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Научни трудове на Съюза на учените в България-Пловдив Серия Г. Медицина, фармация и дентална медицина т.ХХ1. ISSN 1311-9427 (Print), ISSN 2534-9392 (On-line). 2017. Scientific works of the Union of Scientists in Bulgaria-Plovdiv, series G. Medicine, Pharmacy and Dental medicine, VoLXXI. ISSN 1311-9427 (Print), ISSN 2534-9392 (On-line). 2017.
CHARACTERIZATION OF POWDERED FLAX SEEDS MUCILAGE Yana Georgieva 12, Bissera Pilicheva 12, Plamen Katsarov 12, Todor Naydenov1, Margarita Kassaoova1^
1. Department ofPharmaceutical sdences, l^^cu^^^f^li^rmacy, Medical
University-Plovdiv, Bul. Vanll Apoiiov 15A Piovdlu,Bulgaria
2. High-tecOnoiogicf lCcnter of Amergnnfy Udkin^, Bui. Vasil Aprilov
15A Pioonio, BuSgaria
Abstract
The purpose of this study is to characterize powdered flax seeds mucilage obtained by spray drying method. Aqueous flax seed extracts were prepared with seed concentration of 10%. We vary the extracting conditions as the seeds stay for 72 hours in water at 20 o C, 40 o C and under mixed conditions with warming and standing at room temperature. These three models are pulverized under certain conditions of the apparatus by monitoring the effect of the extraction temperature on yield and rheological properties of the powder. The moisture content as well as the shape and size of the particles were evaluated to determine the possibility of incorporation the powdered mucilage into tablets as a superdisintegrant. Key words: Flax seeds, mucilage, spray-drying method, moisture content, flow ability
Introduction
Flax seed (Linum usitatissimum, Linaceae) is rich of different polysaccharides. According to literary data it includes rhamnose, fucose, arabinose, xylose, galactose, glucose, uronic acid and proteins. The polysaccharides can be extracted with water at a certain temperature in the form of a mucilage (Leon-Martinez, 2010). The resultant dry extract can be further used in orodispersible tablets as a superdisintegrant due to its ability to swell in contact with liquid - water or saliva (Naydenov, 2015). Dry extracts can be obtained by spray drying - method of transformation of material from a fluid state into a powder by spraying it through a hot drying medium (Cervantes-Martinez, 2014).
The purpose of this study was to establish the optimal conditions for obtaining and spray drying of flax seeds mucilage and to characterize the resulting powders by yield, size and shape, moisture content and flow ability.
Materials and methods
Plant material and mucilage extraction
The flax seed was purchased from Bilec Ltd., Troyan, Bulgaria. We prepared three models of linseed water extracts in the following ratio: 25 grams of linen seed in 225 grams distilled water for 72 hours (10% seed concentration in water). Model 1 (M1) - the extract was aquired at 20 ° C under stirring for 72 hours. Model 2 (M2) - the water temperature is kept constant at 40 o C and stirred for 72 hours. At model 3 (M3) the seeds are soaked in hot water (40 °C) and the temperature was maintained for 36 hours, followed by cooling down to 20 ° C for another 36
hours under constant stirring. After 72 hours, the resulting aqueous extracts, called mucilages, are filtered through a gauze to remove the seeds.
Spray-drying (Katsarov, 2015)
Aqueous extractions were spray-dried using Mini Spray Dryer Buchi B-290 (Buchi Labortechnik AG, Flawil, Switzerland) through a 0.7 mm nozzle. The conditions of the spray-drying method were as follows: inlet temperature - 110 o C, aspiration - 60%, pump- 20%, spray flow rate - 601 L/hour.
Powder analysis
Production yields of the obtained powders were calculated using the equation:
Yield (%) = (W1/W2) x100 where W1 is the weight of the resulting powder, W2 - the weight of the filtered mucilage. The visualization of the microparticles shape was achieved using light microscope Leica DM2000 LED with camera Leica DMC2900 (Wetzlar, Germany). The particle size distribution was determined using LS 13 320 Laser Diffraction Particle Size Analyzer (Beckman Coulter, USA). The moisture content was expressed in terms of percentage of residual moisture. The loss on drying was defined using drying oven, where the three model powders were dried for 2 hours under 100o C to reach constant weight.
Flow properties (Pilicheva, 2015)
The angle of repose was measured using fixed funnel method at three measurements. The funnel (7 mm diameter) is fixed at a height of 5 cm and 0.5 g of powder is flown through it to form a cone on a horizontal surface. The following equation was used (1):
Angle of repose (9 ) = tan"
v J
(1)
where 0 is the angle of repose, h - the height of the formed cone, r - the radius of the cone's base.
