Near-infrared transmittance spectroscopy: a potential tool for non-destructive determination of oil content in groundnuts
✍ Scribed by Misra, Jitendra B; Mathur, Ram S; Bhatt, Dilip M
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 76 KB
- Volume
- 80
- Category
- Article
- ISSN
- 0022-5142
No coin nor oath required. For personal study only.
✦ Synopsis
The oil content of 64 samples of groundnut kernels, representing 47 genotypes, was determined by the conventional Soxhlet extraction procedure (Oil SOX ). The values of Oil SOX ranged from 403 to 536 g kg À1 . The optical densities (ODs) of these samples were determined at 12 wavelengths (918, 928, 940, 950, 968, 975, 985, 998, 1010, 1023, 1037 and 1045 nm) in the near-infrared (NIR) region using a food composition analyser (essentially a ®lter-based NIR spectrophotometer). The instrument also recorded the temperatures of the sample (Temp S ) and the air (Temp A ) surrounding it. A sample holder (75 mm  150 mm; optical path length 25 mm) was used for optical density measurement. The data obtained were subjected to multiple linear regression analysis using the ODs at 12 wavelengths, Temp S and Temp A as the independent (predictor) variables, and Oil SOX as the dependent variable. The multiple linear regression equation comprising 14 predictors showed a signi®cant relationship between predicted values of oil content (Oil NIR ) and Oil SOX . The standard error of calibration and the coef®cient of determination for calibration (R 2 c ) were 3.54 and 0.821 respectively, while the standard error of prediction and the coef®cient of determination for prediction were 5.82 and 0.865 respectively. The ratio of standard error of calibration and standard error of prediction was 0.608. The differences between Oil SOX and Oil NIR were less than AE 20 g kg À1 for samples having oil contents in the range from 480 to 510 g kg À1 . However, for samples having Oil SOX lower than 480 g kg À1 or higher than 510 g kg À1 , differences greater than AE 20 g kg À1 were observed. There exists scope for further re®ning the regression equation by using a larger number of samples for generating optical data. The results demonstrated the potential of NIR transmittance spectroscopy for determining the oil content of groundnuts in a non-destructive manner.