Comparison of Oil,Shortening, and a Structured Shortening on Wheat Dough Rheology and Starch Pasting Properties

Monoacylglycerol‐stabilized oil in water emulsion (MAG gel) is an alternate shortening that is free of trans fatty acids, and low in saturated fatty acids. However, the behavior of MAG gels in comparison to other lipids has not been studied. This study investigated effects of structured MAG gel, a mixture of MAG gel unstructured components (Mixture), canola oil (Oil), or interesterified soy shortening (IE Soy) at different levels (6–24%) on hard or soft wheat dough properties. Doughs were prepared with different lipid types at equivalent lipid contents. Dough mixing and water absorption parameters were evaluated using a farinograph; gluten behavior was measured using a gluten peak tester (GPT); and pasting characteristics were measured using a micro‐viscoamylograph (MVAG). Water absorption values decreased with increasing lipid content. Dough development times were similar between the MAG gel and IE Soy, but farinogram curve characteristics during mixing were similar between MAG gel, Mixture, and Oil. The trend for peak max time in GPT was similar between MAG gel and IE Soy exhibiting delayed gluten aggregation; whereas Mixture and Oil exhibited earlier gluten aggregation. In MVAG, starch interaction with monoglyceride component of MAG gel and Mixture appeared to be the dominating factor resulting in increased pasting temperature and a second viscosity peak during cooling at higher levels of lipid addition.     

Influence of Early and Delayed Transplantation of Paddy on Physicochemical,Pasting, Cooking,Textural, and Protein Characteristics of Milled Rice

Milled rice of four indica cultivars (PR114, PR116, PR118, and PAU201) obtained from early (June 5 and 15) and delayed (June 25 and July 5) transplanted paddy was evaluated for physicochemical, pasting, cooking, and protein characteristics. During the grain‐filling and development stage, early transplanted paddy experienced average maximum and minimum temperatures of 32.8 and 22.3°C, respectively, against 30.8 and 15°C, respectively, for delayed transplanted paddy. Lightness (L*) value, protein content, and lipid content of milled rice were lower, whereas apparent amylose content, cooked grain hardness, final viscosity, and setback viscosity were higher in the delayed transplanted paddy. Whiteness of milled rice of PR114, PR116, and PR118 from delayed transplanted paddy was lower than milled rice from early transplanted paddy. PAU201 did not show any change in whiteness with delayed transplantation. Cooked rice of PAU201 showed exceptionally higher adhesiveness and lower hardness compared with other cultivars. Protein profiling showed a lower accumulation of prolamines in milled rice from PR114 and PAU201 upon delaying the transplantation from June 5 to July 5, whereas PR116 and PR118 showed a decrease in prolamine accumulation from transplantation on June 25. The changes in milled rice caused by delayed transplanting of paddy might be because of cool nighttime air temperature that affected the accumulation of starch, protein, and lipid.     

Lupin Flours as Additives: Dough Mixing,Breadmaking, Emulsifying,and Foaming

The nutritional quality of various food products could be improved by supplementation with grain legumes to increase protein content and to improve the balance of essential amino acids. The lupin grain is a good candidate for this role, given its yield potential in a range of climatic environments and soil types. To establish the practicality of extending the use of lupins as food additives, the functional properties of various species and cultivars of lupin were studied for their effect as additives to baked products and their ability to provide foaming and emulsifying properties. Of the two lupin species that are commonly cultivated commercially, Lupinus albus showed the greater potential as a bread additive; loaf height and structure were maintained when lupin flour was substituted for wheat flour at levels up to 5%. This level of substitution offered the advantage of reducing mixing time. The detrimental effects at higher substitution levels appeared to be associated with the nonprotein components of the lupin flour. L. albus showed better functionality than L. angustifolius in emulsifying attributes, although L. angustifolius showed greater potential as a foaming agent. Defatting the lupin flour may be necessary to show these properties to best advantage. Certain cultivars (within each species) showed preferable performance, indicating the potential for plant breeding to provide germplasm better suited to uses as food additives.     

