Functional properties of chhana whey powders

The protein solubility, emulsifying, foaming and gelation properties, and viscosity of solutions of chhana whey protein powders, produced by ultrafiltration and reverse osmosis followed by drying, were studied over the pH range 2.5–9.0. Protein solubility varied from 57–100% and was greatest at low pH values. Chhana whey protein powders had similar emulsifying properties to commercial cheese whey protein powders of similar protein content, although the capacity to form gels when heated to 80°C was much lower, particularly at alkaline pH. the viscosity of solutions of the chhana whey powders was sensitive to pH, but was particularly high in the acidic range. These studies demonstrate considerable potential for the utilization of chhana whey, products in the food industry.     

Modification of bean starch by γ-irradiation: Effect on functional and morphological properties

Starches isolated from Red, White, Yellow and Black Kidney beans were treated by γ-irradiation doses of 5, 10 and 20 kGy. Physicochemical, morphological and pasting properties of irradiated bean starches were investigated. Microscopic observation under scanning electron microscope (SEM) showed that some of the bean starch granules were destroyed by γ-irradiation and the breakage was greater at a higher dose (20 kGy). Physicochemical properties differed significantly and showed strong dose-dependent relationship. Carboxyl content, solubility, water absorption capacity and transmittance increased, whereas swelling power, apparent amylose content, syneresis and pasting properties decreased upon the irradiation of kidney bean starch. Radiation doses were positively correlated with water absorption capacity and solubility index and negatively correlated with swelling index, peak viscosity, trough viscosity, breakdown and final viscosity. There were high positive correlations between pasting properties. X-ray diffraction pattern remained same upon irradiation but a decrease in crystallinity was observed with increasing irradiation dose.     

The effect of sterilizing doses of γ-irradiation on the molecular weight and emulsification properties of gum arabic

Experiments were performed on raw, kibbled and spray-dried gum arabic. Microbiological tests showed that following a radiation dose of 10 kGy the contaminating micro-organisms were effectively inactivated. The average molecular weight of kibbled and spray dried gum arabic was shown by viscosity measurements to be somewhat reduced as the result of γ-irradiation. No significant radiation-induced changes in the molecular weight of raw gum arabic could be detected. The yields of radiolytically produced strand breaks (breaks/100 eV of radiation absorbed) have been calculated for spray-dried [G(strand breaks) = 4.1 × 10⁻¹] and for kibbled [G(strand breaks) = 2.9 × 10⁻¹]. Gel permeation chromatography confirmed this order of radiation stability and indicated that gum arabic consists of at least three major components, the larger molecular weight fraction appearing to be the more radiation sensitive. There was no measurable change in the total hexuronic acid content (20%) of any of the samples on γ-irradiation. Finally, measurements showed no adverse effect of γ-irradiation, even up to doses of 30 kGy, on the ability of the gum arabic to stabilize emulsions. The extent of chemical change induced by irradiation with sterilizing doses has no practical adverse significance and demonstrates that this technique is suitable for processing raw gum arabic samples.     

Modification of Rice Starch by Gamma Irradiation to Produce Soluble Starch of Low Viscosity for Industrial Purposes

Because starch of low viscosity is important for industrial purposes this research was carried out to study the possibility of producing this sort of starch by treating rice starch with γ-irradiation. Results indicated that when rice starch was modified by γ-irradiation, the reducing power increased and degradation as well as molecular breakdown occured followed by sharp decrease of its viscosity, specific viscosity and intrisinc viscosity. Results showed that starch became more soluble by treating with γ-irradiation and lost its resistance to water as its swelling capacity decreased. All these changes were proportional to the doses of γ-irradiation.     

Protein Denaturation and Emulsifying Properties of Plasma and Granules of Egg Yolk as Related to Heat Treatment

Solubility, electrophoresis, viscosity and emulsifying properties of heated solutions of yolk, plasma and granules were determined. Plasma and yolk were not affected when heated under 69°C. Above 69°C, protein solubility dropped sharply and apparent viscosity rose sharply because of aggregation of proteins. For granules, protein solubility and apparent viscosity were not modified up to 76°C. The constituents of granules were not denatured. Emulsifying activity of yolk and plasma decreased after heating at 72°C but remained steady for granules. Emulsion stabilization properties of yolk, plasma and granules were not influenced up to 76°C. Results suggested that intact granules withstood more severe heat treatments than egg yolk without lessening their emulsifying properties.     

