Hi all… so we’re evaluating what extraction techniques we want to use on incoming food for the Real Food Campaign Lab.
We are trying to create a common extraction to run 3 different tests - Bradford protein, polyphenols, and antioxidents (FRAP). Details on each method below for those so inclined.
Polyphenols (using liquid part (aka supernatant) after centrifugation)
There are two possible methods - one using Folin-Colteau reagent, another using Fast BB reagent. Both are described in the paper below.
Method - https://drive.google.com/file/d/161rYcERQIbg0Xj51HVOlf8N_vN1_9clu/view?usp=sharing
Antioxidents (using liquid part (aka supernatant) after centrifugation)
Ordering page - https://www.cellbiolabs.com/ferric-reducing-antioxidant-power-assay-kit-frap
Full directions - https://www.cellbiolabs.com/sites/default/files/STA-859-frap-assay-kit_0.pdf
Bradford Proteins (using solid part (aka pellet) after centrifugation)
Ordeing page - https://www.biobasic.com/us/better-bradford-protein-assay-kit-improved-linearity
Full directions - https://www.biobasic.com/us/amfilerating/file/download/file_id/21555/
There are many options - extractants - ethanol, methanol, ultra-pure water, how to macerate the sample - blender, food processor, freeze dryer, … every option produces different results depending on the nutrient extracted, and there is no perfect cost/ease/efficacy answer.
I’m struggling with a few questions, but they boil down to the following:
As the RFC… what is the nutrition we’re attempting to measure? The total nutrition in the sample? The nutrition in the sample that’s able to be absorbed by a human? Something else which, so long as it’s comparable from one sample to the next? I’ve been struggling to create a consistent, easy, fast way to fully macerate (smash all the cells) in order to measure the total nutrition as accurately as possible… but I’m wondering if that’s even the right number to report if we could get it. If there’s 1000 mg/g beta carotene, but the normal process of chewing and digesting raw food only absorbs 200 mg/g, should we be reporting 1000? Then… if we’re off by a factor of 5 all the time, does that matter as long as it’s always a factor of 5… or is there differential absorbance of beta carotene depending on it’s location in the cell… like perhaps different samples will contain beta carotene in different locations, which may be accessible to me in the lab using super maceration, but inaccessible to you in your gut. This has left my quite confused, and wondering if I’m going through all this trouble just to get a more accurate but less useful result.
I know there are many more questions than this - different compounds will extract in different ways, do different extraction methods differentially oxidize or otherwise make unmeasurable compounds impacted by heat/oxygen/time etc… but the above question feels much more central to what we do next.
So - in the end… I think we can macerate the crap out of a wide range of samples quickly and efficiently, better than juicers or blenders or whatever and faster… but I’m not sure if that’s even the right thing to be doing.