Morphological changes of starch granules during grain filling and seed germination in wheat

In this study, the morphological changes of wheat starch granules during grain filling and seed germination were observed under scanning electron microscopy. Until 3 days post anthesis (DPA), the pericarp tissue was the major site of starch deposited. From 6 DPA, the size and the number of granules in endosperm gradually increased. The “double disk structure”, “pin holes”, and “equatorial groove” at the surfaces of the granules were observed during grain filling, these micro‐structural features might aid the enzymatic hydrolysis of starch granules during seed germination. The equatorial groove of granule was more susceptible to enzymatic hydrolysis than the flat surface.     

Effect of γ‐radiation and microwave heating of wheat grain on some starch properties in irradiated grain as well as in grain of the next generation crops

Grains of the Polish winter wheat variety Begra were subjected to γ‐radiation (grain harvested in 1996) within the dose range of 0.05–10 kGy and microwave heating (grain harvested in 1997) from 28°C to 98°C. Later the grains were divided into two parts, the first was used for direct analyses after treatment. The second part was sown on the experimental fields. The obtained crop was described as the first generation and divided into two parts. One part was destined to determination of starch properties and the second part was sown in order to obtain the second generation crop. The same pattern was conducted in order to achieve the third generation crop. γ‐Irradiation directly applied on the wheat grain reduced statistically significant falling number values and gelatinisation enthalpy (ΔH) of the grain treated by 5 and 10 kGy. Calculated linear regression correlation coefficient between the falling number values and the gelatinisation enthalpy was equal to 0.94 (p ? 0.001) and showed that these two starch characteristics are well correlated in the case of directly irradiated wheat grain. The falling number values, peak temperatures (T_p) and gelatinisation enthalpy (ΔH), in three generations of wheat grain crop studied, did not show any statistically significant differences as a result of indirect effect of γ‐irradiation. Microwave direct heating of wheat grain to 98°C caused a statistically significant increase in the falling number value and decrease in starch gelatinisation power expressed by the enthalpy of gelatinisation (ΔH). The statistically significant changes in the falling number values, slight changes in the peak temperatures (T_p) and enthalpy of gelatinisation (ΔH) were found in all three generation crops as an indirect effect of microwave heating.     

Microstructural changes of starch in cooked wheat grains as affected by cooking temperatures and times

The changes of starch microstructure in soft and hard wheat grains after cooking in a pressure cooker were investigated using a scanning electron microscope (SEM) and a light microscope (LM) in conjunction with image analysis. The conditions studied included variation of the cooking times (20-120 min) at the constant temperature (120 °C) and with variable temperatures (110-140 °C) for constant time (40 min). SEM images showed that steam induced changes in the intact starch granules of cooked wheat grains, with the microstructure becoming more in mud-like structure, with increased cooking time or temperature. The swelling and gelatinization of starch granules could contribute to this change. Suspensions of cooked wheat flour were selectively stained with iodine, for observation using the LM. The image analysis software was used for quantitative analysis of the images captured from the LM, providing both the number and area of the starch granules (determined from the dark-blue spots) per fixed image size. With increased cooking time or temperature, the number of starch granules decreased and the area increased as a result from the swelling and melting of starch granules. This study demonstrated the use of SEM and LM for the investigation of starch granules in cooked wheat grains without prior starch isolation.     

谷蠹蛀食对玉米中淀粉及油脂品质的影响

探讨谷蠹不同虫口密度和为害时间对玉米加工品质的影响,为谷蠹蛀食玉米的有效利用和谷蠹的科学防控提供参考。以河南玉米为试材,以谷蠹为试虫,设置不同虫口密度进行为害,测定不同为害期玉米粗淀粉含量、破损淀粉含量、淀粉颗粒形貌、淀粉糊化特性、粗脂肪含量、脂肪酸值、过氧化值、品尝评分值等品质指标。结果表明：随着虫口密度和为害时间的增加,玉米品质指标变化幅度增加;谷蠹为害65 d时,各处理组玉米中粗淀粉减少幅度和破碎淀粉增加幅度都不超过8%,而在为害25 d时脂肪酸值和过氧化值上升幅度都已超过10%。初始虫口密度为15、25头/kg和5头/kg的玉米中淀粉的糊化特性分别在谷蠹为害25 d和45 d时出现明显变化,尤其是衰减值下降超过10%。另外,谷蠹为害会造成玉米淀粉颗粒形态改变,制成窝头颜色加深,表面粗糙,品尝评分值降低。因此,在玉米储藏过程中,应密切监测谷蠹虫口密度,并适时安排出库,合理进行加工,以降低损失。     

