If you can not find a source, you might try isolating your own. It usually not that difficult. And you can isolate what ever starch type you may want directly from its source.
Dear Jamel Mejri,
You can use the tools available on the internet such as Molar Mass, Molecular Weight and Elemental Composition Calculator
https://www.webqc.org/molecular-weight-of-C4H8O4+%28flour%29.html
For the additional information please kindly consult:
Zarroug Y et al. (2020), Extraction and Characterization of Tunisian Quercus ilex Starch and Its Effect on Fermented Dairy Product Quality. Int J Anal Chem. 2020 Aug 4;2020, doi: 10.1155/2020/8868673. PMID: 32831842; PMCID: PMC7424496.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7424496/
When looking for molar mass of starches, there are 3 major issues of importance:
1. Because most starches consist of 2 components, linear amylose (Am) and branched amylopectin (Ap), you cannot strictly speak of ‘the’ molar mass (MM) of starch. Generally, amylose MM ranges between 10^5 and 10^6 g/mol, whereas amylopectin has MM in the order of 10^8 g/mol. These values are valid for the so-called ‘weight average molar mass’ (MW). Here, every individual molecule contributes to the average according to its mass. As a consequence, in MW the average is biased toward the larger molecules. Because most common starches have Ap/Am ratio about 4, MW of amylopectin gives a reasonable estimate of MW of entire starch.
2. MW of amylopectin strongly depends on the botanical origin of the starch and probably (?) much less on other factors like variety (within species), growth conditions, and country of origin.
3. Because MW of starch is so high, starch molecules are very sensitive to molecular degradation during sample preparation for MW determination. There exists no simple effective and non-degradative solvent for starch. That is why many protocols are described in the literature with a large spread in published MW values. In my opinion a 3-steps approach is the best one: (a) swell the starch in 90 % DMSO; (b) precipitate the swollen granules with excess ethanol or butanol; (c) dissolve the starch pellet in boiling water (preferable with N2 flush). A publication is added with protocol and results.
Hello Jamel
This topic has been published recently by
Mehdi Taib & Lahboub Bouyazza for acorn starch extracted from
Quercus spp. It may help
https://www.hindawi.com/journals/jchem/2021/9988570/
Regards
David
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