In The Best Light

Study sheds light on merchandise appeal using spectroscopy

Have you ever noticed that the bananas you bought look different in the store than they do when you get them home? This is because not all lights used in grocery display cases are the same. The main reason for having different lighting is to improve shelf life of perishable products. Nevertheless, you can be sure some research has gone into determining the best light to entice you to make a purchase.

Spectrum in grocery department

Spectrum in meat department

Spectrum in bananas department

Spectrum in vegetables department

Spectrum in floral department

Spectrum in oranges department

Here are some questions you might ask your students based on our data:

• Compare and contrast the spectra for the different lights used in this grocery store.
• What wavelengths of light are missing from the banana lights compared to the green vegetable lights? What effect might this have on the appearance of the bananas?
• The lights in the floral department have peaks below 400 nm. What portion of the electromagnetic spectrum is this? Give several possible reasons why only the floral department lights would include energy peaks in this region of the spectrum.
• Do any of the lights used in the grocery store contain mercury? Explain how you know.

Special thanks to Vernier consultant Walter Rohr for collecting the data at his neighborhood grocery store using a spectrometer and fiber optic cable from Vernier.