Studi Kerusakan Protein dalam Emulsi Ganda Air-dalam-Minyak-dalam-Air Natrium Klorida Menggunakan Instrumen Fourier Transform Infrared Spectroscopy

Abstract

Penelitian ini bertujuan untuk mengetahui kerusakan protein dalam emulsi ganda W/O/W pada suhu penyimpanan (4, 25, 40°C) dan kadar NaCl yang berbeda (0; 0,2; 0,4; 0,6; 0,8; 1%) setelah 3 minggu penyimpanan dan dianalisis menggunakan instrumen FTIR. Protein lazim digunakan sebagai penstabil dan emulsifier alami dalam emulsi pangan, namun memiliki kelemahan dalam stabilitas terhadap suhu tinggi dan nilai pH rendah mendekati titik isolelektriknya. Penelitian ini menggunakan 2 jenis protein yaitu gelatin untuk fase air internal (W1) dan isolat protein kedelai (IPK) untuk fase air eksternal (W2). Emulsi ganda dibuat melalui tahap emulsifikasi ganda yaitu emulsifikasi primer untuk mendapatkan emulsi W/O dan emulsifikasi sekunder untuk mendapatkan emulsi ganda W/O/W. Analisis FTIR menunjukkan bahwa bahan baku yaitu gelatin dan isolat protein yang digunakan dalam pembuatan emulsi masih dalam kondisi baik. Interpretasi spektra protein yang digunakan dalam emulsi menunjukkan adanya penambahan dan hilangnya gugus Amida utama yang terkandung dalam gelatin dan isolat protein kedelai, yaitu Amida I, II, IV, V dan VI. Kesimpulannya, proses pemanasan emulsi pada suhu 4, 25, dan 40°C dan penyimpanan emulsi selama 3 minggu menyebabkan kerusakan struktur protein pada gelatin dan isolat protein kedelai yang tercermin melalui spektra protein melalui FTIR.

This experiment aims to observe protein deterioration in food double emulsion W/O/W in various NaCl concentrations i.e. 0; 0.2; 0.4; 0.6; 0.8; 1% and storage temperatures, i.e. 4, 25, 40°C after 3 weeks storage by FTIR analysis. Protein is commonly used in food emulsion as stabilizer and natural emulsifier. However, protein has bad performance in high temperature and low pH value near to its isoelectric point. This experiment used 2 types of protein: gelatin as a protein that was added in internal water phase (W1) and soy protein isolate as a protein that was added in external water phase (W2). Double emulsions were produced by 2 phase emulsification, which were primary emulsification (to generate primary W/O emulsion) and secondary emulsification (to produce double emulsion W/O/W). FTIR analysis showed that gelatin and soy protein isolate as main ingredients for W/O/W double emulsion were in a good condition. Protein spectra interpretation showed that emersion and loss of main Amide group of gelatin and soy protein isolate in double emulsion, which were Amide I, II, IV, V and VI. It was concluded that heating and storing process caused protein structure damage to gelatin and soy protein isolate that was able to be visualized by FTIR analysis.