Morphology and structure of chestnut starch isolated by alkali and enzymatic methods

The structure and morphology of starch from fruits of two chestnut (Castanea sativa Mill.) varieties, Martainha and Longal, isolated by alkaline (A3S) and enzymatic (ENZ) methods were assessed. Chestnut starch granules were found to be round and oval in shape, consisting of medium/small granules, with a mean granule size ranging between 9 and 13 μm. Isolated chestnut starch appeared to the naked eye as a white powder, with high values of L^∗, and the Longal variety produce starches duller than Martainha. No differences between samples were observed by FTIR analysis. The X-ray patterns of isolated starches are of C-type (more specifically of C_b type) with a relative crystallinity between 31.5% and 39.8%. The ¹³C CP/MAS NMR spectra are similar for both varieties but different for the used isolation methods. The amorphous phase in the starch granules isolated by A3S methods was lower than that of the starch extracted by the ENZ method, making the B-type allomorph in the C-type starch granules more evident than in the A-type. Those differences in the structure of isolated starches are shown by a lower degree of damage, and a higher level of crystallinity of starches isolated by the A3S method, which means that its original structure is less affected or partially destroyed. This study would be helpful to better understand the relationships among structure and functional properties for a eventual industrial application of chestnut starches.     

Physicochemical properties of starch isolated from Antiaris africana seeds in comparison with maize starch

Antiaris africana seeds yielded 29.6% starch which showed appreciable high contents of ash, protein, and fat. The average diameter of A. africana starch granules was 3.98 µm compared to 8.93 µm for maize starch. A. africana starch had a C‐type XRD pattern and crystallinity of 41.5%. A. africana starch had higher AM content (24.1%) than maize starch (20.9%). The gelatinization onset temperature of A. africana starch (66.7°C) was higher than maize starch (63.1°C), but its gelatinization temperature range (8.57°C) and enthalpy (13.97 J/g) were lower than the values for maize starch (14.02°C, 14.65 J/g). The pasting temperature (P_t) and setback (V_s) were lower and breakdown (V_b) higher for A. africana starch (P_t = 82.5°C, V_s = 173.8 RVU, and V_b = 121.42 RVU) than for maize starch (P_t = 84.9°C, V_s = 183.73 RVU, and V_b = 78.58 RVU). The GPC analysis gave M_w of 2.18 × 10⁷ g/mol and radius of gyration of 95.1 nm for Antiaris starch. Antiaris starch paste exhibited poor freeze‐thaw stability but its small granule size indicates potential for application as dusting starch.     

Use of triticale flours in cracker-making

In general, triticale is not a good raw material for bread making. However, some varieties produce flours of good quality for cookie production. It is a well-known fact that cracker quality depends on the flour used for cracker production. All over the world, a blend of hard and soft wheat is used; however, the use of soft flour is recommended. Since additional soft wheat cultivation is not allowed in Argentina, triticale represents a good alternative for cracker production. In the present study 15 triticale cultivars and a flour of optimum cracker quality were used to produce crackers in order to establish criteria to evaluate flour quality in cracker-making. The factors that determine cracker quality, as well as the relationships between different quality parameters were investigated. Electrophoretic patterns of triticale proteins extracted from flours were determined. Five cultivars produced crackers of similar quality to that of standard flour of industrial good quality. A protein band with a 110 kDa molecular mass influenced flour quality, measured as the ratio of the mean between weight and length, WL and the height of ten crackers (H₁₀), WL/H₁₀, while other flour constituents such as pentosans, soluble proteins and damaged starch could affect its weight.     

Rheological properties of starches from grain amaranth and their relationship to starch structure

Amaranth starch (Amaranthus cruentus L. and Amaranthus hypochondriacus L.) in this investigation possessed a relatively small and uniform granule size of a type “A” pattern obtained by X‐ray diffraction, with the degree of crystallinity ranging from 24.5 to 27.9%. This was followed by work on steady and dynamic rheological properties on shear of seven native amaranth starches. Aqueous pastes (5% solids) exhibited shear‐thinning behavior, and the flow behavior was fitted with the Herschel–Bulkley equation (regression coefficients were over 0.99). Cultivar V69 showed much higher G′ (storage modulus) and G″ (loss modulus) than the other samples and produced a solid‐like gel, which could be attributed to the high amylose content of its network. Correlation analysis revealed that amylose content was positively correlated with G′ and negatively with the loss tangent (tan δ) of the material.     

