Electronic Theses and Dissertation

Sistem deteksi kadar sianida (CN-) dan kekeruhan pada umbi janeng (Dioscorea hispida Dennst.) telah berhasil dikembangkan. Sistem ini direalisasikan dalam bentuk prototipe portabel berbasis mikrokontroler ESP32. Di dalamnya, terintegrasi sensor optik LDR (konfigurasi transmitan dan reflektan) serta modul TDS. Sistem dirancang untuk memantau parameter fisis larutan hasil rendaman secara simultan dan real-time. Parameter yang dipantau meliputi konduktivitas listrik, konsentrasi padatan terlarut, serta intensitas cahaya transmisi dan hamburan. Pengujian dilakukan pada sampel umbi janeng dengan variasi waktu perendaman 3–24 jam serta produk kering siap pasar. Hasil pengukuran menunjukkan sensor TDS efektif merekam dinamika difusi senyawa hidrofilik. Konsentrasi TDS tercatat meningkat dari 58,78 ppm pada 3 jam hingga mencapai puncak 303,74 ppm pada 18 jam. Setelah itu, nilai TDS berfluktuasi turun karena tercapainya kesetimbangan transfer massa dan dekomposisi senyawa organik. Sementara itu, sensor optik merekam penurunan tegangan transmitan hingga 2.383,63 mV pada 15 jam. Penurunan ini berkorelasi langsung dengan peningkatan absorbansi. Tegangan reflektan gabungan juga tercatat naik hingga 2.647,56 mV pada 12 jam akibat hamburan cahaya oleh partikel koloid. Pada produk kering, sistem mendeteksi kadar TDS yang sangat rendah yaitu 1,42 ppm. Nilai ini berada jauh di bawah ambang batas aman FAO/WHO sebesar 10 ppm. Hasil tersebut didukung oleh tingkat transmitansi tinggi sebesar 2.774,38 mV yang mengindikasikan kejernihan optimal. Secara keseluruhan, sistem ini terbukti andal sebagai instrumen deteksi cepat dan objektif untuk menjamin keamanan pangan lokal berbasis umbi janeng.
Kata kunci: umbi janeng, sianida, sensor turbidity, LDR, ESP32, detoksifikasi

A detection system for cyanide (CN-) levels and turbidity in janeng tubers (Dioscorea hispida Dennst.) has been successfully developed. This system is realized as a portable prototype based on the ESP32 microcontroller. It integrates Light Dependent Resistor (LDR) optical sensors in both transmittance and reflectance configurations, alongside a Total Dissolved Solids (TDS) sensor module. The system is designed to monitor the physical parameters of the soaking solution simultaneously and in real-time. These parameters include electrical conductivity, dissolved solids concentration, and transmitted as well as scattered light intensities. Testing was conducted on janeng tuber samples with varying soaking durations of 3–24 hours, as well as on ready-to-market dried products.Measurement results demonstrate that the TDS sensor effectively records the diffusion dynamics of hydrophilic compounds. The TDS concentration increased from 58.78 ppm at 3 hours to a peak of 303.74 ppm at 18 hours. Subsequently, the TDS values fluctuated downward due to the attainment of mass transfer equilibrium and the decomposition of organic compounds. Meanwhile, the optical sensor recorded a decrease in transmittance voltage down to 2,383.63 mV at 15 hours. This decrease directly correlates with increased absorbance. The combined reflectance voltage also rose to 2,647.56 mV at 12 hours due to light scattering by colloidal particles. In dried products, the system detected a very low TDS level of 1.42 ppm. This value lies far below the FAO/WHO safety threshold of 10 ppm. This result is supported by a high transmittance level of 2,774.38 mV, indicating optimal clarity. Overall, this system has proven reliable as a rapid and objective detection instrument to ensure the food safety of local janeng tuber-based products. Keywords: janeng tuber, cyanide, turbidity sensor, LDR, ESP32, detoxification