Red Lentil Seeds Research Articles

Microwave fluidised bed drying of red lentil seeds: Drying kinetics and reduction of botrytis grey mold pathogen

Botrytis grey mould (BGM) is a problematic seed-borne disease of lentil crop, with little known about its possible physical control. Microwave fluidized bed dryers have been widely studied for grain, fruit and vegetable drying. In the present study, simultaneous drying and disinfection of red lentil seeds, were investigated in a microwave fluidized bed at 4 microwave powers of 0, 300, 400 and 500W using fluidizing hot air at 50 and 60°C. Moisture diffusivities of lentil seeds were defined by considering the Fick's second law of diffusion in one direction in a sphere with convective boundary conditions as well as negligible external resistance to mass transfer. They varied from 0.44×10−10 for hot air alone at 50°C to 3.06×10−10m2/s for microwave power and air temperature combinations of 500W and 60°C by considering convective boundary condition for the seeds. Drying times obtained from well-fitted Page's model were applied for drying of the seeds contaminated with BGM. The results indicated that infected seeds percentage (IS%) could be reduced by 30% by applying combinations of microwave power and hot air at 300W and 60°C or 400W and 50°C, without a significant loss of seed viability. Thus, microwave fluidized bed drying has a good potential to reduce seed born BGM in lentil crop.

Effect of Microwave Radiation on Internal Inoculum of Ascochyta Blight in Lentil Seeds at Different Seed Moisture Contents

Abstract. Considering the development of pest and pathogen resistance to chemical treatments and the cost of developing new chemicals, proper physical methods for integrated pest management seem to be gaining interest. Microwave treatment has been considered a potential postharvest pest and disease management strategy in legume and grain seeds. The effect of this process on pathogens related to legumes, which could be expressed as a very fast and volumetric thermal treatment, has not been fully studied. In this study, a domestic microwave oven with full output power of 1100 W (company information) or 485 W (calibrated with 150 g of water) was used to treat red lentil seeds that were naturally infected with the Ascochyta blight (AB) pathogen, a problematic seedborne fungi of lentil. Microwave radiation was applied at three moisture contents of red lentil seeds (9.1%, 16%, and 19% wet basis) and two power levels (50% and 100%). Three exposure times for each moisture content and power level were selected to achieve the same final average temperatures with low and high moisture contents (approx. 65°C to 85°C). The complementary error function was used to model and compare the pathogen and seed death rates based on the normally distributed susceptibility of the AB pathogen and seed germination to microwave heating. At 9% moisture content with water activity of 0.4, the percentage of infected seeds decreased from 17% to 9% without significant loss of seed viability when a power level of 100% (9.7 W g-1) and exposure time of 51 s were applied, and the final average surface temperature reached 84°C. However, seed vigor, measured by the electrical conductivity of the seed leachate, decreased at this power level and exposure time. Despite the feasibility of fungi elimination at higher moisture content at the same final average temperatures, eliminating fungi from the seeds without harming their viability and vigor was challenging. Keywords: Ascochyta blight, Lentils, Microwave energy, Pathology.

Monitoring of Chemical Changes in Red Lentil Seeds during The Germination Process

Abstract Red lentils are a very important raw material in the food industry due to their high protein content and high level of health-promoting components. The nutritive value of red lentils is the most important attribute from a research point of view; it can be increased by germination, soaking as well as physical and biochemical processes. The antinutritive materials are reduced or denatured by the germination process and indigestible components become available to the human body. Heat treatment was applied to achieve different temperatures and increase the microbiological stability of germinating samples. The effect of heat treatment on the amounts of certain components and the activity of oxidative enzymes was tested during our experiments; the nutritional characteristics (water-soluble total polyphenol content (WSTPC), water-soluble protein content (WSPC), water-soluble antioxidant capacity, in addition to peroxidase and polyphenol oxidase enzyme activities) of different treatments in red lentil samples were monitored. The WSTPC in our samples ranged from 0.726 mg Gallic Acid Equivalent GAE/g DW (DW being dry weight) to 1.089 mg GAE/g DW, and the WSPC varied from 19.078 g / 100g DW to 29.692 g / 100 g DW. Results showed that germination led to an increase in the WSTPC and WSPC. The peroxidase enzyme activity also exhibited an increase during germination which could result in deepening of the colour of the finished products. Germination resulted in the water-soluble antioxidant capacity of red lentil samples decreasing.