Characteristics of pores in native and hydrolyzed starch granules

Low‐temperature nitrogen adsorption and mercury porosimetry were applied for analyzing effect of α‐amylolysis upon the porosity of granules of native corn, wheat, rice, and potato starches. Specific surface area (S_BET), porosity, pore size distribution, total pore area, and mean pore radius were determined for native and digested granules. It was found that native starch granules are macroporous materials with a small participation of mesopores. In the case of native starches, the highest value of S_BET was obtained for rice starch (1.27 m²/g) and the lowest – for potato starch (0.14 m²/g). Pore size distribution curves obtained by nitrogen adsorption showed peaks in the range of diameters 2–3 nm (for all starches) and 100–200 nm (for corn and rice starches). After 60 min of enzyme action, surface area of all starches doubled in comparison to native ones. Arising of the new pores was also noted. The results of mercury porosimetry measurements showed that rice starch had the highest total area of pores and porosity but the lowest mean pore radius among all native starches. The pore size distribution curves for all starches exhibited solely one peak corresponding to the dominant group of pores of the radii in the range 0.5–8 µm, dependent on the starch source. There were also much smaller peaks situated within the range of 3–30 µm. After α‐amylolysis of corn and rice starches, the average radius of the dominant group of pores diminished. No substantial changes in the pore radii could be noted for potato starch.     

Relationships between amylopectin internal molecular structure and physicochemical properties of starch

BackgroundStructure-property relationships of starch components remain a subject of research interest. In recent years, there has been increasing evidence revealing the importance of amylopectin internal structure in determining physicochemical properties of starch. The part between the sole reducing end and out branches of amylopectin forms the internal part of the molecule. It contributes to the formation of the amorphous lamellae of the granules.Scope and approachThis mini-review focuses on the impact of amylopectin internal molecular structure on different physicochemical properties of starch. The properties include gelatinization, swelling power, amylose leaching, pasting, retrogradation, and digestibility of starch. The statistical approach to analyze the structure-property relationships of starch is also discussed. Related nomenclatures are described.Key findings and conclusionsAmylopectin with a longer internal chain length tends to give more ordered packing of double helices in the granules with a higher thermal stability. A longer internal chain length of amylopectin also contributes to the formation of recrystallized amylopectin with a more ordered structure and higher thermal stability. The results summarised in this mini-review clearly show that the molecular structure of amylopectin internal part should be considered in order to better understand the complex structure-property relationships of starch components.     

Extraction and fractionation of alkylresorcinols from triticale bran by two-step supercritical carbon dioxide

Bran from triticale cultivars Ultima and Pronghorn and Canadian Prairie Spring (CPS) wheat were fractionated using a two-step sequential supercritical carbon dioxide (SC-CO₂) extraction technique with and without ethanol to selectively extract and enrich high-value alkylresorcinols (ARs). Pure SC-CO₂ (70 °C; flow rate 25 g/min; pressure 35 MPa), was used for the first extraction step. The non-polar lipids yield ranged from 3.08 to 3.26 g/100 g and they were composed mainly of C18:2 (33-41 g/100 g), C18:1 (15-21 g/100 g), C16:0 (15-19 g/100 g), and C18:3 (4-5 g/100 g) fatty acids. The second extraction step, performed on the bran remaining after the first extraction, was carried out with SC-CO₂ plus 0.5 mL/min ethanol (70 °C; flow rate 5 g/min; pressure 35 MPa). The resulting total polar lipid yield of bran samples ranged between 0.62 and 0.86 g/100 g and the main compounds present in the polar lipids were ARs. The total AR contents of triticale cv Ultima, wheat, and triticale cv Pronghorn were 70, 68 and 36 mg/100 g, respectively. Saturated and unsaturated AR homologues of C15:0, C17:0, C19:0, C19:1, C21:0, C21:1, C23:0 and C25:0 were detected in all samples. Over 98% of the triticale ARs and over 95% of the wheat ARs were extracted under the SC-CO₂ conditions used.     

