Optimisation of hydrothermal treatment for dehulling pigeon pea

This study was carried out to investigate the effect of hydrothermal treatment and drying time at a constant drying temperature of 50 °C on the dehulling behavior of pigeon pea seed. Response surface methodology (RSM) based on a two-factor, five-level, central composite design was employed to study the effect of the independent variables and optimize processing conditions. A second-order polynomial model described dehulling quality in terms of: (1) dehulled seeds, (2) undehulled seeds, (3) broken seeds, (4) powder loss and (5) dehulling efficiency. The process parameters showed significant effects on dehulled seeds and dehulling efficiency. The optimized processing conditions for maximum dehulled seeds, dehulling efficiency and minimum powder loss were a hydrothermal treatment time of 10.2 min and a drying time of 2.9 h.     

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.     

Effects of Dehulling on Phytic Acid, Polyphenols, and Enzyme Inhibitors of Dry Beans (Phaseolus vulgaris L.)

Effects of dehulling on phytic acid; trypsin, chymotrypsin, and α-amylase inhibitory activities; and tannins of ten cultivars of dry beans (Phaseolus vulgaris L.) were investigated. Phytic acid content of whole beans ranged from 1.16-2.93%. Dehulling significantly increased the phytic acid content of beans (range 1.63-3.67%). Dehulling also increased trypsin, chymotrypsin, and α-amylase inhibitory activities of the beans. Tannin contents of whole and dehulled beans ranged from 33.7-282.8 and 10.0-28.7 me. catechin equivalent/100g beans, respectively. Removal of seed coats lowered the tannin content of beans by 68–95%. Tannins were not detected in white seeded cultivars of Sanilac, Great Northern, and Small White. Dehulling significantly improved the in vitro digestibility of bean proteins.     

Effect of cultivar,cultivation year and dehulling on raffinose family oligosaccharides in Australian sweet lupin (Lupinus angustifolius L.)

The aim of this study was to determine the effect of cultivar, cultivation year and dehulling on raffinose family oligosaccharides (RFOs) in current cultivars of Australian sweet lupin. Seed samples of ten cultivars grown in 2011, 2012 and 2013 were used in the study. Both whole seed and dehulled lupin samples were analysed for RFOs by high‐performance liquid chromatography with evaporative light scattering detector. Lupin cultivar had a significant effect on RFO contents. Total RFO contents in whole seed and dehulled lupin samples varied between 7.3–10.1 g/100 g DM and 7.6–16.8 g/100 g DM, respectively. Belara and Mandelup cultivars had high levels of RFOs indicating the suitability for functional foods with prebiotic effect. Gungurru and PBA Barlock contained low levels of RFOs and recommended for lupin‐enriched foods with low flatulence effect. Cultivation year with similar climatic conditions had no significant effect on RFO contents. Dehulling increases raffinose, stachyose and total RFO contents in lupin.     

Comparative studies of some properties of undehulled, mechanically dehulled and manually dehulled cowpea (Vigna unguiculata Walp. L.) flours

A comparative evaluation was made of some physico‐chemical and rheological characteristics of undehulled, manually dehulled and mechanically dehulled cowpea (Vigna unguiculata Walp. L.) flours from brown and white varieties of the legume. The flours were used to prepare steamed bean paste, ‘Moinmoin’, which was analysed for some sensory parameters. Dehulling and dehulling methods had no appreciable influence on the physical characteristics and proximate composition of the flours, except ash content, which was slightly higher in undehulled flour samples. Amylograph pasting characteristics of the flours showed varying trends because of dehulling method and/or presence of seed coats. ‘Moinmoin’ samples prepared from the flours received similar ratings for all sensory attributes, with no significant differences (P < 0.01 and P < 0.05), except for the low‐rated (poorer) colour of the undehulled brown product.     

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

BACKGROUND: 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     

Air Classification of Peas (Pisum sativum) Varying Widely in Protein Content

Four samples of field peas, ranging in protein content from 14.5–28.5% (dry, dehulled seed basis), were pin milled and air classified yielding protein concentrates and starch concentrates containing 33.6–60.2 and 3.8–11.3% protein, respectively. The protein content of the dehulled peas were negatively correlated with their starch content (49.7–59.8%), lipid content (3.0–4.1%) and cell wall material (CWM) content (7.1–9.6%). The % protein in all air classified fractions was positively correlated to % protein in the dehulled peas, whereas, lipid and CWM content was negatively correlated. Air classification at lower air flows (smaller cut sizes) resulted in protein and starch fractions containing higher levels of protein. Starch separation efficiency and protein separation efficiency generally increased with increasing protein content.     

