Influence of pentosans on texture of starch gels during storage,and effects after enzyme treatment

The effects of commercial soluble (SAX) and insoluble (IAX) arabinoxylans (AX), and water extractable pentosans (WEP) from wheat doughs on texture profile analysis (TPA) of starch gels have been determined. Gels were also subjected to enzyme treatment with a amylase/pentosanase preparation, a lipase and their combination. SAX delayed starch gel aging and gave more cohesive and less elastic gels than starch, whereas IAX showed only a slight influence. With their combination the TPA of gels showed a predominant effect of SAX. The effect of enzyme addition was enhanced in presence of AX, but they did not improve the effect of AX without treatment. When WEP were used the addition of enzymes was more effective in delaying gel staling. Kinetics of aging depended on the type of AX present and the enzyme combination used to prepare the starch gels.     

Production and Size Distribution of Rice Maitodextrins Hydrolyzed from Milled Rice Flour using Heat-Stable Alpha-Amylase

Maltodextrins were produced from milled rice flour in a single-step process using a heat-stable α-amylase preparation. The starting solids content was 30% (w/w), and processing temperatures and times were varied between 70–97°C and 15–75 min, respectively. Optimum liquefied starch yields, which accounted for virtually all of the starch present, were obtained at temperatures of 80°C and above, but reducing sugars and DE values were highest at 70°C. Low molecular weight saccharide concentrations (DP 1–10) were greatest at 80°C. Because processing at temperatures of 90–97°C resulted in decreased levels of reducing sugars and DP 1–10 concentrations without providing a substantial increase in solubilized starch yields, it was concluded that rice maltodextrins could be most effectively produced at a processing temperature of 80°C.     

Effect of low molecular weight dextrins on gelatinization and retrogradation of starch

!-Amylases, usually added to bread recipes as anti-firming agents, are known to produce low molecular weight dextrins by starch hydrolysis. The influence of these compounds on the gelatinization and retrogradation of starch was studied by differential scanning calorimetry. Adding oligosaccharides to starch caused a delay in gelatinization, although its extent was not quantified. However, oligosaccharides of degrees of polymerization (DP) 3-5 reduced the enthalpy of the retrogradation endotherm, shown as the staling endotherm. The addition of gluten to starch and starch/oligosaccharide mixtures had no effect on the gelatinization and retrogradation of starch. The retrogradation of starch in dough samples was also analysed, after 'baking' in the calorimeter, to obtain additional information about starch retrogradation during storage. Oligosaccharides of DP 3-5 also reduced the enthalpy of the retrogradation endotherm. This work provides evidence that oligosaccharides influence starch changes during the baking and storage of bread. These effects could be considered as the mechanism by which the bacterial !-amylase reduces starch retrogradation and acts as an anti-firming agent.     

Effect of Pullulanase and α-Amylase on Hydrolysis of Waxy Corn Starch

Using commercial pullulanase, α-amylase and their mixture, partial hydrolysis of waxy corn starch was characterised for optimising production of maltodextrins free of D-glucose. Compared to pullulanase or α-amylase alone, the mixture of these two (simultaneous or successive addition) on the substrate enhanced the efficiency of maltodextrin turnover with low or traces of D-glucose production in a short time. D-glucose was removed from dextrins by membrane filtration and the yield of dextrin above DP6 was 60–65%.     

Influence of Gluten-free Flours and their Mixtures on Batter Properties and Bread Quality

Gluten is a major component of some cereals and is responsible for flour technological characteristics to make bakery products. However, gluten must be eliminated from the diet of celiac patients because its ingestion causes serious intestinal damage. The objectives of this study were to assess the effect of different flours and their mixtures on thermal and pasting properties of batters, and to study the quality parameters and staling rate of gluten-free breads. Starch gelatinization temperatures and enthalpies depended on batter composition. Soy flour addition had a higher effect on rice than on corn starch, indicating some differential interaction between starch and proteins. Inactive soy flour incorporation improved all bread quality parameters in both corn- and rice-based breads. Higher batter firmness of formulations with soy addition (extrusion force was doubled in rice/soy and rice/corn/soy batters with regard to rice and rice/corn batters) partially explained higher specific volume (rice breads: 1.98 cm³/g; rice/soy 90:10 2.51 cm³/g, corn/soy 90:10: 2.05 cm³/g, whereas corn/soy 80:20: 2.12 cm³/g), as these batters retained more air during proofing. The staling rate was decreased by soy flour incorporation on rice (staling rate of rice breads with 10% soy diminished 52%, and with 20% of soy addition, 77%, both regarding to 100% rice breads) and corn formulation (the staling rate of corn/soy 80:20 breads was 5.9% lower than corn/soy 90:10) because of the high water-holding capacity of soy proteins and the interactions established with amylopectin that could retard the retrogradation process. Breads made with rice, corn, and soy flours showed the best quality attributes: high volume, good crumb appearance, soft texture, and low staling rate.     

