Fat-reduced soybean protein material and soybean emulsion composition, and processes for production thereof
A fat-reduced soybean protein material containing a protein and a carbohydrate at a total content of 80 wt % or more in terms of dried form content, containing a fat (as an extract from a chloroform/methanol mixed solvent) at a content of less than 10 wt % relative to the content of the protein, and containing campesterol and stigmasterol (as plant-derived sterols) at a total content of 200 mg or more relative to 100 g of a fat; and a soybean emulsion composition containing a protein at a content of 25 wt % or more in terms of dried form content, containing a fat at a content of 100 wt % or more in terms of dried form content relative to the content of the protein in terms of dried form content, and having an LCI value of 60% or more.
1. A process for producing a soybean emulsion composition, which comprises the steps of:
(1) adding water to
a modified fat-containing soybean, which comprises, as a raw material, a fat at a content of 15 wt % or more (as an extract with a chloroform/methanol mixed solvent) in terms of dry basis and having a Nitrogen Solubility Index (NSI) value in a range of from 20 to 65, wherein “modified” means that protein in the fat-containing soybean is denatured to 20 to 65 of NSI,
to prepare a suspension liquid;
(2) subjecting the suspension liquid of the modified fat-containing soybean to a solid-liquid separation to transfer a neutral lipid, a polar lipid and a protein comprising lipophilic protein as a major component to an insoluble fraction comprising fiber,
removing a soluble fraction comprising sugar and a protein comprising glycinin and β-conglycinin as major components, and
then recovering the insoluble fraction;
(3) homogenizing the recovered insoluble fraction; and
(4) subjecting the homogenized insoluble fraction to a solid-liquid separation to remove the fiber, and then recovering a supernatant to obtain the soybean emulsion composition,
wherein the NSI value is determined by the following procedure:
(a) adding 100 ml of water to 2.0 g of a sample to obtain a first mixture,
(b) stirring the first mixture at 40° C. for 60 minutes, and then subjecting the first mixture to centrifugation at 1400×g for 10 minutes to obtain a supernatant 1,
(c) adding 100 ml of water to a residual precipitate to obtain a second mixture,
(d) stirring the second mixture obtained in step (c) at 40° C. for 60 minutes, and then subjecting the second mixture to centrifugation at 1400×g for 10 minutes to obtain a supernatant 2,
(e) combining supernatant 1 and supernatant 2, and adding water to 250 ml to obtain a third mixture,
(f) filtering the third mixture with No. 5A filter paper to obtain a filtrate,
(g) determining a nitrogen content in the filtrate by the Kjeldahl method,
(h) determining a nitrogen content in the sample by the Kjeldahl method, and
(i) calculating the NSI value as wt % by dividing the nitrogen content in the filtrate by the nitrogen content in the sample.
2. The process according to claim 1 , wherein the NSI value of the modified fat-containing soybean is 20 or more and less than 60, wherein “modified” means that protein in the fat-containing soybean is denatured to 20 to 60 of NSI.
3. A process for producing a soybean emulsion composition comprising the steps of:
(1) adding water to
a modified fat-containing soybean, which comprises, as a raw material, a fat at a content of 15 wt % or more (as an extract with a chloroform/methanol mixed solvent) in terms of dry basis and having a Nitrogen Solubility Index (NSI) value in a range of from 20 to 65, wherein “modified” means that protein in the fat-containing soybean is denatured to 20 to 65 of NSI,
to prepare a suspension liquid;
(2) subjecting the suspension liquid of the modified fat-containing soybean to a solid-liquid separation to transfer a neutral lipid, a polar lipid and a protein comprising a lipophilic protein as a major component to an insoluble fraction comprising fiber,
removing a soluble fraction comprising sugar and a protein comprising glycinin and β-conglycinin as major components, and
then recovering the insoluble fraction;
(3) homogenizing the recovered insoluble fraction; and
(4) subjecting the homogenized insoluble fraction to a solid-liquid separation to remove the fiber, and then recovering a supernatant,
to obtain the soybean emulsion composition, which comprises a protein at a content of 25 to 50 wt % in terms of dry basis, and a fat at a content of 100 wt % or more (as an extract with a chloroform/methanol mixed solvent) relative to the protein content, wherein the soybean emulsion composition has a Lipophilic Proteins Content Index (LCI) value of 60% or more,
wherein the NSI value is determined by the following procedure:
(a) adding 100 ml of water to 2.0 g of a sample to obtain a first mixture,
(b) stirring the first mixture at 40° C. for 60 minutes, and then subjecting the first mixture to centrifugation at 1400×g for 10 minutes to obtain a supernatant 1,
(c) adding 100 ml of water to a residual precipitate to obtain a second mixture,
(d) stirring the second mixture obtained in step (c) at 40° C. for 60 minutes, and then subjecting the second mixture to centrifugation at 1400×g for 10 minutes to obtain a supernatant 2,
(e) combining supernatant 1 and supernatant 2, and adding water to 250 ml to obtain a third mixture,
(f) filtering the third mixture with No. 5A filter paper to obtain a filtrate,
(g) determining a nitrogen content in the filtrate by the Kjeldahl method,
(h) determining a nitrogen content in the sample by the Kjeldahl method, and
(i) calculating the NSI value as wt % by dividing the nitrogen content in the filtrate by the nitrogen content in the sample.
4. The process according to claim 3 , wherein the NSI value of the modified fat-containing soybean is 20 or more and less than 60, wherein “modified” means that protein in the fat-containing soybean is denatured to 20 to 60 of NSI.