Pre-milling Treatment Research Articles

The Effect of Pre-Milling Treatments on Functional and Rheological Properties of Brachystagia eurycoma (Achi) Seed Flour and Gum

The Effect of Pre-Milling Treatments on Functional and Rheological Properties of Brachystagia eurycoma (Achi) Seed Flour and Gum

Influence of Pre-Milling on the Mn Solid Solubility in the Al-Mn-Cu Alloy during Mechanical Alloying

Increasing the strength of Al-based alloys is an important issue of physical metallurgy and industrial processing. Severe plastic deformation and related extension of solid solubility during mechanical alloying provide an opportunity for significant strengthening due to grain refinement, solid solution, and precipitation strengthening mechanisms. During mechanical alloying, an anomalous increase in the solid-state solubility of alloying elements occurs. The present study focuses on the investigation of the pre-milling treatment to the microstructure, phase composition, and solubility in Al-7.7 Mn-3.5 Cu (wt%) alloy processed by a high-energy ball milling of Al-14.3 Mn-6.5 Cu (wt%) master alloy diluted with Al powder. During milling, the mean granular size decreased to ~5 µm, and a strong grain refinement occurred. According to our TEM and XRD data, ball milling provided a mean grain size of 13–14 nm and a microhardness of 490–540 HV. The lattice parameter of the Al-based solid solution decreased with an increase in the milling time to 7.5–10 h, which suggested the dissolution of the alloying elements, and the lattice parameter increased at a higher milling time of 12.5–40 h, which suggested the decomposition of the solid solution. The XRD data revealed the dissolution of the Al6Mn and Al20Cu2Mn3 solidification-originated phases with a further precipitation of the Al6Mn dispersoids. Pre-milling of the master alloy entailed a significant decrease in the minimal lattice parameter value from 0.4029 nm to 0.4023 nm due to an increase in the Mn solute content from 6.2 wt% (3.3 at%) to 7.5 wt % (4.0 at%) in the studied alloy during high-energy ball milling.

Effect of infrared heating on the nutritional properties of yellow pea and green lentil flours

AbstractBackground and ObjectivesTo enhance the utilization of pulse ingredients, greater knowledge of the effect of infrared (IR) processing on protein and starch nutrition is needed. The current study investigated the use of tempering (20% vs. 30% moisture) with IR heating (120°C vs. 140°C) to improve the nutritional value of two commercially important pulses: green lentils and yellow peas.FindingsProximate composition remained mostly unchanged after IR heating for both pulse types. The protein's secondary structure transitioned to a state with a higher amount of random coils as IR processing conditions intensified (increase in moisture and temperature). In vitro protein digestibility (IVPD) increased from 73% to 78%−82% for green lentil and 78% to 81%−85% for yellow pea, depending on IR processing treatment. Tryptophan was the limiting amino acid in all samples. The IVPD corrected amino acid scores were not significantly altered by IR processing. The content of rapidly (RDS) and slowly (SDS) digestible starches increased, whereas that of resistance starch declined with IR processing.ConclusionsThe combined effect of tempering moisture and IR heat as a premilling treatment changed the protein secondary structure but did not improve the overall protein quality of the pulses. Starch digestibility was improved with IR processing.Significance and NoveltyEmploying tempering and IR heating techniques on pulses may be useful in food and feed applications where improved starch digestibility is desired.

