| Home  | About ScienceAsia  | Publication charge  | Advertise with us  | Subscription for printed version  | Contact us  
Editorial Board
Journal Policy
Instructions for Authors
Online submission
Author Login
Reviewer Login
Volume 46 Number 1
Volume 45 Number 6
Volume 45 Number 5
Volume 45 Number 4
Volume 45 Number 3
Volume 45 Number 2
Earlier issues
Volume 45 Number 6 Volume 46 Number 1

previous article next article

Research articles

ScienceAsia 46 (2020): 52-58 |doi: 10.2306/scienceasia1513-1874.2020.004


Flow-based titration with a colorimetric detection box using a smartphone for the determination of titratable acidity in coffee


Sarawut Somnam*, Miki Kanna

 
ABSTRACT:     Acidity is one of the key components for coffee quality which could be determined by titration. However, the endpoint observation with bare eyes might give error because of the dark color of coffee. Although this problem could be solved by using a pH meter, the calibration and maintenance processes including the cost of the device may be the drawbacks. In this research, a digital image colorimetric detection system was established with economic devices. The caption of image was carried out by a smartphone under the control of light intensity and focus range in a homemade detection box to assess the primitive color (red/green/blue or RGB) data from the color change of an acid-base indicator. In addition, to make process more comfortable and reduce the detection time, the flow-based technique was also applied to the setup for the signal monitoring process. The method was highly reproducible with %RSD less than 1 (n = 11) and detection time of 24 s was achieved. From the analyses of roasted coffee beans, the results obtained agreed well with those from the potentiometric standard method.

Download PDF

14 Downloads 65 Views


a Department of Chemistry, Faculty of Science and Technology, Chiang Mai Rajabhat University, Chiang Mai 50300 Thailand

* Corresponding author, E-mail: sarawut_som@cmru.ac.th

Received 18 Apr 2019, Accepted 22 Dec 2019