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Soybean Composition and Nutrients
Soybeans are grown primarily for their protein content, and secondarily for
their oil. But that is only the beginning of the story because processing of
soybeans yields a number of other products as well.
In the main form of processing, or "crushing" as it is often called, the
soybeans are cleaned, cracked, dehulled, and rolled into flakes. This ruptures
the oil cells for efficient extraction. The "crude" oil is removed with solvents
or screw presses, and after further processing the refined soybean oil goes into
such products as margarine, salad dressings, and cooking oils.
After the oil is extracted, the flakes are toasted and ground to produce soybean
meal, most of which is used as a high-protein component of animal feeds.
However, some of it is also processed into products for human consumption. These
include soy flour, soy protein concentrate, and soy protein isolate which can be
incorporated into a wide range of food products. In recent years, we have
learned that isoflavones and other phytochemicals found in the soybean meal
portion have documented health benefits. These are now being extracted and
marketed as nutriceuticals in functional foods.
The soy hulls removed in the initial crushing can be processed into fiber for
use in breads, cereals and snacks. Lecithin, extracted from soybean oil, is used
for everything from pharmaceuticals to protective coatings. It is a natural
emulsifier and lubricant. Lecithin is used, for example, to keep the chocolate
and cocoa butter in a candy bar from separating. Soybean oil is also a natural
source of vitamin E. That portion of the vitamin E that is extracted as part of
the refining process is recovered and marketed with other vitamin supplements.
Nevertheless, refined soybean oil remains a good source of vitamin E.
Essential amino acid composition of selected soybean
ingredients (mg/100g protein)
Amino acid |
Whole bean |
Soy
flour |
Soy concentrate |
Soy
isolate |
Soymilk |
Tofu |
|
|
| Isoleucine |
35 |
46 |
48 |
49 |
46 |
48 |
|
|
| Leucine |
79 |
78 |
79 |
82 |
79 |
83 |
|
|
| Lysine |
62 |
64 |
64 |
64 |
60 |
61 |
|
|
Methionine
& Cystine |
21 |
26 |
28 |
26 |
16 |
14 |
|
|
Phenylalanine
& Tyrosine |
87 |
88 |
89 |
92 |
80 |
83 |
|
|
| Threonine |
41 |
39 |
45 |
38 |
40 |
40 |
|
|
| Tryptohan |
n/a |
14 |
16 |
14 |
n/a |
n/a |
|
|
| Valine |
37 |
46 |
50 |
50 |
48 |
49 |
Fatty acid profile of soybean oil
| Fatty Acid |
|
% Composition |
|
|
| Saturated |
|
|
|
|
| C12 (lauric acid) |
|
tr |
|
|
| C14 (myristic acid) |
|
tr |
|
|
| C16 (palmitic acid) |
|
11.0 |
|
|
| C18 (stearic acid) |
|
4.1 |
|
|
| C20 (arachidic acid) |
|
tr |
|
| Unsaturated |
|
|
|
|
| 16:1 (palmitioleic acid) |
|
tr |
|
|
| 18:1 (oleic acid) |
|
22.0 |
|
|
| 18:2 (linoleic acid) |
|
54.0 |
|
|
| 18:3 (linolenic acid) |
|
7.5 |
| NUTRIENT CONTENTS OF SOYFOOD |
| |
Calories |
Protein |
Fat |
Carbo
hydrate |
crude fiber |
Calcium |
Iron |
Zinc |
Thiamine |
Riboflavin |
Niacin |
Vitamin B4 |
Folacin |
| |
|
(g) |
(g) |
(g) |
(g) |
(mg) |
(mg) |
(mg) |
(mg) |
(mg) |
(mg) |
(mg) |
(mg) |
| Soybeans, boiled, 1/2 cup |
149 |
14.3 |
7.7 |
8.5 |
1.8 |
88 |
4.4 |
1 |
0.1 |
0.3 |
0.3 |
0.2 |
46.2 |
| Soybeans, dry roasted, 1/2 cup |
387 |
34 |
18.6 |
28.1 |
4.6 |
232 |
3.4 |
4.1 |
0.4 |
0.7 |
0.9 |
0.19 |
175.9 |
| Soy flour, full fat, roasted, 1/2 cup |
185 |
14.6 |
9.2 |
14.1 |
0.9 |
79 |
2.4 |
1.5 |
0.2 |
0.4 |
1.4 |
0.15 |
95.5 |
| Soy flour, defatted, 1/2 cup |
165 |
23.5 |
0.3 |
19.2 |
2.1 |
120 |
4.6 |
1.2 |
0.4 |
0.1 |
1.3 |
0.29 |
152.7 |
| Soy protein concentrate, 1 ounce |
93 |
16.3 |
0.13 |
8.7 |
1.1 |
102 |
3 |
1.2 |
0.9 |
0.04 |
0.2 |
0.04 |
95.2 |
| Soy protein isolate, 1 ounce |
95 |
22.6 |
0.95 |
2.1 |
0.07 |
50 |
4 |
1.1 |
0.05 |
0.03 |
0.4 |
N/A |
49.3 |
| Soymilk, 1/2 cup |
165 |
3.3 |
2.3 |
2.2 |
0.92 |
5 |
0.7 |
0.1 |
0.19 |
0.08 |
0.18 |
0.049 |
1.8 |
| Miso, 114 g |
284 |
16.3 |
8.4 |
38.6 |
3.4 |
92 |
3.8 |
4.6 |
0.13 |
0.35 |
1.19 |
0.297 |
45.5 |
| Natto, 1/2 cup |
187 |
15.6 |
9.7 |
12.6 |
1.4 |
191 |
7.6 |
2.67 |
0.14 |
0.17 |
0 |
N/A |
N/A |
| Okara, 1/2 cup |
47 |
2 |
1.1 |
7.7 |
2.5 |
49 |
0.8 |
N/A |
0.01 |
0.01 |
0.06 |
N/A |
N/A |
| Tempeh 114 g |
165 |
15.7 |
6.4 |
14.1 |
2.5 |
77 |
1.9 |
1.5 |
0.1 |
0.09 |
3.8 |
0.25 |
43.2 |
| Tofu, firm, raw, 120 g |
118 |
12.8 |
7.1 |
3.5 |
0.1 |
166 |
8.5 |
1.3 |
0.13 |
0.08 |
0.31 |
0.08 |
23.7 |
| Tofu, regular, raw, 114 g |
88 |
9.4 |
5.6 |
2.2 |
0.83 |
122 |
6.2 |
0.93 |
0.9 |
0.06 |
0.23 |
0.08 |
0.06 |
| N/A - data not listed or unavailable |
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