Validasi Metode Kjeldahl untuk Penentuan Nitrogen Total dalam Produk Kecap Manis di PT Kraft Heinz ABC Indonesia

Abstract

Penetapan kadar nitrogen total penting dalam menjamin mutu kecap manis. Metode Kjeldahl umum digunakan namun memiliki kelemahan durasi destruksi panjang. Penelitian ini mengoptimalkan waktu destruksi dengan mengganti katalis konvensional (CuSO4–K2SO4) menjadi SeO2, serta memvalidasi metode berdasarkan presisi, akurasi, ketahanan, dan ketangguhan. Optimasi dilakukan melalui variasi suhu dan massa katalis. Hasil menunjukkan bahwa 0,4 gram SeO2 dengan tahapan suhu 240 °C (20 menit), 280 °C (10 menit), dan 540 °C (20 menit) mampu memangkas waktu destruksi dari 3,5 jam menjadi 50 menit. Validasi metode menghasilkan presisi (%RSD) 0,56–0,69% (< 2/3 CV Horwitz), akurasi (% recovery) 99,07–100%, serta uji kekuatan dan ketangguhan yang memenuhi kriteria (t-hitung < t-tabel). Dengan demikian, metode Kjeldahl hasil optimasi valid untuk analisis rutin nitrogen total dalam kecap manis dan berpotensi meningkatkan efisiensi laboratorium tanpa mengorbankan keandalan hasil.

Total nitrogen determination was a crucial parameter for ensuring the quality of sweet soy sauce. While the Kjeldahl method was widely used for this analysis due to its high accuracy, it suffered from prolonged digestion time. This study aimed to optimize the digestion time of the Kjeldahl method by replacing the conventional catalyst (CuSO4–K2SO4) with selenium dioxide (SeO2) and validating the optimized method based on precision, accuracy, robustness, and ruggedness parameters. Optimization was conducted by varying temperature and catalyst mass to achieve the fastest digestion conditions. The results demonstrated that using 0.4 g SeO2 with a stepwise temperature program of 240 °C (20 min), 280 °C (10 min), and 540 °C (20 min) reduced digestion time from 3.5 hours to 50 minutes. Method validation showed excellent precision (%RSD 0.56–0.69%, below 2/3 Horwitz CV), accuracy (% recovery 99.07–100%), and acceptable robustness and ruggedness (t-calculated < t-table). Thus, the optimized Kjeldahl method was valid for routine total nitrogen analysis in sweet soy sauce and had the potential to enhance laboratory efficiency without compromising result reliability.