Can a spectrometer be used to figure out spice ratios in a sauce? There is a really good sauce that a local restaurant makes. I have had trouble recreating it, but have gotten somewhat close. I had the following idea:

I could take an "image" of the sauce's color spectrum under good light using a USB spectrometer, and compare it to the spectrum of my home made version. I could then slowly tweak the ingredients and resample the color spectrum of the home made sauce until it started converging and eventually matched the restaurant's.

What could prevent this from working well?
Could this realistically outperform taste testing?
Unfortunately, this will not even qualitatively work because taste which is a sense of perception and UV-Vis are barely related.. The USB spectrometer would be great for color matching, but you are assuming the taste and aroma comes from UV-Vis absorbing compounds only. This may not be the case. Let us assume, the taste comes from UV-Vis absorbing compounds, as you know from Beer's law, an $n$-component mixture will have  absorbance sum from $n$-components. If some of these molecules are in trace quantities, they might have a little effect on the overall spectrum but they might have a huge influence on the taste and aroma of your sauce. Food chemists prefer more of gas chromatography and mass spectrometry &amp; infrared spectrometer which may cost more than 100K.