Dehulling Efficiency Research Articles

Optimization of process parameters and mathematical modelling for dehulling of pigeonpea

SummaryIn this study, hulling efficiency and hulling losses were optimised for pigeonpea. Effects of hulling time, moisture content and cottonseed oil as pre‐milling agent were studied and optimised using response surface methodology. A quadratic model satisfactorily described the hulling efficiency with an R2 value of 0.93. It predicted maximum dehulling efficiency of 89.98% at 9.82% moisture content (wet basis), 12.05‐s time of hulling and 0.28% cottonseed oil treatment. Linear model developed for hulling loss showed significant effect of time of hulling whereas effect of oil treatment and moisture content were non‐significant. The model predicted hulling loss of 2.92% on optimum conditions. The results of the model were validated experimentally and were within the range.

Dehulling performance and textural characteristics of unshelled and shelled sunflower ( Helianthus annuus L.) seeds

A study was carried out to determine the effect of moisture content and variety on dehulling performance and textural characteristics of unshelled (seed) and shelled (kernel) sunflower seeds. Four sunflower varieties were selected and conditioned to five levels of moisture content from 6.24% to 14.31% for seed and 6.18% to14.29% (db) for kernel. Dehulling performance of seed was evaluated in terms of dehulling efficiency (DE) and non-recoverable kernel fraction (NRKF). The textural characteristics of both seed and its kernel were measured in terms of initial cracking force (ICF), average rupture force (ARF) and average rupture energy (ARE). Variation in moisture content and variety either individually or in combination showed a statistically significant effect on the dehulling performance and textural characteristics of sunflower seed, as well as the kernel. It was revealed that dehulling parameters could be well correlated with the textural characteristics.

Effect of variety and crude protein content on dehulling quality and on the resulting chemical composition of red lentil (Lens culinaris)

AbstractBACKGROUND: Dehulling is one of the most important operations in post‐harvest handling of red lentils (Lens culinaris). However, little information is available on how variety and crude protein content affect the dehulling quality characteristics and on how dehulling affects chemical composition of red lentils. Therefore, the main objective of this work was to investigate the effect of variety and crude protein content on dehulling quality and on the resulting chemical composition of red lentils.RESULTS: Four varieties of red lentil, each with two levels of protein content, were selected for this study. Crude protein content overall ranged from 225.7 to 311.7 g kg−1 dry matter. Results indicated that variety and crude protein content had a significant effect on dehulling efficiency (DE), powder produced, broken seeds (BRK) and hull removed. Dehulled seeds exhibited higher protein, starch, phytic acid, stachyose and verbascose content, but lower TIA, tannin, sucrose and raffinose content than raw seeds.CONCLUSION: Variety and protein content had a significant effect on DE. Dehulling affected chemical composition of lentils. DE was positively correlated with starch content but negatively correlated with protein and crude fiber content of raw seeds. Information gathered from the study will be useful for lentil breeders, processors and marketers. Copyright © 2008 Society of Chemical Industry

Optimisation of the pigeon pea dehulling process

Dehulling efficiency and loss were optimised for pigeon pea. The effects of dehulling time, moisture content and the use of mustard oil as a pre-milling treatment agent were studied and optimised using response surface methodology. A quadratic model satisfactorily described the dehulling efficiency with high value for the coefficient of determination R 2 (0.95) values. It predicted a maximum dehulling efficiency of 83.2% at 10.1% moisture content, 12.3 s. dehulling time and 0.3% mustard oil treatment. Moisture content and dehulling time affected dehulling loss significantly whereas the effect of mustard oil treatment was non-significant. A dehulling loss of 2.5% was predicted at optimum conditions. The results of the predicted optimum conditions were validated experimentally. Dehulling efficiency and loss at optimum conditions were observed to be 82.4±0.8% and 3.1±0.4%, respectively, and were close to the predicted values.

Milling performance in desi‐type chickpea (Cicer arietinum L.): effects of genotype, environment and seed size

AbstractBACKGROUND: Commercial experience suggests that desi chickpea cultivars vary in their milling quality. However, the relative effects of cultivar, growing environment and their interaction are unknown. This study examined the Australian pulse quality method for its effectiveness in comparing the milling quality of breeding lines. The main aims were (1) to determine if there were significant genotypic differences, (2) to quantify the effects of trial, testa content and seed size and (3) to determine if any of the milling quality or seed parameters were correlated. This information would then be used to improve the reliability and efficiency of testing breeding lines.RESULTS: Large genotypic differences were observed for the milling parameters dehulling efficiency (DE) and splitting yield (SY). The range was greater for SY (16.6%) than for DE (5.8%). Genotype × Trial interactions were significant for DE and SY, while genotype rankings were generally consistent between trials. Seed size and testa content were not significantly associated with either DE or SY. Environmental stresses that affected yield did not appear to influence milling results.CONCLUSION: The methodology used in this study was able to measure genotypic differences in milling quality. The results suggest that an efficient protocol for testing milling quality of chickpea genotypes would include analysis of at least two sites early in the breeding programme to discard very‐low‐SY genotypes, and further testing in subsequent years including at least one other site to identify high‐SY genotypes if desired. Copyright © 2007 Society of Chemical Industry

