Electronic Theses and Dissertation

Abstrak penelitian ini bertujuan untuk mengetahui pengaruh tingkat kematangan buah kopi (hijau, kuning, orange, merah terang, dan merah gelap) terhadap sifat fisis dan morfologi biji kopi robusta sidikalang sebelum dan setelah melewati proses roasting. pengukuran sifat fisis meliputi massa hilang, rapat massa, porositas, dan kadar air. sebuah metode semi-basah telah diterapkan untuk setiap tingkat kematangan buah kopi. hasil yang diperoleh menunjukkan bahwa setelah melewati proses roasting biji kopi mengalami kehilangan massa sebesar 16,82% hijau, 17% kuning, 18,7% orange, 18,32% merah terang dan 16,76% merah gelap. selisih perubahan rapat massa biji kopi sebelum terhadap sesudah roasting sebesar 0,418 g/cm3 hijau, 0,307 g/cm3 kuning, 0,397 g/cm3 orange, 0,34 g/cm3 merah terang, dan 0,246 g/cm3 merah gelap. porositas biji kopi setelah roasting mengalami penurunan sebesar 13,56% hijau dan 16% kuning, serta mengalami peningkatan sebesar 12,22% orange, 3,44% merah terang dan 6,88% merah gelap. sedangkan kadar air yang dimiliki biji kopi sebesar 8,38% hijau, 9% kuning dan orange, 7,91% merah terang dan 10,83% merah gelap. perubahan-perubahan ini semakin diperkuat dengan pengujian morfologi dengan menggunakan sem, bahwa adanya perubahan morfologi biji kopi sebelum terhadap setelah dilakukan proses roasting. penelitian ini menyimpulkan bahwa perbedaan tingkat kematangan buah kopi mempengaruhi sifat fisis biji kopi dan proses roasting menyebabkan perubahan morfologi pada biji kopi. kata kunci: robusta sidikalang, roasting medium, kematangan buah kopi abstrack this research aims to determine the level of coffee bean ripeness (green, yellow, orange, bright red, and dark red) on the physical properties and morphology of sidikalang robusta coffee beans before and after roasting process. a semi-wet method has been applied for each coffee fruit ripeness. the physical properties measurements included mass lost, density, porosity and water content. the results illustrated that after having been roasted, the coffee beans mass declined by 16.82% green, 17% yellow, 18.7% orange, 18.32% bright red and 16.76% dark red. additionally, the coffee beans density has decreased after roasting by 0.418 g/cm3 green, 0.307 g/cm3 yellow, 0.397 g/cm3 orange, 0.34 g/cm3 bright red, and 0.246 g/cm3 dark red. the porosity of coffee beans after being roasted drained by 13.56% green and 16% yellow, and increased by 12.22% orange, 3.44% bright red and 6.88% dark red. moreover, the water content of coffee beans was 8.38% green, 9% yellow and orange, 7.91% bright red, and 10.83% dark red. these alterations were further strengthened by morphological testing using sem, which there were transformations in the morphology of the coffee beans before and after having been roasted. to conclude, the differences in the ripen level of the beans affect these physical properties, and the roasting process, therefore, causes morphological changes in these. keywords: robusta sidikalang, roasting medium, coffee fruit ripeness