In vitro multienzyme digestibility of protein of six varieties of African yam bean flours

The in vitro multienzyme protein digestibilities of the flours of six varieties of African yam bean (Sphenostylis stenocarpa), made from both whole seeds and dehulled seeds were investigated. The multienzyme system consisted of trypsin, chymotrypsin and peptidase. Digestibilities were determined for a 10 min digestion period. Both dehulling and heat treatment improved digestibility. Comparison of flours from raw whole seeds with those from dehulled seeds showed that digestibility was better in the latter, with an increase of 6.78%. Heat-treated whole seed flcurs gave a digestibility increase of 6.06% compared with raw flours whereas in the dehulled samples the digestibility increase of heat-treated flours over raw was 5.19%. Heat-treated dehulled seeds were better, with a digestibility increase of 5.90% over the heat-treated whole seed flours. No significant differences (P < 0.05) were observed in the digestibilities among the whole seed flours but significant differences were observed in the dehulled seed flours.     

Microscopic, Nutritional and Functional Properties of Cowpea Flours and Protein Concentrates During Storage

During storage for 6 mo at 64% RH, whole seed flour, dehulled seed flour and air-classified protein concentrate from cowpeas showed little change in nutritional or sensory properties but there were improvements in functional properties. However, wet-processed protein concentrate, after drum-drying, darkened and had reduced functionality by the 6th mo. When storaged at 79% RH, all cowpea products darkened significantly, showed decreased lysine contents and lower nitrogen, solubility, all emulsification and foaming characteristics. Both dehulling and air classification improved the storage properties of cowpea products but drum drying of a wet-processed product had an adverse effect on functionality and nutritive value, especially when stored at 79% RH.     

Decontamination of aflatoxin‐contaminated maize by dehulling

Dehulling of maize grains as an aflatoxin decontamination method was investigated. Sixty kilograms of maize (whose average moisture content was 110 g kg^?1) were thoroughly mixed and divided into two samples. The kernel moisture content of one sample was adjusted to 200 g kg^?1 while the other (control) was left at 110 g kg^?1. The two samples were kept at ambient temperature (25–30 °C) for 21 days. Twenty sub‐samples, ten from each, were further divided into two so that one lot was dehulled while the other was not dehulled. These sub‐samples were then milled to pass through a 1 mm screen and the meal was evaluated for aflatoxin contamination. It was found that there was a 92% decrease in aflatoxin levels in dehulled maize meal compared with undehulled maize meal. We therefore suggest that dehulling the grain can be used to reduce aflatoxin levels in maize. Copyright © 2005 Society of Chemical Industry     

去皮豆粕的生产与应用

在大豆浸出制油过程中,通过增加脱皮工艺,可得到高蛋白去皮豆粕.将豆粕与收集的豆皮分别粉碎后,把豆皮按需添加至去皮豆粕中,可得到不同粗蛋白(CP)含量的的等级豆粕.影响脱皮效果的因素主要有干燥温度、破碎辊间隙、吸风量、豆皮筛网规格等.高蛋白豆粕比普通豆粕具有较高的营养与使用价值,随着饲料工业的发展,我国高蛋白豆粕在饲料中所占比例将逐步增加.     

The effects of soaking of whole, dehulled and ground millet and soybean seeds on phytate degradation and Phy/Fe and Phy/Zn molar ratios

The degradation and leaching of phytates, phytase activity and iron and zinc concentrations have been studied after soaking of whole seeds, dehulled seeds and flours of millet and soybean, in order to investigate the efficiency of soaking on reducing Phy/Fe and Phy/Zn molar ratios. When using millet grains, dehulling and milling before soaking facilitated the leaching of phytates and phytases in the aqueous medium and hence phytate degradation. Dehulling of soybean seeds led to a marked increase in phytate content, whereas milling favoured reactions between phytases and phytates. The Phy/Fe and Phy/Zn molar ratios decreased only slightly during soaking. The highest decreases for millet were obtained after soaking of flour for 8 h (Phy/Fe: 10.8–7.7 and Phy/Zn: 20.3–15.1), and after soaking of whole seeds for 24 h for soybean (Phy/Fe: 10.4–9.4 and Phy/Zn: 23.8–19.1). Cooking of flours with water used for soaking did not increase phytate degradation.     

