QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hayward, J. W. Articles by Bohstedt, G. Search for Related Content PubMed Articles by Hayward, J. W. Articles by Bohstedt, G.

The Effect of Heat as used in the Extraction of Soy Bean Oil upon the Nutritive Value of the Protein of Soy Bean Oil Meal¹

Departments of Agricultural Chemistry and Animal Husbandry, University of Wisconsin, Madison

Raw soy beans were found to contain protein of low nutritive value as determined by the grams of growth per gram of protein eaten. Commercial soy bean oil meals such as the expeller meal processed at low temperatures, 105°C. for 2 minutes or the hydraulic meal cooked at 82°C. for 90 minutes contained proteins similar in nutritive value to the raw soy beans. On the other hand, commercial soy bean oil meals which had been prepared at medium and high temperatures such as expeller meals processed at 112 to 130 and 140 to 150°C. for 2 minutes or hydraulic meals cooked at 105 and 121°C. for 90 minutes contained proteins which had about twice the nutritive value of the raw soy beans or low temperature meals. These expeller and hydraulic meals prepared at medium temperatures, respectively, were light brown in color while the meals prepared at high temperatures were brown in color. Heating the extracted soy beans at 98°C. for 15 minutes, as in the commercial solvent method of oil extraction, was also found to be an effective method of heat treatment. This solvent meal, however, was light colored. When the ground whole soy bean was autoclaved in the laboratory until the meal was brown in color, the protein had a high nutritive value. These results together with the fact that the commercial solvent meal was found to contain a very efficient protein suggest that brown color can only be used as an index of the probable efficiency of the proteins of commercial soy bean oil meals produced by the expeller and hydraulic processes.

The food intake of all rats which received either the raw or heated soy bean diets ad libitum was found to be similar for the first few days of the feeding period. This suggested that the poor growth resulting from the raw soy beans and low temperature meals was due to some deficiency in these constituents rather than to a lack of palatability.

When casein was incorporated in the diet which contained ground raw soy beans, normal growth resulted. These results suggested that the deficiency in the soy bean existed in the protein fraction.

Heating the raw soy bean to a high temperature in the expeller method of oil extraction caused an increase in the digestibility and biological value of the protein. The digestibility increased only about 3 per cent while the increase in biological value was about 12 per cent. This increase in biological or nutritive value of the protein established by metabolism tests agreed with the increase in nutritive value as determined by growth experiments.

The possibility appeared that heat caused some essential protein fraction, which was unavailable in the raw soy bean, to become available for absorption and metabolic use.

Manuscript received 23 October 1935.

This article has been cited by other articles:

				R. W. Carroll, G. W. Hensley, and W. R. Graham Jr. The Site of Nitrogen Absorption in Rats Fed Raw and Heat-treated Soybean Meals Science, January 11, 1952; 115(2976): 36 - 39. [PDF]