国外燃料酒精和淀粉加工产品的生产和发展

为了减少对石油的依赖 ,把 12 %的无水酒精 (燃料酒精 )加入汽油 ,2 0 %于柴油中 ,此含氧汽油不再加入四甲基叔丁基醚 ,成为汽车排放废气污染环境少的绿色燃料。　　列举了北美 (美国和加拿大 )燃料酒精厂的规模 ,所用原料、厂址、原料和产品价格的变化。在世界范围内 ,主要产品 (如淀粉、果葡糖浆、酒精等化工产品 )的输出交易量     

Compositional changes in whole grain flours as a result of solvent washing and their effect on starch amylolysis

Whole grain flour is used most often as raw material for fuel alcohol production. However, the dry-milling process and the non-starch components of flours may impact the enzymatic hydrolysis of starch to glucose. The particle size distributions of flours prepared from whole grain triticale, barley, wheat and corn were determined and the effects of pre-washing with water, hexane, 100% ethanol or 50% ethanol on flour composition and the amylolysis of starch were studied. Scanning electron microscopy of the flours revealed that grinding grain to pass a sieve with an aperture size of 0.5 mm effectively released starch granules from endosperm cells. Pre-washing with water or 50% ethanol decreased the protein, phytic acid and total free phenolic contents of flours and, except for corn flour, increased starch content. Pre-washing with water reduced the ash contents of all flours, and reduced the ??-glucan content of barley flour by 98%. Pre-washing with hexane or 100% ethanol removed much of the lipid from the flours. Pentosan content was affected only slightly by any of the pre-washing treatments. Each of the pre-washings was associated with a significant change, positive or negative, in the extent of ??-amylolysis for one or more of the flours. The degree of ??-amylolysis in unwashed flours ranged from 22.4 to 26.1%, and from 21.6 to 28.1% in pre-washed flours, varying with flour source and solvent treatment. Pre-washing of flours increased the degree of hydrolysis achieved with sequential ??-amylase/amyloglucosidase treatment, with values ranging from 61.4 to 72.8% in pre-washed flours compared to 56.2-57.8% in unwashed flours. The highest degrees of hydrolysis were achieved with 50% ethanol pre-washing (72.4 and 72.8% for triticale and barley flours, respectively). The degree of ??-amylase/amyloglucosidase hydrolysis obtained for isolated starches ranged from 83.7 to 93.0%. This study demonstrated clearly that the partial removal of non-starch components from whole grain flours by solvent pre-washing enhanced the degree of amylolysis of starch.     

Quality characteristics of triticale malts and worts

Worts from triticale malts, in particular well modified malts, separated poorly from mashes. Worts prepared at 70° C had high viscosities (10–27 cSt) indicating that problems would occur during filtration in brewing. The viscosities of triticale worts were higher than those of worts from barley malts. In addition, worts from well modified malts were generally turbid. Proteinaceous material (partly degraded prolamins) was the primary cause of this turbidity. Although the degree of malt modification did influence the rate of wort separation, it had little effect on wort viscosity. High viscosity was caused by pentosans dissolved from the triticale malt during mashing. Oxidative gelation was not observed with these pentosans. Grains and malts were fractionated, and the high molecular weight fractions were analysed for their sugar and acyl components. All were rich in arabinose and xylose. There was a rough inverse correlation between the solubility of the poly saccharide fractions and the levels of substitution with acetyl and feruloyl residues. The poor wort separation from triticale malt grists appeared to be related to the particle size distributions, which were narrow. The sedimentation values of the grist ‘fines’ were high.     

