Mechanical Dehulling Research Articles

Mechanical stress on canola seed during dehulling.

The mature canola seed comprises an embryo, a group of structures that have a high content of protein and oil, and a fibrous seed coat held together by endosperm tissues. High-quality canola meal production requires removal of fiber-rich seed hull that typically contributes little nutrient value. Canola hull accounts for more than 70.0% of the insoluble fiber within the seed, which limits its uses as feed. Dehulling canola seed, before oil extraction, increases the protein content and decreases fiber content in the meal, to up to 50.0% and to down to 10.0%, respectively. Due to the complexity in dehulling canola seeds, several methods have been explored by the canola processing industry. However, little research has been conducted in analyzing the effects that mechanical dehulling methods have on seeds. In this study, we conducted mechanical tests to characterize seed behavior and hull fracture under uncoupled stresses such as compression and shear;stresses generated by the common dehulling equipment used in the industry, such as mills. All tests were carried out on single seeds at different moisture contents, from 5.00% to 25.0% wet mass basis (w.b.). Over a range of moisture contents studied, shear loading mode limited deformation of embryos in comparison to compression loading. Additionally, hardness tests were performed with a nano-indenter machine to determine seed hull properties. The overall results from these experiments provided information used to construct a computational model that represents canola seed deformation under compression stress.

Effect of dehulling method on the chemical composition of the lipid constituents of the kernels and oils of Ricinodendron heudelotii seeds

The aim of this study was to characterize the lipids present in the oil and kernels of Ricinodendron heudelotii seeds. Two dehulling methods were used to extract kernels from their husks: a heat treatment and a manual mechanical dehulling technique. Oil from kernels obtained by traditional heat treatment of seeds had a kinematic viscosity of 169 ± 0.5 mPa.s, and an iodine value of 175.6 ± 1.1 g/100 g oil. The oil from kernels isolated by mechanical dehulling had a kinematic viscosity of 128 ± 0.11 mPa.s and an iodine value of 195.2 ± 2.0 g/100 g oil. Determination of the minor compound profile of the oil revealed a total tocopherol content of 135.0 ± 0.4 mg oil from kernels isolated by traditional heat treatment. The oil obtained from kernels isolated by manual mechanical dehulling had a total tocopherol content of 178.3 ± 0.4 mg/100 g. An analysis of the fatty-acid profile of the oil from kernels isolated by traditional heat treatment revealed the presence of α-eleostearic acid (50.5% ±0.1), linoleic acid (24.0% ±0.0), β-eleostearic (8.4% ±0.0) and catalpic acid (0.40% ±0.1). By contrast, the fatty acid composition of oil from kernels isolated by manual mechanical dehulling was of α-eleostearic acid (60.1% ±0.2), linoleic acid (22.8% ±0.1).Ricinodendron heudelotii oil has a very high level (84.4 ± 0.4%) of polyunsaturated fatty acids (CLnA). Some analysis of the triglycerides present in the oil revealed the potential isomerization of α-eleostearic acid to form β-eleostearic acid and catalpic acid.

Biofuel from Balanites aegyptiaca: Optimization of the Feedstock Supply Chain

In arid and semi-arid climates, Balanites aegyptiaca (B. aegyptiaca) is a potential plant to produce oilseed-based biofuels. In this paper an optimization model for a wild biomass supply chain is presented. The model was developed to identify the optimal organization of the supply network that minimizes the cost of supplying the feedstock. It was applied to a case study on a B. aegyptiaca seed supply chain in Burkina Faso. Considering different means of transport and different pre-processing locations, the results show that in contexts such as Burkina Faso’s, the most efficient option for the supply of B. aegyptiaca seeds is using animal drawn carts to transport the biomass from the harvest sites to the collection points. Feedstock pre-processing should take place before transport and an improvement in pre-processing operations by mechanical de-hulling could help reduce the cost price of the seeds. The results also show that more than 35% of the cost price of B. aegyptiaca seed is accounted for by transport costs. Pre-processing, handling, and storage costs account for about 50% of the cost of the seeds.