Effect of Starch Granule Size Distribution and Elevated Amylose Content on Durum Dough Rheology and Spaghetti Cooking Quality

To obtain an indication of the effect of increasing the starch amylose content above normal levels (27–74%) and increasing the percentage of B‐type starch granules (11–60%) on durum dough properties and the quality of the spaghetti derived from these doughs, the reconstitution approach was used. Reconstituted flours were prepared from a common Wollaroi gluten, solubles and tailings fraction combined with starches containing varying B‐granule contents, or with starches from maize with varying amylose content. An increased B‐granule content increased farinograph water absorption. Cooked spaghetti firmness was highest with B‐type granules at 32–44% (volume percentage basis), which is ≈10–15% higher than normally found in durum starch. Increasing the amylose content in the starch caused the dough to be more extensible, increased spaghetti firmness, and decreased water absorption with optimum quality of amylose at 32–44%. The information indicates there would be benefit in producing durum wheats with slightly elevated B‐granule and amylose contents.     

Gluten Enhances Cooking,Textural, and Sensory Properties of Oat Noodles

Whole grain oats are widely regarded as conferring significant health benefits. Composite flour of whole grain oat flour, wheat flour, and tapioca starch in the ratio 1:1:0.16 was formulated to make oat noodles with the addition of gluten at various levels. The influence of gluten on pasting and gelling properties of composite flour, and on cooking, textural, and sensory properties of salted oat noodles was evaluated. Addition of gluten decreased the paste viscosity, reduced hardness and springiness of gel, reduced cooking yield, cooking loss, and broken ratio during cooking, and increased the tensile strength and firmness of cooked noodles. Scanning electron microscopy showed that gluten tightened the network of protein in the noodles by forming oriented fibrils. Addition of gluten had little effect on the color of raw and cooked oat noodles, which were somewhat yellow. Sensory evaluation indicated that addition of gluten could enhance the overall acceptability of cooked oat noodles. This study may stimulate further interest in using functional whole grain cereal ingredients in developing healthy staple foods.     

Structural Modification of Gluten Proteins in Strong and Weak Wheat Dough as Affected by Mixing Temperature

The effects of temperature (≥25°C) on dough rheological properties and gluten functionality have been investigated for decades, but no study has addressed the effect of low temperature (<30°C) on gluten network attributes in flours with strong and weak dough characteristics. This study monitored changes in protein extractability in the presence and absence of reducing agents, the contents of readily accessible and SDS‐accessible thiols, and the secondary structural features of proteins in doughs from commercial hard wheat flour (HWF) and soft wheat flour (SWF) mixed at 4, 15, and 30°C. SWF mixed at 4 and 15°C showed similar mixing properties as HWF mixed at 30°C (which is the standard temperature). The effect of mixing temperature is different at the molecular level between the two flours studied. Protein features of HWF did not change as mixing temperature decreased, with the only exception being an increase in SDS‐accessible thiols. Decreasing mixing temperature for SWF caused an increase in SDS protein solubility and SDS‐accessible thiols as well as an increase in β‐turn structures at the expense of β‐sheet structures. Thus, noncovalent interactions appear to drive protein network at low temperatures (4 and 15°C), whereas covalent interactions dominate at standard mixing temperature (30°C) in doughs from both flours.     

Gelatinization,Pasting, and Gelling Properties of Sweetpotato and Wheat Starch Blends

Sweetpotato starch is high yielding but has very limited uses. It is possible to expand its application by blending it with other starches to obtain novel properties. In this study, functional properties of the blends of native sweetpotato starch with native, acid‐thinned, and hydroxypropylated wheat starch were studied at different ratios (75:25, 50:50, 25:75). The swelling factor, extent of amylose leaching, pasting, and gel textural properties of the blends were nonadditive of their individual components, and could be mathematically modeled by quadratic equations in relation to the ratios. Two peaks during pasting were observed for some starch mixtures studied by Rapid ViscoAnalyser (RVA). The gelatinization and retrogradation enthalpies (ΔH) of the blends were additive of their individual components and could be modeled by linear equations. All starch mixtures exhibited two peaks during differential scanning calorimetry (DSC) scan for gelatinization, but a single peak for retrograded starches. This study may provide basis for formulation of mixtures using starch from diverse sources to develop more natural starch systems with a range of physicochemical properties.     

