EFFECTS OF DEGREE OF CROSS LINKING ON PHYSICAL PROPERTIES

Effects Of Degree Of Cross Linking On Physical Properties-Free PDF

  • Date:20 Nov 2020
  • Views:6
  • Downloads:0
  • Pages:6
  • Size:552.13 KB

Share Pdf : Effects Of Degree Of Cross Linking On Physical Properties

Download and Preview : Effects Of Degree Of Cross Linking On Physical Properties


Report CopyRight/DMCA Form For : Effects Of Degree Of Cross Linking On Physical Properties


Transcription:

Effects Of Degree Of Cross Linking On Physical Properties Pasting And Freeze Thaw Stability Of Cassava Starch Modified By Reactive. Extrusion Process REX, 97 18 0 21 and phosphorus contents of 0 006 cooled to 45 C at the cooling rate of 10 C min The. respectively Sodiumtrimetaphosphate STMP was peak viscosity values of native and cross linked. used as the cross linking agent Sigma Aldrich Inc cassava starch were calculated degree of cross linking. St Louis MO Other chemical agents were supplied according to 6 using 1. by RCI Labscan Bangkok TH,Degree of cross linking A B A x 100 1. 2 2 Preparation of phosphorylated cross, linked starches Where A is peak viscosity of the native starch and B. The co rotating twin screw extruder used in this is peak viscosity of the modified starches. studies was a pilot scale CTE D25L32 Chareon, tut Co Ltd TH with 7 zones of barrel the screw 2 4 Determination of water solubility index. diameter of 24 70 mm and length to diameter ratio WSI and swelling power. L D of 32 Different STMP NaOH Water solubility index WSI and swelling power. concentration and water content levels were were determined according to Lee et al 12 The 2 5. preliminarily designed to produce cross linked g of starch was weighed W1 in 50 ml of pre. cassava starch at low medium and high degree of weighted centrifuge tube then 30 ml of distilled. cross linking respectively as shown in Table 1 Feed water was added capped the tube and shaking in. rate of solid mixture was fixed at 5 3 kg h Water or water bath at 30 C and 80 C for 30 minute The. NaOH solution was injected at zone 1 to adjust pH solution was centrifuged at 3000 rpm for 10 minute. and in barrel moisture Extrusion process was the supernatant was poured to pre weighted moisture. performed at 40 C and screw speed of 200 rpm using can dried at 105 C until the weight was constant and. a 4 mm circular die diameter The control starch record the dry dissolved starch W3 The sediment. sample was prepared without STMP and NaOH was weighted W2 The WSI and swelling power of. solution treatment All starch extrudates were cut to 1 starch samples were calculated as follows. 2 cm size air dried at 60 C for 8 hour grounded, and rinsed with distilled water starch water ratio of weight of dry dissolved starch W.
1 4 for 2 times to remove free STMP then WSI 3 x 100 2. centrifuged at 9000 rpm for 10 minute The pH of dry sample weight W. starch slurry was adjusted to 6 5 with 1 M HCl and. washed with distilled water The starch samples were sediment of starch after centrifuge W. dried at 60 C for 8 hour grounded sieved through Swelling factor. dry sample weight W,100 mesh screening size and stored at 4 C until 1. 2 5 Determination of freeze thaw stability, Table 1 Conditions for phosphorylated cross linked starch The freeze thaw stability of starch was measured. production according to the procedure of Wang et al 13 The. 20 ml of 12 w w starch suspension was prepared in, 50 ml centrifuge tube heated in water bath at 95 C. for 30 minute cooled to room temperature and stored. at 18 C for 18 hour After frozen the starch gel was. thawed for 6 hour at room temperature and,centrifuged for 20 minute at 4000 x g water was. removed and weighted The freeze thaw stability was. measured as syneresis percentage of released,water weight to starch gel weight for 5 cycles.
2 6 Determination of gel properties,The paste clarity of starch suspensions was. determined according to Wongsagonsup et al 14, The 1 w v of starch suspension was heated in water. bath at 95 C with shaken every 5 minute for 30, 2 3 Determination of pasting properties and minute total time and cooled down to room. degree of cross linking temperature The transmittance T of the starch. Pasting properties of a native starch and cross linked suspension at 650 nm was measured using UV VIS. starches were determined using a Rapid Visco spectrophotometer and water was used as a blank. Analyzer RVA Model Super 3 Newport Scientific sample. Pty Ltd AU according to AOAC 11 The 25 ml Gel properties were measured in terms of hardness. distilled water was added to the 3 0 g starch sample and cohesiveness according to method described by. and held at 45 C for 2 min heated up to 95 C at the Wattanachant et al 15 with modification The. heating rate of 10 C min held for 3 minute