Wicaksono, Prama Eko (2018) Penentuan Kadar Kandungan Air Pada Biji Kopi Arabika Dengan Teknik Laser-Induced Breakdown Spectroscopy (LIBS). Undergraduate thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Penentuan kadar air biji kopi merupakan salah satu tolak ukur proses pengeringan agar diperoleh mutu hasil yang baik dan biaya pengeringan yang murah. Pengeringan yang berlebihan (hingga kadar air jauh dibawah 12%) merupakan pemborosan bahan bakar dan merugikan karena terjadi kehilangan berat. Sebaliknya jika terlalu singkat maka kadar air biji kopi belum mencapai titik keseimbangan (12%) sehingga biji kopi menjadi rentan terhadap serangan jamur pada saat disimpan atau diangkut ke tempat konsumen (Prastowo, dkk. 2010). Pada proses penyangraian biji kopi kehilangan kadar air sebesar 3-5% untuk light roasted, 5-8% untuk medium roasted, dan 8-14% untuk dark roasted (Varnam and Sutherland, 1994). Pada umumnya pengukuran kadar air biji kopi dilakukan dengan metode oven (AOAC, 1984) atau menggunakan alat ukur grain moisture meter. Metode oven memerlukan waktu preparasi sampel yang lama sedangkan grain moisture meter (MC-7828G) kurang sensitif pada rentang pengukuran kadar air di bawah 5% (Digital Instrument Catalog). Berdasarkan hal tersebut telah dikembangkan metode penentuan kadar air pada biji kopi arabika dengan teknik LIBS (Laser-Induced Breakdown Spectroscopy). Berdasarkan data penelitian didapatkan kondisi optimum pengujian pada energi laser 100 mJ dan delay-time detection 0.5 µs. Digunakan gas He (helium) dengan laju aliran 20 mL/s sebagai lingkungan pengujian. Pengujian dilakukan pada 4 kelompok sampel dengan kadar air 2.51%, 3.02%, 7.18%, dan 11.69%. Dari hasil penelitian, kadar air pada biji kopi arabika dapat ditentukan dengan cara memasukkan nilai rasio intensitas emisi unsur H/O dari hasil pengujian LIBS ke dalam persamaan regresi linear Y=-1.861X+24.66 dimana X adalah rasio intensitas emisi unsur H/O dan Y adalah kadar air biji kopi arabika (%). Nilai kadar air 2.5% ditunjukkan dengan nilai rasio intensitas emisi unsur H/O sebesar 11.90867648 dan nilai kadar air 11.7% ditunjukkan dengan nilai rasio intensitas emisi unsur H/O sebesar 6.965937896. Setiap peningkatan kadar air sebesar 0.1% setara dengan penurunan rasio intensitas emisi unsur H/O sebesar 0.053725419.Didapatkan nilai koefisien korelasi (R)-0.99779, koefisien determinasi (R2) 0.995584965, dan kesalahan standard estimasi (Se) 0.245914303. Nilai Se menunjukkan bahwa akurasi penentuan kadar air dengan teknik LIBS adalah ±0.25% sedangkan akurasi grain moisture meter (MC-7828G) adalah ±0.5%. Hal ini menunjukkan bahwa teknik LIBS memiliki akurasi yang lebih tinggi dalam penentuan kadar air dibandingkan dengan grain moisture meter (MC-7828G).
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Determination of moisture content of coffee beans is one measure of drying process in order to obtain the quality of good results and cheap drying costs. Excessive drying (up to a moisture content below 12%) is a waste of fuel and is detrimental due to severe loss. Conversely, if too short then the moisture content of coffee beans has not reached the point of balance (12%) so that coffee beans are susceptible to fungal attacks when stored or transported to the consumer (Prastowo, et al. 2010). In the process of roasting coffee beans lose 3-5% moisture content for light roasted, 5-8% for medium roasted, and 8-14% for dark roasted (Varnam and Sutherland, 1994). In general, the measurement of moisture content of coffee beans is done by oven method (AOAC, 1984) or using a grain moisture meter. The oven method requires a long sample preparation time while the grain moisture meter (MC-7828G) is less sensitive in the moisture content range below 5% (Digital Instrument Catalog). Based on that, the method of determination of moisture content in arabica coffee beans using LIBS (Laser-Induced Breakdown Spectroscopy) technique have been developed. Based on the research data, the optimum condition of the test at 100 mJ laser energy and delay-time detection is 0.5 μs. This research usedHe (helium) gas with flow rate of 20 mL/s as the test environment.Tests were conducted on 4 groups of samples with moisture content of 2.51%, 3.02%, 7.18%, and 11.69%. From the research result, moisture content in arabica coffee beans can be determined by entering the value ofH/O emission intensity ratio from LIBS test result into linear regression equation Y=-1.861X+24.66where X is the H/Oemission intensityratio and Y is the moisture content of arabica coffee beans (%). 2.5% moisture content value is indicated by the value of H/Oemission intensityratio of 11.90867648 and 11.7% moisture content value is indicated by the value of H/Oemission intensityratio of 6.965937896. A 0.1% increase in moisture content is equivalent to a decrease in the value of H/O emission intensity ratio of0.053725419. The correlation coefficient (R) -0.99779, coefficient of determination (R2) 0.995584965, and standard error estimation (Se) 0.245914303 were obtained. Se value shows that the accuracy of determination of moisture content with LIBS technique is ± 0.25% while grain moisture meter accuracy (MC-7828G) is ± 0.5%. This suggests that the LIBS technique has a higher accuracy in the determination of moisture content compared to the grain moisture meter (MC-7828G).
| Item Type: | Thesis (Undergraduate) |
|---|---|
| Uncontrolled Keywords: | Biji Kopi Arabika, LIBS, Penentuan Kadar Air |
| Subjects: | T Technology > T Technology (General) T Technology > TA Engineering (General). Civil engineering (General) > TA1573 Detectors. Sensors T Technology > TA Engineering (General). Civil engineering (General) > TA1800 Fiber Optics T Technology > TP Chemical technology > TP248.3 Biochemical engineering. Bioprocess engineering T Technology > TP Chemical technology > TP370 Food processing and manufacture T Technology > TR Photography > TR267.733.M85 Multispectral imaging |
| Divisions: | Faculty of Industrial Technology > Physics Engineering |
| Depositing User: | Prama Eko Wicaksono |
| Date Deposited: | 02 Aug 2021 23:39 |
| Last Modified: | 02 Aug 2021 23:39 |
| URI: | http://repository.its.ac.id/id/eprint/55668 |
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