Gelatinization Profiles of Triticale Starch in Cookies as Influenced by Moisture and Solutes

Starch physicochemical parameters and phase transitions were determined in flours of 10 advanced lines and cultivars of triticale (Cananea, Currency, Eronga, LA 24 Bve, LA 20 FCA, LA 83 FCA, Tatú, Tehuelche, Quiñé, and Yagan). Starch behavior was also analyzed during the baking of cookies prepared with triticale flours. Starch granule size, crystal type patterns, and size distribution were determined by light microscopy, X-ray diffraction, and gel-permeation chromatography, respectively. Two types and sizes of starch granules with characteristic A-form crystals were obtained in all samples tested. The Quiñé cultivar showed the lowest extent of starch crystallinity. Only a monophasic endotherm was found by differential scanning calorimetry for water content >50–60%. Gelatinization temperature and enthalpy values varied significantly among samples. A biphasic endotherm was detected for water contents between 35 and 60%, and no endothermic transitions were observed for water levels <35%. Only one endotherm corresponding to starch gelatinization was detected in baked cookies prepared with five triticale flours. In all samples, the highest enthalpy of gelatinization of starch was detected for the cookie surface, whereas the highest gelatinization temperature was observed for the center. These differences may be attributed to the presence and content of the solutes in cookie dough and also to the degree of starch gelatinization during the cooking process.     

Gelatinizing,Pasting, and Gelling Properties of Potato and Amaranth Starch Mixtures

Physicochemical properties of mixtures of native potato and native amaranth (Amaranthus cruentus), heat‐moisture treated (HMT) potato and heat‐moisture treated amaranth, cross‐linked potato and cross‐linked amaranth, native potato and heat‐moisture treated amaranth, and heat‐moisture treated potato, and native amaranth were tested at different ratios. Two peaks were noticed in the pasting curves when large differences of swelling factor and amylose leaching existed between individual components in the mixture. It seems that amylose leaching from one starch in a mixture may affect the swelling and much of the granular break down of the other. The mixtures showed stabilities in hot pastes that were higher than the less stable components in a mixture. Some mixtures such as HMT potato and native amaranth showed very specific nonadditive pasting behavior. Mixing 10% of native amaranth to HMT potato starch caused a large reduction of peak viscosity and cold paste viscosity, resulting in a very soft gel. In the differential scanning calorimeter, each component of a mixture gelatinized independently, showing two peaks corresponding to the individual components. When transition temperatures of both components were similar in DSC, the result was a single endotherm. Dramatic changes of pasting and subsequent gel properties resulted when thermal transition of the two components occurred in the same temperature range. Retrogradation enthalpies as measured by DSC were between the two individual components in all tested mixtures.     

Structures of Four Waxy Rice Starches in Relation to Thermal,Pasting, and Textural Properties

Waxy rice starches from three japonica cultivars (Taichung Waxy 1 [TCW1], Taichung Waxy 70 [TCW70], Tachimemochi) and one indica cultivar (Tainung Sen Waxy 2 [TNSW2]) were characterized for chemical and physicochemical properties. The amylopectin structures were different for the four waxy rice starches in terms of degree of polymerization (DP), average chain length (CL), exterior chain lengths (ECL), and distribution of chains, indicating the existence of varietal differences. The order of swelling power was TCW1 > TCW70 > TNSW2 > Tachimemochi; the order of water solubility index was TCW70 > TNSW2 > Tachimemochi > TCW1. The low water solubility index of TCW1 might be ascribed to a high DP. All starches shared similar gelatinization temperatures and enthalpies but showed distinct retrogradation patterns. TNSW2 showed the highest retrogradation rate, followed by TCW2, Tachimemochi, and TCW70. TCW70 exhibited the highest overall pasting viscosity, followed by TNSW2, TCW1, and Tachimemochi. The hardness of waxy rice starch pastes from a Brabender amyloviscograph increased rapidly after storage at 5°C for one day and remained the same or slightly increased after seven days of storage, whereas the opposite trend was observed for adhesiveness. The lower degree of retrogradation of TCW70 was probably a result of a larger amount of A chain and a shorter ECL. The changes in hardness correlated with the amount of A and B1 chains. The texture attributes of waxy rice starch pastes were significantly affected by amylopectin retrogradation during storage.     

