US 4,054,679 AGranted

Steam injection and flash heat treatment of isoelectric soy slurries

AssigneeThe Griffith Laboratories, Limited

InventorsIrving Melcer, Louis Sair

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Abstract

A process for preparing a soy protein product having a high concentration of both solubilized carbohydrates and soluble protein, and being characterized by substantial freedom from bacterial activity, absence of objectionable beany flavor, light color, suitability for use in food preparations for human consumption, and enhanced palatability, wherein soybean material in the form of an aqueous slurry is first adjusted to an acid pH in the isoelectric range for the protein content of the material treated, or from about pH 3.5 to about pH 5.5, then subjected to steam injection to bring the temperature of the treated mass to the range of from about 225.degree. to about 400.degree. F, maintaining such temperature for a short time period, preferably from about 3 to about 30 seconds, to destroy viable bacteria and to solubilize carbohydrates. Residual steam is flashed, together with volatile constituents including objectionable flavor elements present in the soybean material. Thereafter, the pH of the hot steam-treated material is promptly adjusted upwardly to a value in the range of about pH 6 to about pH 10.5 to deter and to minimize protein denaturation. The end product, consisting of a viscous or semi-viscous dispersible fluid of milky appearance, may then be dried, as by spray drying, to provide a readily redispersible powder.

Claims18

Dependent claims

In the method of treating a soybean material to provide a soy product, said method including the steps of forming an aqueous slurry of soybean material and processing said slurry under controlled conditions of time, temperature and pH to destroy bacteria, to mofify the physical and the chemical properties of the slurry and to improve the flavor properties thereof,

the improvement wherein the processing of said slurry comprises the steps of:
adjusting the pH of an aqueous slurry of soybean material to an isoelectric pH value characteristic of the protein being treated, said value being in the range of from about pH 3.5 to about pH 5.5,
injecting pressurized steam into said slurry to provide a rapid rise in temperature of from about 225.degree. to about 400.degree. F while said slurry is contained in a confining vessel,
maintaining a short dweel time of contact of said slurry with said pressurized steam in said vessel, said time being preferable of from about 3 seconds to about 3 minutes, duration,
and, while the steam-treated slurry is at a temperature of at least 160.degree. F;
promptly elevating the pH of the slurry to a value in the range of from about 6 to about 10.5 to minimize denaturation of proteins contained in the slurry, and
recovering a homogeneous, readily dispersible water miscible fluid product containing both solubilized carbohydrates and soluble protein,
said fluid product being further characterized by absence of bacterial activity, substantial freedom from objectionable beany flavor and ordor, particular suitability for use in food products for human consumption, and enhanced palatability.

5 more elements

Dependencies are inferred from the claim text.