Aplikasi Six Sigma DMAIC sebagai Metode Perbaikan dan Pengendalian Deviasi Mutu Kimia Susu UHT di PT XYZ

Abstract

Ketidakkonsistenan mutu dapat menurunkan kepercayaan konsumen terhadap merek, yang pada akhirnya berdampak pada loyalitas dan citra perusahaan. Ketidakstabilan parameter mutu kimia seperti kadar lemak, total padatan, dan protein juga dapat menurunkan efisiensi proses industri. Penelitian ini bertujuan mengidentifikasi dan memperbaiki deviasi mutu pada proses produksi susu UHT di PT XYZ menggunakan pendekatan Six Sigma melalui tahapan DMAIC (Define, Measure, Analyze, Improve, Control). Fokus penelitian adalah parameter mutu kimia produk intermediat pada lini produksi 2 PT XYZ. Sebanyak 10 kode sampel dengan nilai deviasi tertinggi diambil dan dikumpulkan sepanjang Agustus–September 2025. Analisis dilakukan menggunakan diagram Pareto, peta kendali I-MR, analisis kapabilitas proses (Cpk), dan why-why analysis. Validasi hasil pengukuran dilakukan dengan membandingkan alat Milkoscan FOSSTM Analytical terhadap metode Kjeldahl dan gravimetri berdasarkan standar ISO. Hasil penelitian menunjukkan bahwa parameter padatan total dan protein merupakan Critical to Quality (CTQ) dengan deviasi tertinggi pada varian full cream dan cokelat. Akar penyebab deviasi meliputi ketidaktepatan formula pengenceran, ketidakakuratan pembacaan alat Milkoscan FOSSTM, dan belum adanya standar penambahan air yang seragam. Perbaikan dilakukan melalui validasi formula pengenceran, penyusunan instruksi kerja penambahan air, serta kalibrasi dan cross-check alat ukur. Setelah perbaikan, nilai Cpk meningkat dari kondisi negatif menjadi positif pada seluruh parameter. Parameter padatan total dan protein varian full cream masing-masing meningkat menjadi 0,14 dan 0,36, sedangkan pada varian cokelat meningkat menjadi 0,80 dan 0,12. Hasil tersebut menunjukkan bahwa penerapan Six Sigma DMAIC mampu meningkatkan stabilitas dan kapabilitas proses pada produksi susu UHT.

Inconsistency of product quality can reduce consumer’s trust in a brand, ultimately affecting their loyalty and the company’s image. Deviation in chemical quality parameters such as fat, total solids, and protein may also decrease industrial process efficiency. This study aimed to identify and improve quality deviations in the UHT milk production process at PT XYZ using the Six Sigma approach through the DMAIC stages (Define, Measure, Analyze, Improve, and Control). The research focused on the chemical quality parameters of intermediate products in production line 2 at PT XYZ. A total of 10 sample codes with the highest deviation values were collected during August–September 2025. Data analysis was conducted using Pareto diagrams, I-MR control charts, process capability analysis (Cpk), and why-why analysis. Measurement validation was performed by comparing the Milkoscan FOSSTM Analytical instrument with Kjeldahl and gravimetric methods based on ISO standards. The results showed that total solids and protein were the Critical to Quality (CTQ) parameters with the highest deviations in both full cream and chocolate variants. The root causes of deviation included inaccurate dilution formulas, inaccurate readings from the Milkoscan FOSSTM instrument, and the absence of standardized water addition procedures. Corrective actions were implemented through dilution formula validation, preparation of water addition work instructions, and routine calibration and cross-checking of measuring instruments. After improvement, the Cpk values increased from negative to positive across all parameters. The Cpk values of total solids and protein in the full cream variant increased to 0.14 and 0.36, respectively, while those in the chocolate variant increased to 0.80 and 0.12. These results indicate that the implementation of Six Sigma DMAIC improved process stability and capability in UHT milk production.