The Hausner ratio (HR) and Carr's Index (CI) were calculated using the bulk density and the tapped density of the powders. The bulk volume and tapped volume were measured using 0,5 g of powder of each model and 5 mL volumetric cylinder by tapping the powder 250 times using SVM tapped density tester (Erweka GmBH, Germany). The rheological parameters were calculated using equations (2) and (3).
(2)
(3)
Results and discussion
The data from Figure 1 shows that the temperature, at which it is produced, is of crucial importance for the production yield. At a higher temperature, a larger amount of polysaccharides is recovered which results in higher powder yields under the same spray-drying conditions. This can also be acertained by the higher viscosity of the liquid extract in Model 2, observed during the preparation of the models. With regard to the spray-drying conditions, these were precisely selected as a result of previous experimental work. It was found that the inlet temperature should not exceed 110 oC because, on such
cases, the polysaccharides adhere to the parts of the apparatus. On the other hand, lower temperatures are unable to evaporate the water from the extract, which results in a lack of
production yields. In terms of the yield, in all studied cases it is not high, which necessitates a higher concentration of the seeds in the water. Optical microscopy (Figure 2) shows the spherical shape of the microparticles and also their tendency to aggregate, which may cause handling difficulties related to unfavourable flow properties.
1
Production 0.8
yield (%) 0:7 f _
0.6 n n
0.5 0.4 0.3 0.2 0.1
0 Ml M2 M3
□ yield % 0.6045 0.7835 0.6515
extracting temp,o C 20 40 40/20
inlet temp, o C 110 110 110
aspiration % 60 60 60
pump % 20 20 20
spray flow litre/hour 601 601 601
Figure 1. Influence of production variables on the production yields
A: % •.. • * . a ;
P . : . J.
' » , A t® 25,000001 I
f A
Figure 2 - Micrographs of the microparticles
The size of the particles ranges from 4 to 10 ^m (Figure 3), but model 3 shows a greater tendency to aggregation which is confirmed by the particle size distribution analysis.
The moisture content (Table 1) is not high and powders with such values are expected to have good flow properties. However, the loss on drying is also very low, which means that the large amounts of polysaccharides retain substantial moisture and together with the van der Waals and electrostatic forces of attraction might be the main reason for cohesion.
Table 1
Model moisture content % ±SD loss on drying %±SD
Ml 2.275 ± 0,502 5 ± 1,414
M2 2.23 ± 0,764 7 ± 1,414
M3 1.875 ± 0,247 7 ± 1,414
The angle of repose, Hauser ratio and Carr's index are shown in Table 2. They are an expression of the flow characteristics of the powders and when compared to the European Pharmacopoeia 7, show very, very poor flowability.
Table 2
Model Hausner ratio HR ± SD Index Carr % ± SD Angle of repose 0 ± SD
M1 1,79±0,08 44,18 ±2,64 59,17±4,20
M2 1,71±0,10 41,50±3,58 57,57±5,16
M3 1,92±0,24 47,32±6,55 63,07±8,30
Conclusion
Spray drying is a method that can be successfully used to produce dry extract of flax seeds. The resulting powders fall into the group of superfine powders and have low residual moisture and loss on drying. They have very, very poor flow properties, which is a precondition for using optimum methods to improve the flowability in case of using them as superdisintegrants in tablet formulations.
References
1. F.M. Leon-Martinez, L.L. Mendez-Lagunas, J.Rodriguez-Ramirez, Spray drying of nopal mucilage (Opuntia ficus -indica): Effects on powder properties and characterization, Carbohydr. Polym.,2010, 81, 864-870
2. C.V. Cervantes-Martinez, L.Medina-Torres, etc, Study of spray drying of the Aloe vera mucilage ( Aloe vera barbadensis Miller) as a function of its rheological properties, LWT- Food Sci and Tech, 2014, 55, 426-435
3. P. Katsarov, B. Pilicheva, M. Kassarova, Influence of the spray drying formulation parameters on the production of polymeric microspheres for nasal administration, Sci w of the Uniof Sci in Bulg-Pl,2015, series G. Med, Pharm and Dental med, Vol. ХVШ, 6568
4. B.Pilicheva,P.Katsarov,M.Kassarova, Flowability Evaluation of Dry Powder Inhalation Formulations intended for nasal delivery of betahistine dihydrochloride,2015, vol 2,77-90
5. Т.Найденов, М.Касърова, Проучване върху приложението на природни и модифицирани полизахариди като супердезинтегранти в диспергиращи се в устата таблетки, II-ра Национална Конференция Фармацевтични Технологични Дни, 10.2014, Цигов чарк, Първо издание 01.2015, ISBN 978-954-91660-7-1