The impact of germination and dehulling on nutrients, antinutrients, in vitro iron and calcium bioavailability and in vitro starch and protein digestibility of some legume seeds

The content of nutrients (protein, starch, ash, calcium, iron, phosphorous and thiamin) and antinutritional components (dietary fiber fractions, phytic acid and tannin), and in vitro bioavailability of calcium and iron and in vitro digestibility of protein and starch were determined in control, germinated and dehulled green gram, cowpea, lentil and chickpea. Germination caused significant (P<0.05) increase in protein, thiamin, in vitro iron and calcium bioavailability and in vitro starch and protein digestibility contents of all the legume samples. Further increase in mentioned parameters was observed after dehulling the germinated legumes. Phytic acid and tannin were reduced by 18-21% and 20-38%, respectively, on germination and more reduction was observed in dehulled over germinated samples. There were negative correlations between nutrients bioavailability and digestibility with antinutritional factors.     

Dehulling Characteristics of Selected Flaxseed Varieties

Dehulling characteristics of six different flaxseed varieties namely Shikha, Rashmi, Shekhar, Sweta, Padmini and Neelam at different residence times (40, 50 and 60 s) were investigated using dry dehulling. The dried flaxseed samples were dehulled in a laboratory model abrasive dehuller (rice polisher) and various dehulling parameters were determined. It was found that dehulling parameters namely embryo recovery, extraction rate, yield, hull and hullability were affected by residence time and varietal characteristics. The embryo recovery, extraction rate, yield, hull and hullability for studied varieties of flaxseed and residence time were 23.71?±?0.77–61.35?±?0.94 %, 58.26?±?2.20–79.11?±?0.43 %, 22.96?±?0.44–43.85?±?1.38 %, 16.83?±?1.75–61.54?±?5.11 % and 45.92?±?0.51–90.62?±?2.85 % (dry basis), respectively. Among the studied flaxseed varieties, Padmini and Neelam varieties were found suitable for dehulling purposes at 60 s residence time. The dehulled flaxseed (embryo), thus obtained, can be utilized for obtaining the good quality edible oil and meal for human consumption and hull as lignin-rich product.     

Determination of the optimum intermittent drying conditions for rough rice (Oryza sativa,L.)

Intermittent drying was studied by tempering rough rice (Philippine Seed Board, PSB-RC 52 variety) in between during hot air drying. The study was performed using a three-level, three-factor fractional factorial design and aimed to determine the optimum combination of drying air temperature (X₁), air speed (X₂) and tempering time (X₃) that resulted in high milling recovery (MR), high head rice ratio (HRR), short drying time (DT), high grain hardness (H), high germination ratio (GR), high degree of whiteness (W) and low cracked grains ratio (CGR). Drying air temperatures used varied from 35°C to 55°C. Airspeed, on the other hand, significantly affected H only and tempering time affected DT at the 95% significance level. Optimum drying conditions of 45°C drying air temperature and a tempering time of 2 h were established for the intermittent drying of rough rice.     

油茶籽脱壳制油工艺的研究与实践

通过研究油茶籽的物料特性,提出了油茶籽加工采用脱壳工艺的重要性。研究建立了与现有预榨浸出工艺配套的油茶籽脱壳设备,油茶籽的脱壳率在98 5%以上,所生产的产品茶籽油符合国家茶籽油标准GB11765-1989。     

Effect of fermentation and dehulling on starch,total polyphenols,phytic acid content and in vitro protein digestibility of pearl millet

Two pearl millet cultivars: Standard and Ugandi, obtained from El Obeid Research Station, were used in this study. Investigation showed that the Ugandi variety had significantly (P⩽0.05) higher polyphenols and phytic acid contents than the standard and significantly lower in vitro protein digestibility (IVPD), (72.7 and 70.4% for the Standard and Ugandi, respectively), indicating lower nutritional quality. The two cultivars were fermented for 14 h at room temperature (30±2° C) and starch, polyphenols, phytic acid and IVPD were determined at 2-h intervals. Dehulling was found to cause a significant reduction in protein, polyphenols and phytic acid contents for the two cultivars. Fermentation and dehulling caused a significant increase in the IVPD for the two cultivars: 82 and 84% for the fermented ones and 79.1 and 78.6% for the dehulled samples.     

