Uken Sukaeni Sanusi Soetrisno. Characterization of yellow pea (Pisum sativum L. Miranda). Proteins and the Proteinate Functional Properties. Oregon State University, Corvallis, OR USA M.S. Thesis.
Nutrition Research and Development Centre
Bogor 16112, Indonesia
ZoeAnn Holmes*
Department of Nutrition and Food Management
Oregon State University, Corvallis, OR 97331-5103
Acid proteinate (AP), magnesium proteinate (MAP), and calcium proteinate (CAP) extracted from yellow pea flour at different pH (P) and temperature, oC (T) levels were evaluated for functional properties. Nitrogen solubility index of AP is the highest (8.9 at pH5.0 to 100% at pH10.0-12.0), followed by MAP (3.4 at pH5.0 to 97.3% at pH 12.0) and CAP (3.5 at pH6.0 to 88.7% at pH 12.0). Maximum fat adsorption of AP, MAP, and CAP were 534.2% (T=30.3C, p=8.9), 522% (T=18.3C, P=10.0), and 510% (T=13.9C, P=10.3), respectively; with T being significant variable for AP and CAP, or T and P for MAP. Least gelation concentration (LGC) measurement for AP and MAP or CAP were 18% and 15%, respectively; with significant effect of P and T for AP. Emulsion capacity of AP, MAP and CAP were 62, 66, and 58 mL/g proteinate, respectively, with AP having the most stable emulsion.
INTRODUCTION
The composition of seed protein extracts such as nitrogen content, amino acid compositions and their conformation, will very much affect the functional properties of the protein (Elizalde et al., 2992; Kinsella, 1979; Okezie and Bello, 1988). These tests have also been used to assist in predicting the protein usefulness in food products, such as soy protein added to beef patties gave better yield and nutrient retention (Rice et al., 1989), or used in rice flour extrusion which gave better protein solubility of texturized products (Noguchi, et al., 1981). Extracted protein and solid in soymilk had been reported to affect yield and texture of tofu (Shen et al., 1991).
Since plant protein not only provides nutritional quality, but also provides desirable characteristics, there is a strong need to know and evaluate both qualities, so that it can be used effectively in the food product development. Some of the many other important criteria to develop viable texturized protein products are the protein should have optimum fat adsorption, emulsification properties, gelation, water absorption and binding (Kinsella, 1979).
Characteristics of protein extracted from yellow pea flour at different pH (P) and temperature (T) regimes have been reported (Soetrisno and Holmes, 1991). There were similar nitrogen content, amino acid composition, and MW patterns among the three proteinates.
This study evaluated isolates extracted at 13 temperature-pH combinations for their nitrogen solubility, least gelation concentration (LGC), fat adsorption (FA), emulsion capacity (EC) and stability (ES). A small run was done to produce protein extrusion products from CAP as the strongest gel former. MATERIALS AND METHODS
Coagulated proteinate by acid (AP), magnesium (MAP), and calcium (CAP) salts from yellow peas (Pisum sativum L. Miranda) flour was prepared (Soetrisno and Holmes, 1991), based on Central Composite Rotatable Design with temperature [C](T) and pH (P) as independent variables. Soybean oil (100%) was used for the measurement of fat absorption (FA), emulsion capacity (EC) and emulsion stability (ES) of the proteinate.
Methods.
Nitrogen Solubility. Nitrogen solubility index (NSI) of 1% (w/v) proteinate solution in the range of pH 2.0-12.0 was determined based on the method of Thompson (1977), by measuring the nitrogen content (micro Kjeldahl, AOAC 1990) in the filtrate after centrifugation compared to that in total solution.
center>
|
% NSI= mg N/mL filtrate X 100 |
Least gelation concentration (LGC). All samples from 13 different extractions (Soetrisno and Holmes, 1991) were tested for LGC. The modified method of Tjahjadi et al (1988) was used. In the previous trial, protein concentrations used were 20, 18,16, and 14% for AP, and 15, 13, 11, and 9% for MAP or CAP. The LGC was determined as the lowest concentration of the proteinate that did not fall down or run when test tube was inverted.
