Massachusetts Agricultural Experiment Station
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| Hersteller: | Forgotten Books (Holland, E. B.) |
| Stand: | 2015-08-04 03:50:33 |
Produktbeschreibung
Excerpt from Massachusetts Agricultural Experiment Station: Trace Metals and Total Nutrients in Human and Cattle Foods, July 1941 Foods have been a subject for investigation by the Massachusetts Experiment Station ever since its organization, and comprise a wide range of products. Recently the determination of trace metals, supposed to have a functional activity in assimilation and possibly some therapeutic value, has received major attention. As natural food products are in themselves responsive in assimilation and growth to seasonal, cultural, and other environmental conditions, the problem becomes somewhat involved. Collection and Preparation of Samples Numerous samples of fruits and vegetables were obtained from the State College and vicinity and many vegetables from the Waltham Field Station and eastern market gardeners. Similar samples were secured from other sections and in addition cereals, nuts, processed human foods, and cattle feeds. Duplicates in succeeding years served to check variability in some measure. All samples were expected to be mature, marketable products in prime condition for use, but some failed to meet these requirements. Immature and overripe products vary appreciably in proximate constituents but to a less extent in trace metals. The type and rapidity of growth are also factors influencing composition. Respiratory changes in some fruits and vegetables during transportation and storage affect composition at the expense of the carbohydrates. The samples were culled as in household practice, washed if necessary, comminuted, and dried in an electrically heated oven in a strong current of warm air (about 50° C). Under such treatment the tissue sets quickly with a minimum of deterioration in fat and carbohydrates. Many of the early samples were pared or scraped but the practice was largely discontinued later. The dried samples were ground to a 1 mm. sieve and preserved in glass containers for subsequent analysis. Basis of Analysis Most fruits and vegetables contain from 80 to 96 percent of water at maturity but lose rapidly on exposure. These foods are frequently marketed fresh, frozen, canned, or dried. On the other hand, most cereal products, navy beans, nuts, oil meals, and other industrial by-products are substantially air-dry when marketed. With such a range in moisture content, dry matter offers the most equitable basis for comparison. Proximate constituents are reported in percentage and trace metals in parts per million. As previously stated, most fruits and vegetables are high in moisture when received by the consumer in fresh condition but lose water on exposure in harvesting and in transportation and storage. The amount of loss will, of course, vary with the character of the product and subsequent treatment. Generally the dry matter will range from 5 to 20 percent. Comparatively few contain less than 5 percent, but others having a long ripening period or suffering undue exposure will contain more than 20 percent of dry matter. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.
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