Soybean: The Future Food Protein Source for Humans. Srinivasan Damodaran Department of Food Science University of Wisconsin-Madison

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1 Soybean: The Future Food Protein Source for Humans Srinivasan Damodaran Department of Food Science University of Wisconsin-Madison

2 The Issue World Population: > 7 billion and growing. Expected to reach 10 billion by 2050 Do we have enough food proteins to feed the population?

3 Global Soybean Production ( ) Country Current (2012/13) World MMT (251 MMT in 2011/2012) Brazil 83.5 USA 82.1 Argentina 53.0 (48 MMT in 2011/12) China 12.6 India 11.5 Almost all of soymeal produced worldwide is used as cattle feed. The efficiency of conversion of plant proteins to animal protein is 8:1 (i.e., ~ 12%).

4 Nutritional Value of Soy Protein Protein source Egg Cow s milk Beef Fish Wheat Rice Maize Barley Soybean Pea Peanut Chemical Score(%) Based on FAO/WHO amino acid pattern, 1985

5 Two major Issues limiting expanded use of soy protein isolate in foods: 1. The first one is its beany, grassy, cardboardy offflavor. Two-thirds of the world population is averse to this beany off-flavor. The source of these off-flavors is residual phospholipids in SPI.

6 Source of Phospholipids: Soybean Oil bodies

7 Formation of Off-Flavors Phospholipid R Hydroperoxide R O 2 o H Decomposition Pentyl Pyridine, Hexanal, and other carbonyl compounds.

8 2. Phyto-estrogens Prevent breast and prostate cancer Reduce the risk of coronary artery disease Improve bone health Lingering Question: Do they reduce the testosterone level in men?

9 We need to develop a single technology that can solve both these issues

10 Beta-Cyclodextrin (bcd) 6.5Å =O 8Å Structure of bcd Toroidal view of bcd Challa et al., 2005

11 Salient Features of the New Technology Soy Protein-bound Phospholipid Phospholipase A2 LPL FFA b-cyclodextrin ph 4.5 Supernatant Precipitate (Protein)

12 Phospholipid content of SPI (%) Removal of Phospholipids by PLA2/b-Cyclodextrin Treatment 2,0 1,8 1,6 1,4 1,2 1,0 0,8 0,6 0,4 0,2 0,0

13 Phospholipid content of SPI (%) % Reduction of PL Relative effects of a, b, and g-cyclodextrins on Phospholipid removal 2,0 1,8 1,6 1,4 1,2 1,0 0, U PLA2, 8 mm CD, ph8 0,6 0,4 0,2 0, Cavity diameter of cyclodextrin (Å)

14 Headspace Volatiles after Accelerated Storage at 40 o C for 90 days Compound Control (ppb) Fresh Samples Treated (ppb) 90 Day Storage Control (ppb) Odor Threshold 1 Flavor Threshold 1 Treated (ppb) ppb ppb Hexane Pentanal Methyl Butanal Ethyl Furan Dimethyl Disulfide Pentanol Hexanal (E)- 2-Nonenal Hexanol Heptanone Heptanal Ethyl Hexanal Heptanol octen-3-ol Hepten-2-one, 6- methyl Pentyl Furan Octanal Hepten-2-one, 5- methyl Octen-2-one Octenal, (E) ethyl-3,5-dimethyl- Pyrazine nonanone Nonanal Decanone Decanal butyl- 2-Octenal

15 Concentration (mg/100 g SPI) Removal of Phytoestrogens (Isoflavones) Control Treated Diadzin Genistin Diadzein Genistein

16 The Process 8% Soy Protein solution (ph 8.0) Add PLA2; incubate for 3 h at 37 o C Lyso-phospholipids, FFA, Isoflavones Add 10 mm bcd and mix the solution for min. bcd Ethanol extract Diafilter the solution using a 10K ultrafiltration membrane in a continuous diafiltration mode to remove bcd and bcd-pl complex OR Adjust the ph to 4.5. Centrifuge to recover the protein precipitate. Wash the precipitate with water at ph 4.5. Re-dissolve the protein in water at ph 8.0 Extract with ethanol Recrystallize bcd Spray dry Supernatant

17 Non-food Uses of Soy Flour.. Soy flour biomass can be used as a feedstock for fabricating several industrial polymers: Examples: Hydrogels Soy flour-based wood adhesive

18 Non-food Uses of Soy Flour.. Rationale Issues Soy Flour-based Wood Adhesive The use of Urea-formaldehyde adhesive in interior-used plywood and other wood products is being phased out in the US. There is a need to develop safe and environmentally friendly wood adhesives using renewable biomass. Soy Flour-based wood adhesives have very poor wet bonding properties when used in wood composites.

19 Our Approach. H 2 N OH Proteins and polysaccharides + POCl 3 O HO - P - OH HN O O P - OH OH High pressure (1.2 MPa) and temperature (150 o C) O O P O OH O O - P - OH HN Plywood panels

20 Wet bonding strength (MPa) Wet Bonding Strength of Phosphorylated Soy Flour Adhesive in Wood veneers 3,5 3,0 2,5 120 C 140 C 2,0 1,5 1,0 0,5 0,0 SF PSF PSF + 0.8% NaClO2 PSF + 1.8% Ca(NO2)2

21 Three Cycle Soak Test: Soak the specimen in water at 25 o C for 4 h and then dry at 50 o C for 19 h. Repeat the cycle three times. Adhesive Number of specimens failed in the three-cycle soak test 1 st Cycle 2 nd Cycle 3 rd Cycle SF 7/7 7/7 7/7 PSF + 1.8% Ca(NO 2 ) 2 0/7 0/7 1/7

22 Water Resistance of PSF Adhesive in plywood Samples in the three-cycle soak test

23 Summary Soy Flour has great potential for use in both food and nonfood applications: Off-flavors in SPI can be minimized using the cyclodextrin technology. Phytoestrogens can be removed from SPI using the cyclodextrin technology. Phosphorylated soy flour has great potential as an environmentally safe wood adhesive.

24 Acknowledgement: This research was funded by grants from USDA-National Institute of Food and Agriculture Agriculture and Food Research Initiative AND USDA Forest Service

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27 bcd-pl complex Oleosin-PL Complex Sterically not favored LAL Oleosin-PL Complex PLA 2 FA

28 Oil Body mm N-Terminal C-Terminal 11 nm Hydrophobic Domain Proline Knot Oleosin Phospholipid Phospholipid Triglycerides Oleosin 11nm

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31 Functional Roles of Proteins in Foods Solubility Emulsification Foaming Gelation Texturization Fat and Flavor Binding