Functional properties and retrogradation behaviour of native and chemically modified starch of mucuna bean (Mucuna pruriens)

Mucuna bean (Mucuna pruriens) starch was isolated and subjected to chemical modification by oxidation and acetylation. The proximate analysis of the non‐starch components of the native starch on a dry weight basis was 92 g kg^?1 moisture, 5 g kg^?1 ash, 2 g kg^?1 fat, 7 g kg^?1 crude fibre and 19 g kg^?1 protein. Chemical modification reduced the values for all the non‐starch components except the moisture level. For all the samples, swelling power and solubility increased as the temperature increased in the range 50–90 °C. The swelling power of mucuna native starch (MNS) and mucuna acetylated starch (MAS) increased with increasing acidity and alkalinity, while that of mucuna oxidised starch (MOS) only increased with increasing pH in the acidic range. The maximal solubility of all the starches was observed at pH 12. All the starch samples absorbed more oil than water. The lowest gelation concentration followed the trend MAS < MNS < MOS. Chemical modification reduced the gelatinisation temperature (Tp), while peak viscosity (Pv), hot paste viscosity (Hv) and cold paste viscosity (Cv) decreased after oxidation but increased following acetylation. The setback tendency of the native starch was reduced significantly after chemical modification. However, the breakdown value of MNS, 65 BU (Brabender units), was lower than that of MOS (78 BU) but higher than that of MAS (40 BU). Differential scanning calorimetry studies of gelatinisation and retrogradation revealed that chemical modification reduced the onset temperature (T_o), peak temperature (T_p) and conclusion temperature (T_c). Oxidation and acetylation reduced the gelatinisation and retrogradation enthalpies of the native starch. The enthalpy of retrogradation of the starches increased as the length of storage increased. Copyright © 2003 Society of Chemical Industry     

Physicochemical and emulsifying properties of mung bean protein isolate as influenced by succinylation

The application of mung bean protein in foods is limited due to its poor functionality. Acylation with succinic anhydride could be used to improve the functionalities of protein. In this study, the influence of the weight ratio of succinic anhydride to protein (0–0.10) on the degree of N-acylation, physicochemical properties and protein functionalities including emulsifying properties of mung bean protein isolates (MPI) were investigated. The extent of N-acylation of MPI increased as the succinic anhydride:protein ratio increased, while the ζ-potential at neutral pH decreased. In addition, succinylation had an impact on the average particle size of MPI depending on the succinic anhydride:protein ratio. Succinylation had no impact on the total and exposed free sulfhydryl groups. Moreover, the isoelectric point (pI) of the succinylated proteins shifted from pH 5 to lower pH. Succinylation increased the emulsifying activity index (EAI), while the impact on the emulsion stability index depended on the succinic anhydride:protein ratio. Thus, succinylation at low succinic anhydride:protein ratio can alter mung bean protein charge and affect physicochemical and functional properties especially emulsifying properties that could be used to increase its utilization.     

Functional and bioactive properties of Velvet bean (Mucuna pruriens) protein hydrolysates produced by enzymatic treatments

Velvet bean (Mucuna pruriens) protein hydrolysates were produced with gastrointestinal enzymes. Functional properties such as nitrogen solubility, emulsifying capacity and emulsion stability, foam capacity and stability of the hydrolysates were determined. Angiotensin I-converting enzyme inhibitory, antioxidant and antithrombotic capacities were evaluated to determine the biological activity of hydrolysates. For pepsin, degree of hydrolysis (DH) increased sharply between 5 min (22.33 %) and 60 min (28.07 %), respectively, with a maximum DH of 33.50 % (90 min). For pancreatin, DH increased sharply between 5 min (25.08 %) and 90 min (34.92 %), respectively, with a maximum DH of 37.23 % (120 min). For sequential system pepsin–pancreatin, DH increased sharply between 5 min (25.21 %) and 60 min (32.82 %), respectively, with a maximum DH of 34.14 % (120 min). Hydrolysates with the lowest DH and the highest DH were selected to assess the functional and biological potential. Mucuna pruriens limited hydrolysates can be considered a useful food additives to provide functional properties, while M. pruriens extensive hydrolysates can be used as nutraceutical ingredients.     