then starch gel was prepared by heating 12 w w starch. Proceedings of The IRES 30th International Conference Tokyo Japan 18th February 2016 ISBN 978 93 85973 35 2. Effects Of Degree Of Cross Linking On Physical Properties Pasting And Freeze Thaw Stability Of Cassava Starch Modified By Reactive. Extrusion Process REX, suspension at 95 C for 30 minute in a 50 ml beaker degree of cross linking suppressed swelling power. with 2 cm height and kept for 24 hour at room and lowered the peak viscosity The more hydrated. temperature before texture analysis The starch gel granule had less space between starch granules. was compressed with 10 mm diameter cylindrical resulting in a resistance to breakdown 14 16. probe at 50 distance with speed of 2 0 mm s using According to Choi and Kerr 17 the cross linking. the Texture Analyzer model QTS25 Brookfield increased the temperature resistances of starch. Engineering Laboratories Inc USA granules since cross linked bonding strengthened the. starch chains, 2 7 Statistical Analysis Other values of pasting properties breakdown.
Statistical analysis was performed using One way viscosity final viscosity and set back all decreased. ANOVA and Duncan s Multiple Range Test DMRT with increase in degree of cross linking The. by SPSS 17 0 software breakdown viscosity is a measure of the fragility of. the granules indicating the stability of starch pastes. III RESULTS AND DISCUSSION and their tendency to resist shear force during the. heating process 18 and 19 Final viscosity of the, 3 1 Pasting properties and degree of cross starch paste which represents an increase in viscosity. linking of starch paste during cooling decreased significantly. The pasting properties and degree of cross linking of with degree of cross linking Highest final viscosity. phosphorylated cross linked starches in comparison was shown in low degree of cross linked starch. with native and control starch samples were presented sample that was non significantly different P 0 05. in Table 2 Degree of cross linking of phosphorylated from native starches The decrease in final viscosity. cross linked starch was determined and found in was degree of cross linking dependent The final. arrange of 56 35 95 14 In this study starch viscosity is largely due to re ordering or. samples were categorized based on degree of cross polymerization of leached amylose and long linear. linking level as high degree of cross linking 90 amylopectin 18 and 20. medium degree of cross linking 70 90 and low, degree of cross linking 50 70 There was a 3 2 Water solubility index WSI and swelling. significant difference in pasting properties by degree power. of cross linking Lower peak viscosity with The WSI and swelling power of starch samples at. increasing degree of cross linking was observed The 30 C and 80 C were shown in Table 3 At 30 C. lower pasting temperature of starches compared to extruded control and all cross linked starches. that of native starch indicated their lower resistance exhibited higher solubility than the native starch This. towards swelling Substantial reduction in peak is due to the extrusion process promoting. viscosity in cross linked starch compared with that of dextrinization and increasing solubility of starch 21. native starch was due to phosphate intermolecular However at 80 C WSI of native starch and extruded. linkage in starch molecules The pasting temperature starch control significantly increased due to its. among cross linked starches was not significantly gelatinization while all cross linked starch samples. different however the peak viscosity and breakdown showed slightly increase in solubility Higher degree. decreased with degree of cross linking due to the of cross linking lowered WSI since phosphate. intermolecular bridge in starch molecule Cross linkage prevented the breakage and leaching solid of. linking decreased amorphous chain mobility and starch granule that resulted in lower solubility This. strengthened the starch molecular structure Higher result suggested that cross linking strengthened the. Table 2 Pasting profiles and degree of cross linking of native cassava starch control starch and phosphorylated cross linked starch. The same lower case letters superscript a in the Swelling power of starches was presented in Table 3. same column each sample group are not significantly Swelling power decreased with an increase in cross. different P 0 05 linking density All starch samples possessed greater. molecular structure of starch and showed higher swelling power at 80 C and showed similar value to. temperature resistance the native starch This is because the starch molecules. Proceedings of The IRES 30th International Conference Tokyo Japan 18th February 2016 ISBN 978 93 85973 35 2. Effects Of Degree