​Biochemical Compositions of Milling Byproduct of Mungbean and its Fractions

Background: Mungbean is consumed as whole, sprouts or dehusked splits, in form of dal. Dal is prepared after removal of outer husk cover and splitting the cotyledons in abrasive emery roller mills to improve esculent properties. In the process of husk removal, milling byproduct, mixture of husk and cotyledon powder, is generated, which is usually utilized as low value cattle feed. The milling byproduct contains bioactive compounds useful for human health. In the study biochemical properties of two mungbean cultivars, namely, Shikha and Virat, were evaluated for whole, dal milling byproduct and its fractions, to explore using milling byproduct of mungbean for potential edible usages. Methods: In this study, mungbean cultivars were milled in abrasive roller after water soaking pre-milling treatment. Milling byproduct was fractionated into three particle sizes, i) greater than 1.0 mm, ii) greater than 0.125 mm and iii) less than 0.125 mm. Biochemical components, viz, protein, phenols, antioxidant activity and calorific values were estimated for whole grain, dehusked split (Dal), milling byproduct and its fractions for the two selected mungbean cultivars. Result: The protein content was observed to be high in split dal and powder fraction ( less than 0.125 mm) of milling byproduct. Antioxidant value and phenolic compound were higher in the byproduct fraction retained over greater than 1.00 mm sieve size due to presence of husk in this fraction. Calorific value of byproduct was higher than that of whole seed, dal and byproduct fractions. The study indicates that the mungbean milling byproduct, with beneficial bioactive component can be utilize to develop value added edible products of therapeutic and health benefits.

Microwave-assisted pre-milling treatments of chickpea (Cicer Arietinum) for higher recovery

This research was undertaken to examine the result of microwave pre-treatment on chickpea dehulling. The experiments were conducted at three microwave power levels (PL), 50, 70, and 90, at different five exposers from 1 to 3 minutes at the time interval of 30 seconds to evaluate chickpea dehulling with the pre-milling treatment of microwave exposure for achieving maximum dehulling yield, dhal yield, good dehulled grains in terms of quality with minimum dehulling loss. It was noted that dehulling yield improved with microwave power and exposure period. The highest dehulling yield, 71.02%, was achieved 90 PL with 2.5 minutes exposure and found maximum dhal yields, i.e., 66.40%, and minimum dehulling loss, 10.25%. So, this requirement was correct and better to get a higher dhal yield. These findings are also valuable for the pulse processing industry and fabricators for designing a continuous type pulse pre-milling treater unit. Hence, it could be highlighted that the microwave pre-milling treatment is more suitable for pulse processing like chickpea. This also presents an improvised method for pre-milling treatments for commercial adoption.

Mechanical-thermal synthesis of NbB2 powder from Mg/B2O3/Nb powder mixture

Abstract Three different approaches were used for the synthesis of niobium boride using a stoichiometric ratio of Mg–B2O3– Nb powder mixture: (i) thermal ignition, (ii) mechanochemical and (iii) a combined mechanical and thermal activation process. Phase transformation analysis and structural evaluation were carried out by means of differential thermal analysis techniques, X-ray diffractometry, scanning electron microscopy and transmission electron microscopy. During the thermal synthesis, the reaction between Mg and B2O3 partially occurred (liquid state reaction). The desired final phase (NbB2) was poorly obtained. Phase analysis revealed that the NbB2 phase was synthesized after 10 h of high energy ball milling. A pre-milling treatment of the powder mixture up to 2 h significantly reduced the reactions temperature (580 °C). Consequently, NbB2 was prepared simultaneously involving magnesiothermic reduction of B2O3 and reaction between elemental of Nb and boron. Mg3(BO3)2, as major by-product, was formed in noticeable amounts during the thermal process, while its quantity significantly decreased during mechanochemical synthesis and completely eliminated by using the combined mechanical and thermal synthesis.

Premilling treatments effects on nutritional composition, antinutritional factors, and in vitro mineral bioavailability of the improved Assosa I sorghum variety (Sorghum bicolor L.).