Nutritional and anti-nutritional characteristics of mucuna (Mucuna utilis) bean seeds

Some nutritional and anti-nutritional characteristics of mucuna (Mucuna utilis (Wight) Burck) bean seeds were studied. The mature seeds contained 264 g crude protein, 63 g crude fibre, 41 g crude fat, 37 g ash and 595 g carbohydrates kg^?1 DM. The essential amino acid profile compared well with the FAO/WHO scoring pattern except for a deficiency of sulphur-containing amino acids. Mineral composition was similar to those reported for most tropical grain legumes. Raw mucuna seed samples contained moderately high levels of anti-tryptic activity (2170 trypsin units inhibited g^?1 DM), but this was completely destroyed by cooking. The other anti-nutritional factors (phytate, cyanide and tannins) are probably of little nutritional significance provided that the beans are properly processed. The in-vitro protein digestibility of raw and cooked beans were 71·5 and 80·3 %, respectively. In view of the high L-DOPA contents reported in some mucuna cultivars, overconsumption of mucuna beans should be viewed with some caution until suitable processing methods are developed.     

Some physicochemical and antinutritional properties of raw flours and protein isolates from Mucuna pruriens (velvet bean) and Canavalia ensiformis (jack bean)

The legumes Canavalia ensiformis and Mucuna pruriens are underexploited in tropical Mexico. Their seeds have good nutritional potential, but contain antinutritional factors. Physicochemical and antinutritional properties were determined for raw flours (RF) and protein isolates (PI) produced from these legumes. Protein content in the PI was 737 g kg^–1 for C. ensiformis and 666 g kg^–1 for M. pruriens. Protein isolation improved in vitro digestibility, while maintaining high lysine levels and adequate sulphur amino acids content. Antinutritional factors such as cyanogenic glucosides, cyanide precursors from hydrolysis, tannins and trypsin inhibitors were lower in the PIs than in the RFs. The reduction in canavanine levels, a structural analogue of arginine, in the C. ensiformis PI was noteworthy. These PIs thus have potential applications in the development of new food ingredients in tropical regions using processes that improve nutritional value.     

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.     

Structural and some nutritional characteristics of Velvet bean (Mucuna pruriens) and Lima bean (Phaseolus lunatus) starches

Velvet bean (Mucuna pruriens) and lima bean (Phaseolus lunatus) starches were isolated from seeds and their structural characteristics evaluated using XRD, size‐exclusion chromatography and light scattering analyzes. Total starch, available starch, RS and in vitro digestibility were also determined. Structural and nutritional characteristics of Velvet bean and Lima bean starches were compared to those of commercial corn starch. The legumes starches presented a C‐type XRD pattern and crystallite sizes of 43.1 Å for velvet bean and 48.3 Å for lima bean. Lima bean starch average molar mass (4.9 × 10⁶ g/mol) was slightly higher than the velvet bean starch (3.04 × 10⁶ g/mol). Size‐exclusion chromatography indicated structural similarity between the lima bean and corn starches which differed from that of the velvet bean starch. Hydrodynamic radius (R_H) for the velvet bean and lima bean starches was 45.5 and 55 nm, respectively, and their radius of gyration (R_G) was 67.7 and 82.5 nm, respectively. Total starch content in all three starches was greater than 98%. Their complex crystalline structure provided the legume starches lower in vitro digestibility values than the corn starch. RS content in both the velvet bean starch (7.72%) and lima bean starch (5.66%) was higher than in the corn starch, essentially qualifying these polysaccharides as natural dietary fiber sources, with the associated physiologic advantages.     

红松种子水溶性蛋白吸水性、吸油性及溶解性的研究

选用黑龙江省伊春市红松种子为原料,以蒸馏水为提取液制备红松种子水溶性蛋白(WPNP)。研究了pH、温度、CaCl2和NaCl浓度对WPNP的吸水性、吸油性和溶解性的影响。WPNP的等电点为4,pH介于4～12之间,吸水性随着pH的增加而升高;温度处于30℃时,吸水性最好,为4mL/g;NaCl离子强度处于0·4mol/L时,WPNP的吸水性最好,为3·4mL/g;温度对WPNP的吸油性有较大的影响,在30～35℃时,WPNP的吸油性较好。但是在35～60℃范围内,随着温度的升高,WPNP的吸油性降低。研究了pH、温度、离子强度、共存盐类对WPNP溶解性的影响,pH4,随着pH增加溶解性也增加,但是pH超过12,会导致蛋白质变性,40℃时溶解性最好,为10·01mg/mL,NaCl的浓度在0·4～0·6mol/L时,蛋白质溶解度随着NaCl的浓度增加而增大,最大值为9·39mg/mL。但是NaCl的浓度再增加蛋白质溶解度反而降低。而CaCl2溶液浓度在0·6mol/L时溶解度最大,为9·12mg/mL。后随着CaCl2浓度的增大蛋白质溶解度下降。NaCl和CaCl2共存,能够促进HSZZSP的溶解,并在一定浓度后变化趋于平缓。     

Solubility and emulsifying properties of barley protein concentrate

Protein concentrates were produced from the flours of two barley cultivars (Bülbül and Tokak) by alkaline extraction procedure. The flour samples and their protein concentrates were examined by SDS-PAGE. Solubility properties of protein concentrates were investigated as a function of pH, NaCl concentration and protein concentration, whereas emulsifying properties were determined as a function of pH and protein concentration. The highest solubility was observed in water among the solvents studied, especially at pH values of 2, 10 and 11 as compared to the other ones. A decrease in solubility was determined with increasing ionic strength of NaCl solutions. The results suggested that emulsifying behavior of protein concentrates generally resembled their solubility behavior in water. Minimum solubility and emulsifying values were observed at pH 6, which is close to the isoelectric point of barley proteins. Both of these functional properties were improved below and above the isoelectric pH.     

