During WWII, the fire extinguishing, soy protein foam, "Aero-Foam", the U.S. Navy's beloved fire-fighting "bean soup", was the brainchild of Percy Lavon Julian. When a hydrolyzate of isolated soy protein was fed into a water stream the mixture was converted into a foam by means of an aerating nozzle. The soy protein foam was used to smother oil and gasoline fires aboard ships, particularly useful on aircraft carriers.
In 1958, Central Soya of Fort Wayne, Indiana acquired Julian's Soy Products Division (Chemurgy) of the Glidden Paint Company, Chicago. Recently, Central Soya's (Bunge) Protein Division, in January,2003, joined/merged with DuPont's soy protein (Solae) business, which in 1997 had acquired Ralston Purina's soy division, Protein Technologies International (PTI), St. Louis, Missouri. Eighth Continent, an "ersatz" soy milk is a combined "venture" product of DuPont's Solae, protein isolate and General Mills with a production facility in Minneapolis, MN.
Food grade soy protein isolate, first became available on October 2, 1959 with the dedication of Central Soya's edible soy isolate, Promine D, production facility on the Glidden Company industrial site in Chicago. An edible soy isolate; and edible spun soy fiber has also been available, since 1960, from Ralston Purina Company of St. Louis, Ill. who had hired Boyer and Calvert. In 1987, PTI became the world's leading maker of isolated soy protein.
Soy protein concentrate is produced by immobilizing the soy globulin proteins while allowing the soluble carbohydrates, soy whey proteins, and salts to be leached from the defatted flakes or flour. The protein is retained by one or more of several treatments: leaching with 20-80% aqueous alcohol/solvent, leaching with aqueous acids in the isoelectric zone of minimum protein solubility, pH 4-5; leaching with chilled water (which may involve calcium or magnesium cations), and leaching with hot water of heat-treated defatted soy meal/flour.
All of these processes result in a product that is 70% protein, 20% carbohydrates (2.7 to 5% crude fiber), 6% ash and about 1% oil, but the solubility may differ. One tonne of defatted soybean flakes will yield about 750 kg of soybean protein concentrate.
Pure soy protein isolate is used mainly by the food industry. It is sometimes available in health stores or in the pharmacy section of the supermarket. It is usually found combined with other food ingredients.
Soy protein concentrate retains most of the fiber of the original soybean. Soy protein concentrate is widely used as functional or nutritional ingredient in a wide variety of food products, mainly in baked foods, breakfast cereals and in some meat products. Soy protein concentrate is used in meat and poultry products to increase water and fat retention, and to improve nutritional values (more protein, less fat).
Soy protein concentrates are available in different forms; granules, flour and spray dried. Because they are very digestible, they are well-suited for children, pregnant and lactating women and the elderly. They are also used in pet foods, milk replacers for calves and pigs, and even used for some non-food applications. soy protein is bad
Of any studied legume, whole soybeans have the highest levels of phytic acid, an organic acid and mineral chelator present in many plant tissues, especially bran and seeds, which binds to certain ingested minerals: calcium, magnesium, iron, and especially zinc — in the intestinal tract, and reduces the amount the body assimilates. For people with a particularly low intake of essential minerals, especially young children and those in developing countries, this effect can be undesirable. However, dietary mineral chelators help prevent over-mineralization of joints, blood vessels, and other parts of the body, which is most common in older persons.
The digestibility of some soyfoods are as follows: steamed soybeans 65.3%, tofu 92.7%, soy milk 92.6%, soy protein isolate 93–97%. Some studies on rats have indicated that the biological value of soy protein isolates is comparable to animal proteins such as casein if enriched with the sulfur-containing amino acid methionine.
Lafayette Mendel and Morris S. Fine of the Sheffield Laboratory of Physiological Chemistry at Yale University made the observation in the September 1911 edition of the Journal of Biological Chemistry that soybeans produce a positive nitrogen (N) balance in a human subject when they conducted a study to determine the utilization of legume proteins. The treatment called for 5 days of a 2400 calorie diet consisting of meat, eggs, nut butter, potatoes and fruit, followed by 6 days where 90.5% of total nitrogen was supplied by soybeans, and then another 5 days of the first diet, minus the nut butter. They discovered that the soy bean nitrogen is "distinctly (if only slightly) less well utilized than that of the preceding and succeeding mixed diets".
