Is it still edible?

How many fruits and vegetables did you throw away the last time you cleaned out your refrigerator? Each year, nearly half of the fruits and vegetables produced globally are wasted, leading to significant economic and social consequences. One major contributor to this waste is the lack of non-destructive methods to monitor food shelf life. Determining shelf life is difficult because the ripening process for many fruits begins internally, making it difficult to assess their viability.

In a recent study published in Nature Food, researchers from Princeton University introduced the “Meta-Sticker,” a non-destructive, biodegradable solution designed to accurately predict the ripeness of various fruits. This innovative sticker features a small metallic structure that adheres to the fruit’s skin and is scanned using sub-terahertz (sub-THz) waves, which provide enhanced penetration and resolution. Unlike conventional scanners that are limited to surface analysis, sub-THz waves can penetrate deeper into the inner layers of the fruit to evaluate its ripeness.The researchers mapped scanner readings from various fruits to established quality metrics, such as Brix (sugar content) and dry matter, which are widely used in the food industry. They demonstrated that this non-invasive method is particularly effective, as it assesses ripeness during the edible stage of the fruit, ensuring accurate predictions without causing damage.

Originally developed for 6G telecommunications, sub-THz technology allows seamless integration with existing and emerging wireless networks. This breakthrough paves the way for more efficient, scalable, and accessible methods of monitoring fruit ripeness, contributing to global efforts to reduce food waste.

Managing Correspondent: Gurminder K. Paink 

This study was led by researchers at Princeton University under the guidance of Yasaman Ghasempour

Press article: On-the-shelf fruit ripeness monitoring using sub-terahertz plasmonic stickers (Nature News & Views) 

Original Journal Article: Sub-terahertz metamaterial stickers for non-invasive fruit ripeness sensing (Nature Food)

Image Credit: Pexels/shvetsa