Development and Physicochemical Characterization of New Resistant Citrate Starch from Different Corn Starches

Resistant starch has drawn broad interest for both potential health benefits and functional properties. In this study, a technology was developed to increase resistant starch content of corn starch using esterification with citric acid at elevated temperature. Waxy corn, normal corn and high‐amylose corn starches were used as model starches. Citric acid (40% of starch dry weight) was reacted with corn starch at different temperatures (120–150°C) for different reaction times (3–9 h). The effect of reaction conditions on resistant starch content in the citrate corn starch was investigated. When conducting the reaction at 140°C for 7 h, the highest resistant starch content was found in waxy corn citrate starch (87.5%) with the highest degree of substitution (DS, 0.16) of all starches. High‐amylose corn starch had 86.4% resistant starch content and 0.14 DS, and normal corn starch had 78.8% resistant starch and 0.12 DS. The physicochemical properties of these citrate starches were characterized using various analytical techniques. In the presence of excess water upon heating, citrate starch made from waxy corn starch had no peak in the DSC thermogram, and small peaks were found for normal corn starch (0.4 J/g) and Hylon VII starch (3.0 J/g) in the thermograms. This indicates that citrate substitution changes granule properties. There are no retrogradation peaks in the thermograms when starch was reheated after 2 weeks storage at 5°C. All the citrate starches showed no peaks in RVA pasting curves, indicating citrate substitution changes the pasting properties of corn starch as well. Moreover, citrate starch from waxy corn is more thermally stable than the other citrate starches.     

Physicochemical and Functional Characterization of Baby Lima Bean (Phaseolus lunatus) Starch

One potential source of starch is the tropical legume baby lima bean (Phaseolus lunatus) that contains around 56—60% of starch. The objectives of this work were to evaluate this starch's physicochemical and functional properties and compare it with the properties of other starches. The chemical composition of lima bean starch was: 10.16% moisture, 0.20% protein, 0.67% fiber, 0.14% ash, 0.54% fat, 98.43% starch and 0.013% phosphorus. The amylose content was higher (32.7%) than that of other cereal and tuber starches but similar to other legume starches. The average granule size (diameter 17.9 μm) was comparable to that of corn starch and of other legume starches. The granule was heterogeneous, presenting an oval shape. The gelatinization temperature was 80.16 °C (range 75—87 °CC), which is similar to other legume starches but higher than that of corn starch. The molecular size (alkali number 3.22), was smaller than that of potato starch but similar to that of corn starch. Compared to corn starch, the gels were firmer and presented a higher degree of retrogradation even at high concentrations. The water solubility was positively correlated with the temperature: i.e., 1.8, 3.4, 8.5 and 12.3% at 60, 70, 80 and 90 °C, respectively. The swelling power had the same behaviour: 2.6, 3.3,12.8 and 19.9 g of water/per gram of starch at 60, 70, 80 and 90 °C, respectively. The amylogram showed that the viscosity (680 Brabender units) and stability were higher than those of commercial corn starch (252 Brabender units). The use of this starch in the preparation of syrups with high glucose contents, as well as in baked and canned products that require heating, is suggested.     

Glucose Production from Treated Sago Starch Granules by Raw Starch Digesting Amylase from Penicillium brunneum

Several microorganisms have been found to produce raw starch digesting amylase. We have isolated Penicillium brunneum from sago palm tree at a sago processing site, which was used as a source of starch digesting amylase. All the raw starch digesting enzymes were effective for cereal starches, but root starches and sago starch were resistant to the enzyme reaction. Treatment of sago starch by heating to temperature below gelatinization temperature at lower pHs resulted in an increase in the ability of enzyme to digest sago starch granules. Heating to 60°C at pH 2.0 resulted in a conversion rate of sago starch granules to glucose near to the conversion rate of raw corn starch to glucose. At higher concentration, the degree of hydrolysis of treated sago starch granules was about 275% as compared to that of untreated sago starch granules. Addition of the enzyme in large amount or small portion at various time intervals was found effective in the hydrolysis of treated sago starch granules.     