油酸和麦芽糖醇混合物对玉米淀粉老化特性的影响

为探究油酸和麦芽糖醇混合物抑制玉米淀粉老化的效果,通过快速黏度分析、差示扫描量热分析、质构分析、动态流变分析、低场核磁共振分析、红外光谱分析和X射线衍射分析等方法比较不同复配比例的油酸和麦芽糖醇混合物对玉米淀粉糊化特性、老化特性、流变学特性、质构及结晶结构等的影响。结果显示：添加油酸和麦芽糖醇混合物后,玉米淀粉的糊化温度升高,回生值和老化速率降低,且当油酸和麦芽糖醇质量比为0.5∶1.5时,糊化温度最高（77.80 ℃）,回生值最低（1 218 cP）,老化速率比原淀粉降低了60%;油酸和麦芽糖醇混合物的添加能增大玉米淀粉的损耗角正切值和横向弛豫时间（T2）,形成较弱的凝胶结构,降低玉米淀粉凝胶的硬度、短程有序度和相对结晶度;当油酸和麦芽糖醇为0.5∶1.5质量比复配时,混合物对延缓玉米淀粉老化存在协同作用。这可能与麦芽糖醇能抑制淀粉体系中水分子运动、油酸能与淀粉形成淀粉-脂质复合物从而有效抑制淀粉重结晶有关。研究结果可为改善玉米淀粉加工特性、提高淀粉基食品品质提供一定的理论依据。     

Investigation of sweet potato starch as a structural enhancer for three‐dimensional printing of Scomberomorus niphonius surimi

Three‐dimensional printing (3DP) of surimi requires a structural modifier to achieve a stable construct. This work investigated the effect of addition of sweet potato starch (0–10% wt/wt) on the physical properties (rheological properties, gel strength, water‐holding capacity [WHC], and microstructural characteristics) of surimi gels and the 3D printed behavior of these gels. The results showed that as the starch content increased, the viscosity of the starch–surimi mixture decreased facilitating the flow of the surimi out of the printer nozzle. The surimi gel with 8% sweet potato starch concentration showed good gel strength (2,021.70 g mm), WHC (82.39%), microstructural characteristics, and less cooking loss (1.95%). A comparison of the traditional surimi preparation method with 3DP showed that the surimi gel prepared by a 3D printed construct was softer in gel strength (1,398.65 g mm) and lower in hardness (945.17 g) although showing slightly higher cooking loss (6.76%) and lower WHC (72.66 g) than the conventional product. The results suggest that sweet potato starch can be effectively used as a structural enhancer for 3DP complex‐shaped surimi.     

The effects of maltodextrins on gluten-free dough and quality of bread

The aim of the study was to check if maltodextrins of various dextrose equivalents (DE) could be used to improve stability and quality of gluten-free bakery products, and effectively reduce starch retrogradation. The maltodextrins, which were used for partial replacement of starch in the recipe for gluten-free dough, were characterised by DE 3.6, 15.3, 18.0 and 21.8. Basing on the obtained results it was concluded, that the addition of applied maltodextrins significantly influences starch gelatinisation, by increasing pasting temperature and reducing viscosity of the obtained pastes. Rheological properties of the obtained dough are also modified by maltodextrins, which weaken its structure and increase deformation sensitivity. The addition of maltodextrins with low DE (3.6) diminishes loaf volume and causes deterioration of bread quality. Maltodextrins with higher DE, especially 18.0 and 21.8, positively influence bread volume and have a beneficial influence on crumb hardening during storage. Maltodextrin with the highest DE is also an effective factor reducing recrystallisation enthalpy of amylopectin.     

Effects of High Hydrostatic Pressure on Rheological Properties of Rice Starch

The effect of high hydrostatic pressure-750 on rheological properties of rice starch-water system was examined. The starch dispersions (20% w/v) were pressurized at 120, 240, 360, 480, and 600 MPa for 30 min. The storage modulus and loss modulus increased with the pressure increase. A yield stress was generated at a low shear rate. The high hydrostatic pressure-treated starch gels performed shear thinning and the apparent viscosity dropped sharply at 480 MPa. Hysteresis loop area increased with the pressure increased and reached the maximum at 600 MPa. High hydrostatic pressure-treated starch gels were found to be weak gels and thixotropic.     

