title: Detection of starch adulteration in onion powder by FT-NIR and FT-IR spectroscopy.
abstract: Adulteration of onion powder with cornstarch was identified by Fourier transform near-infrared (FT-NIR) and Fourier transform infrared (FT-IR) spectroscopy. The reflectance spectra of 180 pure and adulterated samples (1-35 wt % starch) were collected and preprocessed to generate calibration and prediction sets. A multivariate calibration model of partial least-squares regression (PLSR) was executed on the pretreated spectra to predict the presence of starch. The PLSR model predicted adulteration with an R(p)2 of 0.98 and a standard error of prediction (SEP) of 1.18% for the FT-NIR data and an R(p)2 of 0.90 and SEP of 3.12% for the FT-IR data. Thus, the FT-NIR data were of greater predictive value than the FT-IR data. Principal component analysis on the preprocessed data identified the onion powder in terms of added starch. The first three principal component loadings and β coefficients of the PLSR model revealed starch-related absorption. These methods can be applied to rapidly detect adulteration in other spices.
authors.affiliation: Department of Biosystems Machinery Engineering, College of Agricultural and Life Science, Chungnam National University , 99 Daehak-ro, Yuseoung-gu, Daejeon 305-764, Republic of Korea.
authors.forename: Santosh
authors.initials: S
authors.lastname: Lohumi
authors.forename: Sangdae
authors.initials: S
authors.lastname: Lee
authors.forename: Wang-Hee
authors.initials: WH
authors.lastname: Lee
authors.forename: Moon S
authors.initials: MS
authors.lastname: Kim
authors.forename: Changyeun
authors.initials: C
authors.lastname: Mo
authors.forename: Hanhong
authors.initials: H
authors.lastname: Bae
authors.forename: Byoung-Kwan
authors.initials: BK
authors.lastname: Cho
mesh_terms: D005506:Food Contamination / Q000032:analysis*; D019697:Onions / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013213:Starch / Q000032:analysis*
chemical_list: D013213:Starch
keywords: Fourier transform NIR and IR spectroscopy; adulteration; onion powder; partial least-squares regression; principal component analysis; starch