Title

Development and validation of a digital photometric method for milled rice apparent amylose content determination using a smartphone camera

Date of Completion

2018

Document Type

Thesis

Degree Name

Bachelor of Science in Biochemistry

Keywords

Amylose.

Abstract

A digital photometric method for the measurement of milled rice apparent amylose content (AC) has been developed and validated using seven market milled rice test samples. The validated method was then utilized to determine AC of a set of commercial milled rices (n=20) in comparison with the established UV-Vis spectrophotometric method. A light box was contructed to accommodate a cuvette and a smartphone camera for the digital photometric method and the free-access software Image J was utilized for image analysis of the milled rice amylose-iodine blue solutions. Accuracy, linearity and precision (i.e. repeatability and intermediate precision) of the method were determined with the UV-Vis spectrophotometric method as basis. Optimization of the smartphone camera parameters, utilizing all red (R), green (G) and blue (B) image values was accoplished. ISO 100 with shutter speed 1/640 was the most suitable camera settings giving the closest AC values to those obtained via UV-Vis spectrophotometry when the %B image parameter was considered. Validation has proven the method to be repeatable and precise for nonwaxy samples only having RSD values below 7% using %B among all replications within one day and across two different analysis days. The method showed high degree of linearity (r=0.995-0.998) for %B plots as well as high accuracy having <5% error for nonwaxy samples and no significant difference for all test samples (n=7) when digital photometric AC values were compared with UV-Vis spectrophotometric AC values. AC of 17 out of 20 market milled rice samples was accurately measure by digital photometry based on the established UV-Vis spectrophotometric method. further refinement of the method is warranted focusing on the accurate determination of AC of waxy rices since the three waxy samples in this set yielded AC values significantly different and far from the spectrophotometric AC values. Apart from this limitation, the validated method was accurate, precise and repeatable for nonwaxy milled rice AC determination as compared to UV-Vis spectrophotometry.

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