Fat adsorption (FA). All samples were tested for their FA values using method of Tjahjadi et al (1988). Each sample was weighed 0.5 g and put into known weight of centrifuge tube. Add 3 mL oil while stirring on the vortex mixer (speed 4 of 1-10, VWR, Scientific Industries, Inc. Bohemia, NY), for 1 min. Let stand for 30 min (25 + 2C), centrifuged at 3000rpm for 25 min (IEC-International Centrifuge, International Equipment Co., Needham, Mass.). Removed the separated oil then inverted tube for 25 min (25 + 2C) to drain unbound oil. Weigh the tube containing oiled sample, and corrected the weight for tube weight. Calculate the FA as:
|
% FA=(reweighed sample - initial weight) X 100
|
EC= Vol. oil emulsified
Extrusion trial. CAP sample (pH=9.0, T=25C) was selected. Six gram proteinate was blended with 40 mL 1% NaCL for 30 sec (VirTis homogenizer, speed 30), continued with addition of 4 mL oil (1% addition) within 1 min. The blended sample in VirTis flask and simmered in the water bath (80oC) for 30 min. Transferred cooked sample into potato ricer and pressed out and dried the product for 6 hrs (95oC). The product was informally evaluated by laboratory personnel.
Statistical design and analysis. A two factor Central Composite Rotatable Design (CCRD) (Cochran and Cox, 1957) was employed to determine the effect of P and T combinations during protein extraction, and characteristic measurements, as described in Soetrisno and Holmes (1991). Temperature (T) and pH (P) were independent (X) variables, and the results obtained from LGC and FA measurements were dependent (Y) variables. Statistical Analysis System (SAS Institute Inc., Cary, NC.) and Statgraphics (Statistical Graphic Co., Rockville, Md.) programs were used to generate ANOVA, parameter estimates, response surface analysis (RSA), canonical analysis, and ridge maximum and minimum of the responses. Differences were considered statistically significant at P<0.1. the following model of quadratic polynomial regression was assumed for evaluating the individual y-variables;
Y=A + B1*T +B2*P+ B11*T*T + B22*P*P + B12*T*P
Emulsion capacity and stability data were presented as multiplot regression (Statgraphics program), since the data collection only from the extreme treatments. All measurements were done in duplicate.
RESULTS AND DISCUSSION
Nitrogen solubility. The solubility of a product can be dependent on the coagulant used to obtain it. However, there was no significant effect of T-P combination treatments during extraction on the NSI of AP or MAP (Table 4-1, 2), compared to that of CAP (Table 4-3). >a href="http://food.oregonstate.edu/images/uken/fig4-1.jpg">Figures 4-1A, B, C, show the examples of their NSI profiles. NSIs of AP and MAP proteinate were significantly affected by the treatments during extraction. Acid coagulation caused higher NSI of proteinate compare to Mg or Ca coagulation, which were 8.9 at pH 5.0 to 100% at pH 12.0 compared to 3.4 at pH 5.0 to 97.3% at pH 12.0 or were 3.5 at pH 5.0 to 88.7% at pH 12,0, respectively. Similar result had been reported (Hsu et al., 1982; Voutsinas et al., 1983) on NSI of yellow pea protein isolate, with the lowest NSI at pH 4.0-6.0; but higher than the NSI reported by Sumner et al. (1981) on pea protein isolate from a similar preparation.
In the case of AP, NSIs at pH7, 8, and 11 were high when the treatment during extraction was done at combinations of low T-low P, high T-high P, or high T-low P. NSI at pH 2 was high at low T-low P or high T-high P treatment only.
MAP had significantly higher NSIs at pH 2 and 3, when extraction was done at low pH-all T combination treatments. The minim solubility at pH 6 was increased when the extraction was done at higher pH-all level T combination treatments. CAP had a wider pH range of minimum solubility than yellow pea flour, and it was not affected by either factor during extraction.
However, the practical significance of this may be limited. For example, the 100% solubility for acid-coagulated proteinate was at a pH 10 to 12. Rarely are foods at this pH. In the range of pH 5-7, the acid (Figure 4-1A), magnesium (Figure 4-1B), and calcium (Figure 4-1C) proteinates had a NSI of 8.9-81.3%, 3.4-17.2%, and 3.5-9.2%, respectively. The lower NSI for MAP and CAP were probably due to salting-out-denaturation during protein coagulation.
