Minimum Protein Solubility Research Articles

Solubility and functional properties of sesame seed proteins as influenced by pH and/or salt concentration

The protein content, solubility and functional properties of a total protein isolate prepared from sesame seeds (Kenana 1 cultivar) as a function of pH and/or NaCl concentration were investigated. The protein content of the seed was found to be 47.70%. The minimum protein solubility was at pH 5 and the maximum was at pH 3. The emulsifying capacity, activity and emulsion stability as well as foaming capacity and foam stability were greatly affected by pH levels and salt concentrations. Lower values were observed at acidic pH and high salt concentration. The protein isolate was highly viscous and dispersable at pH 9 with water holding capacity of 2.10 ml H 2O/g protein, oil holding capacity of 1.50 ml oil/g protein and bulk density of 0.71 gm/ml.

Nutritional potential and functional properties of sweet and bitter lupin seed protein isolates

Abstract Protein isolates were prepared from both sweet and bitter lupin seed flours by two different methods, i.e. by alkaline water extraction/isoelectric precipitation (P1) and by micellisation (MI), and studied with regard to nutritional quality and functional properties. Protein solubility of both lupin seed flours was increased as sodium chloride concentration increased up to 1.0 M, then decreased. The minimum protein solubility of bitter lupin seed flour was quite sharp at pH 4.5, while it exhibited a broad pH range of 4.3–4.9 for sweet lupin seed flour. No significant (P 0.05) difference between bitter isolates in their alkaloid contents, while both sweet lupin isolates were free of total alkaloids. Bitter lupin isolate-PI had significantly (P

Traditional Processing Treatments as a Promising Approach To Enhance the Functional Properties of Rapeseed (Brassica campestris Var. toria) and Sesame Seed (Sesamum indicum) Meals

Different processing treatments were applied to rapeseed and sesame seed meals, and the functional properties of these products were assessed. All treatments except puffing for both meals and pressure cooking in sesame meal increased water absorption capacity (WAC). Fat absorption capacity (FAC) of rapeseed meals was enhanced significantly by all treatments. The full-fat meals of both sources showed maximum protein solubility when fermented and minimum protein solubility when pressure-cooked. Germinated and microwave-cooked meals enhanced foaming properties of rapeseed meals. Heat treatments, except microwave cooking, considerably reduced emulsifying properties of both meals. Fermentation and germination increased the specific viscosity of rapeseed meals, whereas processed sesame meals showed lower viscosity than dry sesame meals.

Composition and functional properties of raw and heat processed velvet bean (Mucuna pruriens (L.) DC. var utilis) flours

Summary The proximate composition and functional properties of raw and heat‐processed velvet bean (Mucuna pruriens (L.) DC. var utilis) flours were studied. The flours were prepared by soaking raw beans for 14 h, boiling for 30 min (heat‐processed), manual dehulling, oven‐drying (65 °C) and milling. The heat‐processed flour contained 6.8% moisture, 24.3% protein, 4.9% fat, 1.3% crude fibre, 3.5% ash and 61.2% carbohydrate. The flour was rich in potassium (125 mg/100 g), zinc (9.8 mg/100 g) and phosphorus (361 mg/100 g). Differences in proximate and mineral composition of raw and heat‐processed flours were not significant. The flours showed minimum protein solubility at pH 4.5 and formed reasonably stable emulsions and foams. Compared to raw flour, heat‐processed flour had better water and fat absorption capacities, but lower protein solubility, emulsion and foam capacities. The flours have potential for food product development.

Spray‐Dried Soy Protein Isolate Solubility, Gelling Characteristics, and Extractable Protein as Affected by Antioxidants

ABSTRACTWith the addition of antioxidants, spray‐dried soy protein isolates (SPI) exhibited increased solubilities by 8% over the control in 0.1M NaCl. Increased solubilities corresponded to a 15% and 8% reduction in protein oxidation as determined by protein carbonyl contents. The greatest differences in solubility between a spray‐dried SPI with antioxidant (66% protein solubility) and the control (54% protein solubility), as well as the minimum protein solubility, occurred in 0.2M NaCl. Following the initial solubilization step in SPI processing, amount of extracted proteins was increased by 4.5% over the control with addition of antioxidants. Gel fracturability, hardness and adhesiveness for heat set gels of 12% SPI processed with added antioxidants were increased by 26.3%, 23.5% and 24.6%, respectively.

Interactions of free and immobilized myelin basic protein with anionic detergents.

The interaction of free and immobilized myelin basic protein (MBP) with sodium deoxycholate (DOC) and sodium dodecyl sulfate (NaDodSO4) was studied under a variety of conditions. Free MBP formed insoluble complexes with both detergents. Analysis of the insoluble complexes revealed that the molar ratio of detergent/MBP in the precipitate increased in a systematic fashion with increasing detergent concentration until the complex became soluble. At pH 4.8, equilibrium dialysis studies indicated that approximately 15 mol of NaDodSO4 could bind to the protein without precipitation occurring. Regardless of the surfactant, however, minimum protein solubility occurred when the net charge on the protein-detergent complex was between +18 and -9. Complete equilibrium binding isotherms of both detergents to the protein were obtained by using MBP immobilized on agarose. The bulk of the binding of both detergents was highly cooperative and occurred at or above the critical micelle concentration. At I = 0.1, saturation levels of 2.09 +/- 0.15 g of NaDodSO4/g of protein and 1.03 /+- 0.40 g of DOC/g of protein were obtained. Below pH 7.0 the NaDodSO4 binding isotherms revealed an additional cooperative transition corresponding to the binding of 15-20 mol of NaDodSO4/mol of protein. Affinity chromatography studies indicated that, in the presence of NaDodSO4 (but not in its absence), [125I]MBP interacted with agarose-immobilized histone, lysozyme, and MBP but did not interact with ovalbumin-agarose. These data support a model in which the detergent cross-links and causes precipitation of MBP-anionic detergent complexes. Cross-linking may occur through hydrophobic interaction between detergents electrostatically bound to different MBP molecules.

Behavior of adsorbed protein in cane sugar juice

Sugar cane juice is an electrophoretically homogeneous suspension of particles. Protein adsorbed at the particle surface is stabilized by the high concentraiton of sucrose present, but on dilution, there is an increase in pH of the isoelectric point and denaturation takes place. Centrifugal washing completely removes adsorbed protein from the chloroplasts but not from the wax particles present in the system. Some of the protein in juice is rendered soluble in 70% alcohol, and not available for adsorption, below pH 3. Adsorption curves in the cold show minimum protein solubility near the isoelectric point and an increase in area of adsorbent due to calcium phosphate precipitation above pH 6. Protein coagulation on boiling masks the latter effect, and the curve of N/particle against pH is still further changed by the loss of amide N from adsorbable material. Some effects of formaldehyde are mentioned.