# Comparison of Benchtop and Portable Near-Infrared Instruments to Predict the Type of Microplastic Added to High-Moisture Food Samples

## TL;DR

This study compares two near-infrared instruments for detecting microplastics in high-moisture foods like fruits and vegetables.

## Contribution

The study introduces a comparison of benchtop and portable NIR instruments for microplastic detection in high-moisture food samples.

## Key findings

- Benchtop instruments showed better accuracy (R2 CV 0.88) than portable ones (R2 CV 0.54) for predicting microplastic addition.
- Short and long wavelength regions performed similarly with the benchtop instrument (R2 CV 0.88 and 0.86).
- NIR spectroscopy can be used to monitor microplastics in high-moisture food samples alongside quality assessment.

## Abstract

Near-infrared (NIR) spectroscopy is a rapid, non-destructive analytical tool widely used in the food and agricultural sectors. In this study, two NIR instruments were compared for classifying the addition of microplastics (MPs) to high-moisture-content samples such as vegetables and fruit. Polyethylene (PE), polypropylene (PP), and a mix of polymers (PE + PP) MP were added to mixtures of spinach and banana and scanned using benchtop (Bruker Tango) and portable (MicroNIR) instruments. Both principal component analysis (PCA) and partial least squares (PLS) were used to analyze and interpret the spectra of the samples. Quantitative models were developed to predict the addition of Mix, PP, or PE to spinach and banana samples using PLS regression. The R2 CV and the SECV obtained were 0.88 and 0.44 for the benchtop samples, and 0.54 and 0.67 for the portable instruments, respectively. Two wavenumber regions were also evaluated: 11,520–7500 cm−1 (short to medium wavelengths), and 7500–4200 cm−1 (long wavelengths). The R2 CV and the SECV obtained were 0.88 and 0.46, 0.86 and 0.49, respectively, for the prediction of addition in samples analyzed on the benchtop instrument using short and long wavenumbers, respectively. This study provides new insights into the comparison of two instruments for detecting the addition of MPs in high-moisture samples. The results of this study will ensure that NIR can be utilized not only to measure the quality of these samples but also to monitor MPs.