Sorghum (Sorghum bicolor L.) is among the staple cereal crops in different parts of Ethiopia. However, the presence of antinutritional factors restricts the digestion of proteins and bioavailability different minerals. Therefore, this study investigates the premilling treatments effects on nutritional composition, antinutritional factors, and in vitro mineral bioavailability of the improved Assosa I sorghum variety grown in Benishangul‐Gumuz Region, Ethiopia. The experiment was conducted in a completely randomized design with single factor of premilling treatments (control, washing, soaking, and malting). Among evaluated premilling treatments, malting showed significant (p < .05) increase in terms of crude fiber, utilizable carbohydrate, gross energy, and sodium contents. As compared to the raw sorghum, premilling treatments reduced antinutritional contents from 55.81 to 27.4 mg/100 g for tannin, 156.15 to 70.50 mg/100 g for phytates, and 29.9 to 3.22 mg/100 g for oxalate. The premilling techniques also significantly (p < .05) improved in vitro mineral bioavailability as compared to unprocessed sorghum grains. Among the premilling treatments, malting showed significant difference (p < .05) in terms of reduction of tannins, phytates, and oxalate contents with relatively higher mineral bioavailability. In order to enhance the food and nutritional value of sorghum particularly for children and lactating mothers, it is recommended to germinated the grains. Flour from germinated grain also can be used in combination with other nutrient‐dense foods to formulate healthy diets for children and maternal nutrition.

Flour and bread making properties of whole and split yellow peas treated with dry and steam heat used as premilling treatment

AbstractBackground and objectivesPulse flours can impart off‐flavors limiting their use in foods. The objective of this study was to examine the flour and bread making properties of whole and split yellow peas treated with dry and steam heat used as a premilling treatment.FindingsParticle size distributions and pasting properties of flours milled from heat‐treated peas were altered, and starch damage was reduced compared to flours milled from untreated peas. Breads made with flour milled from heat‐treated peas had similar firmness to breads made with flour milled from untreated peas with no change in volume and minimal impact on crumb structure. Changes in crumb color (lower L*, higher a*) were consistent with color changes observed in the flours. Heat treating whole peas produced breads with decreased aroma, flavor, and aftertaste, whereas heat treating split peas produced breads with lower intensities of aroma, flavor, bitterness, and aftertaste and increased acceptability.ConclusionsRevtech dry and steam heating of whole and split yellow peas as a premilling treatment successfully reduced off‐flavors with minimal changes to flour and bread making properties.Significance and noveltyHeat treating pulses prior to milling offers greater opportunities for incorporating pulse flours in foods.

Effect of roasting as a premilling treatment on the functional and bread baking properties of whole yellow pea flour

AbstractBackground and objectivesThere is a growing global interest in partially replacing wheat flour with pulse flours in foods, including bread. However, undesirable flavors associated with pulse flours, especially yellow pea flour, have limited their use in foods. Pretreating pulses prior to milling offers a possible solution for improving the flavor of pulse flours. The objective of this research was to examine the effect of oven roasting and Revtech roasting (with and without steam) on the compositional, functional, and bread baking properties of whole yellow peas.FindingsRegardless of the roasting method used, a roasting temperature of 120°C resulted in flours that retained good functionality and bread baking properties with less detrimental changes in flour color. Bread made with peas roasted at 120°C also had reduced aroma and flavor properties compared to bread made with untreated peas.ConclusionsThe strong aroma and flavor properties of yellow peas can be reduced by pretreating the peas prior to milling using conventional oven roasting and Revtech roasting. By selecting the appropriate roasting temperature, flour functionality for bread baking can be maintained.Significance and noveltyRoasting is a useful premilling treatment for yellow peas. Reducing the off‐flavors associated with pulses while maintaining flour functionality will allow for greater use of pulse flours in formulating foods.

