Penggunaan Poliester Amida pada Bioplastik Protein Kedelai dari Limbah Padat Industri Tahu dengan Gliserol sebagai Bahan Pemlastis

Abstract

The objective of the research was to find out the characteristics bio-plastic film of soy protein – glycerol and bio-plastic film of soy protein– glycerol - polyester amide, and optimum comparison of soy protein – glycerol and polyester amide which are used in bio-plastic film from solid waste of tofu industry. The research includes the process of extraction of soy protein from tofu waste, the formation of bio-plastic film by using solution casting method with the variation of glycerol and polyester amide of 10%, 15%, 30% and 10%, 30%, 50% from soy protein and they were analyzed and characterized. Optimum of glycerol concentration used in making bio-plastic film of soy protein – glycerol – polyester amide is in the glycerol percentage of 15% from soy protein. The optimum result of its mechanical characteristic testing such as tensile strength and the percentage of elongation of soy protein – glycerol – polyester amide of 30% is 8.886 MPa and 170.588%. This is because the molecule component of bio-plastic film composer is on the balance point. The comparison of ester composition and amide in polyester amide influences bio-plastic film of protein content. The testing result of bio-plastic film of protein content indicates that the value of bio-plastic of protein content is decreasing by the addition of polyester amide concentration. The testing result of thermal property of bio-plastic film of soy protein – glycerol – polyester amide, using Thermogravimetric Analysis (TGA) indicates that there is still the residue of bio-plastic film of 24.31%. This value indicates that bio-plastic film of soy protein – glycerol – polyester amide has good thermal property and heat resistance. The crystallization degree of the smaller polyester amide than the crystallization degree of soy protein has caused the biodegradation testing result of bio-plastic film with the fastest rate of biodegradation to be found in bio-plastic film of soy protein – glycerol – polyester amide of 50%. The surface result with Scan Electronic Microscope (SEM) indicates that the morphology of soy protein surface has globular structure. The Fourier Transform Infrared Spectroscopy (FTIR) analysis indicates that there is physical interaction (blending) which is influenced hydrogen bond (O-H) from component soy protein – glycerol – polyester amide so that the new functional cluster is not found in bio-plastic film.

Penelitian ini bertujuan untuk mengetahui karakter film bioplastik protein kedelai – gliserol dan film bioplastik protein kedelai - gliserol - poliester amida, serta perbandingan yang optimum antara protein kedelai - gliserol - poliester amida yang digunakan pada film bioplastik dari limbah padat industri tahu. Penelitian meliputi proses ekstraksi protein kedelai dari ampas tahu, pembentukan film bioplastik menggunakan metode solution casting dengan variasi gliserol dan poliester amida sebesar 10%, 15%, 30% dan 10%, 30%, 50% dari protein kedelai, kemudian dilakukan analisis dan karakterisasi. Konsentrasi gliserol optimum yang digunakan pada pembuatan film bioplastik protein kedelai – gliserol – poliester amida adalah pada presentase gliserol 15% dari protein kedelai. Hasil pengujian sifat mekanik seperti uji kekuatan tarik dan % kemuluran film bioplastik optimum pada film bioplastik protein kedelai – gliserol – poliester amida 30%, sebesar 8,886 MPa dan 170,588%. Hal ini disebabkan karena molekul komponen penyusun film bioplastik berada pada titik kesetimbangan. Perbandingan komposisi ester dan amida pada polister amida mempengaruhi kadar protein film bioplastik. Hasil uji kadar protein film bioplastik menunjukkan bahwa kadar protein film bioplastik nilainya semakin kecil dengan penambahan konsentrasi poliester amida. Hasil pengujian daya tahan panas film bioplastik protein kedelai – gliserol – poliester amida menggunakan Thermogravimetric Analysis (TGA) menunjukkan bahwa masih tersisa residu film bioplastik sebesar 24,31%. Nilai tersebut mengindikasikan bahwa film bioplastik protein kedelai – gliserol – poliester amida memiliki sifat termal dan ketahanan panas yang baik. Derajat kristalisasi poliester amida yang lebih kecil dibanding dengan derajat kristalisasi protein kedelai menyebabkan hasil uji biodegradasi film bioplastik dengan laju biodegradai tercepat terdapat pada film bioplastik protein kedelai – gliserol – poliester amida 50%. Hasil analisis permukaan dengan mikroskop pemindai elektron (SEM) menunjukkan bahwa morfologi permukaan protein kedelai memiliki struktur globular. Hasil analisis spektroskopi infra merah (FTIR) menunjukkan bahwa terdapat interaksi fisik (blending) yang dipengaruhi oleh adanya ikatan hidrogen (OH) dari komponen protein kedelai – gliserol – poliester amida sehingga tidak ada ditemukan gugus fungsi yang baru pada film bioplastik.