Effects of Cumin and Ginger as Antioxidants on Dough Mixing Properties and Cookie Quality

The effects of cumin and ginger as antioxidants on dough mixing properties and cookie quality were evaluated. Antioxidant activities in cookies were estimated by total phenolic compounds (TPC) contents and free radical scavenging activities. The cookie dough development was evaluated using Mixolab equipment which showed that addition of cumin did not change dough stability and C2, but decreased C3 and C4. While the addition of 5% ginger decreased dough stability (from 8.4 in the control sample to 6.7 min with 5% ginger addition), C2 (from 0.49 in the control sample to 0.31 N·m with 5% ginger addition), C3, and C4. Cookies formulated with addition of cumin and ginger had increased spread ratios, were softer, and had lower L* and b* values (were darker) than the control. Sensory analysis showed that cookies with cumin and ginger additions had overall acceptability similar to that of the the control with a slightly darker appearance, as confirmed by color determination. Using cumin and ginger significantly increased TPC contents from 78.5 in the control to 93.0 and 109.8 mg of gallic acid equivalent/100 g, respectively. Similar results were observed in the antioxidant activity measured by 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH), which increased from 41.0% in the control to 51.5% and 64.6%, respectively, for cookies with 5% addition of cumin and ginger.     

Sources of Variation for Starch Gelatinization,Pasting, and Gelation Properties in Wheat

The starch of wheat (Triticum aestivum L.) flour affects food product quality due to the temperature-dependent interactions of starch with water during gelatinization, pasting, and gelation. The objective of this study was to determine the fundamental basis of variation in gelatinization, pasting, and gelation of prime starch derived from seven different wheat cultivars: Kanto 107, which is a partial waxy mutant line, and six near-isogenic lines (NILs) differing in hardness. Complete pasting curves with extended 16-min hold at 93°C were obtained using the Rapid Visco Analyser (RVA). Apparent amylose content ranged from 17.5 to 23.5%; total amylose content ranged from 22.8 to 28.2%. Starches exhibited significant variation in onset of gelatinization. However, none of the parameters measured consistently correlated with onset or other RVA curve parameters that preceded peak paste viscosity. Peak paste viscosity varied from 190 to 323 RVA units (RVU). Higher peak, greater breakdown, lower final viscosity, negative setback, and less total setback were associated with lower apparent and total amylose contents. Each 1% reduction in apparent or total amylose content corresponded to an increase in peak viscosity of about 22 and 25 RVU, respectively, at 12% starch concentration. Of the seven U.S. cultivars, the lower amylose cultivars Penawawa and Klasic were missing the granule-bound starch synthase (GBSS; ADPglucose starch glycosyl transferase, EC 2.4.4.21) protein associated with the Waxy gene locus on chromosome 4A (Wx-B1 locus). Kanto 107 was confirmed as missing both the 7A and 4A waxy proteins (Wx-A1 and Wx-B1 loci). The hardness NIL also were shown to be null at the 4A locus. Apparent and total amylose contents of prime starch generally corresponded well to the number of GBSS proteins; although the hardness NIL tended to have somewhat higher amylose contents than did the other GBSS 4A nulls. We concluded that reduced quantity of starch amylose due to decreased GBSS profoundly affects starch gelatinization, pasting, and gelation properties.     

Starch Damage and Pasting Properties of Rice Flours Produced by Dry Jet Grinding

Milling method and particle size affect some properties of rice flour. To prepare ultra‐fine rice flour of <30 μm, hammer and dry jet grinding methods were examined and the effect of particle size on starch damage and pasting properties of the flour were elucidated. A jet mill could make finer flour (<10 μm mean size) with a narrower particle size distribution than a hammer mill could. Starch damage increased dramatically at a mean size of <10 μm. Particles of a similar size (<60 μm) had different levels of starch damage between mills. Not only the particle size, but also the milling method affected the level of damaged starch. Flour samples of ≥45 μm mean size had similar viscosity curves, but samples of <20 μm had different curves. Peak viscosity and final viscosity decreased sharply at <10 μm. Setback viscosity for particles of 3 μm from both brown rice and white rice were higher than the peak viscosity. Stability to heat and shearing stress were decreased for <20 μm flours as the breakdown viscosities decreased. Starch damage and pasting properties of flour ground from the nonwaxy japonica cultivar Koshihikari changed dramatically at a mean size of <10 μm.     

