Low-fat soy flour (LFSF) obtained by extrusionexpelling processing was investigated for functional properties. Flours with the following various levels of protein dispersibility indexes (PDI) and residual oil (RO) contents were investigated: "high" 67 ± 4/10.4 ± 1, "mid" 42 ± 3/7.4 ± 2, and "low" 14 ± 5/6.5 ± 0. The solubility of all three LFSF was minimal at pH 4.0 and increased at more alkaline and acidic pH levels. Waterholding capacity (WHC) increased with a decrease in PDI and RO content, whereas fat-binding capacity (FBC) decreased. Foaming stability increased as PDI and RO increased, with significant differences between all LFSF samples. Emulsification capacity (EC) was measured at three pH levels (5.5, 6.7, and 8.0). At each pH level, the "low" samples showed the least EC compared to the "mid" and "high" samples, with no significant difference between the "mid" and "high" samples at pH 6.7 and 8.0. Emulsification stability and activity decreased from low LFSF to high LFSF. This study showed that in general low LFSF was less functional than the other flours tested and there was no significant difference in the functionality of mid-and high-LFSF samples.Research efforts to find value-added uses for soybean protein in food and nonfood products have been going for some time. Researchers have found that soy protein is a promising substitute for animal protein in foods because it contains all of the essential amino acids required for the diet, does not negatively affect sensory attributes (except flavor), and has additional health benefits including the lowering of blood cholesterol levels and reduction of risk of some cancers (1,2). In nonfood applications, soy protein has been used in wood adhesives as a partial replacement for petroleum-based ingredients, and in other applications such as biodegradable plastics and paper coatings and sizings (3). These value-added uses for soy proteins are based on the functional properties of the protein that add key characteristics to the food or nonfood product that is being formulated. The properties include emulsification, foaming, gelation, and water and fat binding. Recently, researchers have sought to add additional value to soy protein by using alternative processing techniques, genetic engineering, or traditional plant breeding to incorporate new, desirable characteristics or alter undesirable characteristics inherent in the soybean. In this paper, the potential for adding value to soy through an alternative processing technique, namely extrusion-expelling (EE) processing, will be discussed.Traditional industrial soybean processing involves solvent extraction of the oil with subsequent desolventizing and drying of the meal. The meal is then further processed via grinding and separation steps to produce flour, meal, or grits. An alternative soybean processing technique is the EE process developed by Nelson et al. (4) at the University of Illinois. EE processing relies on the mechanical extraction of soybean oil and thus does not incorporate any chemicals in the ext...

The functional properties (protein solubility, emulsification characteristics, foaming characteristics, water-and fatbinding capacities) of extruded-expelled (EE) soy flours originating from six varieties of value-enhanced soybeans (high-sucrose, high-cysteine, low-linolenic, low-saturated FA, high-oleic, and lipoxygenase-null) and two commodity soybeans were determined. The soy flours varied in protein dispersibility index (PDI) and residual oil (RO), with PDI values ranging from 32 to 50% and RO values ranging from 7.0 to 11.7%. Protein solubility was reduced at pH values near the isoelectric region and was higher at both low and high pH. There were no significant differences for water-holding capacity, fat-binding capacity, emulsification activity, or emulsification stability. Only the high-oleic soy flour had significantly lower emulsification capacity. In general, the PDI and RO values of EE soy flours originating from value-enhanced and commodity soybeans had the greatest influence on protein functionality. The genetic modifications largely did not affect functional properties.Soybeans are traditionally processed by solvent extraction using hexane. Today's solvent extraction plants require a large capital investment and the use of a hazardous and environmentally regulated solvent. One alternative to solvent extraction is the extruded-expelled (EE) method. This technology results in soybean meal containing approximately 6-11% oil depending on the processing conditions used (1). EE processing is gaining in popularity due to reduced capital investment, ease of running EE equipment, and the ability to process identity-preserved (IP) soybeans.IP soybeans cannot be combined with any commodity-type soybean or any other IP soybean. Separation must be provided at every step of processing. In order to maintain IP, the equipment used for the transporting, processing, and storing of these soybeans must be thoroughly cleaned and inspected between uses. Documentation stating that the IP soybeans have been handled properly must follow each step of processing.IP soybeans that offer marketing opportunities include soybeans that are organically produced, certifiable non-genetically modified, and specialty soybeans that are genetically enhanced for specific end-uses (i.e., soybeans with altered FA composition, increased sucrose content, altered protein composition). Although the acreage of IP soybeans is growing, the acreage is not now nearly as large as that of commodity-type soybeans. For this reason, many large soybean processors (processing over 1000 tons/day of soybeans) find it financially difficult, logistically challenging, and inefficient to process IP soybeans.Functional properties have been defined by Kinsella (2) as "any physicochemical property which affects the processing and behavior of protein in food systems, as judged by the quality attributes of the final product." Functional properties or characteristics have been identified as being extremely important to examine before a new protein is used in a food or ...

Texturized soy protein (TSP) originating from varieties of value-enhanced soybeans and commodity soybeans, which were processed by extrusion-expelling, were incorporated into ground-beef patties. The soybean varieties included high-cysteine, low-linolenic, lipoxygenase-null, high-sucrose, low-saturated-fat, and high-oleic. The lower the bulk density was, the better the water-holding capacity of TSP. Neither property was affected by the protein dispersibility index or residual oil of the low-fat soy flours from which the TSP was prepared. All extruded-expelled processed flours from value-enhanced soybeans made acceptable TSP. The high-sucrose soybeans produced TSP with higher expansion and improved water-holding capacity. There were no differences in cooking properties or proximate compositions of patties for all treatments. Inside and outside colors were darker for the TSP-extended patties than for the all-beef control, and there was little difference among soybean varieties. The patties containing TSP had significantly more soy flavor and were harder than the all-beef control patties. Some TSP treatments produced more tender and less cohesive cooked patties than did the all-beef control.

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