Analysis of Moisture Content in Beetroot using Fourier Transform Infrared Spectroscopy and by Principal Component Analysis

Noel Nesakumar,Chanthini Baskar,Srinivasan Kesavan,Subbiah Alwarappan,John Bosco Balaguru Rayappan

doi:10.1038/s41598-018-26243-5

Abstract

The moisture content of beetroot varies during long-term cold storage. In this work, we propose a strategy to identify the moisture content and age of beetroot using principal component analysis coupled Fourier transform infrared spectroscopy (FTIR). Frequent FTIR measurements were recorded directly from the beetroot sample surface over a period of 34 days for analysing its moisture content employing attenuated total reflectance in the spectral ranges of 2614–4000 and 1465–1853 cm−1 with a spectral resolution of 8 cm−1. In order to estimate the transmittance peak height (Tp) and area under the transmittance curve ({int }_{{bar{nu }}_{i}}^{{bar{nu }}_{f}}{T}_{p}dbar{nu }) over the spectral ranges of 2614–4000 and 1465–1853 cm−1, Gaussian curve fitting algorithm was performed on FTIR data. Principal component and nonlinear regression analyses were utilized for FTIR data analysis. Score plot over the ranges of 2614–4000 and 1465–1853 cm−1 allowed beetroot quality discrimination. Beetroot quality predictive models were developed by employing biphasic dose response function. Validation experiment results confirmed that the accuracy of the beetroot quality predictive model reached 97.5%. This research work proves that FTIR spectroscopy in combination with principal component analysis and beetroot quality predictive models could serve as an effective tool for discriminating moisture content in fresh, half and completely spoiled stages of beetroot samples and for providing status alerts.

Highlights

Tpdν over the spectral ranges of 2614–4000 and 1465–1853 cm−1, Gaussian curve fitting algorithm was performed on Fourier transform infrared spectroscopy (FTIR) data
Since the wide and strong bands observed at 3319 and 1637 cm−1 were specific to the moisture content of beetroot test samples, FTIR spectra of fresh beetroot test samples were recorded for a period of 34 days in the spectral ranges of
(Fig. 4(e)) determined the ages of beetroot sample 1 and 2 as 11.83, 11.76 days and 24.59, 24.27 days respectively with an accuracy of 97.5%. All these results suggest that principal component analysis (PCA) combined with FTIR technique can determine the age and moisture level of beetroot with enhanced accuracy

Summary

Introduction

Tpdν over the spectral ranges of 2614–4000 and 1465–1853 cm−1, Gaussian curve fitting algorithm was performed on FTIR data. This research work proves that FTIR spectroscopy in combination with principal component analysis and beetroot quality predictive models could serve as an effective tool for discriminating moisture content in fresh, half and completely spoiled stages of beetroot samples and for providing status alerts. Beetroot (Beta vulgaris L.) is cultivated throughout the world for its vegetable and juice value[1] It contains high concentration of betaine, vitamin A, B6 and C, folic acid, protein, carbohydrates, potassium, iron, soluble fibre, sodium and magnesium[1,2]. According to a report by British Dietetic Association (BDA), beetroot contains anthocyanins which can minimize the effects of pollution on the body. Its shelf-life can be extended by integrating refrigeration with a controlled atmosphere comprising of a mixture of carbon dioxide and oxygen in an airtight room[13,14,15,16]

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