Effect of Mixing Time and Speed on Experimental Baking and Dough Testing with a 200 g Pin Mixer

Undermixing or overmixing the dough results in varied experimental loaf volumes. Bread preparation requires a trained baker to evaluate dough development and determine the stop points of the mixer. Instrumentation and electronic control of the dough mixer would allow for automatic mixing. This study used a 200 g mixer that provided an output signal during dough mixing to evaluate potential mixing stop points. The effect of varied mixing time on the baked loaf volume was tested by using three flours with protein contents of 10.6, 12.4, and 13.8%. Dough samples were undermixed, mixed to peak, and overmixed. Overmixing by 0.6 min reduced the loaf volume in all flours tested, by 16–50 cm³ at 90 rpm and by 29–68 cm³ at 118 rpm. When the high‐protein flour sample was undermixed, the largest baked loaves were produced, with an average volume of 922 cm³. A second objective studied the similarities and differences between a 200 g mixer and a 35 g mixograph. The same flours were mixed on both units. The mixing peaks for the 200 g mixer were normalized with the 35 g mixograph peaks. When flour and water were used, the mixing times for the 200 g mixer averaged 0.7, 1.2, and 1.6 min shorter than the 35 g mixograph, at 90, 104, and 118 rpm, respectively. Although both the 200 g mixer and the 35 g mixograph system look mechanically similar, they both have unique mechanical motion, speeds, and sample sizes. Their results may show similar trends, but their measured values are usually different. However, when other baking ingredients were included in the 200 g mixer at 90 rpm, the mixing times were within 0.2 min of the 35 g mixograph times for three of four flours.     

Comparison of Starch Pasting Properties at Various Cooking Conditions Using the Micro Visco‐Amylo‐Graph and the Rapid Visco Analyser

Pasting profiles of selected starches were compared by using a Micro Visco‐Amylo‐Graph (MVA) and a Rapid Visco Analyser (RVA). Effects of cooking (heating/cooling) rate and stirring speed on starch pasting properties were examined. The pasting viscosity of a starch suspension (8%, w/w, dsb) was measured at a fast (6°C/min) and slow (1.5°C/min) cooking rate while being stirred at either 75 rpm or 160 rpm. The pasting temperatures (PT) of all starches were higher when measured at the fast cooking rate than those at the slow cooking rate, except for wheat measured by using the RVA. PT was also higher when measured at the slow stirring speed (75 rpm) than at the fast stirring speed (160 rpm) in both RVA and MVA. When stirring speed increased from 75 rpm to 160 rpm, peak viscosity of all starch pastes except potato decreased measured by using the RVA, but increased by using the MVA. In general, amylograms of these starches obtained by using the MVA showed less breakdown, but greater setback viscosity than did that obtained by using the RVA. Differences in starch pasting properties between MVA and RVA, measured at the same cooking and stirring rates, were attributed mainly to the difference in spindle structure.     

Batch Steeping of Corn: Effects of Adding Lactic Acid and Sulfur Dioxide at Different Times on Starch Yields,Protein Contents,and Starch Pasting Properties