Effect of premilling treatments on the functional and bread‐baking properties of whole yellow pea flour using micronization and pregermination

AbstractBackground and objectivesThere is interest in partially replacing wheat flour with pulse flours in bread. However, flavor of pulse flours may be detrimental to the final product. Processing pulses prior to milling, using micronization and pregermination (early seed germination without radicle emergence), was investigated as a way to improve the flavor of yellow pea flour while maintaining or improving flour functionality.FindingsMicronization and pregermination of peas prior to milling resulted in changes to flour particle size, color, and compositional and functional properties of the flours. Peas tempered to 18%–20% and micronized to 105–110°C produced a flour that was similar in baking properties to the flour milled from untreated peas with the exception of crumb firmness and aroma and flavor of the bread. All bread made from micronized peas tended to have reduced crumb firmness and improved aroma and flavor properties compared to bread made with untreated peas. Results for the pregerminated peas showed that the flour had higher starch damage and WAC and lower peak and final viscosities compared to the flour milled from untreated peas. Bread baked from pregerminated peas had lower bread quality in terms of bread scores, volume, crumb color, and C‐cell properties, but the bread had reduced crumb firmness and improved aroma and flavor properties, compared to bread made with untreated peas.ConclusionsBoth micronization and pregermination were suitable premilling treatments for yellow peas. Pregermination, however, warrants additional research to determine whether flour and baking properties can be improved.Significance and noveltyPretreating yellow peas using either micronization or pergermination prior to milling were successful in reducing undesirable flavors associated with pea flour. Depending on the treatment and conditions used, flour functionality and bread‐baking properties were maintained.

Effect of premilling treatments on wheat gluten extraction and noodle quality.

Wheat cultivars were treated by four different treatments and their flours were obtained after milling. The quality of the obtained wheat flours was determined using various quality parameters and it was observed that premilling treatments significantly affect the gluten content, wet and dry gluten yield, gluten index, and water absorption capacity of gluten, respectively. Acid-treated wheat flours of all the four wheat varieties (C-306, Raj-3765, PBW-343, and KW-11) showed lower gluten content and quality, whereas conditioning and yeast treatment improve gluten quality as well as its content. Flours obtained after premilling treatments were also utilized for noodle preparation and their sensory and quality parameters were also determined. Also, it was observed that yeast treatment and conditioning improved the noodle quality, whereas acid treatment deteriorates the noodle quality in comparison to tempering. The cultivar PBW-343 produced the best quality noodle among four wheat cultivars. In different milling treatments acid-treated flours of all cultivars showed lowest sensory and quality characteristics, while yeast treatment showed highest.

Effect of thermal treatment on milling performance of pigeonpea (Cajanus cajan)

Pigeonpea [Cajanas cajan (L.) Millsp.] is an important pulse crop of India. It is consumed as dehusked splits commonly, known as dhal. The hull of pigeonpea adheres tightly to the cotyledons through a gummy layer that hinders separation of hull during milling. Hence, pre-milling treatment is an essential step before milling for higher dhal recovery. Thermal pre-milling treatment was conducted at temperatures (5, 85, 105, 125°C) for varying duration (2, 4, 6, 8 min). The experiment consisting of 16 treatment combinations was conducted as per factorial CRD. Treatment at temperature 85±5°C for 4 min resulted in maximum hulling efficiency of 84.28% and finished product recovery of 53.53%, which was significantly higher than untreated sample. Losses in form of broken was found to be only 2.5%.

Debranning of purple wheat: recovery of anthocyanin-rich fractions and their use in pasta production

Debranning is a pre-milling treatment that partially removes the external coats and the aleurone layer of the kernel, allowing the selective recovery of bioactive compounds, such as fiber and phenolic compounds. A two-step debranning process was applied to purple wheat, a naturally antioxidant-rich variety, that removed 9.7% of the material. Debranned fractions from the first (F1; 3.7% of the whole grain) and the second (F2; 6.0% of the debranned grain after the first step) step were used separately to produce fiber-enriched pasta. Bran from conventional milling (CB) was also used as a control. F1 and F2 had a higher or comparable content in total and soluble fiber than CB. Moreover, both samples exhibited a higher ferric reducing-antioxidant power (FRAP) than CB, whereas the highest amount of anthocyanins was found in F1 (695 ± 64 μg/g). When compared with CB-enriched pasta, samples enriched with either F1 or F2 had similar FRAP values (2.6 ± 0.1 and 2.3 ± 0.2 μmol Fe(II)/g for pasta with F1 and F2, respectively), and a higher amount of anthocyanins (67.9 ± 0.9 and 60 ± 1 μg/g for pasta with F1 and F2, respectively), while retaining a fair cooking quality.

