ESIPT-exhibiting protein probes: a sensitive method for rice proteins detection during starch extraction

Area of Science:

• Biochemistry
• Analytical Chemistry
• Food Science

Background:

• Rice starch extraction is a crucial process in food and industrial applications.
• Accurate detection of residual proteins is vital for starch purity.
• Traditional methods like the biuret test have limitations in sensitivity and scope.

Purpose of the Study:

• To evaluate the efficacy of 2-(4'-isothiocyanate-2'-hydroxyphenyl)benzoxazole dye for labeling rice proteins.
• To compare fluorescence-based protein detection with the biuret colorimetric test during alkaline starch extraction.
• To assess the dye's ability to monitor protein presence and separation throughout the extraction process.

Main Methods:

• Alkaline extraction of starch from rice.
• Labeling of rice proteins with 2-(4'-isothiocyanate-2'-hydroxyphenyl)benzoxazole dye.
• Direct fluorescence measurements of labeled proteins at various extraction stages.
• Comparison with the biuret colorimetric test for protein quantification.

Main Results:

• The fluorescent dye successfully labeled rice proteins during alkaline starch extraction.
• Fluorescence was detected in all extraction steps, indicating persistent protein presence.
• The biuret test showed no protein after the third extraction step, highlighting its lower sensitivity.
• The study observed the separation of different rice protein fractions using fluorescence.

Conclusions:

• 2-(4'-isothiocyanate-2'-hydroxyphenyl)benzoxazole is a sensitive and effective label for rice proteins in starch extraction.
• Fluorescence detection offers superior sensitivity over the biuret test for monitoring proteins during extraction.
• This technique enables better assessment of starch purity and protein behavior during processing.