Connaissances Paysannes Et Prédisposition À Adopter Une Innovation En Agro-Alimentaire : Cas Du Décorticage Mécanique Et De La Fortification En Fer Du Sorgho Dans Le Nord-Bénin

The consumption of meals prepared from unshelled sorghum derivatives is a factor favoring iron deficiency anemia among consumers. Mechanical dehulling and iron fortification of sorghum appears as a palliative solution. This study has a dual purpose. First of all, it is a question of assessing consumers' knowledge of sorghum meals with regard to anemia and its causes. Descriptive statistics have been used for this purpose. Then, it was discussed to analyze the determinants of the predisposition of these consumers to adopt mechanical dehulling and iron fortification of sorghum. To do this, the Logit econometric model was used. According to the results, anemia is caused by factors such as malaria, malnutrition, witchcraft, non-respect of fetishes, etc. In addition, households' propensity to adopt innovation is positively influenced by the income of the chef-cuisine, the perception that it has of its social status after the adoption of innovation and the compatibility of it with norms and values of the household. However, it is negatively influenced by the participation of the chef-cuisine in the experimentation phase and by the perceived complexity of the innovation.

Innovative process combining roasting and tempering to mechanically dehull jicaro seeds (Crescentia alata K.H.B)

An innovative process combining roasting and tempering was proposed to promote puffing and mechanical dehulling of jicaro seeds. Roasting was performed at three temperatures (120 °C, 140 °C, and 160 °C) and for six residence times (80–180 s). A previous seed tempering was performed at 15% moisture content for 24 h, by spraying the seeds with an amount of water calculated to reach the final moisture content of 15%. The following parameters were monitored as a function of time to optimize the roasting operation: percentage of open seeds, whiteness of cotyledons, and content of two volatile compounds, 2,5-dimethylpyrazine and ethyl-2-methylbutyrate which are considered as the key jicaro note. The optimal roasting was achieved at 160 °C for 150 s with 90% open seeds. The optimal mechanical dehulling was achieved after tempering the roasted seed at 10% moisture content with a yield of 75%. The lightness evolution followed a zero-order kinetic with an activation energy of 103 kJ mol−1. Ethyl-2-methylbutyrate and 2,5-dimethylpyrazine increased with the temperature and period of roasting.

Development of walnut dehulling machine and assessment of its performance using Ethephon and Tween-80 as pre-treatments for hull loosening.

A power- driven walnut dehulling machine was developed and tested. The machine was evaluated for dehulling after applying Ethephon and Tween-80 to green walnuts by dip and spray methods. The results showed that with the increase in dipping time and post dipping/spraying time, the effective throughput capacity, dehulling efficiency and fully dehulled walnut percentage increased, whereas partially dehulled walnut percentage and labour requirement decreased in both manual and mechanical dehulling. Maximum effective throughput capacity, dehulling efficiency and fully dehulled walnut percentage were observed, when green walnuts were subjected to dehulling after 4days of Ethephon spray treatment (0.3%). The effective throughput capacity, dehulling efficiency and fully dehulled walnut percentage were found significantly higher in mechanical dehulling than in manual dehulling.

Groat proportion in oats as measured by different methods: Analysis of oats resistant to dehulling and sources of error in mechanical dehulling

Groat proportion is the groat yield from an oat dehulling process. We compared hand, impact and compressed-air dehulling to measure groat proportion, and evaluated sources of error. Hand dehulling was the simplest and most accurate method, because all groats and hulls can be accounted for. Mechanical methods dehulled most, but not all, oat kernels. Failure to account for oats resistant to dehulling in calculations resulted in gross errors. Oats resistant to impact dehulling did not differ in groat proportion from the general population, but differed in many physical properties. Hull structure may account the most for their resistance to dehulling. Mechanically dehulled oats consistently yielded lower groat proportions than those from hand dehulling. Since the difference cannot be attributed to oats resistant to dehulling, groats must be lost during the aspiration process, common to all mechanical methods. Uniform aspiration protocols should provide a uniform error. All groat proportion values obtained here were highly correlated among themselves, except when values were not corrected for oats resistant to dehulling. A theoretical groat proportion calculated from the ratio of the mean groat mass (collected by any means available) and the mean kernel mass yielded a groat proportion value that did not differ significantly from the hand dehulling value.Key words: Oat milling, groat proportion, oat dehulling

Evaluation of the Dehulling Efficiency of Soybean Using Attrition and Rice Milling Machines

A process for mechanical dehulling of soybean was developed. Soybean seeds were soaked in boiling water (100oC) for 5, 10, 15, 20 and 25 minutes respectively. The soaked seeds attained a moisture content of 17 – 24%, so as to facilitate dissolution of the gum layer, which bound the seed coats to the endosperm. Conditioned seeds were dehulled in the huller section of commercial rice milling machine and attrition milling machine. A dehulling efficiency (e) value of 55%, which corresponded to an extraction yield (E) of 44% was achieved using the huller section of a commercial rice milling machine, while 90% dehulling efficiency (e), corresponding to an extraction yield (E) of 72%.