Characterization of Starch Isolated from Plantain (Musa paradisiaca normalis)

Starch isolated from unripe plantain (Musa paradisiaca normalis) was evaluated for their chemical, physical, physicochemical, rheological and morphometric characteristics. The average yield of starch was 10–12%, the granules were irregularly shaped and the size varied from 10 to 50μm. The average chemical composition (% of dry matter) of the starch was as follows: crude fat 0.09, crude fiber 0.26, ash 0.02, and total sugar 0.03 (as non reducing sugar). Excluding crude fiber content all these characteristics were smaller than those of commercial corn starch. The pH of both starches ranged from 5.6 to 6.7, while acidity contents were 0.010 and 0.012 for corn and plantain starch, respectively. Absolute density, gel consistency, color and syneresis were similar in both starches, while the reducing value and gel strength were higher in plantain starch than in corn starch. Except for the initial gelatinization temperature, all the rheological parameters of plantain starch also were higher than those of corn starch.     

Morphological,Thermal, Pasting,and Rheological Properties of Barley Starch and Their Blends

Native barley starch, as well as its blends with corn, wheat, and rice starch at different ratios of 75:25, 50:50, 25:75 were examined in terms of morphology, thermal, pasting, rheological, and retrogradation properties. Amylose content varied between 10.9–41.4% in rice, corn, wheat, and barley while it ranged from 18.02–38.40% in blends of barley starch with rice, corn, and wheat. A rapid visco analyzer showed that barley starch and its blends having low amylose content exhibited higher peak viscosity, breakdown, and setback than the high-amylose-containing starches and their blends. Amylose content was found to be negatively correlated with swelling power while it exhibited nonlinear relationship with solubility index. The transmittance of starch suspension stored at 4°C decreased during storage up to 6 days. Barley starch granules were largest (<110 μm) in size followed by wheat (<30 μm), corn (<25μm) and rice (<20μm) starches. Gelatinization temperatures (To, Tp, Tc) and enthalpies of gelatinization (ΔHgel) of starches from different sources also differed significantly. Corn and rice starches showed higher transition temperatures in general than those from wheat and barley; however, they showed higher ΔHgel values. Barley starch showed a higher tendency towards retrogradation than the cereal starches. Barley starch showed highest peak G′, G″ and lower tan Ð than corn, rice and wheat starches during the heating cycle. This study showed that the magnitude of changes in their properties during blending depends on the amylase content and morphological characteristics.     

Characterization of Phosphate Monoester Resistant Starch

The properties and structures of corn, wheat, and potato native starches and their phosphate monoester resistant starches were tested and compared. The results indicated that the resistant starch content, light transmittance, and freeze-thaw stability of the phosphate monoester resistant starch increased after modification. The native starches exhibited much higher peak viscosities compared with resistant starch (RS) and phosphate monoester resistant starches. The phosphate monoester resistant starch from corn and wheat starch exhibited a higher peak and final viscosity and lower gelatinization temperatures compared with the resistant starch, while the peak and final viscosity of the potato phosphate monoester resistant starch samples were lower than that of potato resistant starch. In the FT-IR graph, a new peak at 1244 cm^?1 (P=O bond) was observed for all kinds of phosphate monoester resistant starch.     

Thermal Conductivity of Starch Granules

Data were obtained at 25°C on thermal conductivities of slurries of starch in a carbon tetrachloride-ethyl benzene mixture having a density equal to that of the starch. The thermal conductivity of granular ordinary corn starch was estimated to be 0.125 B.t.u.-foot per hour-foot^2-0 F by calculation and by extrapolation from the slurry data. The thermal conductivities of granular corn starches decreased with increasing amylose content.     

Physicochemical,Pasting, Thermal and Morphological Characteristics of Indian Water Chestnut (Trapa natans) Starch

Starch extracted from Indian water chestnut was investigated for its physicochemical characteristics. The results were compared with those obtained from two commercial starches (corn and potato). The pasting properties were tested in the Rapid Visco Analyser and thermal properties with a differential scanning calorimeter. Water chestnut starch possessed higher breakdown viscosity (BV) and setback viscosity (SV) than corn and potato starches. However, the pasting temperature of water chestnut starch was not significantly different from that of corn starch. Lower ΔH_gel values were obtained for water chestnut starch than for the other two starches whereas the onset, peak and conclusion temperatures of gelatinization (T_o, T_p and T_c) for water chestnut starch were quite comparable with corn starch. Scanning electron micrographs showed similarity in starch granule shape between water chestnut and potato starch with corn starch showing surface wrinkles on starch granule surfaces.     