Quantitative estimation of the action of α-amylase from Bacillus subtilis on native corn starch by HPLC and HPTLC

 The optimal conditions of corn starch liquefaction and dextrinization using α-amylase from Bacillus subtilis to obtain maltodextrins with a dextrose equivalent of 12.9–23.5 were determined. The pattern of action of B. subtilis α-amylase on native corn starch was monitored using high-performance liquid chromatography (HPLC) and high-performance thin layer chromatography (HPTLC). It was possible to separate malto-oligosaccharides of up to 9 glucose units by HPLC and those of up to 12 glucose units by HPTLC, respectively. The results suggest that α-amylase from B. subtilis is an endo-specific enzyme which mainly produces two oligosaccharides, DP3 and DP6. It was shown that both methods can be successfully applied for the characterization of maltodextrins. Received: 22 August 1997     

Effect of chitosan on physical and chemical processes during bread baking and staling

The objective of this research was to investigate the effect of chitosan on the interaction of water with bread ingredients and on the rate of staling. The changes in freezable bound water and total water contents in bread crumb were assessed by differential scanning calorimetry from water melting and evaporation endothermic peak areas. It was found that freezable water content and total water content in bread crumb decrease during staling more rapidly in the presence of chitosan. The weak interaction of freezable water with protein and starch polymeric chains in bread crumb becomes stronger, but the interaction of nonfreezable bound water with protein and starch molecules in bread crumb becomes weaker in the course of staling during bread storage. Two stages of bread crumb staling were indicated. Chitosan increases the rate of bread staling during both stages. It was suggested that during bread staling chitosan increases water migration rate from crumb to crust, prevents amylose-lipid complexation, and increases dehydration rate both for starch and gluten.     

Thermo-physical assessment of bread during staling

Staling of bread is a highly complex phenomenon that is not yet fully understood. This study examined the effect of staling on thermal (DSC) and thermo-physical (DMA) properties of bread. The staling process increased water migration from the crumb to the crust and increased unfreezable water (UFW) fraction. Amylopectin retrogradation incremented during bread staling, and it was showed that the loss in freezable water (FW) was caused from water incorporation into the starch crystalline structure and water migration from the crumb to the crust. DMA was able to follow the shrinking behavior of bread crumb during freezing. Crumb shrank through the entire cooling and freezing process. The matrix shifts through their freezing process incremented the rate of their contraction, probably due to the matrix dehydration as consequence of ice formation. The ageing process changes the thermo-mechanical profile of the crumb, and it was showed that a greater amount of retrogradated starch, affected significantly the contraction capacity of bread crumb.     

Rheological and calorimetric properties of corn‐, wheat‐, and cassava‐ starches and soybean protein concentrate composites

The effect of soy protein concentrate (SPC) on the rheological and calorimetric properties of corn, wheat, and cassava starches was assessed. SPC increased T_o values and decreased the ΔH of all tested starches, which could be related to lower availability of water for starch gelatinization and/or to the interactions between SPC and amorphous regions of starch granules. SPC and sugar addition modified the viscosity parameters (obtained through a rapid visco‐analyser) of starch pastes, which was attributed to an increase in solid content and to the interaction of proteins with the starch dispersed phase. Frequency sweeps were carried out with a rheometer on gels containing starch, SPC, and sucrose. SPC raised storage and loss modulus, producing more consistent starch gels. Besides, penetration tests showed that SPC steadily increased starch gel firmness. Scanning electron micrographs showed that protein concentrate produced gels with closer structures. Summarizing, the starch and SPC in the gels obtained were expected to be arranged in a two‐phase system. Results showed that it is possible to achieve different textures for starch dessert formulations.     