Effects of Chemical Dehulling of Sesame on Color and Microstructure

Sesame seeds must be dehulled before processing for the food industry because the husk provides undesirable darker color and bitter taste. Currently, sesame seeds are mechanically peeled but this procedure requires high volume of water, which is a scarce resource in most of the countries where sesame is consumed by humans. In this study, several chemicals have been used in order to facilitate the peeling process and reduce the water requirement. The feasibility of using chemicals was evaluated by studying the color (instrumental and sensory) and the microstructure of seeds. Addition of both NaClO and H2O2 before the mechanical dehulling of sesame seeds will be the recommended treatments for combining the dehulling and whitening steps of the sesame processing. This recommendation is supported by the high values of the L* and dehulling percentage and the low values of the color coordinates a* and b*. Besides, the scanning electron microscopy proved that the NaClO treatment was able to remove the hulls without causing damage to the cotyledons.

Impact of mechanical shelling and dehulling on Fusarium infection and fumonisin contamination in maize

Mechanical shelling and dehulling methods were tested to evaluate their impact on Fusarium infection and fumonisin contamination in maize. All shelling methods which were tested were found to damage the grains. The IITA® sheller caused the highest level (up to 3.5%) of damage. Fusarium populations were higher on damaged grains, the highest being recorded from grains damaged by the IITA® sheller (2533.3 cfu g−1). Fumonisin levels were higher in damaged grains, the highest being in maize shelled with the IITA® sheller (2.2 mg kg−1). Fumonisin levels were positively and significantly correlated with the percentage of damage caused by the shelling methods, and with the number of Fusarium colonies in maize. Mechanical dehulling methods significantly reduced fumonisin levels in maize, resulting in a mean reduction of 62% for Mini-PRL, 65% for Engelberg, and 57% for the attrition disc mill. It is important for farmers to choose appropriate shelling methods to reduce mycotoxin contamination. Dehulling should be widely promoted for the reduction of mycotoxins in maize.

Some engineering properties of locust bean seed

Locust bean was found to be a protein rich crop whose seed is processed into local food condiment ‘iru’ in Nigeria. To explore the possibility of developing handling and processing equipment for the seed, some engineering properties namely: size, 1000 seed weight, true density, bulk density, porosity, static coefficient of friction on wood, angle of repose, specific heat and cracking force, were studied. At a moisture content of 10.25% (db), seed length varied from 0.80 to 1.20 cm, width from 0.60 to 0.85 cm and thickness from 0.45 to 0.60 cm. One thousand seed weight averaged 0.283 kg with a standard deviation of 0.00264. True density lay between 1098.0 and 1215.7 kg/m 3, while bulk density was between 538.02 and 565.30 kg/m 3 and porosity was between 51.0% and 53.5%. Static coefficient of friction on wood averaged 0.43 with a standard deviation of 0.021, angle of repose 20.32° with a standard deviation of 1.84 and specific heat 1415.3 J/kg K with a standard deviation of 103.81. Minimum cracking force was obtained by loading the seed along its thickness. This force averaged 174.38 N with a standard deviation of 10.21. These results indicate that a mechanical dehulling process to obtain whole kernel from locust bean seed should be possible.

Factors Affecting Groat Percentage in Oat

ABSTRACTThe groat percentage represents an important quality characteristic of oat (Avena sativa L.). Our objectives were to characterize mechanical factors of the oat dehulling process and the physical characteristics of the oat grain that affect groat percentage. Mechanical factors were determined with a compressed air dehuller. Physical characteristics of oat grain were evaluated from 10 genotypes grown at three locations with digital image analysis. Groat percentage as determined by hand dehulling was compared with mechanical dehulling. The strength and duration of mechanical stress required to separate the hull from the groat and the strength of the aspiration required to remove free hulls from the groats had significant effects on groat percentage results. Insufficient mechanical stress resulted in ineffective dehulling, but excessive stress resulted in groat breakage. Excessive aspiration removed groats as well as hulls, but insufficient aspiration left excessive hulls with groats. Groat percentage values obtained by hand dehulling or by mechanical means correlated well. Hand sorting of mechanically dehulled groats to remove hulls remaining after dehulling improved their correlation, indicating the importance of hand‐sorting mechanically dehulled oats. Test weight and oat size uniformity were highly correlated with groat percentage. Negative correlation between hulls remaining after dehulling with groat percentage suggested that heavier hulls, associated with lower groat percentage, were more difficult to remove by aspiration. Positive correlations between groat breakage during dehulling and groat percentage suggest that thin hulls provide less protection to the groat during dehulling, resulting in higher levels of breakage.