Pasting properties of starch and protein in selected cereals and quality of their food products

In an attempt to improve intake of dietary fibre and antioxidants and quality of whole grain products, whole grain meals from barley, millet, rye and sorghum were evaluated individually and in blends with wheat flour in terms of starch pasting properties and protein heat damage, during cycles of heating and cooling in RVA tests. The whole grain meals were blended with either hard or soft wheat flour and processed into bread, cake, cookie or snack products. The products were then evaluated with regard to physical properties and acceptability. Significant differences were observed between cereals in starch peak, breakdown and setback viscosities as well as in protein peak viscosity. The results showed that RVA could be used to help formulate cereal blends with certain pasting properties. Substitution of wheat flour, with 15% of barley, rye, millet or sorghum whole grain, did not have significant detrimental effects on physical properties or acceptability of pita bread. Additionally, replacement of wheat flour with up to 30% of barley, rye, millet or sorghum whole grain meal had no significant effects on quality of cakes or cookies. A multigrain snack-like food was also developed as a healthy product and was highly acceptable in a sensory test. The developed product would help enhance consumption of whole grain foods, resulting in improved intake of fibre and health-enhancing components.     

Effect of baking on nutritional properties of starch in organic spelt whole grain products

Consumers of organic spelt food products claim health benefits or sense of well-being from their consumption as opposed to consumption of common wheat products. This study was designed to help clarify the validity of such claims through the evaluation of nutritional properties of starch in a variety of organic spelt products, including breads, biscuits, cookies and muffins, in comparison with their respective common wheat products. Three fermented bread products, namely, yeast leavened, sour and yeast/sour dough were evaluated. Rate and extent of starch digestion were based on the measurement of starch digestion index (SDI) and rapidly available glucose (RAG). The commercial spelt variety used contained approximately eight to ten fold the amount of resistant starch (RS) as compared to common wheat, averaging 3.7% versus 0.4%, and exhibited lower SDI and RAG values. This is the first report to demonstrate high content of RS in spelt. After mixing and fermentation, RS, SDI and RAG reduced, but were still higher in spelt doughs and batters than in those of common wheat. After baking, slight differences were observed in rate and extent of starch digestion between spelt and common wheat baked products. The study showed that differences among baked products were more pronounced than those between spelt and common wheat products.     

Characteristics of fractionated flours from whole buckwheat grain using a gradual milling system and their application for noodle making

BACKGROUND: Recently, the quality of buckwheat (Fagopyrum esculentum, Moench) flour was improved by using a gradual milling method in which whole buckwheat grains were milled into various fractions. In this study, 16 fractions milled from whole buckwheat grains from the outer to inner parts are characterised and used for noodle making. RESULTS: Protein and ash contents of flours increased in the order from the inner to the outer fractions. Each fraction contained nine main fatty acids in which the concentration of palmitic, stearic, linoleic and linolenic acids tended to decrease from the inner to outer parts of the grain, whereas the concentration of oleic acid in the middle parts of grain was higher than in the other parts. The peak viscosity was different among the fractions and the middle fractions had significantly higher peak viscosity than the other fractions. The optimum cooking time and whiteness of uncooked and cooked noodles substituted with 40% of the fractions decreased from the inner to outer fractions, whereas noodles made from the inner fractions were harder and less elastic than those from the outer fractions. CONCLUSION: The different buckwheat fractions contributed to different quality of soba noodles. However, the appropriate fractions could be used for noodle making to improve the quality of noodles depending on nutritional demands. Copyright © 2007 Society of Chemical Industry     

Pesticide residues in washing water of olive oil mills: effect on olive washing efficiency and decontamination proposal