Least gelation concentration. There were very distinct differences between LGC of AP, MAP, and CAP. Table 4-4 data showed the regression coefficients were zero for CAP. The MAP and CAP could form a strong gel at all concentrations tested, only the amount of water held within the matrix gel made the difference. Almost all MAP and CAP from all extraction treatments had 15% LGC, in which all water was held within the gel system, except MAP extracted at T=15C, P=8.0 which had 13% LGC. Both RSA of MAP and CAP showed flat surfaces (not shown in figure), due to no effect on LGC value of P or T during extraction, probably due to the same concentration of divalent-ions in all proteinates which played the chief role in water imbibing activity.
LGC of acid-proteinate was significantly (P<0.001) affected by the p and t levels during protein extraction. it was 18.0% (t=22.7c, p=9.6) (Table 4-4, Figure 4-2) as the least concentration to form a gel. Low P-high T, and high P-low T combinations gavbe higher LGC values.
Fat adsorption (FA). Acid proteinate gave maximum FA=534.2% (P=8.9, T=30.3C), which is more than twice the value previously reported (Sumner et al., 1981). There was a significant (P<0.01) effect of t level during extraction on the FA ((Table 4-4). The lower T had significantly lowered adsorption ability. The FAs were 522% (T=18.3C, P=10.0) and 510% (T=13.9C, P=10.3), for MAP and CAP, respectively, with significant (P<0.10) effects of t and p for map and of t only for CAP (A href="http://food.oregonstate.edu/images/uken/table4-4.jpg">(Table 4-4). Extreme combinations, low P-low T and high P-high T combination caused decreases FA for CAP. These high FA values were probably due to denaturation of protein during extraction and/or salt coagulation, which brings about the exposure of lipophilic or hydrophobic residues; resulting in increased lipid-protein complexes (Kinsella, 1979).
Emulsion capacity (EC). There were significant (P <0.10) increases in ec with decreasing t or increasing p during extraction of ap (Table4-5). The maximum EC value was 62 mL/g proteinate at T=17.7C, P=10.6. Only decreasing P significantly (P<0.10) increased the ec of map, with maximum value of 66 ml/g (t=24.6c, p=7.9). the ec of cap was not affected by either factor during extraction; its maximum value was 58 ml (t=27.4c, p=8.5). all ec values were higher than the value reported by sumner et al. (1981). this is mostly due to the ability of proteinates to bind fat, in addition to the higher concentration of protein in the dispersion (mine et al., 1991). the ph of dispersion was 7.5 - 8.0; as opposed to the acidic ph that had been reported to give highest emulsion activity.
Emulsion stability (ES). ES as measured by volume changes during standing have maximum of 79, 78, and 76 mL/g proteinate for AP, MAP, and CAP emulsion, respectively. Slight decrease in volume was observed after 6 H for MAP, and was no change for the other two (Table 4-5). Initial volume before homogenization was 75 mL. Emulsion of AP was very stable for more than 6 h (Table 4-6) with very thick mayonnaise-like texture, while the emulsions of MAP and CAP were stable up to 0.5 h only as measured by retained water, with thick dressing-like viscosity. These results were expected as AP formed a more viscous solution than MAP and CAP during protein dispersion, which indicated that AP has higher ability to imbibe water.
Retained water in MAP or CAP emulsion after 2 h standing (Table 4-6) was affected by both increasing T (P<0.10) and decreasing p (p<0.001), with the same maximum volume of 26 ml/g proteinate, at t=35.1c, p=7.8 for map and at t=37.4c, p=8.0 for cap. when the stability was measured by retained oil, ap emulsion was stable up to 6 h, while map and cap emulsion were stable up to 2 h (Table 4-6). Retained oil in MAP and CAP emulsions were not significantly affected by either factor during extraction. Maximum volumes of retained oil in AP, MAP, and CAP emulsion were 50, 49, and 55 mL, respectively, after 6 h standing. Figure 4-3A and B show the differences on response surface model for emulsion stability of MAP when measured by retained oil and retained water after 6 h standing.
