellington and Tressler (1938) ; Lunde, Kringstad, and Olsen (1940) ;Brinkman, Halliday, Hinman, and Hamner (1942) ;Higgins (1942) ; MacGregor (1942) ;Oser, Melnick, and Oser (1943) ;Gleim, Tressler, and Fenton (1944) ; Ireson and Eheart (1944) ; and Noble and Waddell (1945).…”

Effects of Four Cooking Pressures on Locally Grown Broccoli: Cooking Time, Palatability, Ascorbic Acid, Thiamine, and Riboflavin

“…Reported retentions in drained cooked broccoli range from 83% by Oser, et al (15), and from 83% to complete retention by Collings ( 5 ) depending upon the method of cooking. Collings also reported some increases of riboflavin during cooking.…”