A low-cost optical sensor to quantify bioactive compounds in fruit

This paper discusses the design, development and construction of a low cost system to measure plant-based bioactive compounds. The proposed system uses a light emitting diode (LED), an optical filter, a cuvette holder, a photodiode, an electronic board and a mechanical structure. The results are based on transmittance and reflectance absorptiometric measurements. In order to evaluate the sensitivity of the prototype sensor it was tested against a commercial spectrophotometer. The two systems measured the bioactive compounds of a variety of different fruits (acerola, pineapple, plum, atemoya, banana, cashew apple, kiwi, pitomba, sapodilla, yellow mombin and grape). The coefficient r of the two systems were similar (r = 0.99 for total polyphenols, r = 0.95 for total flavonoids, r = 0.99 for ascorbic acid). Nevertheless, further research is required to improve the precision of this optical sensor, which has significant potential for industrial applications.