Solubility nitrogen

Nitrogen Solubility Index. Nitrogen solubility index (NSI) indicates the extent of denaturation of a protein and correlates well with the functional characteristics of protein ingredients. 

Nitrogen solubility index is inversely related to protein level, i.e., as the protein level increases, NSI decreases (8). Another factor related to solubility of seed nitrogen in a flour and distilled water suspension is the concentration of water-soluble naturally occurring salts, since salt-soluble globulins are the major proteins found in peas (21). Also, differences in pea mineral content may play a role in NSI. 

Water Absorption. Water absorption of pea protein isolates depends on pH and processing method used to produce the isolate. Isoelectric pea protein isolate absorbed 2.7 to 2.8 times its weight of water at pH 7 while UF pea protein isolate absorbed 3.3 times its weight of water at pH 2.5 and twice its weight in water at pH 8.5 (13). These low water absorption values may be due to the high nitrogen solubilities of these proteins (35). 

The protein fraction showed low nitrogen solubility and rather low water hydration and oil absorption values relative to those of the proteinates but oil emulsification was quite high. Refined legume fiber had a water hydration capacity of over 20 g/g product. 

Functional property tests were conducted in duplicate. AACC (21) methods were used for the determination of water hydration capacity (Method 88-04) and nitrogen solubility index (NSI) (Method 46-23). Oil absorption capacity was measured by the procedures of Lin et al. (22) and oil emulsification by a modification (22) of the Inklaar and Fortuin (23) method. Pasting characteristics of 12.0% (w/v, db) slurries of the flours and processed products were determined on a Brabender Visco/Amylograph (Method 22-10). The slurries were heated from 30 to 95°C before cooling to 50°C to obtain the cold paste viscosity value. Gelation experiments were conducted by heating 15% (w/v db) slurries in sealed stainless steel containers to 90°C for 45 min in a water bath C3). 

The field pea and fababean flours, which were ground to 60-mesh, showed hieh nitrogen solubility (Table III). However, the orocess of oin milling reduced the NSI values to approximately one-half that of the original flours. The air classified protein... 

Process and product PH Nitrogen solubility index % Water hydration capacity g/g sample Oil absorption Oil emulsification capacity g/g sample % ... 

Figure 4, Mean nitrogen solubility index (%) for protein flour dry roasted under various processing conditions bean/bean ration (1/10, 1/15) residence time (1, 2 min) and bead...

The severity of agitation and separation determines whether the separated medium is considered to have proteins in solution (protein solubility values) or in dispersion (protein dispersion values). The terms Nitrogen Solubility Index (NSI) and Protein Dispersibility Index (PDI) are to be used only when the official... 

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). ... 

To vary the Nitrogen Solubility Index (NSI) of the Soya Fluff 200W (NSI 65), 600-g batches of flour were heated on baking pans in an oven (135 C) for 2, 4 and 12 hr. These heat treatments reduced the 65% NSI flour to 51, 46 and 14% NSI, respectively. Extra Acted Soy Flour 200 I, with an NSI of 55.8%, was also included in this study without any heat treatment. 

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). ... 

Effects of Nitrogen Solubility Index. Nitrogen solubility indexes of soy flour (initial NSI 65%) were modified by heating in an oven (135 C) for 2, 4 and 12 hr prior to extrusion. These treatments resulted soy flours with NSI values of 51, 46 and 14%, respectively. The NSI-14 flour was found unusable for extrusion. The original flour (NSI 65%) produced extrudates having low... 

Beuchat et al. (24) also examined the nitrogen solubility profiles for enzymatically hydrolyzed and control peanut flour samples in 0.03M Ca2+ (as CaCl2). Solubilities of controls between pH 2.0 and 5.0 in 0.034 Ca solutions were similar to those noted for water however, very little increase in nitrogen solubility of controls was noted in the pH 5.0 tc 11.0 range. 

Sekul et al. (29) studied the nitrogen solubility properties of enzyme-hydrolyzed peanut proteins. A deionized water dispersion of peanut flour (1 10, w/v) was treated with papain (0.5% total volume) at 45OC for 15 min. Solubility was tested over a range of pH 1 to 9. In general, papain treatment improved solubility at all levels examined except pH 2 and 8 (Figure 6). 

Figure 6. Nitrogen solubility (Kjeldahl) of peanut proteins P.H.P. = partial hydrolysis by 5% papain CON. = control (no papain) (2i).

Table 1 (Part 1). Multiple regression models for prediction of nitrogen solubility and emulsifying properties of soy flour as influenced by pH and salt concentration.

In any quantitative work on protein hydrolysis, it is necessary to have a measure of the extent of the hydrolytic degradation. The measurement of the number of peptide bonds cleaved during a hydrolytic process is related to the activity of proteinolytic enzymes and the extent of hydrolysis. Various techniques that evaluate the progress of hydrolysis have been reported, such as the trichloroacetic acid (TCA) solubility index, which evaluates the percentage of nitrogen soluble in TCA after partial hydrolysis of the protein. 

Figure 12. The concentration dependences of hydrogen solubility in Pd-Pt (a), Fe-V (b) alloys, carbon solubility in Fe-Ni (c) and nitrogen solubility in Fe-Co, Fe-Mn (d, e) alloys...

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