Physiochemical characterization of starch from different sorghum varieties
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Transcript of Physiochemical characterization of starch from different sorghum varieties
Physicochemical characteriza0on of starch from different sorghum varie0es
Sarah Beazley, Lynsey Jones, Alexis Prillhart, Philipus Pangloli, Vermont P Dia
Results
Conclusions and Future Direc2ons • Starch isolated from different varie2es of sorghum showed similar morphology as determined by polarized microscopy. • The gela2niza2on temperature of sorghum starches ranged from 65.16 to 87.5 °C as measured by differen2al scanning calorimetry. • Physicochemical and rheological proper2es of starch obtained from different sorghum varie2es are similar to each other. • Our preliminary results provide the evidence for the poten2al applica2on of sorghum starch for food and food products. • Tes2ng of sorghum starch in different food products must be carried out.
References 1. de MoraisCardoso et al. (2015). Sorghum (sorghum bicolor l.): Nutrients, Bioac0ve Compounds, and Poten0al Impact on Human Health. Crit. Rev. Fd. Sci Nutr. DOI: 10.1080/10408398.2014.887057. 2. ) Beta T, Chisi M, Monyo ES. 2004. Sorghum/harvest, storage, and transport. In: Wrigley CW, Corke H, Walker CE, editors. Encyclopedia of grain science. Oxford: Elsevier. p. 119–26. 3. Roemer, Earl. 2012, Food. United Sorghum Checkoff. http://sorghumcheckoff.com/food/
Acknowledgement Dr. Angela McClure for providing sorghum samples.
Figure 1. Polarized microscope images of sorghum starch isolated from different varie2es of sorghum. All starch samples showed similar morphology under polarized light showing birefringent property of starch granules consistent with the appearance of other commercially available starches.
Figure 4. Swelling power and solubility of sorghum starches are similar to each other. Significant differences were not detected in solubility and swelling power of starches obtained from different varie2es of sorghum (P > 0.05).
A B
D E
C
F
24 °C 41 °C 54 °C 68 °C 81 °C
Figure 2. Changes in the appearance of sorghum starch variety B granules during hea2ng. Sorghum starch at room temperature shows the regular birefringent property common to all starches. Hea2ng in the presence of water shows that sorghum starch started to swell associated with water imbibi2on during hea2ng at 41 °C, starch granules con2nue to swell un2l 68 °C. At 81 °C, sorghum starch granules are completely disrupted indica2ng complete gela2niza2on.
Sorghum Variety
Onset of Gela2niza2on
Temperature (°C)
Peak Temperature (°C) End of Gela2niza2on Temperature (°C)
Enthalpy of Gela2niza2on (J/g)
A 65.16 69.89 85.5 87.4 87.0 87.5 86.9 84.9
4.145 3.438 3.422 2.835 3.767 3.576
B 65.8 69.71 C 66.34
66.93 66.7 66.0
70.76 71.48 70.96 70.28
D E F
Table 1. Thermal proper2es of starch obtained from different varie2es of sorghum as determined by differen2al scanning calorimetry.
Figure 3. Representa2ve differen2al scanning calorimetry curve for sorghum variety A. The curve was used to determine the different thermal proper2es for each sorghum starch as listed in Table 1. As shown in Table 1, thermal proper2es of sorghum starches are very similar to each other indica2ng uniformity of starch that can be obtained from sorghum.
Abstract Sorghum is one of the most important crops in the United States. The objec0ve of this study is to characterized starch isolated from different varie0es of sorghum in order to explore the poten0al food applica0ons of sorghum starch. Starch from pre-‐soaked sorghum was extracted by blending with water followed by sieving, standing and centrifuga0on. A\er centrifuga0on, the pellet was dried under vacuum and the dried material, starch, was ground to fine par0cles. The starch was characterized for their gela0niza0on, solubility, swelling power and gela0on proper0es. Morphology of starch granules was visualized using polarized microscope. Preliminary data indicate that onset of gela0niza0on ranged from 65.2 to 66.9 °C, gela0niza0on temperature of 69.7 to 71.5 °C and end of gela0niza0on of 85.6 to 87.5 °C. The enthalpy associated with starch gela0niza0on ranged from 2.8 to 4.1 J/g. Our results will provide preliminary evidence to support the use of sorghum starch for food and food products.
0
5
10
15
20
A B C D E F
Swellin
g Po
wer
Sorghum Variety
A
0
10
20
30
40
A B C D E F Percen
tage Solub
ility
Sorghum Variety
B
A B
D E
C
F
Figure 5. Least gela2on concentra2on of sorghum starches ranged from 3.2%(varii2es A, D, E and F) to 6.4% (varie2es B and C) as indicated by an arrow. Least gela2on concentra2on refers to the lowest concentra2on of starch that will lead to forma2on of a three-‐dimensional network called gel.
Department of Food Science and Technology, The University of Tennessee, 2510 River Drive, Knoxville, TN 37996-‐4591, USA
Introduc2on • Sorghum is the fi\h most produced cereal in the
world and contains bioac0ves with poten0al health-‐promo0ng proper0es1.
• Plays a cri0cal role in food security for some semiarid areas of Asia, Africa, and La0n America2
• Sorghum is a good wheat subs0tute for those who cannot tolerate gluten.
• Sorghum is an excellent source of energy, containing about 75% complex carbohydrates. It is also a good source of iron and zinc and is rich in B complex vitamins. It provides phytochemicals such as phenolic acids, anthocyanins, and phytosterols2.
Objec2ve The objec0ve of this study was: • To characterize starch isolated from different
varie0es of sorghum in order to explore the poten0al food applica0ons of sorghum starch
Materials & Methods • Extrac2on of starch
• Morphology of starch granules Starch was observed under a polarizing microscope
• Determina2on of changes in starch granule morphology as affected by hea2ng
Samples were heated using a hot stage and changes in the morphology of starch granules were observed during hea2ng.
• Determina2on of thermal proper2es The samples were analyzed using differen2al scanning calorimetry; onset of gela2niza2on, peak temperature, end of gela2niza2on, and enthalpy of gela2niza2on were recorded
• Determina2on of solubility and swelling power Solubility was calculated as the weight of soluble dry powder divided by weight of ini2al sample Swelling power was calculated as the weight of wet sediment divided by the weight of ini2al sample
• Determina2on of least gela2on concentra2on Starch concentra2ons of 0.2, 0.4, 0.8, 1.6, 3.2 and 6.4% were placed in plas2c tubes. Aeer gela2niza2on and cooling, the lowest concentra2on at which the starch gel did not slip was the least gela2on concentra2on
100g of each of the 6 samples was soaked in 0.1% sodium bisulfite solu2on for 24 hours Blended using a Waring Blender Mixture was sieved using a 100 mesh sieve and the filtrate was allowed to segle overnight. The precipitate was repeatedly washed with water aeer centrifuga2on three 2mes. The precipitate was vacuum dried, ground and called sorghum starch.