Of Cross Linking On Physical Properties Pasting And Freeze Thaw Stability Of Cassava Starch Modified By Reactive. Extrusion Process REX, were gelatinized sufficiently and the amylopectin cross linked starch gels had the lowest syneresis of. chains were hydrolyzed at a temperature of 80 C Our 0 91 0 99 after the first cycle and it showed the. observed results were similar to the studies reported highest stability compared with the native starch and. by Wongsagonsup et al 22 It was shown that the extruded starch control while the high degree of. swelling power increased with temperature but cross linked starch showed the worst stability. declined by cross linking At low level of cross However the syneresis of all starch samples. linking the repulsion of negative charge of phosphate increased with increasing number of freeze thaw. in starch chain could enhance hydration On the other cycles When starch gels are frozen phase separation. hand at high degree of cross linking the bonding occurs upon the formation of ice crystals Upon. between adjacent molecules was denser and restricted thawing syneresis occurs because the water can be. the swelling and hydration of starch granules easily expressed from the dense network 23 The. formation of dense network was mainly related to, 3 3 Freeze thaw stability amylose amylose interaction which enhanced starch. The freeze thaw stability of starch was presented as retrogradation 36 At high degree of cross linking. the percentage of syneresis which indicated the starch granules were highly dense and compacted. released water from starch gel during freeze thaw with bridge of cross link in the molecules that made it. cycle process When starch paste was rapidly cooled difficult to complete gelatinization and cannot form. down after heating process the water could be gel resulting the gel have high content of exceed. released especially in starches contained high water at the same concentration The results also. amylose Syneresis is an important parameter critical suggested that appropriate degree of cross linking. to the tendency of retrogradation and the stability of a minimized freeze thaw damage by reducing the. gel system 23 No syneresis indicates good water available water to form ice crystals As shown in. holding capacity of the gel 24 The syneresis of all Table 4 starches at low and medium degree of cross. starch samples as a function of 1 5 freeze thaw linking displayed the best performance of total. cycling is shown in Table 4 In general the native syneresis of 15 41 15 83 after five cycles. cassava starch contains low amylose content and low. percentage of syneresis However the freeze thaw 3 4 Gel properties. stability of native starch was poorer compared to The clarity of starch solution was indicated by the. cross linked starch samples For starch gel the starch percentage of transmittance T The clarity of. granules absorbed more water during heating process starch solution decreased with an increase in degree. which the gelatinization of starch occurred and of cross linking indicating lower solubility As shown. formed gel after cooling Low and medium degree of in Table 5 the native cassava starch and. Table 3 Water solubility index and swelling power of native cassava starch control starch and phosphorylated cross linked starch. at 30 C and 80 C,The same lower case letters superscript a in the.
same column each sample group are not significantly. different P 0 05, Table 4 Syneresis values of starch gels 12 total solid during freeze thaw cycles. Proceedings of The IRES 30th International Conference Tokyo Japan 18th February 2016 ISBN 978 93 85973 35 2. Effects Of Degree Of Cross Linking On Physical Properties Pasting And Freeze Thaw Stability Of Cassava Starch Modified By Reactive. Extrusion Process REX, The same lower case letters superscript a in the showed higher swelling power than native starch and. same column each sample group are not significantly extruded control samples at room temperature The. different P 0 05 freeze thaw stability and gel hardness of starch were. The same upper case letters superscripts A in the significantly enhanced by cross linking at optimal. same row are not significantly different P 0 05 level The modified starch produced by cross linking. starch control showed highest clarity with the in combined with reactive extrusion could be used as. Effects Of Degree Of Cross Linking On Physical Properties Pasting And Freeze Thaw Stability Of Cassava Starch Modified By Reactive Extrusion Process REX Proceedings of The IRES 30th International Conference Tokyo Japan 18th February 2016 ISBN 978 93 85973 35 2 51 suspension at 95 C for 30 minute in a 50 ml beaker with 2 cm height and kept for 24 hour at room temperature before texture

Related Books