We built a simple spectrophotometer that you can use it to measure the current changes of the materials by simply using the transmittance as the intended wavelength. You can subject your material to the a Led light with a specific wavelength and the measure the transmitted light by photo detector.

Please follow the link:Article LED Based Spectrophotometer can compete with conventional one

Best wishes

Dear Akram,

Why do go away from simple method to measure colour change? I have a simple method is to use image analysis to monitor changes of colours in foods. All you need to do is to spend 2-3 hours to practice that with Adobe Photoshop with camera and good laptop. I have recently use it and I have attached the propose method here. please do not hesitate to ask again if you need that.

Best regards

Aky

 Dear Aly

Thank you for your response. This nice article measures the color of food. I want to measure the color of clear ligature elastics discolored by food.

Since they are clear the camera flash severely affects their color.

Best regards

Akram Alhuwaizi 

Simply make the flash off and use the white lighting.There are several specifications to use the camera read them well. Through the histogram you can find out the lightness, redness and yellowness of your samples. when you do the lab parameter you should use the attached equations. This technique can be used for any material including foods and others.

Best regards

Aly

There was a similar question posted on ResearchGate. You may find the answers there useful.

https://www.researchgate.net/post/Does_someone_have_experience_about_measuring_colour_CIELab_in_liquids_using_a_Konika-Minolta_CM-600d_with_or_without_a_CM-A514_Sample_Holder