Functional aspects of blood plasma proteins.

The viscosity of solutions (6% w/w protein in 45% sucrose) of porcine and bovine whole blood plasma, porcine serum and porcine plasma fractions exhibited Newtonian behaviour between 20°C and 73°C. On further heating, the viscosity of these solutions increased exponentially producing a reversible gel structure at 76°C and an irreversible gel at 79°C. In contrast, egg albumen protein solutions indicated a relatively low initial viscosity but started to thicken at 65°C, forming reversible gels at 73°C and irreversible gels at 76°C. The viscosity of the egg albumen protein solutions was similar to that of the serum proteins and plasma protein fractions and less than that of whole plasma protein solutions. Viscosities lower than expected were exhibited by mixtures of whole porcine or bovine plasma and egg albumen proteins. However, synergistic interaction between the proteins of egg albumen and porcine plasma fraction I and fraction III (albumin) and porcine serum occurred at high temperatures of heating.     

Effects of γ-irradiation on the quality changes of fresh noodles prepared from wheat cultivated with N-fertilization treatments

Quality changes of fresh noodles prepared from wheat cultivated with N-fertilization treatments, followed by γ-irradiation were investigated. The protein content of the KPS60 was the highest of all treated samples, and protein contents of wheat cultivated with N-fertilizer was increased. γ-Irradiation did not affect the protein contents of the samples. However, the water holding capacity and resistant starch contents was increased by irradiation. The dry gluten and wet gluten contents of samples were further increased by γ-irradiation. The pasting properties were influenced by γ-irradiation but not N-fertilization. The hardness of noodles made with irradiated wheat flour was decreased, but the degree of decrease was small compared with that of viscosity. The gumminess and chewiness of noodles made with irradiated flour having higher protein content and WG showed also higher score. Thus, treatment of wheat flour with N-fertilization and γ-irradiation may improve the quality of Korean-style noodles during storage.     

Milk powders ageing: effect on physical and functional properties

Milk powders are now considered as food ingredients, mainly because of the functional properties of milk proteins. During the storage of milk powders, many physicochemical damages, mainly dependent on lactose glass transition occur. They have important consequences on physical (flowability) and functional properties (solubility, emulsifying, and foaming properties) of milk powders. First, lactose crystallization modifies the microstructure and chemical composition of the surface of powder particles. Thus, milk powders flowability is decreased. Since the structure of milk proteins is destabilized, its solubility is damaged. Moreover, particle collapse and caking occur and mainly decrease the physical properties of milk powders (density and flowability). The mechanical stresses involved may also enhance proteins unfolding, which is detrimental to solubility. Finally, molecular mobility is favored upon ageing, and both chemical (Maillard reaction) and enzymatic reactions occur. Maillard reaction and oxidation enhance protein interactions and aggregations, which mainly lessen milk powders solubility. Maillard reaction also decreases emulsifying and foaming properties. Storage temperature and relative humidity have been considered as the predominant factors involved, but time, milk components, and their physical state also have been implied.     

Surface protein coverage and its implications on spray-drying of model sugar-rich foods: Solubility,powder production and characterisation

We have investigated the amount of protein required to produce amorphous sugar powders through spray-drying. Pea protein isolate was used as a model plant protein and sodium caseinate was used as a model dairy protein. Powder recovery in a laboratory spray dryer was used as a measure of the ease of spray drying for a given formulation. More than 80% of amorphous sucrose and fructose was produced with the addition of sodium caseinate, while the pea protein isolate was able to produce only recoveries of less than 50% of amorphous sucrose. Sensitivity of low molecular weight surfactants has been demonstrated using both ionic (sodium stearoyl lactylate) and non-ionic (polysorbate-80) surfactants. Spray-dried powders were subjected to physico-chemical characterisation and dissolution experiments. The maximum solubility of all powders was obtained after 5 min of dissolution. The solubility of the sodium caseinate increased by 6–7% in the presence of fructose and low molecular weight surfactants. The solubility of the amorphous powders of sucrose–pea protein isolate was found to be lower than amorphous powders of sucrose–sodium caseinate and fructose–sodium caseinate. The addition of sucrose in water increased the solubility of the pea protein isolate from 16.84% to more than 83%. The non-ionic surfactant (Tween-80) has reduced the solubility of sucrose–pea protein isolate–Tween-80 powders significantly (p < 0.05) compared to those of sucrose–pea protein isolate–sodium stearoyl lactylate powders. The solubility of sucrose–sodium caseinate powders was comparable to that of pure sodium caseinate, indicating that addition of sucrose into 0.13% sodium caseinate does not have any significant effect on the solubility of this protein at this concentration.     