Extrusion trial. CAP as the strongest gel former was the only product used for extrusion. The product, which had 10% added fat gave a good product, based on texture, flavor, and overall acceptance. The only slight objection was that the product had a slightly dark color, which may hae been due to the oven drying method after extrusion.
Descriptive Evaluation. Although objective color measurements were not taken, there were consistent color differences. The dry acid-coagulated proteinate has shiny-white color with fluffy particles. Mg-coagulated proteinate has white color with denser particles, while Ca-coagulated proteinate has creamy-white color with densest particles.
SUMMARY
The functional properties of proteinates may be used to predict the application of these protein in food systems. Laboratory scale extractions of yellow pea flour can already recover more than 62% of its protein. Although acid or salt coagulation gave similar nitrogen content, their solubilities, gelation properties, and emulsion stabilities were different.
Acid proteinate was easily dispersed and had high solubility in low pH, making it possible to be incorporated in beverages or soups; together with salt proteinates can also be sued as animal protein replacer or extender. Based on these data of functional properties, all the three proteinates have marketability, especially if the final exploration on food product development is accomplished.
REFERENCES
AOAC. Official Methods of Analysis. Association of Official analytical Chemist. 15th ed., Helrich, k., Arlington, VA 1990, vol. 1, No. 960. 52, p. 342.
Cochran, W.G. and Cox, G.m. Some methods for the study of response surfaces, Ch. 8A. p. 335. In "Experimental Design" 2nd ed. 5th printing. John Wiley and Sons, Inc. NY. 1957, p. 335.
Elizalde, B.E., Pilosof, A.M.R., and Bartholomai, G.B. Prediction of emulsion instability from emulsion composition and physicochemical properties of proteins. J. Food Sci. 1991, 56(1), 116-119.
Food Processing. Ingredients: Isolated soyprotein in meat products aids school lunches. Food Processing. 1991, March, 88-92.
Hsu, D.L., Leung, h.K., Morad, M.M., Finney, P.L. and Leung, C.T. Effect of germination on electrophoretic, functional, and bread-baking properties of yellow pea, lentil, and faba bean protein isolates. Cereal Chem. 1982, 59, 344-350.
Kinsella, J.E. 1979. Functional properties of soy proteins. J. Am. Oil Chem. Soc. 1979, 56, 242.
Mine, Y., Noutomi, t. and Haga, N. Emulsifying and structural properties of ovalbumin. j. Agric. Food Chem. 1991, 39: 443-446.
Noguchi, A., Kugimiya, W., Haque, Z. and Saio, K. Physical and chemical characteristics of extruded rice flour and rice flour fortified with soybean protein isolate. j. Food Sci. 1981. 47, 240-245.
Okezie, B.O. and Bello, A.B. Physicochemical and functional properties of winged bean flour and isolate compared with soy isolate. J. Food Sci. 1988, 53(2), 450-454.
Rice, D.R., Neufer, P.A. and Sipos, E.F. Effect of soy protein blends, fat level, and cooking methods on the nutrient retention of beef patties. Food Technology 1989, 43, 88, 90, 95, 97.
Shen, C.F., De Man, L., Buzzel, R.I. and De Man, J.M. Yield and quality of tofu as affected by soybean and soymilk characteristics: Glucono-delta-lactone coagulant. J. Food Sci. 1991, 56, 109-112.
Soetrisno, U. and Holmes, Z.A. 1991. Protein yields and characteristics from acid and salt coagulation on yellow pea (Pisum sativum L. Miranda) flour extractions. Nutrition and Food manag. Dept., OSU., Corvallis, OR. 97331.
Sumner, A.K., Nielsen, M.A. and Youngs, C.G. production and evaluation of pea protein isolate. j. Food Sci. 1981, 46, 364-366, 372.
Thompson, L.U. Preparation and evaluation of mung bean protein isolates. J. Food Scie. 1977, 42, 202-206.,p> Tjahjadi, C., Lin, S., and Breene, W.M. Isolation and characterization of adzuki bean (Vigna angularis cv. Tanaka) proteins. J. Food Sci. 1988, 53(5), 1
Voutsinas, L.P., Cheung, E. and Nakai, S. Relationships of hydrophobicity to emulsifying properties of heat denatured proteins. J. Food Sci. 1983, 48, 26-32.
