Valorization of Sour Milk to Form Bioplastics: Friend or Foe?

A demonstration was developed to introduce students to waste valorization in order to form bioplastics. Waste valorization is the process of reusing, recycling, or composting, from waste, useful products or sources of energy. In this demonstration, waste valorization is introduced by converting sour milk into a bioplastic via the addition of lemon juice upon heating. Utilizing lemon juice to perform the acidification offers a greener procedure than the traditional formaldehyde (used commercially to make galalith) and enhances the transferability in remote locations such as the Amazon Rainforest in comparison to vinegar. Students can establish connections to relevant United Nations Sustainable Development Goals (UN SDGs) by adopting a systems thinking approach. However, through this, it is noteworthy that this process is also used (particularly in the Indian subcontinent) to make paneer, a farmer cheese. While this also enables students to make a link to additional UN SDGs pertaining to "zero hunger", there is an ethical discussion to be had as to whether such a process that is utilized to feed malnourished citizens should be used to make a decorative bioplastic. As such, despite this demonstration being transferrable, instructors may consider carefully whether to utilize this resource, and, if so, to use this as an opportunity to teach the importance of ethics in science.