Texturized soy flour

Some breads contain flour made from soybeans, which gives them added protein and a different texture. Soy flour absorbs water to make a gel, making the bread denser. 

Some of the uses of soy proteins to augment meat proteins are summarized in Table III. Textured soy flour, though not included in that table, can be used in the same meat systems, where soy grit or coarse soy protein concentrate are used. Besides the economics associated with the use of soy protein, they are utilized in such meat products because of their functional and nutritional properties. 

Rakosky ( ) reported that if a 25% shrink were obtained with an all meat product, the shrink in a meat product augmented with soy concentrate would be about 22.5%, or a 10% reduction in shrink. Use of textured soy rather than soy concentrate (Table IV) has been shown to reduce shrink in beef patties ( ,7 ). In a comparison of textured soy, soy concentrate and soy isolate, Berry et al. (7) found isolates gave the lowest cooked yields. In that study, cooking yields were directly related to the amount of dry soy in the ground beef-soy formulations. The greater quantity of soy (and correspondingly less water) in the textured soy flour formulation increased moisture retention and decreased total cooking loss. 

Advances in soy protein processing technology have allowed extensive diversification of protein product applications. More sophisticated soy protein products now manufactured have more functionality, better performance, more consistency and better flavor than commercially available defatted soy flour and grits (50% protein dry basis). Among these products are improved textured soy flours, concentrates, and isolates (50%, 70% and 90% protein dry basis, respectfully), functional and non-functional soy protein concentrates (70% protein dry basis) and highly soluble, highly functional isolated soy proteins (90% protein dry basis) (6-8 14-18). 

To investigate the hypothesis that dissociation of disulfite bonds into subunits might be a reaction occurring during formation of texturized soy flour (2 ), two disulfide bond reducing agents (Na2SO3, and cysteine-HCl) were added to soy... 

Microscopic structure of texturized water-extracted soy flour and texturized soy concentrate were quite similar to that of texturized soy flour. Scanning electron microgrpahs showed that water extraction of soy flours had little effect on morphological characteristics of texturized soy products (Figure 10). Solubility of soluble sugars was not affected by texturization, whereas solubility of proteins decreased sharply when soy flour was texturized (Table VII). It appears that soluble sugars did not interact with proteins during texturization. Based upon results of microscopy and solubility studies, it is reasonable to speculate that natural soluble carbohydrates are not required (do not play an important role) in development of texture or stabilization of structure. 

Figure 23. TLMs and TEMs showing the ultrastructure of texturized products (1) TLM of texturized soy flour (2) TLM of texturized 25.5% succinylated soy flour (3) TLM of texturized 61.7% succinylated soy flour (4) TLM of texturized 83% succinylated soy flour (5) TEM of texturized soy flour (6) TEM of texturized 25.5% succinylated soy flour (7) TEM of texturized 61.7% succinylated soy flour and (8) TEM of texturized 83% succinylated soy flour. SAC, small air cell C, insoluble carbohydrate and P, protein.

Textured soy flours were reported to have oil absorption values that ranged from 65 to 130% of their dry weight with small particles absorbing more oil than large ones. The maximum fat absorption occurred within 20 min for all particles. 

Sato et a2- (34) demonstrated that a variety of common meat additives, inclucnrTg cottonseed flour, nonfat dry milk, spray-dried whey, wheat germ, and textured soy flour, inhibited WOF in the meat system. These products may have exerted their inhibitory effect on WOF through the Maillard reaction, since most of them contain some reducing sugars. Pratt (40) reported soybeans and soy protein concentrate had an inhibitory effect upon development of WOF and was able to demonstrate that the active components are water soluble. Fractionation and analysis of the water-soluble fraction showed the antioxidant activity was due to the presence of isoflavones and hydroxylated cinnamic acids (40). This confirms earlier work showing that the flavonoTcis present in plant extracts inhibit oxidation in sliced roast beef (41 ). 

Fig. 19.25. Single-screw extruder used for preparing full-fat flours and texturized soy flours and concentrates (Source provided by Wenger Manufacturing Company, Sebetha, KS).

Protein-Based Substitutes. Several plant and animal-based proteins have been used in processed meat products to increase yields, reduce reformulation costs, enhance specific functional properties, and decrease fat content. Examples of these protein additives are wheat flour, wheat gluten, soy flour, soy protein concentrate, soy protein isolate, textured soy protein, cottonseed flour, oat flour, com germ meal, nonfat dry milk, caseinates, whey proteins, surimi, blood plasma, and egg proteins. Most of these protein ingredients can be included in cooked sausages with a maximum level allowed up to 3.5% of the formulation, except soy protein isolate and caseinates are restricted to 2% (44). 