Effect of pH and heat treatment of cheese whey on solubility and emulsifying properties of whey protein concentrate produced by ultrafiltration

The effects of pH and heat treatment of cheese whey on protein solubility (PS) at pH 4.6 and on emulsifying properties of whey protein concentrate (WPC) were studied by response surface methodology (RSM). PS followed a quadratic relationship with pH and a linear relationship with heat treatment. Highest values for PS were found between pH 6.0 and 6.6 with heat treatment at 68 °C for 2 min, and maximum solubility was reached at pH 6.3. Heat treatment strongly decreased protein solubility throughout the entire pH range. The emulsifying properties were notably benefited by raising the pH from 6 to 7, best values being shown at pH 7 with a heat treatment of 70 °C for 2 min. The effect of heat treatment on the emulsifying properties was dependent on the pH level. At about pH 7, the heat treatment adversely affected the emulsifying properties, probably due to excessive protein denaturation.     

超声处理对绿豆分离蛋白乳化性的影响

研究超声处理对绿豆分离蛋白乳化性的影响,对不同超声功率、超声时间、底物蛋白浓度对绿豆分离蛋白乳化性的影响进行分析,并通过响应面实验,最终得到超声处理提高绿豆分离蛋白乳化性的最佳条件。结果表明,超声处理提高绿豆分离蛋白乳化性的最佳条件为:超声功率410 W、超声时间10.5 min、底物蛋白浓度11.5%。该处理条件下得到改性后的绿豆分离蛋白乳化性为35.01 m2/g。      

Studies on antioxidant activities of mucuna seed (Mucuna pruriens var utilis) extract and various non‐protein amino/imino acids through in vitro models

The antioxidant activities of a methanolic extract of mucuna beans (Mucuna pruriens var utilis) and several non‐protein amino/imino acids, namely L ‐3,4‐dihydroxyphenylalanine (L ‐dopa), L ‐3‐carboxy‐6,7‐dihydroxy‐1,2,3,4‐tetrahydroisoquinoline (compound I), (?)‐1‐methyl‐3‐carboxy‐6,7‐dihydroxy‐1,2,3,4‐tetrahydroisoquinoline (compound II) and 5‐hydroxytryptophan (5‐HTP), were evaluated. By virtue of their hydrogen‐donating ability, all the tested compounds and the mucuna seed extract showed excellent reducing power, with the highest values being recorded for L ‐dopa in a dose‐dependent manner. Similarly, as compared with synthetic antioxidants (BHT and BHA) and quercetin, all the tested compounds and the seed extract were found to be more potent in free radical‐scavenging activity (P < 0.05) against α,α‐diphenyl‐β‐picrylhydrazyl (DPPH^?) radicals. Hydroxyl radicals (OH^?) and superoxide anion radicals (O₂^??) were effectively scavenged by the tested compounds, with the exception that no scavenging activity of 5‐HTP was observed on (O₂^??) up to a concentration of 2 mg ml^?1, as was also the case for BHA. Among the tested non‐protein amino/imino acids and seed extract the highest peroxidation‐inhibiting activity (95%) was recorded for 5‐HTP. On the other hand, in the linoleic acid/β‐carotene‐bleaching system, L ‐dopa, compound I and compound II acted as pro‐oxidants, whereas the seed extract showed only weak antioxidant activity as in the linoleic acid emulsion system. Copyright © 2003 Society of Chemical Industry     

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 (M ucuna 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.     