Mechanical damage to green and red lentil seeds

In this research, the breakage susceptibility of two classes of lentil (green and red) was evaluated as affected by impact energy and seed moisture content. The experiments were conducted at impact energies of 0.1, 0.2 and 0.3 J, and moisture contents of 10, 12.5, 15, 17.5, 20 and 25% (wet basis). Results showed that red lentil seeds had more breakage than green seeds and the difference in breakage percentage between green and red lentil seeds was significant at 0.01% level according to analysis of variance (p < .01). Percentage breakage of both green and red lentil seeds increased as the energy of impact increased. With increasing the seed moisture content of the both green and red lentils, the breakage percentage of seeds decreased. The average values of seeds breakage green and red lentil seeds varied from 100 to 67.7% and from 100 to 93.1%, respectively, as the seeds moisture content increased from 10 to 25%. The optimum seed moisture at which minimum damage was observed was 17.5% for green lentil and 15% for red lentil. Mathematical relationships composed of lentil seeds moisture content and energy of impact were developed for accurate description of the breakage percentage of green and red lentil seeds under impact loading.

Evaluation of physical properties and hydration kinetics of red lentil (Lens culinaris) at different processed levels and soaking temperatures

Hydration kinetics of red lentil seeds were carried out for whole, dehusked and splits at different temperatures (15 to 45°C). Several physical properties were evaluated as function of soaking temperatures. Henderson and Pabis, Page, two term exponential and Peleg models were fitted to the obtained hydration kinetics data. To assess the adequacy of models three statistical parameters, coefficient of multiple determinations (R2), root mean square error (RMSE) and chi-square (χ2) were employed. Peleg model (R2>0.990; RMSE<0.018; χ2<0.001) was found to be adequate in describing the hydration behavior of red lentil seeds. Effective diffusivity of water over a temperature range of (15–45°C) for whole, dehusked and splits varied from 6.890×10−11 to 1.142×10−10, 1.030×10−10 to 1.584×10−10 and 1.231×10−10 to 1.927×10−10 with the activation energy of 12.239, 11.145 and 10.741, respectively. Soaking temperatures pose significant effect on water absorption capacities and all the evaluated physical properties of red lentil seeds.

Chalky spot damage caused by stink bugs on red lentil seeds in Southeast Anatolia Region, Turkey

Chalky spot damage on red lentil is the most important problem waiting for a solution regarding plant health at lentil cultivation in Southeast Anatolia Region, Turkey. The stink bugs, Piezedorus lituratus (F.) and Dolycorus baccarum L. were subjected to trials in cages and in sprayed and unsprayed plot trials in open lentil fields and fields containing windrowed lentils after harvesting. The study revealed that P. lituratus and D. baccarum feeding on red lentil caused chalky spot damage. Average damage to lentil seeds caused by P. lituratus was 13% and 7.8% and by D. baccarum was 4.9% and 2% in 2010 and 2011, respectively. There was a positive relation between P. lituratus density and chalky spot damage (r =0.788, r2 =0.621, P=0.000). The study also showed that after the harvesting, the stink bugs gathered under windrowed lentils and continued feeding and causing chalky spot damage. The damage in unsprayed windrowed lentils (6.60%) was approximately 12-fold higher than that in sprayed windrowed lentils (0.57%). Study suggests conduction of future work on environmental friendly control methods of stink bugs and alternative harvesting methods.

Aerodynamic properties of lentil seeds

Abstract Aerodynamic properties of solid materials have long been used to convey and separate seeds and grains during post-harvest operations. The objective of this study was evaluation of the aerodynamic properties of green and red lentil seeds as a function of moisture content from 10 to 25% (w.b.). The results showed that as the moisture content increased from 10 to 25%, the terminal velocity of seeds increased, following a linear relationship, from 6.90 to 9.14 and from 6.37 to 7.67 m s−1 for green and red lentil seeds, respectively. Seeds of the green variety had terminal velocities with a mean value of 7.89 m s−1, while the red variety had a mean value of 7.02 m s−1, for moisture content from 10 to 25%. The Reynolds number increased linearly from 2 310.90 to 3 269.23 and from 1 215.02 to 1 535.09 for green and red lentil seeds, respectively, with the increase of seeds moisture content from 10 to 25%. While, drag coefficient decreased from 0.69 to 0.40 and from 0.84 to 0.69 for green and red lentil seeds, respectively, with the increase of moisture content. Mathematical relationships were developed to relate the change in seeds moisture content with the values of aerodynamic properties obtained. The analysis of variance showed that the effect of moisture content on all aerodynamic properties of lentil beans was significant at the 1% probability level.