不同蜡制玉米淀粉对肌原纤维蛋白凝胶特性的影响

将蜡制玉米淀粉、酯化蜡制玉米淀粉和交联酯化蜡制玉米淀粉以添加量分别为0%、2%、4%、6%、8%、10%添加到肌原纤维蛋白中,形成蛋白淀粉复合物,研究3?种淀粉对肌原纤维蛋白凝胶保水性、质构特性、白度值、表面疏水性、流变特性和微观结构的影响。结果表明,相比纯肌原纤维蛋白,淀粉均能显著提高复合凝胶的保水性、硬度和弹性（P＜0.05）,且随添加量的增加而显著增加（P＜0.05）,但在添加量为10%时,各指标上升不显著（P＞0.05）,其中交联酯化蜡制玉米淀粉效果最好;3?种淀粉均能增加复合凝胶的白度值,但交联酯化蜡制玉米淀粉的添加会使复合凝胶的白度值过大（P＜0.05）,对色泽不利;同时,淀粉能显著提高复合蛋白的表面疏水性和凝胶的弹性模量（P＜0.05）,且随着添加量的增加而显著增加（P＜0.05）,与肌原纤维蛋白凝胶相比,复合凝胶结构趋于致密均匀。在实验的3?种淀粉中,除色泽因素外,交联酯化蜡制玉米淀粉提高凝胶性能的效果要优于其他两种淀粉。?     

Isolation of Velvet Bean (Mucuna pruriens) Starch: Physicochemical and Functional Properties

The velvet bean (Mucuna pruriens) is an excellent potential starch source as it contains approximately 52 % of this carbohydrate. The physicochemical and functional properties of velvet bean starch were evaluated and compared to those of other starches. The chemical composition was: moisture 10.78 %; solid matter: protein 0.71 %; fiber 0.54 %; ash 0.28 %; fat 0.40 %; starch 98.1 %; and phosphorus 0.015 %. Amylose content was higher (39.21 %) than in tuber and cereal starches but similar to other legume starches. Average granule size was 23.6 μm, granules having an oval shape. Paste properties were: gelatinization temperature, 74.82 °C; gelatinization temperature range, 70—80 °C; and alkali number, 3.22. Gels produced with velvet bean starch were firmer than those produced with corn starch, and had a higher degree of retrogradation, even at high concentrations. At 90 °C, solubility was 16.2 % and swelling power was 16.17 g of water/g of starch. Given these properties, velvet bean starch has potential applications in food products requiring high temperature processing, such as jams, jellies and canned products.     

Gel Textural Characteristics of Corn,Cassava and Yam Starch Blends: A Mixture Surface Response Methodology Approach

Blends of native starches can be used to obtain special sensory properties avoiding the use of chemically modified starches. The mixture design approach was used to analyze the textural properties (hardness, adhesiveness, cohesiveness and gumminess) of gels obtained with different proportions of yam, corn and cassava starches (6% total solids) and related to microstructural characteristics. Maximum limits of 60% yam starch and 70% corn starch and minimum level of 30% cassava starch were fixed to minimize syneresis under storage. Hardness, adhesiveness and gumminess increased with the proportion of corn starch in the blends. The lowest values of hardness corresponded to the blends containing higher proportions of cassava starch, that has the lowest amylose content. Corn starch was the component that less contributed to cohesiveness. The characteristic high cohesiveness of cassava starch pastes (related to its higher amylopectin content) was reduced when it was mixed in adequate proportions with yam and/or corn starches. Gels containing only yam starch presented syneresis values close to 40% after 24° h storage at 4°C; the decrease of the maximum level of yam starch to 60% as well as the inclusion of cassava starch in the blends reduced weight losses. Disadvantages found in gels containing individual starches, such as exudate in yam and corn starch gels, and excessive cohesiveness in cassava starch gels, are minimized improving their possible applications, when blends are used.     