皂荚糖胶对玉米淀粉老化性质的影响及体系的水分分布

以玉米淀粉为原料,用流变分析、食品物性分析、差示扫描量热分析、低场核磁共振成像分析等研究冷藏过程中不同含量（相对玉米淀粉干基质量的1%、3%、5%和7%）皂荚糖胶对玉米淀粉老化特性的影响。动态流变时间扫描结果表明：随着老化时间的延长,玉米淀粉的弹性模量增加,皂荚糖胶的加入使复配体系弹性模量的变化率减小,一定程度上抑制玉米淀粉的短期老化;凝胶强度实验表明：随着冷藏时间的延长,玉米淀粉凝胶体系的硬度值增加,皂荚糖胶的加入使玉米淀粉形成质地更柔软的凝胶,硬度值明显降低;差示扫描量热测定结果表明：随着皂荚糖胶含量的增加,复配体系的老化率逐渐减小。用低场核磁水分运动性实验方法,通过5%皂荚糖胶加入前后淀粉凝胶中自由水、结合水和不易流动水含量的对比证实该胶对凝胶的水分分布有较大的影响;该研究能进一步丰富植物胶体对淀粉老化性能影响的理论。     

Effect of non-starch polysaccharides on the in vitro digestibility and rheological properties of rice starch gel

The starch digestibility and rheological properties of gels were evaluated in the presence of three non-starch polysaccharides (agar, xanthan gum and konjac glucomannan) with rice starch. Each polysaccharide was added to 30% (w/w) rice starch suspension at defined concentrations and starch gels were prepared. The extent of starch gel digestibility was determined by an in vitro method and rheological properties by a dynamic oscillatory test and a compression test. The added polysaccharides suppressed starch hydrolysis in the gels compared with the control, and a concentration dependency of this suppressive effect was observed. Adding agar and xanthan gum increased the storage shear modulus (G′) of starch gels, while adding konjac glucomannan decreased G′ values. The results indicate that the suppressive effect of non-starch polysaccharides on starch digestibility appears to be not only due to the rigidity of the gel, but also the interaction between starch and non-starch polysaccharides.     

The effect of freeze–thaw cycles on microstructure and physicochemical properties of four starch gels

The effect of repeated freeze–thaw (FT) cycles (up to seven) on microstructure, thermal and textural properties of four starch gels from various botanical origins (gingko, Chinese water chestnut, potato and rice) was investigated and compared by scanning electronic microscope, differential scanning calorimetry and texture analyzer. The chemical composition and molecular structure of four starches were also examined. The Chinese water chestnut, potato and rice starch gels formed a honey-comb structure after 7 FT cycles, while gingko starch gel exhibited lamellar structure. The 7 FT cycles decreased the transition temperatures and enthalpies of four starches in comparison with each native starch, and the retrogradation percentage followed the order: rice > gingko > Chinese water chestnut > potato. The 7 FT cycles increased the hardness of all the evaluated starch gels and decreased springiness and cohesiveness. Results showed that the molecular structure of starches caused notable differences to the microstructure and textural properties of starch gels. The higher amount of longer branch chain (degree of polymerization (DP) > 18) might benefit the formation of the lamellar structure of gingko starch. The percentage of branch chains (DP 18–23) was negatively related with the springiness and cohesiveness of native starch gels, while the percentage of medium chains (DP 12–17) was positively related to the springiness of starch gels after 7 FT cycles.     

Comparison of Thermal and Viscoelastic Properties of Four Waxy Starches and the Effect of Added Surfactant

The waxy starches used in this investigation (maize (WM), barley (WB) and two rice starches RD4 and IR29) showed different gelatinization temperatures (GT) and enthalpies (ΔH_G) measured with differential scanning calorimetry (DSC). The differences in GT and ΔH_G could only partially be related to X-ray crystallinity. The high GT waxy starches WM and RD4 retrograded to a greater extent measured with DSC and the order of increased retrogradation agreed well with the order of X-ray crystallinity of the retrograded waxy starches. The melting temperature (T_C) of the retrograded waxy starches in contrast to GT was very similar for all starches. This indicates that the temperature of the glass transition (T_g) of the amorphous regions in the starch granules controlled the onset GT and perhaps also the extent of retrogradation. Addition of cetyl trimethyl ammonium bromide (CTAB) decreased the extent of retrogradation more than 45% compared to the melting enthalpy (ΔH_C) of the waxy starches without CTAB addition. The rice starch RD4 was most affected by the CTAB addition, and the WM starch the least. The viscoelastic behaviour in the temperature interval 25–90°C of 12%(w/w) gels differed between the waxy starches. The WB starch gels showed the highest storage modulus (G′) value and the lowest phase angle (δ), i. e. strongest and least viscous gels. The WM starch gels showed the lowest G′ value and the highest δ. The rice starches were in between with the RC4 starch (high GT) showing higher G′ value and lower δ than the IR29 (low GT). The viscoelastic parameters changed only slightly with increased temperature. The addition of CTAB to the waxy starch gels changed the viscoelastic behaviour of the stronger and less viscous starch gels of the WB and RD4 as their G′ value decreased and δ increased with increased temperature. The effect on WM and IR29 was only small.     