Effect of γ-irradiation on granule structure and physicochemical properties of starch extracted from two types of potatoes grown in Jammu & Kashmir,India

In this study red and white potato starches were treated with γ-irradiation of 0, 5, 10 and 20 kGy. Physicochemical, pasting and morphological properties of the irradiated starches were investigated. Apparent amylose content, pH, moisture, swelling power and syneresis decreased; whereas carboxyl content, water absorption capacity and solubility increased with increasing irradiation dose. Pasting properties also decreased significantly (p ≤ 0.05) upon increasing the irradiation dose. Observation under scanning electron microscope (SEM) showed surface cracking of the starch granules by γ-irradiation which increased with increase in irradiation dose. X-ray diffraction pattern remained the same upon irradiation but a decrease in relative crystallinity was observed with increasing irradiation dose.     

pH值碱性偏移结合热处理对米糠蛋白结构和功能性质的影响

本文采用不同pH（2.0~13.0）处理箭筈豌豆白蛋白（common vetch albumin protein,CVAP）和球蛋白（common vetch globulin protein,CVGP）,研究了其分子量组成、表面疏水性、Zeta-电位、溶解度、乳化性和起泡性等物化性质。结果表明pH处理使箭筈豌豆蛋白二级结构展开,表面疏水性和Zeta-电位均呈现出动态变化。SDS-PAGE分析表明pH的变化导致了蛋白组分的变化,这种变化被认为是引起蛋白物化性质发生变化的主要原因。同时,pH处理使箭筈豌豆蛋白的溶解度、乳化性和起泡性发生较大变化。当pH<5.0时,CVGP溶解度高于CVAP;pH>7.0,CVAP溶解度高于CVGP;箭筈豌豆蛋白在pH11.0~12.0时的乳化性能和起泡性能要优于其他pH。可见,pH变性处理可以改变箭筈豌豆蛋白的物化性质,其中pH11.0~12.0时的处理可改善蛋白的乳化性能和起泡性能。     

Effect of Amaranthus and buckwheat proteins on the rheological properties of maize starch

The relationship between pasting properties (determined with a Rapid Visco-Analyser) of maize starch and the texture of the resulting gel was examined after addition of Amaranthus and buckwheat proteins. An increase in the peak viscosity due to the addition of protein concentrates was observed, and a lesser increase from the addition of protein hydrolysates. The increase in starch pasting viscosity was related to protein solubility, and could be attributed to the starch granule stabilizing action of proteins. The interactions between starch and proteins were further investigated using oscillation and creep/recovery rheological tests. Generally, the proteins weakened starch gel structure, shown by the lower elastic modulus (G′) and higher phase degree (δ) compared to gels without any proteins added. The same results were obtained from creep/recovery experiments. It seemed that, since native proteins interact more with the granules, they act as a barrier to the release of amylose molecules; hence the resulting gels became weak. If desired, such effects could be lessened by partially hydrolyzing the proteins. ©     

Characterization of amaranth proteins modified by trypsin proteolysis. Structural and functional changes

Amaranth protein isolates were prepared from Amaranthus hypochondriacus and hydrolyzed using trypsin. Degrees of hydrolysis varied between 2% and 7% with the time of hydrolysis reaction. The structure, solubility and foaming properties of protein isolates were studied. SDS-PAGE analysis demonstrated that polypeptides from 11S-globulin and P globulin were the main targets for the protease, while a polypeptide of 45 kDa from the 7S globulin was more resistant to trypsin action. The FPLC analysis of hydrolyzed proteins showed that the structure is partially conserved, while an increase of the fraction of lower molecular weight is observed. Such structure exhibits a single endotherm of lower denaturation heat than the protein isolate.The solubility and foaming properties of protein isolates and hydrolysates were analyzed, in the later case at two protein concentrations (1 mg and 2.5 mg of solid matter per ml). Protein solubility increased markedly with hydrolysis, while changes in foaming properties were less dramatic. Nevertheless, foams obtained with amaranth protein hydrolysates were more dense and stable than those prepared with non-digested proteins, specially for foams produced with the protein hydrolysate of higher concentration.     