Influence of electrolytes on the heat-induced swelling of aqueous dispersions of native wheat starch granules

The gelatinization of native wheat starch granules in some monovalent salt solutions (i.e. sodium and potassium chlorides and nitrates) was studied as a function of type and concentration of electrolyte by different techniques. The granular swelling at different temperatures was derived on a macroscopic scale from the swelling volume, whereas particle size analysis yielded information on a microscopic scale. Crosscorrelation revealed a close relationship between both approaches. Differential scanning calori-metry (DSC) indicated that all studied monovalent salts had a similar (protective) effect at 0.1 M concentration. However, at higher concentrations, a markedly different effect was observed for chlorides as compared to nitrates. A highly similar tendency was also observed from the gelatinised starch viscosity: whereas the consistency coefficient gradually decreased with increasing chloride concentration, it displayed a minimum value at low nitrate concentrations followed by a steady increase at higher concentrations. The sensitivity of the swelling of native wheat starch granules to ions could be explained from a combination of a general electrolyte effect at low concentrations and specific ion effects (in line with the Hofmeister anion series) at higher concentrations.     

淀粉对鸡蛋蛋白凝胶特性的影响

研究了几种淀粉对鸡蛋蛋白凝胶特性的影响,着重研究了绿豆淀粉对鸡蛋蛋白凝胶特性的影响,并在此基础上,研制出一种新型的速冻食品-甜蛋。     

马铃薯凝胶淀粉的理化特性研究

通过与玉米淀粉和马铃薯淀粉相比较,系统研究了马铃薯凝胶淀粉的理化特性,包括:粘度的测定;热糊与冷糊的稳定性;不同pH值及电解质(NaCl)和非电解质(蔗糖)存在下的粘度曲线;凝胶强度;冻融稳定性. 结果表明:马铃薯凝胶淀粉比天然淀粉具有优良的热糊与冷糊的稳定性,电解质(NaCl)和非电解质(蔗糖)的存在,对马铃薯凝胶淀粉的热糊与冷糊的稳定性基本上无影响,凝胶强度高,冻融稳定性好,尤其是耐酸性能强,可作为凝胶剂而广泛应用于各种食品加工体系。     

Physico‐chemical and functional properties of starch isolated from ginger spent

Studies were carried out on starch isolated from ginger spent, obtained after the extraction of oleoresin, to explore the possibility of its use as a food ingredient. AM content was found to be 25.5%. SEM showed the granules were disc‐shaped as well as ovoid with a smooth surface. The average granule size was 22.5 ± 3.5 µ in length and 16.9 ± 4.8 µ in width with thickness of ∼3 µ. Ginger spent starch exhibited a high gelatinization temperature (88°C), peak viscosity (678 Brabender units (BU)) and cold paste viscosity (777 BU). It also possessed low paste clarity and higher freeze–thaw stability. Dynamic rheological properties of ginger spent flour, measured using parallel plate geometry showed that the storage modulus (G′) increased and loss modulus (G″) decreased as a function of frequency. Starch from ginger spent flour with high gelatinization temperature and low in vitro starch digestibility (45%) is suitable to use for development of speciality food formulations.     

Molecular structure,rheological and thermal characteristics of ozone-oxidized starch

The effects of oxidation by ozone gas on the molecular structure, rheological and thermal properties of starch (corn, sago and tapioca) were investigated. Starch, in dry powder form, was exposed to ozone for 10 min at different ozone generation times (OGTs). Average molecular weight decreased in oxidized corn and sago starches but increased in oxidized tapioca starch. All oxidized starches exhibited non-Newtonian shear-thinning behaviour. Starch viscosity decreased drastically with increasing OGT. Young’s modulus for all oxidized corn and sago starch gels stored for 1 and 7 days at 4 °C increased significantly compared to unmodified starch. No differences were noted in gelatinization temperatures and gelatinization enthalpies of all oxidized starches compared to unmodified starch. Retrogradation enthalpy increased markedly in corn starch after 1 min OGT. These results show that the extent of starch oxidation varies among starches of different botanical origins under similar ozone treatment conditions.