Enhancement of Resistant Starch (RS3) in Amylomaize,Barley, Field Pea and Lentil Starches

Native starches isolated from amylomaize. Glacier high amylose barley, field peas and lentils contained 3–5% (w/w) resistant starch (RS3). Retrograded gels that were prepared from these starches had higher RS3 (6–9%) contents. The effects of gel concentration (% starch), storage temperature and time on the RS3 content of the retrograded gels were investigated; the optimum RS3 content was determined in gels prepared at = 10% (w/v) starch concentration and stored under = 20°C for = 5 days. Annealing of the retrograded starch gels by heating and cooling cycles, further enhanced RS3 content to 9–19%; the effect of annealing temperature and number of heat-cool cycles on the RS3 content of the annealed gel were studied. The hydrolysis of retrograded starch gels by pulanase enzyme or acid (2.2 N HCl), prior to annealing, enhanced the RS3 formation during annealing; the enzyme or acid treatment increased RS3 content of the annealed gel to 15–24% or 17–24%, respectively. The potential molecular mechanism that is responsible for the RS3 increase is discussed.     

Effect of cellulose-derivatives and emulsifiers on creep-recovery and crumb properties of gluten-free bread prepared from sorghum and gelatinised cassava starch

The effect of cellulose-derivatives and emulsifiers on the creep-recovery behaviour of gluten-free dough prepared from gelatinised cassava starch and sorghum was studied. Cellulose treated doughs, except the treatment with 2.4% w/w fwb CMC, had lower resistances to deformation (range 10–33%) than emulsifier-treated doughs (range 3–13%). The higher elastic recovery of emulsifier-treated doughs corresponded to lower compliances and higher zero shear viscosities than for doughs treated with cellulose-derivatives. Addition of egg white powder (6.7% w/w fwb) eliminated several textural defects associated with gluten-free bread. Cellulose-derivatives did not decrease crumb firmness or staling rate when compared to the control. Though increasing emulsifier concentration (from 0.4% to 2.4% w/w fwb) decreased crumb firmness, crumbs treated with 2.4% w/w fwb emulsifiers, except diacetyl tartaric acid esters of mono- and diglycerides, were weak and difficult to handle after slicing. Nevertheless, all gluten-free breads treated with 2.4% w/w fwb emulsifiers staled at a slower rate than the control.     

IMPROVEMENT OF SHELF LIFE STABILITY OF CAKES

ABSTRACT

The effects of new ingredient strategies to slow down starch retrogradation rate in cakes were investigated. In this study, devil's fudge cakes were formulated using gum, modified starch and enzyme technology. Cake samples that were prepared with combinations of gums, bacterial amylases and pregelatinized starch were found to have slower starch retrogradation rates. An accelerated shelf life protocol was followed to observe the effect of predescribed ingredients on slowing the starch retrogradation rate. The samples were evaluated for moisture content, water activity, texture and thermal properties, as well as morphological characteristics. The staling rate was found to be accelerated by the fluctuations in temperature from high to low temperatures. Modified starches, enzymes and gums were found to decrease the rate of staling and improve product quality. The formulated cakes were found to have 25% lower toughness and hardness values as compared with the control product. It was found that for all the cake formulations, there was a significant decrease in both hardness and toughness values, whereas springiness values did not change much. The basic differences within formulations were created by incorporation of gums, enzymes, soluble fibers, emulsifiers and modified flours in the cake.

PRACTICAL APPLICATIONS

Nutritional balance is quite important for each individual. For certain groups of people, based on their activity levels, high energy supplies are required to help them to achieve their optimal performance. Cakes, waffles and pancakes are in the group of breakfast bakery items that provide high energy for these groups of people. In bakery food products, staling reactions start before microbial deteriorations; as a result, they are the major factor in determining shelf life. Cakes that are acceptable to the consumers should be moist and soft in texture. Starch retrogradation is the primary mechanism determining the shelf life of the product. Although the product is microbiologically safe, the adverse affects of starch crystals on textural properties is the main cause of product rejection by the consumer, which leads to huge economical losses. The current methods of controlling starch retrogradation lean on technologies of the 1980s. Despite several studies on bread staling, there is hardly any study on the staling mechanism of cakes and other bakery food items. This study provides information on how to retard staling in cakes by the use of an in‐house developed accelerated shelf life protocol.