Removal of phytate from soy protein

Abstract

Phytate, as a minor constituent of soybeans, has been reported to interfere with the dietary mineral absorption of mammals. Commercial soy protein isolate contains 2–3% tightly bound phytate. Practifrom soy protein materials. However, in this reported process, the phytate content was reduced to extremely low levels using commercially feasible processing techniques. The first step of this process was the extraction of water soluble components from soy flakes using routine commercial procedures. In the second step, the extract was adjusted to pH 11.6 at 28 C to insolubilize the phytate. The phytate was removed by centrifugation or vacuum filtration. Neutralization followed the phytate removal. The temperature and pH are critical for phytate removal but also must be carefully controlled to prevent protein degradation. Lysinoalanine was not detected nor was cysteine or other amino acids found to be degraded. The third step of this process was purification of the protein. In this case, the low phytate soy extract was purified by Ultrafiltration until permeate equivalent to 1/2 times the volume of the extract was collected. The phytate and phosphorus contents of the resulting soy protein isolate were 0.1 and 0.2%, respectively, compared to 2.6 and 0.8 for typical commercial soy protein isolate. The PER was significantly better than an acid isolate prepared from the same soy flakes or the commercial soy isolate tested. The retenate obtained after purification by Ultrafiltration was a translucent liquid with a protein content of 5–6%. This protein was in a very soluble form and was stable to heat.

Properties of spray‐dried and freeze‐dried faba bean protein concentrates

“…They also reported that these two steps, soaking and dehulling, decreased the levels of phytates by 4%. However, the more substantial decrease of tannins and phytates in these concentrates can be attributed to the alkaline treatment during the process of protein concentrate preparation (Hartman, 1979).…”

Change of the apparent digestibility of nutrients and phosphorus as a function of phosphorus source and phytase supplementation in pigs

“…Similarly, no significant changes were found in the apparent digestibility of other nutrients following phytase supplementation. Hartman (1979) stated several decades ago that 2-3% of soyabean protein forms a very stable complex with phytate. The binding form of this complex determines the extent to which the digestibility of protein can be increased by enzyme supplementation.…”

A simple and rapid procedure for phytate determination in soybeans and soy products

“…Phytic acid is also known to have a strong affinity for zinc, iron, and trace minerals in foods and feeds. Its association with storage proteins results in relatively high concentrations of phytic acid in commercial soy protein products, such as soy meal, that are mainly used for swine and poultry feeds (1,2,5). The presence of phytic acid has a definite effect on the economic value and nutritional quality of the animal feeds.…”

“…Phytic acid, myo-inositol hexaphosphate, is the principal storage form of phosphorus in soybeans (1) and is known to associate with the β-conglycinin (7S) fraction of the storage proteins (2)(3)(4). Phytic acid is also known to have a strong affinity for zinc, iron, and trace minerals in foods and feeds.…”