Properties of Cast Films Made of HCl‐Methanol Modified Corn Starch

The molecular and physicochemical properties of the studied starches modified with 0.36% HCl in methanol at 25 °C and 45 °C were related to the film properties of these starches. The weight‐averaged molecular weight (M_w) and the number of long‐chain branches (DP 13‐36) of HCl‐methanol modified starch decreased with increasing degree of acid modification, but the number of short‐chain branches (DP < 6) increased. HCl‐methanol modification significantly decreased the ghost formation in gelatinized starch dispersions and the viscosity of starch film‐forming dispersions. Thus, the homogeneity of the produced starch films was improved and their opacity reduced. Proper HCl‐methanol modification produced corn starch films with lower moisture absorption rate and maximum moisture content under high relative humidity (RH = 97%) condition.     

酸解对不同链/支比含量玉米淀粉特性的影响

以4种不同链/支比含量的玉米淀粉为原料,酸解处理不同时间,以酸解玉米淀粉的形貌特性、冻融稳定性、膨胀度、溶解度、晶体性质为指标衡量不同酸解时间对玉米淀粉结构性质的影响。结果表明:4种玉米淀粉酸水解程度的顺序为:蜡质玉米普通玉米淀粉G50G80。酸解后,同品种的4种玉米淀粉的析水率随着酸解天数的增加而增加;溶解度增加,膨胀度降低。酸解并未改变淀粉的晶型,随着酸解时间的延长,蜡质玉米淀粉和普通玉米的相对结晶度先增大后保持不变,G50和G80的相对结晶度随着酸解时间的增加而增大。表明酸解对低直链淀粉(蜡质玉米淀粉和普通玉米淀粉)的结构、性能影响最大。     

Facile Preparation of Starch Triacetates

Commercial high-amylose corn, ordinary corn and potato starches were fully acetylated by reacting the starches at 123°C for 5 h in fourfold quantities of acetic anhydride to which 11% (w/w starch) of sodium hydroxide catalyst had been added as 50% aqueous solution. Intrinsic viscosities of the starches regenerated from their esters were slightly lower than the values for the corresponding unreacted starches and indicated that only minor degradation hat occurred during acetylation. Amylose obtained by the butanol fractionation of corn starch was also readily acetylated by this procedure. However, commercial potato amylose required removal of the small amount of magnesium sulfate present to achieve both full acetylation (44.8% acetyl) and minimum depolymerization of the starch.     

Physical Properties of Starch from Cavendish Banana Fruit

Starch was isolated from green Cavendish bananas after sodium hydroxide treatment, and its physical properties as they affected its potential acceptance as a food ingredient were measured and compared with those of corn, waxy corn, waxy corn diphosphate, acetylated waxy corn diphosphate, potato, and tapioca starches. Banana starch granules had a moisture content of 15.5%, an amylose content of 19.5% on a dry weight basis, and were highly irregular in shape and size, with the mode of characteristic length falling at 15 μm. The gelatinization range was 70.1 °C to 74.6 °C. Scanning electron micrography showed that in water the granules underwent surface cracking at 65 °C and progressively greater swelling, deformation, and erosion between 70 °C and 90 °C. At 95 °C, 6% banana starch paste in a Brabender Amylograph had a viscosity four times that of corn starch paste of the same concentration, and viscosity decreased rather slowly with stirring. The paste was somewhat longer than that of corn starch, but appreciably shorter than tapioca starch paste. Gelled banana starch was nearly as strong as corn starch, and also was nearly as opaque and reflective.     

Physical Properties of Starch from Two Genotypes of Amaranthus cruentus of Agricultural Significance in China

Starches were isolated from the two genotypes of Amaranthus cruentus most widely cultivated in China, R104 and K112. These starches, plus a corn starch standard were mixed with either distilled water or a 1% NaCl solution and characterized for gelatinization parameters by Differential Scanning Calorimetry (DSC), pasting properties using a Rapid Visco-Analyzer (RVA), and texture of the cooled gels. Significant findings were: 1. A. cruentus starches had higher gelatinization temperature and higher endothermic energy than corn starch; 2. Wide differences in pasting properties were found between the two A. cruentus genotypes, although the waxy line R104 had lower hot-paste viscosity and set-back than K112; 3. The pasting properties (peak viscosity and set-back), of K112 were similar to those of corn starch. 4. In 1% NaCl solution, compared to distilled water, corn starch set-back decreased while that of the A. cruentus starches increased. Where Amaranthus starch is to be used in food processing applications, careful selection of genotype is necessary to achieve desired functionality.     

