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ABSTRAK
Bioplasik adalah plastik yang dapat digunakan seperti plastik konvensional, namun akan hancur terurai oleh aktivitas mikroorganisme menjadi hasil akhir air dan gas karbondioksida setelah habis terpakai dan dibuang ke lingkungan. Penelitian bioplastik berbasis pati dilakukan untuk mengurangi akumulasi plastik di lingkungan, meningkatkan kesuburan tanah, dan mengurangi biaya perawatan limbah. Tujuan dari penelitian ini untuk mengetahui karakterisasi dari biji alpukat serta mengetahui pengaruh penambahan kitosan dan sorbitol pada sifat fisikokimia bioplastik dari limbah biji alpukat. Pati sebagai bahan baku dalam pembuatan bioplastik diekstrak dari biji alpukat dengan menggunakan air. Dilakukan analisis pada pati yang dihasilkan yaitu meliputi analisis kadar pati, kadar amilosa, kadar amilopektin, kadar air, kadar abu, kadar lemak dan kadar protein, analisis FT-IR (Fourier Transform Infra – Red), SEM (Scanning Electron Microscopy), dan RVA (Rapid Visco Analyzer). Pembuatan bioplastik merujuk pada metode Weiping Band, dimana dilakukan modifikasi kimiawi pati dengan penambahan plasticizer sorbitol dan pengisi kitosan. Komposisi pati biji alpukat – kitosan yang digunakan adalah 7:3, 8:2 dan 9:1 (m/m), sedangkan volume sorbitol digunakan adalah 0,2 ml/g, 0,3 ml/g, dan 0,4 ml/g. Temperatur pemanasan larutan bioplastik divariasikan pada 80 oC, 85 oC, dan 90 oC. Bioplastik yang dihasilkan dianalisis sifat fisika dan kimianya, meliputi analisis FT-IR, SEM, RVA, kekuatan tarik, perpanjangan pada saat putus, penyerapan air, dan densitas. Dari hasil analisis FT-IR ditunjukkan adanya peningkatan bilangan gelombang gugus O-H dimana O-H pada pati biji alpukat memiliki bilangan gelombang 3317,56 cm-1 dan pada bioplastik dengan penambahan kitosan dan sorbitol meningkat menjadi 3533,59 cm-1 dan gugus N-H muncul pada bilangan gelombang 1593,20 cm-1 pada bioplastik dengan penambahan kitosan meningkat bila dibandingkan dengan bioplastik tanpa kitosan yaitu pada bilangan gelombang 1585,49 cm-1. Dari hasil SEM ditunjukkan bahwa pati biji alpukat berbentuk oval dan berukuran 5,9 μm dan ditunjukkan pula bahwa struktur patahan bioplastik dengan pengisi kitosan dan plasticizer sorbitol lebih rapat dan kompak dibandingkan bioplastik tanpa pengisi kitosan dan plasticizer sorbitol. Dari analisa pati biji alpukat diperoleh kadar pati 67,6950%, kadar amilosa 32,4739%, kadar amilopektin 35,3212%, kadar air 1,087%, kadar abu 1,007%, kadar lemak 1,86%, kadar protein 10,44%, suhu gelatinisasi 85,17 oC dengan peak viscosity sebesar 3847 cP dan kondisi terbaik bioplastik dari biji alpukat adalah pada perbandingan pati-kitosan 7:3 dengan volume sorbitol 0,2 ml/g dan temperatur pemanasan larutan bioplastik 85oC, dimana nilai kekuatan tarik bioplastik adalah 8,826 MPa, nilai perpanjangan pada saat putus 3,59%, nilai Modulus Young 245,85 MPa, nilai penyerapan air 29,41 %, dan nilai densitas 2,632 g/ml.
Kata kunci : pati, kitosan, sorbitol, bioplastik, biodegradable, weiping band
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ABSTRACT
Bioplastic is plastic that can be used as conventional plastic, yet it could be decomposed by microorganism to produce the end product water and carbondioxide after being used and thrown to environment. Researches on biodegradable starch-based bioplastics have been made to reduce the consumption of conventional plastics, improve the fertility of soil, and reduce treatment cost of waste. The aim of this study is to find out characteristics of avocado seed starch and find out the effect of chitosan and plasticizer sorbitol on the physico-chemical properties of bioplastics from avocado seed starch. Starch which is the raw material for bioplastics was extracted from the avocado seed with water. Analysis of starch produced which includes analysis of starch content, amylose content, content of amylopectin, moisture content, ash content, fat content and protein content, the analysis of FT-IR (Fourier Transform Infra - Red), SEM (Scanning Electron Microscopy) and RVA (Rapid Visco Analyzer). Manufacture of bioplastics refers to methods Weiping Band, which performed chemically modified starch with the addition of plasticizers sorbitol and fillers chitosan. The composition of avocado seed starch - chitosan used was 7: 3, 8: 2 and 9: 1 (w/w), while the volume of sorbitol used was 0,2 ml/g, 0,3 ml/g, and 0,4 ml/g. The heating temperature of bioplastic solution was varied at 80 oC, 85 oC, and 90 oC. Bioplastics were analyzed physical and chemical properties, which include the analysis of FT-IR, SEM, tensile strength, elongation at break, water absorption and density. From the results of FT-IR analysis indicated an increase in wave numbers OH which wave numbers OH on avocado seed starch is 3317,56 cm-1 and on bioplastic with adding chitosan and sorbitol increases to 3533,59 cm-1 and NH groups on bioplastics due to the addition of chitosan is found on wave number 1593,20 cm-1 is bigger than bioplastic without adding chitosan with the wave number 1585,49 cm-1. From results of SEM analysis indicated that avocado seed
starch shape is oval with size 5,9 μm and also indicated that the structure of fracture bioplastic with filler chitosan and plasticizer sorbitol was denser and more compact than bioplastics without filler chitosan and plasticizer sorbitol. From the analysis of starch produced starch content 67,6950%, amylose content 32,4739%, amylopectin content 35,3212%, moisture content 1,087%, ash content 1,007%, fat content 1,86%, and protein content 10,44%, gelatinization temperature occurs at 85,17 oC with peak viscosity 3847 cP and the best conditions of bioplastics is on starch-chitosan ratio of 7: 3 by 0,2 ml/g volume of sorbitol and heating temperature of solution bioplastics at 85°C, where the value of tensile strength bioplastic is 8,826 MPa, value of extension at break 3,59%, value of Modulus Young 245,85 MPa, value of water absorption 29,41%, and the value of density 2,632 g/ml.
Key words: starch, chitosan, sorbitol, bioplastic, biodegradable, weiping band