Specific Heat, Thermal Conductivity and Thermal Diffusivity of Red Lentil Seed as a Function of Moisture Content

Thermal properties of red lentil seeds, including specific heat, thermal conductivity and thermal diffusivity in the moisture content range of 9.5–21.1% (w.b) were determined. The specific heat was measured using method of mixtures and found to be between 1.08 and 2.03 kJ/kg·K as the moisture content increased. The thermal conductivity of seed increased from 0.191 to 0.241 W/m·K by increasing moisture content (P < 0.05). This relationship has been established in the form of a second-order regression equation. Moreover, the thermal diffusivity computed from the values of thermal conductivity, specific heat and bulk density showed polynomial decrease from 2.15 × l0−7 to 1.65 × 10−7 m2/s in the specified range of moisture content (P < 0.05). Determination of these characteristics is practical in modeling thermal behavior of red lentil seeds during thermal processing operations, such as frying, drying and baking. Practical Application Thermal properties of agricultural materials and foods need to be known to better understand their nature and to be able to develop new technologies. Knowledge of thermal properties is important for mathematical modeling and simulation of heat and moisture transport. However, the moisture content significantly affects different thermal characteristics. The presented models and equations in this study allow engineers to predict these properties, thus saving time, material and cost.

Detection of Common Vetch (Vicia sativa L.) in Lentil (Lens culinaris L.) using unique chemical fingerprint markers

Detection of adulteration of split red lentil (Lens culinaris L.) seeds with low level addition of split common vetch (Vicia sativa L.) is hampered by a lack of reliable detection methods. An analytical method was developed using high performance liquid chromatography with diode array detection (HPLC-DAD) based on two unique chemical markers found in common vetch: ß-cyanoalanine (BCA) and γ-glutamyl-ß-cyanoalanine (GCA). These two markers were present in samples of common vetch seed grown in Canada and Serbia. Authentic lentil samples grown in Canada, Australia, USA, Turkey, Syria, and Morocco had no detectable levels of these chemical markers. Commercial lentil samples for export from lentil processing plants in Saskatchewan, Canada, also had no detectable levels of GCA and BCA. The presence of vetch in intentionally adulterated lentil samples could be determined via chemical markers with a detection limit of 5% (w/w). The proposed method is a simple sample extraction and rapid HPLC analysis that could be widely used to detect intentional adulteration of lentils with common vetch.

The Effect of Moisture Content on the Thermal Properties of Red Lentil Seeds

The specific heat, thermal conductivity, and thermal diffusivity of red lentil (cv. Firat-87) seeds were determined as a function of the moisture content. The specific heat and thermal conductivity were measured using the methods of mixture and transient-state heat transfer, respectively. The thermal diffusivity was calculated from measured specific heat, thermal conductivity, and bulk density. Within the moisture range of 7.13% to 17.46% (d.b.), the specific heat, thermal conductivity, and thermal diffusivity varied with the moisture content. The specific heat and thermal conductivity of red lentil seeds increased from 1506.81 to 2457.15 J kg-1 °C-1 and from 0.121 to 0.162 W m-1 °C-1, respectively, as the moisture content increased in the above range. However, the thermal diffusivity decreased from 9.45 × 10-8 to 8.35 × 10-8 m2 s-1 with the increase in moisture content.

Antioxidant Activity of a Red Lentil Extract and Its Fractions

Phenolic compounds were extracted from red lentil seeds using 80% (v/v) aqueous acetone. The crude extract was applied to a Sephadex LH-20 column. Fraction 1, consisting of sugars and low-molecular-weight phenolics, was eluted from the column by ethanol. Fraction 2, consisting of tannins, was obtained using acetone-water (1:1; v/v) as the mobile phase. Phenolic compounds present in the crude extract and its fractions demonstrated antioxidant and antiradical activities as revealed from studies using a β-carotene-linoleate model system, the total antioxidant activity (TAA) method, the DPPH radical-scavenging activity assay, and a reducing power evaluation. Results of these assays showed the highest values when tannins (fraction 2) were tested. For instance, the TAA of the tannin fraction was 5.85 μmol Trolox® eq./mg, whereas the crude extract and fraction 1 showed 0.68 and 0.33 μmol Trolox® eq./mg, respectively. The content of total phenolics in fraction 2 was the highest (290 mg/g); the tannin content, determined using the vanillin method and expressed as absorbance units at 500 nm per 1 g, was 129. There were 24 compounds identified in the crude extract using an HPLC-ESI-MS method: quercetin diglycoside, catechin, digallate procyanidin, and p-hydroxybenzoic were the dominant phenolics in the extract.

An antifungal peptide from red lentil seeds

An antifungal peptide, with a molecular mass of 11 kDa, was isolated from dry seeds of the red lentil ( Lens culinaris) using a procedure that involved four chromatographic steps. The antifungal peptide was unadsorbed on DEAE-cellulose, and adsorbed on Affi-gel blue gel and S-Sepharose. The final chromatographic step involved gel filtration by fast protein liquid chromatography on Superdex 75. The antifungal peptide inhibited mycelial growth in Mycosphaerella arachidicola with an IC 50 of 36 μM. It also exhibited antifungal activity against Fusarium oxysporum, but there was no inhibitory activity toward tumor cell lines and human immunodeficiency virus type 1 reverse transcriptase (RT).