The effect of adding lactic acid and sulfur dioxide at different times from the start of batch steeping on corn starch yields was studied. Five commercial hybrids were steeped with 0.5% lactic acid or 0.2% sulfur dioxide added over the first 15 hr of steeping and wet-milled following a 100-g corn wet-milling procedure. No significant differences were observed in starch yields when lactic acid was added to the steep solution (SO₂ and water) from 0 hr (start of steeping) to 15 hr. Addition of SO₂ to the steep solution (lactic acid and water) resulted in significantly higher average starch yields when SO₂ was added between 5 and 15 hr compared with addition at 0 hr (SO₂ and lactic acid for full 24 hr of steeping). Based on the results of the first experiment, a second experiment was done in which one of five original hybrids was steeped for 24 hr, during which lactic acid or SO₂ was added until 23.9 hr (i.e., 5 min before milling) after the start of steeping. Similar results were found in the second experiment. Residual protein in starch samples did not exceed 0.85%. Steepwater protein content decreased with delays (16–20 hr) in adding either chemical to the steep solution. A significant effect on starch pasting properties of chemicals and duration of chemicals in steep-water was observed. Testing these findings using a larger scale (1,000 g) corn wet-milling procedure produced results similar to those obtained with the 100-g corn wet-milling procedure.     

Effects of Cultivar and Temperature During Grain Filling on Wheat Protein Content,Composition, and Dough Mixing Properties

Three wheat cultivars, Bastian, Polkka, and Tjalve, were grown in growth chambers at 9, 12, 15, 18, and 21°C during grain filling in 1994, 1995, and 1996. The wheat samples were analyzed for protein content and sodium dodecyl sulfate (SDS) sedimentation volume. The mixing properties of sifted flours were determined by mixograph, and the flour protein composition was determined by size-exclusion fast protein liquid chromatography (SE-FPLC). The protein content, sedimentation volume, and mixogram parameters were affected by the temperature during grain filling. The protein content increased as the temperature increased. The sedimentation volumes and the mixograph data showed temperature effects that could not be explained by variation in protein content. The proportion of the polymeric flour proteins increased with increasing temperature. Positive correlations were found between the proportion of polymeric proteins and SDS sedimentation volume and, within each year, between the proportion of polymeric proteins and mixograph peak time. Negative correlations were found between the proportion of low molecular weight flour proteins (proportion of fraction IV) and sedimentation volume. The differences in these quality parameters among cultivars exceeded the effect of temperature during grain filling.     

Effect of Heat Treatments on Starch Pasting,Particle Size,and Color of Whole‐Grain Barley

Barley β‐glucan has cholesterol‐lowering properties and can be positively affected by heat treatments. The aim of this study was to examine the effects of heat treatments of whole‐grain barley on starch pasting, particle size, and color. Three heat treatments (micronization, roasting, and conditioning) were performed on three cultivars of barley (CDC Rattan, CDC McGwire, and CDC Fibar). All three heat treatments increased peak, breakdown, setback, and final viscosity of CDC Rattan and CDC Fibar. However, they had little effect on the starch‐pasting profile of CDC McGwire. Roasting and conditioning reduced the mean particle size compared with untreated particles, whereas micronization had minimal effect. Heat treatments reduced L* and increased a* and b* compared with no treatment. Overall, this research shows that heat treatments can change other properties of barley that may affect its function in food applications.     

Effects of Nitrogen and Sulfur Fertilizer on Protein Composition,Mixing Requirements,and Dough Strength of Four Wheat Cultivars

Two field trials using four New Zealand wheat cultivars were undertaken to observe the effects of nitrogen and sulfur fertilization on protein composition, mixing requirements, and dough strength and to compare the results with that observed with a single cultivar, Otane. The results confirmed that adequate sulfur fertilization was necessary to ensure lower dough mixing requirements. The existence of a nexus between mixing requirements and dough strength was confirmed and genotype has significant effects on it. Variation in the content of HMW‐GS in the protein corresponded to changes in dough mixing requirement of Otane. Across the four cultivars, dough mixing requirements (mechanical dough development work input and mixograph development time) and dough strength (Extensigraph resistance to extension) depended on different aspects of protein composition. As the content of polymeric proteins increased, MDD work input increased, but mixograph development time decreased, while the effect on Rmax was small. Rmax, however, was more affected by either the content of small monomerics in the flour or the ratio between HMW‐GS peak area to total gliadin peak area. The ratio of MDD work input to Rmax was largely explained by the gliadin content of the flour. Thus, depending on the genetic background, it should be possible to adjust dough mixing requirements by modifying overall HMW‐GS, LMW‐GS, or gliadin content while maintaining dough strength.