In this micrograph you can see processed cheese spread with buttermilk powder taken by SEM. I suppose it can be the result of interactions between proteins and the buttermilk powder used as thickener but I'm not sure. I will be glad if anyone could help me in this matter. Thank you.
Looks like an artefact. It would be useful to have pictures taken in SE and BSE from the same place. You should not have Z contrast in BE for you specimen (it's basically should be all the same in terms of brightness), so it appears you have just topographical contrast. Again, checking with SE could be helpful.
Mateusz Florczuk Although here you can observe micellar structures, the sample does not look ready for SEM to me. To distinguish between such species, you might have to reduce the crowding. This would help in discerning each species. Also, SEM instruments are often connected to elemental composition analysis. If you are in doubt, perform this analysis on multiple areas to obtain the kind of species you are seeing. Hope that helps!
Dear Mateusz Florczuk , the white dot marked by the red arrow could be just an artefact. What I mean is, if you look at the image it is roughly composed of polydisperse (multiple sizes) grey spheroids which show different grey tone depending on their sizes (the larger, the darker). Image´s resolution is not good enough to distinguish if there is a grey goo embedding the spheroids or if these dark areas are just accumulations of spheroids. These dark goo and spheroids are distributed quite randomly on a clear substrate (white to clear grey). These whitish substrate is more visible where the accumulation of dark areas is smaller, therefore one can think that the image shows an uneven surface, with something like irregular troughs and valleys caused by accumulation of these spheroids and the grey goo. Valeis appear clear grey and the white spot maked by the red arrow would be just the cleanest valey, the one with less spheroids and therefore clearer. There are some spheroids on it that provides a contrast, for instance the darker one close to the arrow tip.
The detector used to record this image is a CBS (Circular Back Scatter) and with this kind of detectors, low atomic number (Z) elements appear dark or grey while heavy elements appear clear. Cheese and buttermilk powder are both organic and so rich in C, O, H, N and one will expect they both appear as dark in the image, so it would be difficult to distinguish each other. If cheese was salty, it could happen that you could spot a clear grain of table salt.
The white spot and the rest of white-whitish valleis are probably the substrate where you placed or spred your sample (may be a silicon wafer or may be a metal slide).
In any way, as Nabodita Sinha has suggested, the best idea is to make an EDX analysis to asses what is the composition of each part of your sample .This method will not solve your problem of distinguish cheese and buttermilk powder, because their constituent elements are basically the same, however, it would solve the question you asked, if your white spot shows the same elemental composition than your substrate... it means it is just a clean valley where there is few sample.
Hope it helps.
Looks like an artefact. It would be useful to have pictures taken in SE and BSE from the same place. You should not have Z contrast in BE for you specimen (it's basically should be all the same in terms of brightness), so it appears you have just topographical contrast. Again, checking with SE could be helpful.
As Dr Dusevich said, it looks like topographical contrast. I'd add that it can be just a local charging. Try to decrease the accelerating voltage and current. Have you coated the sample with something conductive?
Thank you all for the answers. I will try the SE and BSE to check if it is the artefact. The sample were not coated with anything conductive.
If your sample is not conductive enough (and not coated even with simple Carbon), a local charge can appear particularly using 30kV High Voltage and BS electrons which means a high value of spotsize... All bad conditions to observe such biological sample ! As suggested start with SE image decreasing spotsize and HV (5 to 10 kV is enough).
And if available, used low-vaccum condition cause the vacuum can also remove hydratation of the cheese sphénoïdites...
As a user for 35 years and professional trainer of SEM users, your conditions seem to me inappropriate.
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