Soy protein copy

HEALTH IMPACTS OF SOY PROTEIN- and its comparison with milk protein

DEVANG N. SHAH (12BBT0006) 1

HEALTH IMPACTS OF SOY PROTEIN

(TOFU)

AND IT’S COMPARISON WITH MILK PROTEIN (PANEER)

Presented by-

Devang N. Shah

(12BBT0006)



Acknowledgements

In the making of this project I would like to acknowledge Professor C. Shanthi for her guidance and

encouragement this project. I would also like to express my heartfelt gratitude towards my school

teacher, Ms. Vidhi Parmar who helped me choose this topic and encouraged me at every step. I would also like to thank VIT University for providing me facilities

that helped me complete this project without any hindrance.



ABSTRACT

Soy protein products such as flour and Tofu are used as food materials because of their functionality, nutritional value and low cost. The project investigates on major soy proteins present in Glycine max (soya bean) which are found to be glycinin and β-conglycinin. The project also provides an insight into some of the biochemical properties of these globular proteins which lead to anti nutritional activities and proper manipulation of which lead to desirable functional properties of soya protein. Soybean glycinin was also found to improve HDL-C (high density lipo-protein) and suppresses the effects of rosuvastatin on hypercholesterolemic rats. Finally the project compares milk protein-α-lactalbumin (found in paneer) and soy protein (found in tofu) in terms of their protein content and ease in digestion.

KEYWORDS: Soy protein, Tofu, Glycinin and β-conglycinin, HDL-C, α-Lactalbumin



SCOPE OF THE PROJECT

The reason why I chose this project is due to increasing demand of soy products now a days. Soy Proteins are commercially cheap as they are taken from a plant source which is abundantly available. They have more nutritional value from normal milk protein and contain lesser amount of saccharides. They are recommended for growing children and marathon runners for this reason.

I started off this project with simple comparison between tofu and paneer but as I went on with my research I found that soy protein has many other benefits and can be commercially exploited by simple alterations in their biochemical structure also according to a study they were found to improve HDL- C in our body. However normal milk protein can be more easily digested that is the reason why tofu is not recommended for old people and people with weak digestive system.



Soy Proteins:

Glycinin β-conglycinin

The ribbon diagram of native β-conglycinin.The view

in A is depicted as threefold symmetry axis runs perpendicular to the paper and the view depicted in B is related to the view

in A by rotation of 90°(15)

The principal storage proteins are glycinin (11S) and β-conglycinin (7S) and constitute over 70 % of soluble protein . Their content, ratio

and dynamics of biosynthesis vary with soybean varieties and environment . Glycinin (m.w ∼360 kDa) is a protein with compact

quaternary structure stabilized via disulfide, electrostatic and hydrophobic interactions. It is made up of six A-SS-B subunits. Each

subunit is composed of an acid (m.w.∼38 kDa) and basic polypeptide (mw∼20 kDa) linked by single disulfide bond, except for the acid

polypeptide -A4- . Subunits are packed into two hexagons placed one over the other to form a hollow oblate cylinder . Basic polypeptides

are placed in the interior of the glycinin molecule.

β- Conglycinin is a major protein of 7S fraction with molecular weight of 150 -180 kDA. It is composed of three subunits, -α`-, -α-

and -β- which interact to produce seven isomers . Molecular weight of these subunits is 72kDa, 68 kDa and 52 kDa, respectively. The

original β-conglycinin is a glycoprotein and it contains the carbohydrates as one unit attached to the aspartic acid residue at

the N-terminal end of the molecule.



Milk Protein

(α-lactalbumin)

α-Lactalbumin is an important whey protein in cow's milk (~1 g/l), and is also present in the milk of many

other mammalian species. α-Lactalbumin forms the regulatory subunit of the lactose synthase (LS) heterodimer and β-1,4-

galactosyltransferase (beta4Gal-T1) forms the catalytic component. Together, these proteins enable LS to produce lactose by transferring galactose moieties to glucose. As a multimer, alpha-lactalbumin strongly binds calcium and zinc ions and may possess bactericidal or antitumor activity. LA

consists of 123 amino acid residues forming a compact globular structure stabilized by four disulfide bonds (Cys6–Cys120, Cys61–Cys77, Cy73–Cys91, and Cys28–Cys111). LA is a

globular, calcium metalloprotein with an isoelectric point of 4.6, a molecular mass of 14 200 Da and has no free thiol groups



