How to Predict the Freshness of Peppers by Spectroscopy

author: Susan

2022-03-02

How to Predict the Freshness of Peppers by Spectroscopy

Abstract

Several researchers from the University of Bonn in Germany recently published a paper, "Non-destructive optoelectronic determination of fruit freshness and shrinkage in sweet peppers". In their study, they set out to identify suitable parameters to determine the freshness of bell pepper fruit of three colors (yellow, red and green) over a two-week period, including the occurrence of shrinkage using non-destructive real-time measurem.
1. Experiment objective:
Determination of suitable parameters to determine the freshness (degree) of bell pepper fruit of three colors (yellow, red and green) over a two-week period, including the occurrence of shrinkage using non-destructive real-time measurements.
2. Materials and methods:
Surface gloss was measured nondestructively using a CZ-H72 gloss sensor (Keyence Corporation, Osaka, Japan), a colorimeter, a spectrometer, and a VR-5200 profiler (Keyence) to obtain RGB images.

3. Experiment System:
The VIS-NIR spectral reflectance of peppers with different freshness and shrinkage was measured non-invasively using a portable ATP2000P General Spectrometer micro-spectrometer, and the data was processed using SpectraWizTM software provided with the instrument. Measurements were made in the 500-850nm wavelength range using an ATG1002 tungsten halogen light source and an Reflection Probes reflectivity probe to provide a 2mm measurement spot with a measurement time of less than 1s.

4. Results:
The initial 230-245 g bell pepper fruit lost 2.9-4.8 g FW per day at 17°C and 55% rh during storage and shelf life. After 4-5 days, shrinkage begins with 6-8% weight loss and becomes more pronounced. Gloss decreases from 450-500 au (no shrinkage of fresh fruit) to 280-310 au (moderate shrinkage of fruit) to 80-90 au, regardless of color, on a background of the same color < (eg, light red and dark red) The fruit is severely shrunk.

Conclusions:
Overall, it can be concluded that color measurements are not suitable for determining the freshness of bell pepper fruits, whereas profilometers, gloss sensors and light reflectance spectroscopy are suitable candidates for novel optoelectronic methods to define and parameterize fruit freshness.
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