Effect of thermal treatments on the storage life of pearl millet (Pennisetum glaucum) flour

Effect of pre-milling treatments, viz. roasting and hydrothermal treatment was evaluated on pearl millet [Pennisetum glaucum (L) R Br] flour stored at ambient condition (average maximum and minimum temperatures 33.1±4oC and 21.4±2oC, respectively, and 84.4±2% RH) and controlled condition (30±1oC at 50±2% RH) packed in zip-lip low density polyethylene (LDPE) pouches of 10 µm thickness having permeability 23.13g/m2 24h. Roasting and hydro thermal treatment significantly reduced fat acidity by 8% and 12%, phytic acidity by 10% and 4% and trypsin inhibitor activity by 9% and 5%, respectively, of pearl millet flour. It was observed that pearl millet flour can be stored at controlled condition in superior form than ambient condition. Storage period had significant (P&lt;0.05) effect on moisture content, fat acidity, phytic acid and trypsin inhibitors activity of pearl millet flour. It was found that untreated, roasted and hydrothermally treated pearl millet flour can be stored up to 2, 2 and 30 days at ambient conditions and 3, 3 and 45 day, respectively, at controlled condition without undue deterioration in quality.

Effect of Microwave Treatment on Dehulling of Pigeon Pea

Dehulling of pulses is an energy intensive operation, also associated with significant product losses. In the present study, microwave energy was examined as an alternative pre-milling treatment for pigeon pea. Response surface methodology (RSM) based central composite design was used to study the effect of the independent variables (microwave power and exposure time) on the dehulling parameters. The process parameters showed significant effects on various dehulling parameters (per cent dehulled whole and splits, un-dehulled whole and splits, fines/ broken, powder and hulls). Highest dehulling efficiency and lowest loss were observed for a microwave treatment at 630 W for 90 s. With the rising market demand for pulses, microwave energy can prove to be a profitable pretreatment technique for dehulling of pigeon pea.

Mechanochemical synthesis of NbC–NbB2 nanocomposite from the Mg/B2O3/Nb/C powder mixtures

An experimental study was conducted on the preparation and characterization of nanocrystalline niobium boride and carbide composite (NbB2–NbC) in the Mg–B2O3–Nb–C system via mechanochemical method. The thermodynamic appraisal indicated that the reduction and synthesis reactions were highly exothermic and should be self-sustaining. According to the differential thermal analysis (DTA) results, a pre-milling treatment of powder mixture up to 2h not only reduced the reaction temperature, but also induced a different reaction path. In addition, the amount of Mg3(BO3)2, as a major by-product of the thermal synthesis, was significantly decreased by applying adequate mechanical activation. The phase analysis revealed that the NbB2 phase was achieved after 3h high energy ball milling in self-stunning mode; meanwhile, the formation of NbC was progressively completed after a longer period of milling up to 7h. According to the morphological evolutions, the range of particle size was within 100nm.

Optimization of Enzymatic Hydrolysis Parameters of Pigeon Pea for Better Recovery of Dhal

