I am currently doing a research on starch extraction using physicochemical cell disruption method (NaOH as solvent). The starch obtained upon disruption was decreasing from 10 mins to 30 mins at 60 ℃. However, the starch obtained at 90 ℃ was increasing from 10 mins to 30 mins. I am confuse whether gelatinization process occur at low temperature or high temperature ? But according to some journals, gelatinization occur at around 65 ℃ . Besides,, if gelatinization occur, what will happen to the starch and the starch content? (viscosity increase?, why?) Last but not least, will the starch content increase if gelatinization happen? Thanks for your response in advance!
I wonder why you are working with aqueous NaOH (what concentration?) at elevated temperature to extract starch from plant cell material. At these conditions, dissolution and oxidative degradation of starch (and other cell constituents) may occur. This would explain the decrease of starch yield at increasing time at 60 degrees C, but I do not understand why your starch yield increases at 90 C. You refer to a gelatinization temperature of around 65 C but this applies to starch in water, not in aqueous NaOH; in the latter solvent, starch gelatinizes already at room temperature.
It is not clear what the aim of your work is. If you want to isolate starch from grain kernels, tubers or roots, then the general procedure is wet milling at room temperature and physical separation of starch, protein and fibre with some variation in the details depending on the botanical source. By working at room temperature the starch granules remain intact and can be easily recovered by centrifugation and filtration. (As an exception, wheat starch is isolated from wheat flour obtained by dry milling.) See for example J. BeMiller, R. Whistler (eds.), Starch Chemistry and Technology, 3rd ed., Elsevier (2009).
Hi, Peter! My research is extraction and separation of starch from Chlorella salina biomass and the objectives are:
-To determine the efficiency of different type of starch extraction methods
- To determine the starch recovery
The NaOH concentration that i used was 1 M, as the previous research indicated that this concentration achieved higher starch content using other strain of microalgae.
Physicochemical method was one of my starch extraction methods.
But previously I conducted the experiment at the same conditions using different batch of microalgal biomass with the result obtained as below:
60 ℃ & 90 ℃ : increasing of starch from 10 mins and 30 mins
Is it due to different batch of microalgal biomass? Thanks!
Hi Ying Po Wong. That you find an increase in recovery at both T suggests that starch solubilization in aqueous NaOH is a slow process, even at high T. The aim of my previous message was to let you know that starch looses its native granular form when treated with aqueous NaOH which makes it difficult to recover. It is also degraded at high T in this medium.
If you want to recover the starch, algal starch (from Chlamydomonas) can be isolated by a sonication and centrifugation treatment (A. Buleon et al., Plant Physiol. 115 (1997) 949-957, see attached file). I am not sure if this leads to quantitative recovery.
You also need to know if complete starch extraction is obtained. One group of reseachers did starch quantitation in algae by (1) chlorophyll extraction with methanol, followed by (2) autoclaving at 120 C to dissolve the starch and (3) an enzymatic glucose assay (M. Siaut et al., BMC Biotechnol. 2011 11:7 (open access).
- Badges
- Science topic
- Similar topics
- Social Science
- Media
- Journalism