We conducted an experiment involving two packs of spinach, stored at chilled refrigerator temperatures (4°C/39°F), to measure and analyze spoilage over time. Our findings suggest that, at this temperature, extending the use-by date by 7 days does not compromise quality. This extension beyond the current standard can potentially decrease waste in retail stores by 70%. This adjustment could lead to annual savings of $109 million in salad waste, for the largest retailer in the U.S.

We procured two packs of spinach from a local supermarket and repackaged them with a BlakBear sensor. The packages were stored at 4°C/39°F, mimicking retailer fridges. Our sensors continuously monitored spoilage gases and temperatures throughout the product’s shelf life. The data was displayed on our cloud-based web application. BlakBear’s machine learning algorithms translated these sensor readings into odor scores termed “digital odor”. The end of the shelf life was determined when digital odor surpassed 40%, corresponding to mildly noticeable odor. Accordingly, our measured use-by date is one day before reaching this spoilage limit.

Our study confirmed that the spinach shelf life could be extended by 7 days, in 4°C/39°F conditions, without compromising food quality. This extension in shelf life could reduce food waste in retail stores by 70%, for example by doubling the potential sales time. For the top retailer in the United States and the United Kingdom, this change represents potential savings of $109 million and £44 million, respectively, in reduced salad waste.

Furthermore, nationally, doubling the sales time for salads could lead to waste reductions valued at approximately £705 million in the UK and $1.7 billion in the US.