EVALUATION OF STRAWBERRY CULTIVARS WITH DIFFERENT DEGREES OF RESISTANCE TO RED STELE

Sixteen commercially grown strawberry cultivars with different degrees of resistance to red stele were evaluated for yield, plant characteristics and fruit quality. `Bounty', `Midway', and `Sparkle' had sufficient interior and exterior fruit color, good to satisfactory flavor and suitability for freezing. However, these cultivars as well as `Redcoat' lacked sufficient fruit firmness. `Bounty', `Redcoat', `Redchief and `Sparkle' had the highest yield in the three-year test. `Annapolis', `Earliglow' and `Scott' had reflexed calyx whereas `Allstar', `Annapolis', `Cornwallis', `Earllglow', `Guardian' and `Sunrise' were characterized by a raised neck suitable for mechanical dehulling. `Sunrise' appeared to be the only cultivar free of leaf scorch and leaf spot. `Tristar', `Redchief, `Lester', `Darrow' and `Arking' roots had the lowest incidence of red stele when planted in a naturally-infested field. No relationship between fruit characteristics was observed which suggests the necessity to examine each Individual tralt.

Some engineering properties of pumpkin ( Cucurbita moschata) seeds

Manual dehulling of pumpkin seeds is very tedious. In order to explore the possibility of developing a mechanical dehulling process, the engineering properties of the seed kernels and hulls, such as dehulling load, surface roughness, transport velocity and densities, were studied. Effects of size and moisture conditioning on some of the properties were also evaluated. The results showed that it is possible to dehull the seeds mechanically by a system in which the sharp tips of the seeds impinge on a hard surface. It is also possible to separate kernels, hulls and any unhulled seeds in suitable equipment using the differences in their properties such as surface roughness, densities and transport velocities.

Densities of melon seeds, kernels and hulls

True density, bulk density and apparent density of the seeds, kernels and hulls of commercial varieties of muskmelon, longmelon and watermelon were determined. There is a significant difference between the apparent densities of kernels and of seeds. Kernels are denser than water whereas seeds are less dense; hence kernels sink while seeds float in water. A suitable water separation tank, either batch or continuous, based on this property can be designed for separation of the kernel and seed fractions obtained by mechanical dehulling of the melon seeds.

Effect of treatment on composition and protein and energy utilization of rice and mung bean by rats

Yellow rice derived from stack-burned unthreshed grains had lower lysine content than white milled rice. Stack burning did not affect energy digestibility in growing rats but decreased true nitrogen digestibility and net protein utilization (NPU). Increasing parboiling time from 20 to 60 min had no adverse effect on energy and protein utilization of parboiled milled rice. Defatting of rice bran-polish with petroleum ether at 50°C had no effect on protein utilization but decreased energy content and utilization. Mechanical dehulling of mung bean (Vigna radiata [L.] Wilczek) reduced fiber content, increased energy and protein digestibility but decreased biological value (BV) and NPU. Toasting and winnowing the bean reduced lysine content, improved digestible energy but decreased BV and NPU. Cooking the bean preparations improved the biological value only in mechanically dehulled bean with resultant higher NPU than that of whole bean.

Identification of Australian barley cultivars by laboratory methods: gel electrophoresis and gel isoelectric focusing of the endosperm proteins

A range of laboratory methods was examined for their ability to distinguish between 19 barley cultivars currently grown in Australia. Aleurone colour, revealed after mechanical or chemical dehulling, differentiated Abyssinian, Atlas, Cape and Corvette from the other cultivars. Peroxidase and phenol testing were not useful. Seven different patterns were obtained for the hordeins of lowest mobility by starch gel electrophoresis. Further distinction was provided by flat gel isoelectric focusing of the water-soluble and hordein proteins for which 13 different pattern-groupings were obtained. The two electrophoretic techniques complemented one another, so that the use of both methods left only a few cultivars that could not be distinguished.

Microstructure of Rapeseed

AbstractThe microstructure of the rapeseed kernel was studied by light microscopy, scanning electron microscopy and transmission electron microscopy The structural effect of mechanical dehulling was investigated and attempts were made to localize a major alkali-soluble 12 S glycoprotein. Rapeseed is a small, spherical kernel characterized by the major cell inclusions common to most oilseeds, i.e. nuclei, oil droplets and protein bodies or aleurone grains. Dehulling by pneumatic attrition produced changes in microstructure that may reflect a loss of cellular material. 12 S glycoprotein does not appear to be localized in any specific part of the seed.

Processing of pistachio nuts

New mechanical procedures for processing pistachio nuts make economical preparation for marketing possible in the United States. These new developments include mechanical dehulling, methods for separating empty nuts from those with well developed kernels, and methods for separating split nuts from those with closed shells.