When measuring the nutritional value of protein, the original Protein Efficiency Ratio (PER) method first proposed by Osborne and Mendel in 1917, was the most widely used method until 1990. This method was found to be flawed for the biological evaluation of protein quality, because the young rats used in the study had higher relative requirements for sulfur-containing amino acids than did humans. As such the analytical method that is universally recognized by the FAO/WHO (1990) as well as the FDA, USDA, United Nations University (UNU) and the National Academy of Sciences when judging the quality of protein is Protein Digestibility Corrected Amino Acid Score, as it is viewed as accurately measuring the correct relative nutritional value of animal and vegetable sources of protein in the diet. Based on this method, soy protein is considered to have a similar equivalent in protein quality to animal proteins. Egg white has a score of 1.00, beef 0.92, isolated soy protein 0.92, and soy concentrate 0.99. In 1990 at an FAO/WHO meeting it was decided that proteins having values higher than 1.0 would be rounded or "leveled down" to 1.0 as scores above 1.0 are considered to indicate that the protein contains essential amino acids in excess of the human requirements. The approach of 'capping off' scores at 1.0 as the highest possible rating implies injustice to high-quality proteins which can compensate for low-quality ones by virtue of their high content of essential amino acids. Egg has an actual PDCAA score of 1.19 compared to 0.92 for isolated soy protein, however when leveled down, they appear much closer.
Main Article: Biological Value
Another measure of a protein's use in nutrition is the Biological Value scale. The Biological Value method, which dates back to 1911 relies on nitrogen retention as a measurement of protein quality. Soybean protein isolate has a biological value of 74.
According to the 1972 publication Soybeans: Chemistry and Technology, highly refined isolated soy protein has an average biological value of 71, which contrasts sharply with the biological value of whole soybeans at 96, soybean milk (91), whole eggs (97) and cow's milk (90).
The FDA granted this health claim for soy: "25 grams of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease." One serving, (1 cup or 240 mL) of soy milk, for instance, contains 6 or 7 grams of soy protein.
In January 2006 the American Heart Association published a review (in the journal "Circulation") of several studies of soy protein benefits. The panel found that soy isoflavones do not lessen vasomotor symptoms of menopause, and the efficacy and safety of soy isoflavones for preventing or treating cancer of the breast, endometrium, and prostate are not established. Furthermore, using these and other soy foods to replace foods high in animal protein that contain saturated fat and cholesterol may confer benefits to cardiovascular health. The original paper is in the journal Circulation: January 17, 2006.
A recent study found that 56g of soy protein powder per day caused serum testosterone to fall 4% in four weeks in a test group of twelve healthy males (Please note, there was an error in the abstract that said 19%, and this figure was erroneously reported by the media. If you read the article, you will see that it reports 4% and not 19%. Please see the following Web site for a more complete analysis of this study and the error in its abstract: http://findarticles.com/p/articles/mi_m0KFY/is_9_25/ai_n27410483). According to the study, this data supports further studies of these hormonal effects as a mechanism in prostate cancer prevention. However, a study conducted by the Miami Research Associates refutes the finding of the Goodin study, finding that soy protein had no significant impact on testosterone levels in healthy males. In fact, only one participant in the Goodin study actually saw a drop in testosterone. The participant in question had testosterone levels 200% higher than all of the other subjects, and during the study, his levels dropped to bring him inline with the other participants. The Goodin study did not conclusively prove that the participant's erratic testosterone levels were related to the soy protein.
While TSP has a shelf life of more than a year when stored dry at room temperature, it should be used at once or stored for no more than three days in the refrigerator after rehydration. It is usually rehydrated with cold or hot water, but a bit of vinegar or lemon juice can be added to quicken the process.
TSP can replace ground beef in most recipes, completely or partly. It can also replace up to 33% "tuna" fish in tuna salad. It is high in protein and low in fat and sodium. It is also a good source of fibre and isoflavones.