BACKGROUND: Washing olives in the olive oil mill (a commonly used preliminary step to remove foreign materials and leaves) can help to remove pesticide residues, especially herbicides that are present in olives due to contamination either during application or as a consequence of contact with contaminated soil. The aim of the present work was the study of washing efficacy during washing cycles, i.e., from the beginning of the cycle until the water was changed. RESULTS: Four active ingredients, namely diuron, oxyfluorfen, terbuthylazine and endosulfan (α and β isomers) as well as the latter's degradation product endosulfan sulfate, were the most frequently found pesticides in raw olives after harvest. At the beginning of the washing cycle, diuron, terbuthylazine and oxyfluorfen residues were effectively removed from olives. However, progressive water contamination with pesticide residues decreased the efficiency of the washing step, specially for diuron and terbuthylazine residues. CONCLUSION: A decontamination method to enable water recycling in olive oil mills was proposed and optimized. It employed FeCl₃ as coagulant and active charcoal as adsorbent, and was effective in removing both suspended solids and pesticide residues. Copyright © 2008 Society of Chemical Industry     

Rates of starch hydrolysis and changes in viscosity in a range of common foods subjected to simulated digestion in vitro

A range of common starch-rich foods and pure starches was analysed for available carbohydrates and dietary fibre content, and subjected to a simulated digestion procedure in vitro. The initial rates of free sugar release differed markedly between foods; the time required for the release of 50% of the starch content of some legumes was up to 100 fold longer than that for foods such as potatoes and rice. A significant correlation (r=0.806; P<0.01) between the time required for hydrolysis and the total dietary fibre content of the foods was observed. The viscosity of the food samples declined during the course of digestion, but always remained markedly higher than that of pure starch. The rate of hydrolysis of starch appears to be the most important factor governing the human glycaemic response to foods described by other authors, but the final viscosity of partially digested foods may be of some significance.     

Starch as a Pore‐forming and Body‐forming Agent in Ceramic Technology

Wheat and corn starch can be used for the preparation of porous alumina ceramics via the SCC (starch consolidation casting) process, resulting in porosities ranging from > 20% to approx. 50% (using nominal starch contents of 10 – 50%, v/v), with open porosity dominating (closed porosity < 6.5%). The character of porosity and the shape of the pores corresponds to the starch granules used, but the pore size is determined by a complex interplay between starch swelling (during the body‐forming step) and pore shrinkage (during sintering of the ceramic). Typically, for low starch contents (e.g. nominal starch contents of around 10%, v/v) starch swelling is a significant effect, and the pores after sintering are larger than the size of the starch granules. For higher starch contents swelling is constrained (by limited space and/ or water availability), and the matrix shrinkage during sintering overcompensates the swelling effect, so that the final pores in the ceramic can be significantly smaller than the original starch granule size. In this paper it is shown how porosity is related to pore size. In particular, it is demonstrated that the porosity indirectly determined from image analysis (via the median pore size) is closely related to the porosity directly measured via the Archimedes method. On the other hand, mercury porosimetry measures the distribution of pore throat sizes. With increasing starch content in the suspension, the pore throat size in the as‐fired ceramic materials increases, resulting in a more open microstructure.     

Determination of starch and lipid in pea flour by near infrared reflectance analysis. the effect of pea genotype on starch and lipid content

Equations were derived for predicting starch and lipid content of pea varieties from near infrared data measured on a filter instrument (Technicon InfraAlyzer 400). The accuracy of the predictions were tested against separate data sets and were found to be better than ±2.6% for starch (range 20–45%) and ±0.3% for lipid (range 1.4–3.3%). Together with the previous work on the near infrared determination of protein it is possible to analyse rapidly for three components important to a plant breeding programme. The study has also demonstrated a clear-cut delineation between round and wrinkled pea genotypes.     

Effect of sowing time on protein quality and starch pasting characteristics in wheat (Triticum aestivum L.) genotypes grown under irrigated and rain-fed conditions

The effect of varying sowing time on wheat flour protein quality and starch pasting characteristics was studied in two genotypes differing in their water requirements for two years under irrigated and rain-fed conditions. Delayed sowing associated with high temperature during grain filling resulted in an overall increase in total grain protein. Low temperature prevailing under early sown conditions enhanced insoluble glutenin (IG) but reduced total protein accumulation in both the genotypes. IG and residue proteins increased but soluble glutenin and amylose decreased under rain-fed conditions. Amylose, hold- and final viscosity (FV) increased but setback decreased with change in normal sowing time. Peak viscosity (PV) increased under late sown conditions. Pasting temperature, setback, FV and breakdown (BD) were enhanced under rain-fed conditions. This study inferred that by selecting suitable irrigation practices and different sowing times for subjecting the crop to desirable temperature range, flour properties of given cultivars can be manipulated.     