Production and functional properties of beef lung protein concentrates

This work investigated the production and the properties of meat protein concentrates from beef lungs (BLPC) at pilot scale. Protein recovery and functional properties were compared to those of BLPC obtained using membrane technology in a previous work (Selmane, D., Vial, C., & Djelveh, G. (2008). Extraction of proteins from slaughterhouse by-products: Influence of operating conditions on functional properties. Meat Science, 79, 640–647). An alkaline solubilisation method was applied for protein extraction, followed by pI precipitation for concentration. The physicochemical properties of BLPC such as molecular mass, solubility, surface hydrophobicity, surface tension and interfacial tension, as well as technofunctional emulsifying and foaming properties were determined. These were compared to those of commercial protein ingredients, such as sodium caseinates, whey protein isolates, egg white proteins and soy protein isolates. Results showed that proteins from BLPC included a low-molecular-weight fraction and exhibited good solubility and high hydrophobicity with small surface and interfacial tensions. This explained their excellent emulsifying activity, better than sodium caseinates, and their good foaming properties.     

喷雾干燥和冷冻干燥莲子蛋白结构及其功能特性的比较

采用碱溶酸沉的方法提取莲子湿蛋白,通过喷雾干燥和冷冻干燥两种方法制备莲子蛋白粉,并对两种蛋 白粉的结构及其功能特性进行比较分析。研究表明：与冷冻干燥莲子蛋白（freeze-dried lotus seed protein,FLSP） 相比较,喷雾干燥莲子蛋白（spray-dried lotus seed protein,SLSP）明度大,色泽较好;扫描电子显微镜结果显示 SLSP呈现不规则的向内折叠起皱的球状结构,FLSP为盘状的大片层结构;X射线衍射测定表明两种干燥方法所得 蛋白都呈现非结晶性;圆二色谱进一步表明两种干燥蛋白的二级结构无明显变化,但两者均从有规则的结构向无规 则的结构转化;SLSP除了持水性和起泡性优于FLSP（P＜0.05）,其他功能特性如溶解性、持油性、乳化特性均有 所降低。因此,不同的干燥方法会改变莲子蛋白的结构特性,并进一步影响其功能特性,预示不同干燥方法所获得 的蛋白粉可能适用于不同产品的加工。     

Protein co-precipitates from milk and blood plasma: Preparation and investigation of some functional properties

Various processing methods were investigated for the production of milk and porcine blood plasma co-precipitates. Factors considered included pH and temperature treatments as well as the ratio of milk to plasma proteins in mixtures of the raw materials. The recovery of protein in precipitates was measured and the following method was selected accordingly for further studies: pH adjustment of skim milk and blood plasma mixtures to pH 9.5, heating to 70° C, readjustment of pH to 9.5, holding for 3 min, cooling to 68°C, pH adjustment to 3–5, holding for 5 min, cooling to ambient temperature and final pH adjustment to 4.7. Two co-precipitates (70/30 M/P and 30/70 M/P) were prepared from a 70:30 and a 30:70 mixture of skim milk (M) and blood plasma (P). Some of the functional properties of these preparations were measured and compared with those of total milk protein (TMP) and blood plasma precipitate (P) prepared by the same procedure as well as acid-precipitated casein. The protein contents of preparations freeze-dried at pH 7.0 varied between 91.5 and 92.3% and those freeze-dried at pH 4.7 varied between 93.1 and 96.0%. The solubility profile and emulsifying capacity of the 70/30 M/P compared favourably with those of caseinate and TMP. The solubilities of 30/70 M/P and 100% P were, however, poor. The viscosity of solutions of 70/30 M/P was considerably higher than those of caseinate and TMP solutions. Water adsorption isotherms of protein preparations were constructed and are presented in graphical form. Precipitates freeze-dried at pH 7.0 adsorbed more moisture than the same preparations freeze-dried at pH 4.7. These differences were especially evident a water activities >0.8.     

