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

Hardware

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...
$17.50
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...
Out of 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...
Out of Stock

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 Mar 16, 2024.

This page (Overview) was last updated on Mar 08, 2024.

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