Effect of Acid Hydrolysis and Ball Milling on Porous Corn Starch

Porous corn starch from glucoamylase hydrolysis of native corn starch was examined before and after cross-linking, acid hydrolysis and dry ball milling. Cross-linking does not significantly change the crystallinity, water absorption or gelatinisation properties but acid hydrolysis at 60°C increases, proportionately, crystallinity and water absorption capacity and decreases moisture adsorption at humidities less than 80%, in comparison to untreated porous corn starch. Highly crystalline porous starch has a fragile granule structure. Ball milling destroys crystallinity in both normal, porous, and cross-linked or partially hydrolyzed starches. Particle sizes of 1–2m are obtained by milling dry starches for 48 h. Water absorption for milled starches is more than 200% (weight water/weight starch d.b.). Viscosities of these products were significantly reduced at high temperatures. Products formed stable gels in 25–30% dispersions in cold water.     

玉米淀粉与玉米变性淀粉性质比较研究

测定了玉米淀粉、羟丙基淀粉、羧甲基淀粉、淀粉磷酸酯的冻融稳定性、透光率、膨胀度、粘度、糊化特性等主要物理性质并进行了比较。试验结果表明：变性淀粉与玉米淀粉的性质不同，由于变性淀粉引进了羟丙基、羧甲基、磷酸基团等亲水性基团，使淀粉极性增强，亲水能力增大，使其都具有较强的冻融稳定性、抗凝沉性，较高的膨胀度、透明度，因此变性淀粉具有更广阔的应用性。     

Degradability of Different Phosphorylated Starches and Thermoplastic Films Prepared from Corn Starch Phosphomonoesters

Different starch types (corn, rice, potato, corn amylose and corn amylopectin) were phosphorylated to varying degrees of substitution (DS) and tested both for acid hydrolysis during 3 h in a boiling bath and for enzymatic hydrolysis with a thermostable bacterial α‐amylase (Bacillus licheniformis) for 30 min at 95 °C. Generally, phosphorylated starches showed a reduced degree of acid hydrolysis during the entire time of hydrolysis (3 h) as well as reduced susceptibility to α‐amyIase hydrolysis. The enzyme action was inhibited by the presence of phosphate groups in the modified starch molecules and the extent of inhibition increased with increasing degree of phosphate substitution, regardless of the starch type. Thermoplastic films were fabricated by blending modified corn starches of different DS with polyacrylate, urea and water at a ratio of 4:5:1:50, heating for 30 min at 95 °C before casting and allowing to cool, stand and dry at room temperature. The plastic films prepared from phosphorylated corn starch showed both higher disintegration rate and a greater degradability by thermostable bacterial α‐amylase than the ones prepared from non‐phosphorylated starch. These new acquired properties can meet the increasing demand for biodegradable disposable plastic bags.     

Physicochemical,Morphological, Pasting,and Rheological Properties of Tamarind (Tamarindus indica L.) Kernel Starch

Starch was isolated from tamarind kernels, which are at present considered as waste. It was compared with corn and mung bean starch for its physicochemical, rheological, and morphological properties. Tamarind kernel starch showed significantly lower amylose content, light transmittance, solubility, and higher swelling power in comparison to corn and mung bean starch. The micrographs of tamarind kernel starch revealed its small oval shape granules with smooth surfaces. X-ray diffraction pattern of tamarind kernel starch was similar to corn starch with strong diffraction peaks at 15, 17, and 23° (2θ). Changes in storage modulus (G?), loss modulus (G??), and loss tangent (tan δ) during heating of starches showed the lowest peak G? for tamarind kernel starch, whereas the highest was observed for corn starch. Changes in G? and G?? during cooling, holding and subsequently heating were also studied. The frequency dependence of G? and G?? of starches measured at 25 and 95°C revealed their weak gel behavior. During cooling tamarind kernel starch showed lower increase in G? in comparison to other starches. Tamarind kernel starch was different from corn and mung bean starch in exhibiting highest peak, breakdown, and lowest setback viscosity. Tamarind seeds have potential as a relatively new, cheap, and underutilized source of starch in food applications.