Optimization of a Laboratory Dehulling Process for Lentil (Lens culinaris)

ABSTRACTRed lentil (Lens culinaris) is mainly processed into dehulled and split forms before human consumption and characteristics such as dehulling efficiency (DE), which is the sum of percent dehulled whole seed (PDW) and percent dehulled split seed (PDS), are important to lentil breeders, processors, and exporters. A laboratory Satake dehuller was used to evaluate the dehulling characteristics of red lentil. The effects of dehulling conditions (abrasive wheel speed, dehulling time, and seed moisture content) were investigated using response surface methodology. Increasing dehulling time and seed moisture content decreased DE. Increasing seed moisture content decreased powder and broken fractions but increased the undehulled whole seed fraction. PDW was decreased but PDS was increased as dehulling time was increased. Percent hull removed during dehulling process decreased as seed moisture content was increased but increased as abrasive wheel speed or dehulling time was increased. The optimum dehulling conditions for the laboratory dehuller, based on maximizing DE and percent hull removed while minimizing powder fraction (loss), were established. Good agreement was found between experimental values for dehulling characteristics (DE, PDW, PDS, hull removed, and powder produced) obtained at optimum dehulling conditions and predicted values for those characteristics obtained using the models developed.

Splitting and dehulling lentil (Lens culinaris): Effects of seed size and different pretreatments

AbstractA conservative estimate of 800 000 T of red‐cotyledon microsperma lentil (Lens culinaris Medikus) is consumed annually after postharvest processing into split dehulled seed. This process consists of cleaning the seed of foreign matter, brief immersion in water, spin‐drying, standing to temper, separation into seed size fractions, dehulling/splitting and final separation. The effects of seed size (4 and 4.5 mm fractions), immersion times (1, 5, 10 and 30 min), temperature (19° and 36°) and duration (0, 30, 60 and 120 min) of air drying, and tempering time (0 and 24 h), on the efficiency of dehulling and splitting lentil were examined. Dehulling efficiency (%) was estimated as the sum of split dehulled seed, whole dehulled seed, and whole hulled seed (whole seeds are separated for recycling to the dehuller). Dehulling efficiency was best with the small seed fraction (4 mm), an immersion time of 1 min, no air drying, and a tempering time of 24 h. The drying air temperature did not have a significant effect on dehulling efficiency. Dehulling efficiency was highest with a low seed moisture content.

Splitting and dehulling lentil (Lens culinaris): Effects of genotype and location

AbstractMost red‐cotyledon microsperma lentils (Lens culinaris Medikus) are utilised after postharvest processing into split dehulled seed. This study examined the effects on dehulling of 23 diverse genotypes of red‐cotyledon microsperma lentil, each grown at three sites ranging from 245 to 663 mm total seasonal rainfall in Lebanon and Syria. Dehulling efficiency (%) was measured as the sum of split dehulled seed, whole dehulled seed, and whole hulled seed. Despite a range in location means of 464–2018 kg ha−1 for grain yield, the corresponding mean dehulling efficiencies varied only from 84.8 to 85.9%, indicating that the location effect on dehulling efficiency is of minor importance. There was more variation among genotypes for dehulling efficiency (80.8–87.7%) and for preparation of split dehulled seed (62.1–80.2%) than between locations. Seed processing variables showed medium to high broadsense heritabilities. Correlations between seed processing characters and agronomic variables were generally low. An approach to seed selection for optimum processing variables within the ICARDA breeding programme is discussed.

A low‐cost manual dehuller for soybeans

SummaryRemoval of the hull is essential for processing soybean into human food, and a low‐cost manual dehuller was developed for use by unskilled people in rural areas without electricity. Using two labourers, its capacity is 35 kg h−1 at 96% dehulling efficiency, at a cost of Rs 0.13 kg−1. At a capital cost of Rs 2000, it would be an affordable communal item with potential to improve soybean utilization and nutrition in poor villages.

Evaluation of a general purpose abrasive mill for pearling of coarse cereals and dehusking of pulses

SummaryA general purpose abrasive mill, developed to pearl and dehusk cereals and pulses, has integral milling and cleaning chambers and a 10‐grinding wheel rotor driven by a 3.7 kW motor. Its capacity is between 96 and 340 kg h−1, depending upon the grain being handled, with a maximum dehulling efficiency of 75%. The cost of processing varied from Rs 4.5 to 9.2 per tonne of feed. It could be owned, operated, and manned by small‐scale processors in rural and semi‐urban areas.

Factors Affecting the Efficiency of Abrasive-Type Dehulling of Grain Legumes Investigated with a New Intermediate-Sized, Batch Dehuller

An intermediate-sized, batch dehuller capable of processing 2-8 kg of a wide variety of cereal or legume grains was developed. Grains are dehulled by abrasion provided by abrasive wheels (10 in, diam) mounted on a horizontal shaft. The dehuller was successfully applied to eight legume grains varying widely in seed characteristics. The yield of dehulled grain after at least 90% of the hull had been removed, ranged from 74-89%. Dehulling efficiency, a measure of the amount of hull in the abraded material, ranged from 0.11-0.72. Multiple-regression analysis showed that greater than 75% of the variability in dehulling efficiency or yield could be accounted for by seed hardness and resistance to splitting of the seed into individual cotyledons.