Semi-transparent plastic vacuum packed liquid

Looking for any ideas/tips on how to approach modelling/shaders for this vacuum packed liquid product.

Modelling: I’ve been having some success with sculpting the creases and bumps to get a natural looking shape, and for the liquid inside, I’ve duplicated the pouch part of the mesh and scaled it down slightly, giving it my liquid shader, and leaving the entire rest of the mesh with the plastic shader.

Materials: The final renders seem to be coming out far too ‘clean’. I’d love some feedback on how I could add more realism here. I’ve played around with noise textures as bump maps, adding bubbles etc. but can’t seem to get it looking right.

Lighting: I’m lighting with the ‘artist workshop’ HDRI from HDRI Haven https://hdrihaven.com/hdri/?c=indoor&h=artist_workshop

Plastic shader

Liquid shader (All different colours in scene just variations of this).

Example of product (2nd picture down you can see a vac sealed cocktail):

Example render:

Thanks in advance, any help would be amazing. Cheers!

To me it appears the color variation in the reference image is mostly based on the absorption of the liquid in combination with the thickness variation due to the wrinkly geometry (which you already have). Talking about volume absorption (which can be done with the shader of the same name).

Can you try to replace the whole liquid shader with just volume absorption (and nothing at surface) for starts? Or did I get it all wrong and you actually want an intransparent paste-like ‘liquid’?

To get liquid looking right inside a container - you need to properly consider the IOR interfaces between surfaces and also ensure that the normals are pointed in the right direction.

Because your plastic shader doesn’t have any IOR and because your liquid is separated from the plastic by what is in effect and air gap - it’s not going to match your reference photo.

You need to properly consider the IOR transitions at interfaces between Air --> Plastic and Plastic --> liquid for this to look right.

Take a look at these references for the principles you need to consider (note in this case, your ‘glass’ is the plastic bag)

https://download.autodesk.com/us/maya/2009help/mr/shaders/architectural/arch_mtl.html#Water_and_Liquids