Chemical,functional and nutritional properties of wet dehulled niger (Guizotia abyssinica Cass.) seed flour

Niger seeds were dehulled using hot lye treatment. Dehulling of niger seeds increased the protein and fat contents from 24 to 35 and 31–53 g/100 g and decreased the crude fiber from 16.9 to 2.2 g/100 g, respectively. The defatted flour prepared from dehulled niger seeds was evaluated for chemical, functional and nutritional properties and compared to the undehulled flour. The protein content of the dehulled flour increased from 44 to 63 g/100 g. Dehulling resulted in inactivation of trypsin inhibitor activity. The dehulled flour had higher water and fat absorption capacities. However, the nitrogen solubility, emulsification capacity and foaming properties decreased. Chemical score of the dehulled flour was higher; threonine was the first limiting amino acid followed by lysine and isolecuine. The in vitro digestibility of the protein increased due to dehulling (85.5%) compared to that of undehulled flour (76%). The calculated nutritional indices, essential amino acid index, biological value, nutritional index and C-PER, were higher in dehulled flour compared to undehulled flour. The available lysine content appeared to be unchanged.     

Effect of processing on the antioxidant activity of millet grains

Millets are generally dehulled and subjected to a hydrothermal treatment before consumption, thus the hulls can be used as a potential source of antioxidants. Several millet grains, namely kodo, finger (Ravi), finger (local), proso, foxtail, little and pearl millet were studied. Antioxidant activities of phenolic extracts obtained from whole grains, as well as their corresponding dehulled and cooked grains and hulls were studied for their total phenolic content (TPC), radical scavenging capacity, and antioxidant activity in a β-carotene/linoleate emulsion. The phenolics present in whole grains were identified and quantified using HPLC and HPLC/MS and results were expressed as total for each of the phenolic groups. The TPC ranged from 2 to 112 μmol ferulic acid equivalents/g defatted meal. All varieties exhibited effective inhibition of 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl, peroxyl and superoxide radicals. Dehulling and cooking affected the TPC and radical scavenging and antioxidant activities of the grains, depending on the variety. In general, the antioxidant activity of phenolic extracts was in the order of hull > whole grain > dehulled grain > cooked dehulled grain With the exception of the two finger millet varieties, hulls of other millet grains had high TPC, thus demonstrating their superior antioxidant activity. Hydroxybenzoic acids, hydroxycinnamic acids and flavonoids in whole grains were identified as contributors to the observed effects. Therefore, dehulling of grain and hydrothermal treatments affect the phenolic content and antioxidant potential of millet grains.     

Predicting Guar Seed Splitting by Compression between Two Plates Using Hertz Theory of Contact Stresses

Hertz's theory of contact stresses was applied to predict the splitting of guar seeds during uni-axial compressive loading between 2 rigid parallel plates. The apparent modulus of elasticity of guar seeds varied between 296.18 and 116.19 MPa when force was applied normal to hilum joint (horizontal position), whereas it varied between 171.86 and 54.18 MPa when force was applied in the direction of hilum joint (vertical position) with in moisture content range of 5.16% to 15.28% (d.b.). At higher moisture contents, the seeds yielded after considerable deformation, thus showing ductile nature. Distribution of stresses below the point of contact were plotted to predict the location of critical point, which was found at 0.44 to 0.64 mm and 0.37 to 0.53 mm below the contact point in vertical and horizontal loading, respectively, depending upon moisture content. The separation of cotyledons from each other initiated before yielding of cotyledons and thus splitting of seed took place. The relationships between apparent modulus of elasticity, principal stresses with moisture content were described using second-order polynomial equations and validated experimentally. Practical Application: Manufacture of guar gum powder requires dehulling and splitting of guar seeds. This article describes splitting behavior of guar seeds under compressive loading. Results of this study may be used for design of dehulling and splitting systems of guar seeds.