How can I determine protein content of random cottage cheeses at home?

Question

I'm currently in the Republic of Georgia, and locals sell farmer cottage cheeses at the markets. These cheeses are albumin-based "nadugi" and casein-based "hacho". No nutritional info is available for them. I would like to measure protein content of the cheeses I buy, even if approximately. Is there a way to do this at home?

Answer 1

No, this is not something you can do at home (except if you are Walter White). Here is a good overview of common methods: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7597951/pdf/foods-09-01340.pdf

Below is a chart from page 2 which summarizes the methods:

Table 1. Protein quantification methods—advantages and disadvantages.

Protein Quantification Method	Advantages	Disadvantages
Kjeldahl method—digestion of food with a strong acid so that nitrogen is released which is then quantified using a titration technique.	Considered the standard method globally and therefore easy to compare results with other laboratories	Does not measure true protein and overestimations of protein can result due to use of standard nitrogen correction factor 6.25
Dumas method	Fast and does not use chemicals; can measure several samples at a time	Costly to set up and is not very accurate as it does not measure true protein.
UV spectroscopy methods	Simple, does not require any assay agents	Highly error prone due to other compounds that absorb at the selected absorbance wavelength (280 nm)
Biuret methods—protein–copper chelation and secondary detection of reduced copper, includes the bicinchoninic acid (BCA) and Lowry assay methods	Less protein–protein variation than the Coomassie dye-based assays; compatible with most surfactants used for protein extraction	Incompatible with copper-reducing surfactants and reducing agents including DTT
Bradford Coomassie Blue assay method—protein–dye binding and direct detection of the color change	Fast, performed at room temperature, compatible with most solvents	High protein–protein variation; incompatible with detergents
Fluorescent dye methods—protein–dye binding and direct detection of increase in fluorescence associated with the bound dye includes the Qubit assay and EZQ TM assay	Very sensitive and uses less protein	Requires a fluorescence detector
Direct amino acid analysis using hydrolysis and HPLC quantification	Accurate	Initial investment in HPLC equipment required; hydrolysis step required; time consuming

I'm not going to pretend to understand all of that, but the takeaway is that you either need semi-hazardous and (relatively) hard to obtain chemicals or access to expensive analyzers (often both).

You may consider contacting local universities' food science or chemistry departments. It's possible they will programs set up where they perform this sort of analysis for a fee or perhaps such analysis was already done and the university library can locate the journal article.