The classic method for testing for milk freshness is to give it a quick sniff check. If it smells "bad", then it probably is. This is great, as long as your sense of smell is working. But maybe covid, congenital anosmia, a stuffy cold, or something else has reduced your sense of smell. What then?

In this guide we investigate the potential for using a gas sensor as a way to test for milk freshness. An SGP30 and a CLUE are used to make a little "freshness checker" device. We then use this in a simple experiment to see if it can detect spoiled milk.

This project does NOT require any soldering and is a great little science experiement


Here is a summary of the hardware needed for this project.

Animated GIF showing CLUE board  displaying data from the many on-board sensors.
Do you feel like you just don't have a CLUE? Well, we can help with that - get a CLUE here at Adafruit by picking up this sensor-packed development board. We wanted to build some...
Out of Stock
Angled shot of a Adafruit SGP30 Air Quality Sensor Breakout.
Breathe easy with the SGP30 Multi-Pixel Gas Sensor, a fully integrated MOX gas sensor. This is a very fine air quality sensor from the sensor experts...
In Stock
Angled shot of STEMMA QT / Qwiic JST SH 4-pin Cable.
This 4-wire cable is a little over 100mm / 4" long and fitted with JST-SH female 4-pin connectors on both ends. Compared with the chunkier JST-PH these are 1mm pitch instead of...
In Stock

This is the battery shown in the guide:

Angled shot of a rectangular lipo battery with a 2-pin JST connector. The battery specs are listed on the body: 3.7V 250mAh.
Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This...
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but you can use any other similar lithium ion battery option:

This guide was first published on Mar 03, 2021. It was last updated on Dec 08, 2023.

This page (Overview) was last updated on Feb 28, 2021.

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