Non-Destructive Analysis and Testing Laboratory of Rajamangala University of Technology Isan for Standard Certification of Foods and Agricultural Products
Abstract:
The non-destructive analysis and testing laboratory of Rajamangala University of Technology Isan,
dedicated to the standard certification of foods and agricultural products project, aims to develop standard
methods for inspecting and controlling the quality of agricultural products. Thai jasmine rice is classified as an
agricultural product and is considered the highest quality rice in Thailand. However, it is susceptible to
adulteration and is easily deemed substandard. A simple, rapid, and accurate method for determining the
quality of Thai jasmine rice was developed to ensure that it meets the standards. In this study, the ATR-FTIR
technique was used to determine the characteristics of Thai jasmine rice. Peaks at 3300, 1640, and 1510 cm-1
appeared in the Jasmine rice spectrum, which were assigned to the results of the vibration of protein-derived
bonds. The spectral patterns of Jasmine rice are different from other white rice and mixed rice. Therefore,
protein content was used as a quality indicator for the 150 local jasmine rice samples in Non Sung District, the
plantation area, compared to 30 packed Thai jasmine rice samples in Nakhon Ratchasima Province. The Kjeldahl
method, a method for crude protein estimation, was developed by modification from the standard method
ISO 5983-2:2005 - Animal feeding stuffs Determination of nitrogen content and calculation of crude protein
content Part 2: Block digestion/steam distillation method. The method's instrumentation and analytical
conditions were determined for nitrogen losses, protein digestion efficiency, and distillation and titration
efficiency. It was found that all analytical results met the acceptance criteria of the standard method,
demonstrating that the analytical instruments and conditions are efficient for laboratory use. Validation of the
developed analytical methods was studied by analyzing the Certified Reference Material (CRM). The accuracy
of the analytical method, in terms of the average protein content, confidence interval, and recovery, showed
no statistically significant difference from the CRM value at the 95% confidence level. The precision of the
analytical method, as reproducibility and repeatability by Horwitz's equation, was evaluated, and the HORRAT
value obtained from CRM was within the acceptance criteria. All statistical values met the acceptance criteria
of the international standard method, demonstrating that the developed method, according to the analytical
laboratory, provides accurate, precise, and reliable results following international standards. Internal quality
control of the sampling and developed analytical processes was assessed using a quality control chart. The
results showed that all points of the sample group were within the control limit, indicating that the sampling
process and quality control system of the developed analytical method have sensitivity and efficiency for
analysis. Therefore, this method can be used as a standard method for quality control of Thai jasmine rice.
Protein content in packed Thai jasmine rice products and Thai local jasmine rice ranged from 6.40 ± 0.18% to
7.13 ± 0.48% and 4.78 ± 0.05% to 5.43 ± 0.04%, respectively. The protein contents in all Thai local jasmine
rice are statistically significantly lower than that of packed jasmine rice at the 95% confidence level, influenced
by planting area, soil nutrients, and the amount of fertilizer used in rice cultivation. The ATR-FTIR technique
combined with protein determination by the Kjeldahl method and statistical methods developed by a research
laboratory can be used as a standard method for quality control of jasmine rice and can be applied as a
prototype of analytical methods for the quality control of foods and agricultural products.