Pigeon pea is mostly consumed in the form of splits and it provides good source of proteins. The pigeon pea grain is considered as most difficult for dehulling as compared to other pulses owing to its seed coat which is more firmly attached with the cotyledons through a layer of gum and mucilage. Pre milling treatments are generally employed to loosen the seed coat to remove husk without losing any edible portion. The effect of four enzymatic hydrolysis parameters, i.e., enzyme concentration (20–60 mg/ 100 g dry matter), incubation time (3-15 h), incubation temperature (40-60 0C) and tempering water pH (4.0-6.0) on hulling efficiency were optimized using response surface methodology. Three enzymes i.e. xylanase, pectinase, and cellulase were used in combination for enzymatic pre treatment. A quadratic model satisfactorily described the dehulling efficiency with high value for the coefficient of determination R2 (0.9062). It predicted a maximum dehulling efficiency of 88.37 % at enzyme concentration; 37.80 mg/100 g dry matter, incubation time, 8.69 min, incubation temperature, 48.48 0C and tempering water pH, 5.49. The results of the predicted optimum conditions were validated experimentally. Dehulling efficiency at optimum condition was observed to be 88.12 % and showed 0.28 % deviation from the predicted values. Results of the study revealed that dehulling efficiency of enzyme treated dhal could be increased 13.81 % compared to the control, i.e., the oil treated sample.

Low temperature carbothermal and boron carbide reduction synthesis of LaB6

Abstract Rare-earth hexaborides are widely used as thermionic emitters however their economic production for large scale applications such as solar thermionic electricity generation is hampered by a need to synthesise them at lower temperature without post-synthesis cleaning treatments. Two simple synthesis techniques for producing pure lanthanum hexaboride (LaB6), carbothermal reduction using La2O3–boron–carbon and boron carbide reduction using La2O3–B4C blends respectively were studied. Using fine grained starting materials and a mild pre-milling treatment, the carbothermal method was found to produce high-purity LaB6 at a temperature 1400 °C or below. The B4C method also appeared from XRD and SEM analyses of abraded surfaces to produce high-purity LaB6 at 1400 °C however EDS maps of polished cross-sections revealed the presence of unreacted B4C necessitating a temperature of 1450 °C to complete the reaction. XRD and SEM analyses indicate that the mean particle sizes of LaB6 using the boron carbide method (220 nm) is smaller than that for the carbothermal reduction method (600 nm). The finer grains of samples prepared via the boron carbide method result in a partially sintered powder. LaB6 prepared in this way is shown to have a Richardson work function of 2.64 eV.

Effect of Pre-Milling Treatments on Storage Stability of Pearl Millet Flour

This work was undertaken to evaluate the effect of pre-milling treatments viz pearling, heat treatment and fermentation on pearl millet flour quality during storage. The pre-treatments yielded in significant reduction in antinutritional factors (phytic acid content and total polyphenol) as well as in fat acidity and free fatty acids (FFA). The phytic acid, fat acidity and FFA increased with increase in storage period. Heat treatment (at 110C for 60 s) was inferred as the best pre-milling treatment as the fat acidity and FFA were found to be the minimum in case of heat treated flour. Additionally, heat treatment did not cause significant reduction of iron and zinc contents of pearl millet flour. In contrast, pearling and fermentation significantly lowered iron and zinc contents. It was found that heat treated pearl millet flour could be stored up to 6 days without undue deterioration in quality at ambient condition. Practical Application Result of present research shows that the pearl millet is rich in nutrient but unstable during storage. Therefore, with the use of different pre-milling treatments (fermentation, pearling and roasting), the storage stability as well as nutritional properties of the flour can be enhanced through reduction of antinutrients factors. The improved shelf life of flour can result in its better marketability.

Effect of Pre-milling Treatments on Green Gram Dhal Recovery

Effect of oil and thermal treatments on milling quality of green gram was studied at 8 to 12% moisture content (w.b) with 2.40 to 4.00 g.kg-1 oil for treatment and holding time of 5 to 10 h, thermal treatment at temperature of 80 to 120°C and roasting duration of 1 to 5 min. These pretreatments showed dhal recovery of 70.01 to 74.93% in case of oil treatment, and 71.18 to 78.12% in case of thermal treatment as against 61.19 to 65.64% without any pretreatment. Optimum conditions for oil treatment for maximum dhal recovery were 10.26% (w.b), oil quantity of 3.17 g.kg-1 and holding for 7.72 h, roasting for 2.86 min at temperature of 99.24°C and 10.25% moisture content (w.b) for thermal treatment of green gram.