Pendugaan Umur Simpan Keripik Ubi Ungu Menggunakan Metode Accelerated Shelf-Life Testing Pendekatan Kadar Air Kritis

Keripik ubi ungu merupakan produk inovasi olahan ubi jalar ungu yang cukup banyak dikembangkan oleh Industri Kecil Menengah (IKM) di beberapa daerah yang berpotensial seperti di Desa Ciloto. Namun, sebagai produk pangan yang sensitif terhadap penyerapan uap air, keripik ubi ungu memiliki umur simpan yang terbatas dan relatif pendek. Sehingga, untuk mengetahui umur simpan produk tersebut dilakukan pengamatan pendugaan umur simpan menggunakan metode akselerasi pendekatan kadar air kritis. Variabel yang digunakan yaitu kadar air awal, kadar air kritis, kadar air kesetimbangan, kemiringan kurva ISA, permeabilitas kemasan, luas kemasan, bobot padatan per kemasan, dan tekanan uap air jenuh pada suhu penyimpanan. Diperoleh nilai kadar air awal keripik ubi ungu sebesar 0,0103 g H2O/g padatan, nilai kadar air kritis sebesar 0,0287 g H2O/g padatan, nilai kadar air kesetimbangan yang semakin besar seiring meningkatnya kelembaban relatif. Model yang terpilih yaitu model Henderson karena memiliki nilai R2 yaitu sebesar 0,9788 dengan persamaan log(In(1/(1-aw))) = 0,6344+0,5446 In Me dan nilai slope sebesar 0,1720. Pendugaan terbaik pada umur simpan keripik ubi ungu yaitu pada penyimpanan kelembaban relatif 70% menggunakan kadar air kritis SNI, diperoleh umur simpan pada kemasan PP yaitu selama 31 hari dan aluminium foil selama 123 hari. Kata kunci: kadar air, kelembaban relatif, keripik ubi ungu, umur simpan.

Purple sweet potato chips are an innovative product of processed purple sweet potato which is quite widely developed by Small and Medium Industries (IKM) in several potential areas such as in Ciloto Village. However, as a food product that is sensitive to moisture absorption, purple sweet potato chips have a limited and relatively short shelf life. Thus, to determine the shelf life of the product, observations were made to estimate the shelf life using the acceleration method of critical moisture content approach. The variables used are initial moisture content, critical moisture content, equilibrium moisture content, slope of the ISA curve, packaging permeability, packaging area, solids weight per package, and saturated water vapor pressure at storage temperature. The initial moisture content value of purple sweet potato chips was 0,0103 g H2O/g solids, the critical water content value was 0,0287 g H2O/g solids, the equilibrium moisture content value increased with increasing relative humidity. The model chosen is the Henderson model because it has an R2 value of 0,9788 with the equation log(In(1/(1-aw))) = 0,6344+0,5446 In Me and a slope value of 0,1720. The best estimate on the shelf life of purple sweet potato chips is at 70% relative humidity storage using SNI critical water content, obtained in PP packaging for 31 days and aluminum foil for 123 days. Keyword: moisture content, purple sweet potato chips, relative humidity, shelf life

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