Functional properties of isolated porcine blood proteins

The isolated proteins contained in the blood from slaughterhouses could be recovered and used to improve the functional and nutritional properties of food products. In this work some functional properties, namely solubility, emulsifying capacity, gelling and foaming capacity have been tested for different protein fractions of porcine blood. The blood proteins studied were globins (α, β and γ), albumin and fibrinogen and the whole plasma from the plasmatic fraction, and haemoglobin and globin obtained from the haemoglobin by a chemical method from the cellular fraction. The effect of pH and protein concentration on functional properties was determined. Results indicate that blood proteins present good functional properties specially solubility, gellation and emulsifying capacities that could make blood protein useful as food additives in the formulation of food products.     

Effect of the extrusion process on allergen reduction and the texture change of soybean protein isolate-corn and soybean flour-corn mixtures

Soy protein and corn meal are widely used as main ingredients in the cereal and snack industries. We studied the effect of extrusion processing on the immunoreactivity of proteins in soy protein isolate-corn meal (SPI-corn) blends and soy flour-corn meal (SF-corn) blends using a full-factorial design with two levels of temperature, moisture, and screw speed (SS). The changes in protein solubility, protein secondary structure and physical properties, such as the expansion ratio, specific volume, water hydration capacity (WHC), texture, and color, were also studied. The western blotting results illustrated that extrusion processing decreased the immunoreactivity of proteins in SPI-corn and SF-corn blends and eliminated certain allergenic proteins in SF-corn extrudates. The enzyme-linked immunosorbent assay (ELISA) results indicated that different extrusion conditions decreased the immunoreactivities of SPI-corn and SF-corn blends in the ranges of 53%–68% and 80%–86%, respectively, compared with the raw material. The protein solubility decreased after extrusion by >58.7% for SPI-corn extrudates and by 66.3% for SF-corn extrudates compared with the initial materials and decreased significantly for both SPI-corn and SF-corn extrudates with the increase in extrusion temperature (P < 0.05). The α-helix structure decreased and β-strand structure increased after extrusion for both SPI-corn and SF-corn blends. Higher moisture significantly decreased the expansion ratio, specific volume and WHC of SPI-corn and SF-corn extrudates, as well as increased the energy required to cut the samples. Thus, the effect of extrusion on allergenic proteins using the human plasma of subjects allergic to soybean and corn showed that moisture had a clear effect on their reduction. Product treated with low moisture (20%), regardless of the starting material used, was the most effective based on the reduction of allergenic proteins.     

Effect of succinylation on physicochemical and functional properties of milk protein concentrate

Milk protein concentrate (MPC) is a complete dairy protein ingredient (containing both caseins and whey proteins) available with protein concentrations ranging from 40 to 90%. However, MPC powders are poorly soluble which thus, restricts their potential use for food application. Succinylation involves chemical derivatisation of ϵ-amino group of lysine in proteins and enhances solubility of less soluble proteins. In the present investigation, highest degree of succinylation was achieved at the level of 4 mol of succinic anhydride/mole of lysine in MPC. Findings from intrinsic tryptophan intensities stated that succinylation of milk proteins showed structural modification and increase in hydrophobicity. Further, the effects of succinylation on the functional properties (solubility, water- and oil-binding capacities, viscosity, foaming capacity and stability, emulsion activity and stability) of MPC were evaluated. Succinylation of proteins significantly (P < 0.05) increased solubility as a result of altered charge on protein and reduced particle size of native MPC, which in turn improved other functional properties of native MPC. The microstructure of succinylated MPC at different degrees of succinylation by scanning electron microscopy revealed that the size and number of white patch like structures present on protein increased with degree of succinylation.     

Physicochemical characterisation of raw fish and stickwater from fish meal production

Chemical and microbiological properties of raw fish (RF) and chemical properties of stickwater (SW) samples were studied as a function of the staleness level of the fish. As time elapsed from fish capture increased, the microbial count in RF, volatile nitrogen content in RF and SW, and dissolved solids and dissolved protein in SW, increased. The apparent viscosity of SW increased as the temperature decreased and as the dry solids or suspended matter content increased. The size distribution of suspended particles in SW depended on the sample preparation technique, method used to measure particle size and whether the size distribution was expressed in terms of the weight or population of fractions. The average size (by weight) of suspended solids in SW was 2.5 μm as estimated by electronic counting. The solubility of protein in SW decreased when acid or alkali were added or thermal treatment (1 h at 90°C) applied. A minimal solubility point occurred near pH 5. The molecular weight of most dissolved proteins in SF was 3 kD. SF also contained a small proportion of 67 kD proteins. The significance of this basic characterisation study for the selection of improved processes for stickwater recovery is discussed.