利用固定化酶改善酸法大豆浓缩蛋白持水性和吸油性的研究

利用固定化谷氨酰胺转胺酶(MTG)对酸法大豆浓缩蛋白(SPC)进行改性,并对改性SPC进行红外光谱分析。通过单因素和正交实验研究了MTG改性对SPC持水性和吸油性的影响。结果表明,当固定化MTG添加量1U/g,pH6.0,50℃下反应2h时,改性后大豆浓缩蛋白的持水性和吸油性分别比对照提高了24.8%和64.5%;与大豆分离蛋白相比,其凝胶性和吸油性分别高出58.3%和27.0%,持水性则低8.0%。     

磷酸化共价交联条件对大豆浓缩蛋白持水性的影响

醇法大豆浓缩蛋白生产过程中由于醇的变性作用导致其持水性较差,相较于酸法大豆浓缩蛋白持水性545.00%,醇法大豆浓缩蛋白持水性只有425.40%。本实验以提高醇法大豆浓缩蛋白持水性为目的,采用三聚磷酸钠对醇法大豆浓缩蛋白进行磷酸化共价交联,并研究磷酸化共价交联改性过程中,大豆浓缩蛋白添加量、三聚磷酸钠添加量、温度、反应时间、pH对持水性的影响。实验表明,磷酸化共价交联能够改善醇法大豆浓缩蛋白持水性,最适改性条件为:大豆浓缩蛋白与三聚磷酸钠添加量比值为9.33%∶9.55%、反应温度66℃、反应时间283min、pH为8.8,磷酸化共价交联后浓缩蛋白持水性提高了94.18%,经过本实验改性的醇法大豆浓缩蛋白有利于应用在肉制品中。     

Changes in physicochemical and functional properties of whey protein concentrate upon succinylation

The highest degree of succinylation was achieved at the level of 6 moles of succinic anhydride/mole of lysine in whey protein concentrate (WPC). Structural modification of protein or the presence of a high negative charge on the surface of protein upon succinylation exposed buried hydrophobic sites. The solubility of succinylated protein derivatives increased at alkaline pH but decreased at acidic pH values as compared to native WPC. The physicochemical properties of succinylated protein derivatives, such as water– and oil– binding capacity, viscosity and emulsion properties increased significantly (P < 0.05) compared to native WPC, whereas, foaming stability reduced significantly (P < 0.05) and there was no change in the foaming capacity.     

多糖对大豆蛋白在水相介质中乳化特性的影响研究

主要研究多糖对大豆蛋白在水相介质中的乳化特性的影响,研究结果表明,黄原胶与CMC能显著提高大豆分离蛋白的乳化活性和乳化稳定性,果胶与海藻酸钠次之,阿拉伯胶与卡拉胶对乳化特性没有改善;大豆分离蛋白与黄原胶在广泛的pH范围内表现出良好的乳化活性和乳化稳定性,氯化钠浓度在0～1.0mol/L的范围内,也表现出良好的乳化特性;在豆奶模拟体系中,在总胶用量为0.05%,黄原胶与CMC的配比为3∶2时,能使豆奶中的蛋白质稳定下来。     

The amino acid composition,solubility and emulsifying properties of sweet potato protein

A protein was purified from the high-protein type sweet potato variety 55-2 available in China. The amino acid composition, solubility and emulsifying properties of the sweet potato protein (SPP) were studied. The SPP was rich in aspartic acid (18.5%) and glutamic acid (9.30%) while essential acid amino acids made up approximately 40.7% of the SPP. The SPP was highly soluble in distilled water over a wide range of pH. However, solubility of the SPP in 1.0 M NaCl and 1.0 M CaCl₂ solutions was low especially at pH below the pI of the SPP. The SPP in CaCl₂ demonstrated emulsifying activity index (EAI) and emulsion stability index (ESI) many folds higher than those in distilled water and NaCl solution (P < 0.05).     

微波对醇法大豆浓缩蛋白乳化性的影响

为改善和提高醇法大豆浓缩蛋白的乳化功能特性,采用微波对醇法大豆浓缩蛋白进行改性,并以微波功率、改性时间、均质时间、pH、料液比、溶液质量、NaC l浓度及不同种类盐为改性影响因素,研究了其对改性蛋白乳化性的影响。结果表明,当蛋白浆液处理量为55 g,均质6 m in,微波功率640 W,改性时间1.5 m in,料液比1∶9(W/V),pH为9时,可使乳化能力达到96.9%。     

Improvement of the water solubility and emulsifying capacity of rice proteins through the addition of isolated soy protein

The market for rice protein (RP) has been steadily growing, but applications of RPs as food ingredients and functional materials are limited due to poor solubility in water. Here, the complex of RP and isolated soy protein (ISP) was prepared, and the potential utility of RP–ISP complex as an emulsifier was evaluated. The solubility of the RP solution was 25.8% whereas it was greatly increased to 68.4% in the RP–ISP complex. The properties of RP and RP–ISP complex were assessed by scanning electron microscope, gel electrophoresis, circular dichroism, and surface hydrophobicity test. Next soybean oil emulsions were prepared using the RP and RP–ISP complex. The RP-stabilised emulsion was unstable to storage. In contrast, the RP–ISP complex-stabilised emulsions showed good stability, especially when more than 0.2% ISP was added. These data suggest that the preparation of soluble RPs by ISP could expand the applications of RP in the food industry.