Field Pea Flours in Pasta. Incorporation of non-wheat flours into noodles improves the protein content and quality, but may have an adverse effect on the flavor and texture of the pasta. Hannigan (38) reported that 10% substitution of wheat flour with pea or soy flour resulted in satisfactory quality of Japanese Udon noodles. 

In the study by Thompson, et al. (11), the ml of gel released per 100 g emulsion for the reference emuTsion without soy, with soy isolate (SIF), soy concentrate (SCF) or soy flour (SF) was 6.07, 5.83, 5.49 and 3.08, respectively, when the hydration ratios were 1 4 (flourrwater) for SIF, 1 3 for SCF and 1 2 for SF. The ml gel released per 100 g emulsion containing 10, 15, 20, and 25% soy protein was 6.70, 5.01, 3.94 and 3.57, respectively. When soy protein concentrate was incorporated into an emulsion at the 3.5% level, the processing yields, textural profile and sensory textural attributes of frankfurters were not different among the products with and without added soy concentrate (13). An objective measure of compression and shear modulus indicated that soy protein concentrate incorporated into frankfurters at the 3.5% level had no effect on batter strength or texture ( M). The addition of a cottonseed protein to frankfurters to replace 5, 10 or 15% of the meat resulted in higher pH, less cured color, less firmness of skin, softer texture and reduced desirability as judged by a sensory panel (J5J. 

Textured Soy Proteins. Textured vegetable proteins, primarily textured flours and concentrates (50% protein and 70% protein, dry basis, respectfully) are widely used in the processed meat industry to provide meat-like structure and reduce ingredient costs (3-6, 9-10). Available in a variety of sizes, shapes, colored or uncolored, flavored or unflavored, fortified or unfortified, textured soy proteins can resemble any basic meat ingredient. Beef, pork, seafood and poultry applications are possible 03, 4-7, 15, 19) Proper protein selection and hydration is critical to achieving superior finished product quality. Textured proteins have virtually no solubility and, thus, no ability to penetrate into whole muscle tissue Therefore, textured soy proteins are inherently restricted to coarse ground (e.g. sausage) or fine emulsion (e.g. weiners and bologna) products, and comminuted and reformed (i.e. restructured) meat products. None are used in whole muscle absorption or injection applications (2-4, 6, 11). 

Ingredients most commonly used in textured vegetable protein products are defatted soy flours or grits. Preferably, the defatted soy flour should contain a minimum of 50% protein with a nitrogen solubility index of 50 to 70, a maximum of 30% insoluble carbohydrate, and less than 1% fat (9). ... 

Surfactants have been, reprotedly, used to prevent extensive puffing of extruded cereal products. It was found in these studies that surfactants could effectively inhibit gelatinization of cereal starch. However, effect of surfactants on protein texturization has not been reported. Two types of surfactants, sodium stearoyl-2-lactylate and calcium stearoyl-2-lactylate (at levels of 0.2 and 0.4% based on the weight of the flour), were mixed with soy flour prior to extrusion. A yeast protein (Torutein, manufactured by Amoco Inc.), claimed to be an extrusion helper although its function is not known, was added. 

Assay Methods for Evaluation of Flours and Texturized Products. Nitrogen solubility index of soy flour at neutral pH was determined by the Official and Tentative Methods of the American Association of Cereal Chemists (.29). ... 

FACTORS AFFECTING EXTRUSION TEXTURIZATION PROPERTIES OF SOY FLOUR... 

Figure 3. TLMs of extrusion texturized pH-modified soy flours (I) pH 9.0 (2) pH 8.0 (3) pH 6.6 (4) pH 5.6 (5) pH 5.3 extruded at LFR (6) pH 5.3 extruded at HFR. Note that alkaline pH could increase the fihrousness of the protein matrix acidic pH produced the opposite effect. P, protein C, insoluble carbohydrate.

Effects of Surfactants. Two types of surfactants [sodium stearoyl lactylate (SSL) and calcium stearoyl lactylate (CSL)] at two concentrations (0.2 and 0.4%) were added to soy flours to study the effect of surfactants on the texturization properties of soy flours. An extrusion helper (Tolutein, yeast cell protein) was also included at two concentrations (1 and 2%) in this study because of its behavior similar to a surfactant upon extrusion. 

TABLE IV. Selected Physical and Rheological Properties of Extrusion Texturized Unmodified and Enzyme-modified Soy Flours... 

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