Anti-nutritional activities of Soy protein and their minor modification which can make them

commercially important

INHIBITORY ACTIVITY

Inhibitor activity of soybeans is result of two proteins, Kunitz (KTI) and Bowman-Birk (BBI) trypsin inhibitors. Trypsin inhibitors in raw soybeans cause growth inhibition, pancreatic hypertrophy and hyperplasia in experimental animals . Depending on cultivar soybeans have not more than three Kunitz isoinhibitors and 5-12 Bowman –Birk inhibitors . Kunitz inhibitor consists of 181 amino acid residues with two disulfide bridges; one of these bridges being essential for inhibitor activity. BBI is a low-molecular weight protein (7-8 kDa) consisting of 70-80 amino acid residues with seven disulfide bridges. BBI is a rich source of amino acid residues with sulfur; these amino acids represent 18-20% of all residues. Although both types of inhibitors represent 8-10 % of total soybean proteins they are responsible for 40 % of adverse effect of raw soybean consumption.

Simple thermal treatment is the solution!!!

Thermal treatments reduce protease inhibitor activity, eliminate lipoxygenase and volatile compounds that induce undesirable flavor, improve specific functional properties. Also, heating increases digestibility of soy proteins. The effects of heating on pure glycinin and β–conglycinin solutions, their mixtures and soy flour extracts are well known. Heating soy proteins above 70°C causes dissociation of their quaternary structures, denatures their subunits, and promotes



the formation of protein aggregates via electrostatic, hydrophobic and disulfide interchange mechanisms. Heating breaks the disulphide bonds and makes the trypsins inactive.

Chemical inactivation of protease inhibitors

Kunitz and Bowman-Birk inhibitors of soybean can be inactivated by chemical treatments. These inhibitors can be inactivated by cleavage of two disulfide bridges in Kunitz and four of the seven disulfide bonds in Bowman-Birk inhibitors. Sulfiting agents, such as sodium metabisulfite (0.05M-1.00 M) at increased temperature (75°C) reduced TI activity to 75-94% within 1 hour, while in combination with glutaraldehyde under same conditions inactivated up to 99% inhibitors. Sodium metabisulfite cleave disulfide bonds and destroy TI activity. Glutaraldehyde, a protein cross-linking reagent interacts with reactive groups of active site of inhibitors and inactivates them. l-cysteine and N-acetyl-l-cysteine in conjunction with increased temperature are used to inactivate inhibitors and to increase nutritive value of soybean flour. Inhibitor activity may be reduced by amino-carbonyl interactions between glucose and arginyl or lysine residues near reactive center of inhibitor.



PHYTIC ACID CONCENTRATION

For a long time, phytic acid (PA) has been considered as an antinutrient. At high concentrations it can reduce the bioavailability of minerals. Further, phytic acid interacts with proteins and decreases their digestibility. In opposite, today it is well known that low concentration of PA has some beneficial effects; these include controlling dental caries; improving oxygen-providing ability of red blood cells; cancer preventing activity.

Small change…..

The degree of interaction of phytic acid and proteins is affected by the protein charge, conformation and ionic strength of the solution at a given pH. Changes in these parameters decrease these interactions. Methods involved are the decrease of pH of mother liquor solution to 2.5-4.0 in the presence of Ca2+- or Mg 2+ ions and ultrafiltration, or the increase of pH to 7.0-11.0 in the presence of EDTA.



Soybean glycinin improves HDL-C and suppresses the effects of rosuvastatin on

hypercholesterolemic rats

Soy protein are known to reduce plasma lipids (cholesterol, LDL-C, TG), in the context of growing concern about hyperlipidemia and hypercholesterolemia and their consequences. The quantity of

favorable experimental evidence, supported by epidemiological and clinical studies, resulted in the approval of a health claim by the FDA in 1999, which suggested the inclusion of 25 grams of soy protein in the daily diet to reduce cardiovascular disease. Studies with isolated soy protein in hypercholesterolemic rats indicate that, in addition to lowering serum cholesterol, it decreases serum triglycerides levels.

Soy protein can modulate the levels of hepatic LDL-C receptors, suppressed in hypercholesterolemia.

In order to collect evidence on this complex mechanism, we investigated the effects of ingesting a daily dose of isolated glycinin soy protein (11S protein), alone or combined with rosuvastatin (a

statin drug), on the control of hypercholesterolemia in experimental animals.



Comparison of Soy Protein (Tofu) with Milk Protein (Paneer)

Advantages of Tofu over Paneer.

Tofu comes from plants (commercially cheaper) whereas Paneer comes from animal source.

Tofu has NO cholesterol, while Paneer contains cholesterol.

Tofu is good for vegetarians and those who are lactose intolerant.

Tofu is gluten-free.

Tofu can have lots of fiber, depending on how they are processed.

It contains high glutamine levels that increase muscle volume and growth hormone levels. Increased glutamine levels can naturally help us lose weight while maintaining muscle mass.