日粮中不同比例小麦替代玉米对奶牛乳脂合成和乳脂脂肪酸组成的影响

选择8头泌乳时间为(84±17)d,体重为(569±47)kg的经产中国荷斯坦奶牛作为试验动物,研究了日粮中不同比例小麦替代玉米对奶牛乳脂合成和乳脂脂肪酸(FA)组成的影响。采用重复4×4拉丁方设计,分别饲喂含不同比例粉碎小麦(GW)和粉碎玉米(GC)的日粮,4个处理组分别为(DM基础):W0组(0%GW+27.9%GC),W9.6组(9.6%GW+19.2%GC),W19.2组(19.2%GW+9.6%GC)和W28.8组(28.8%GW+0%GC)。结果表明:随着日粮中小麦比例的增加,瘤胃p H值线性降低(P=0.01);产奶量未受显著影响,平均为27.1 kg/d;乳脂率(P=0.02)、乳脂产量(P=0.02)和3.5%乳脂校正乳(FCM)(P=0.05)产量呈线性降低趋势;乳脂FA(g/100 g总FA)中C16∶0呈线性(P0.01)和二次曲线增加(P0.01),而C18∶0和FAC16呈线性(P0.01)和二次(P=0.03和0.01)曲线降低;C8∶0(P=0.01)、C15∶0(P=0.06)、C16∶1(P=0.01)和C18∶1n9t(P=0.10)呈线性增加趋势,而C14∶0(P=0.09)和C18∶2n6c(P=0.08)呈线性降低趋势;与W0和W9.6组相比,W19.2和W28.8组乳脂C16∶0、C16∶1及C16∶0与C16∶1之和显著增加(P0.01),而C18∶0显著降低(P0.01)。结果提示:奶牛日粮中可用适当比例的粉碎小麦来替代玉米,替代比例不宜超过日粮DM的19.2%;高比例小麦日粮饲喂奶牛(W28.8组)可引起瘤胃p H值和乳脂率下降,进一步引起乳脂FA组成发生变化。     

Effects of high hydrostatic pressure (HHP) on bioaccessibility,as well as antioxidant activity,mineral and starch contents in Granny Smith apple

The aim of this work was to study the effect of high hydrostatic pressure on the bioaccessibility of specific nutrients (antioxidant, minerals and starch) in apple and to establish processing conditions that maximise the health benefits. The apple was pressurised at 500 MPa during 2, 4, 8 and 10 min. The antioxidant activity, mineral and starch content and bioaccessibility of apple samples were significantly affected by the processing and digestion conditions. Therefore, these results indicated that in vitro digestion has a noticeable effect on the antioxidant concentration, IC₅₀, with much lower values (a smaller IC₅₀ value corresponds to a higher antioxidant activity) of apple samples compared with those untreated and non-digestion. Apple has the highest calcium content (30.33 ± 1.94 mg/100 g), iron (14.46 ± 3.49 mg/100 g) and zinc (6.22 ± 0.91 mg/100 g). High hydrostatic pressure increased the mineral contents availability by 2.11–303.00% for calcium, 4.63–10.93% for iron and 8.68–28.93% for zinc. The dialysability and solubility of calcium, iron and zinc with respect to the values for the untreated sample were reduced by this high pressure technique. Consumption of apple under high hydrostatic pressure may supply substantial antioxidants, mineral and starch, which may provide health promoting and disease preventing effects.     

Treatment of wx corn starch dispersions in a microwave reactor and their hydrodynamic properties determined using asymmetrical flow field‐flow fractionation

Hydrodynamic properties of aqueous wx corn starch (native, un‐pregelatinised) dispersions treated in a dedicated single‐mode microwave reactor at temperatures ranging from 180 to 210°C were determined using asymmetrical flow field‐flow fractionation coupled with an RI detector. The dedicated microwave reactor enabled the fine control and monitoring of heating parameters (especially temperature) during the treatment. The translational diffusion co‐efficient and hydrodynamic radii (R_h) values determined for wx corn starch treated at 180 and 200°C indicate that the majority of the material (∼98%) consisted of highly mobile, small and compact molecules/particles, with R_h values ranging from 10 to 90 nm, while the remaining ∼2% of the material consisted of considerably larger molecules/particles R_h values ranging from ∼100 to ∼200 nm). Degradation of wx corn starch was observed at 210°C.