It has higher arginine levels that can help increase blood flow. During intensive exercise, arginine actively releases hormones and insulin, which helps deliver nutrients more efficiently to the muscles.

It contains many essential amino acids, which help increase muscle mass.

It may reduce the risk of breast and prostate cancers. Essential fatty acids and isoflavones can help to reduce the chance of having high cholesterol and heart disease.



Disadvantages of Tofu over Paneer.

Soy’s Biological Value (BV) is lower than that of whey. This means that our body may not be as efficient when digesting proteins and transferring them to the blood stream.

Here are the Biological Value (BV) numbers: isolated soy protein 0.92, soymilk 0.91, soybeans 0.96, and soy concentrate 0.99. The biological value of beef is 0.92 or less.

The digestibility of soy products are as follows: tofu 92.7%, soymilk 92.6%, boiled soybeans 65.3%, and isolated soy protein 93–97%.

The bioavailability and digestibility of soy protein is lower than that of milk protein (whey).

In addition, some infants and people do have allergic reactions to soymilk and soy products. Certain people also experience side effects from abusing soy products, such as soymilk.



Advantages of Paneer over Tofu.

Whey protein (BV=100+). It has a high Biological Value (BV), higher than egg whites (100) or soy.

Milk protein contains greater amounts of essential amino acids than soy does. These amino acids must be INGESTED to promote muscle growth and improve your body’s performance.

It has more protein that is more easily digested and absorbed by the body.

It helps to maintain a lean body mass.

It is a rich source of branched chain amino acids (BCAAs) that are directly transported to the muscle tissue to repair or build a certain muscle.

It contains 50% more leucine than isolated soy protein. Leucine helps promote muscle protein synthesis and preserves lean muscle.

It helps athletes perform closer to their optimum level by increasing the levels of glutathione, which boosts the immune system.

It controls the appetite by stabilizing blood glucose levels in the bloodstream. This is accomplished by the release of two appetite-suppressing hormones: cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1).



Disadvantages of Milk Protein over Soy protein

According to the comparison, SOY vs. Milk Protein, Milk Protein usually contains added sugar, which is included to make it taste better. So if we are looking for a lean diet that will help us increase muscle without gaining unnecessary weight from fat, whey may not be our best option.

Whey also may lead to gas or bloating if we have lactose intolerance or a weak stomach. If we don’t have enough enzymes to digest the lactose that whey contains, gas is a by-product that can result from this lack of enzymes. This gas will lead to constipation. Whey also doesn’t contain any fiber, which can also lead to constipation. Additionally, whey contains some gluten.

CONCLUSION

Hence, in the above project various aspects of Soy protein (Glycinin and Conglycinin) were explored. They have a few antinutritional

activities but simple manipulation of them and make them nutritional as well as commercially important. Also they are able to reduce cardiovascular diseases. Soy protein was then compared to normal milk protein and was found that if we want to have muscles

with a lean body soy protein is the best option. However Milk protein has its own benefits because it is more easily digested as compared

to soy protein.



References:

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Murphy, P. A.and Resurreccion: Varietal and Environmental Differences in Soybean

Glycinin and β-conglycinin Content, J. Agric. Food Chem. 32 (1984) 911-920.

6. Pernollet, J.C.: Biosynthesis and Accumulation of Storage Proteins in Seeds, Physiolog.veg. 23 (1985),45-59

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Structure, Physical and Chemical Properties of the Soybean Protein Glycinin, Biochem. Biophys. Acta 412 (1975) 214-228.

2. Marcone M.F., Kakuda, Y. and R.Y.Yada: Immunochemical Examination of the Surface Physico-Chemical Properties of Various Dicotyledonous and Monocotyledonous Globulin Seed Storage Proteins, Food Chem. 63 (1998) 85-95.

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2003. Gelation of soy glycinin; influence of pH and ionic strength on network

structure in relation to protein conformation. Food Hydrocolloids 17(3):365–77.

Lefèvre T, Subirade M. 2000. Molecular differences in the formation and structure of fine-stranded and particulate -lactoglobulin gels. Biopolymers54:578–86.

Carroll KK, Kurowska EM. Soy consumption and cholesterol reduction: review of animal and human studies. J Nutr. 1995;125:594S–597S.

Food and Drug Administration. Food labeling: health claims: soy protein and coronary heart disease. HHS: final rule. Fed Regist. 1999;64(206):57700–57733.

Ferreira ES, Silva MA, Demonte A, Neves VA. β-Conglycinin (7S) and glycinin (11S) exert a hypocholesterolemic effect comparable to that of fenofibrate in rats fed a high-cholesterol diet. J Functional Foods. 2010;2:275–28. doi: 10.1016/j.jff.2010.11.001.

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