The roasting process will determine the flavor in which chemical reactions occur and changes in components in coffee beans. Changes can occur in phenol compounds that contribute to antioxidant activity. This study aims to study the effect of roasting levels on Arabica and Robusta coffee beans on the content of phenol compounds and their antioxidant activity. The roasting process is carried out at three levels, namely light, medium and dark. The analysis was carried out on the total phenol content and antioxidant activity expressed in the radical capture activity of the compound 2,2-diphenyl-1-picrylhydrazyl (DPPH). The results show that increasing the roasting level causes a decrease in antioxidant activity as indicated by increasing IC50, EC50 values. Meanwhile, ARP and AAI are decreasing. This corresponds to the phenol content which decreases with increasing roasting levels. This finding also proves that Robusta coffee has higher antioxidant activity than Arabica. This corresponds to a greater total phenol robusta content than arabica.

Tujuan dari penelitian ini adalah untuk menentukan kondisi optimum fermentasi asam laktat pada beberapa perbandingan konsentrasi substrat dan inokulum yang berasal dari pemanfaatan limbah kulit pisang sebagai subtrat dan Lactobacillus casei sebagai inokulum. Optimasi dilakukan dengan rancangan percobaan menggunakan Central Composite Design (CCD) dengan penentuan titik optimum variabel menggunakan Respon Surface Methodolgy (RSM). Tiga belas satuan percobaan, yaitu konsentrasi substrat (X 1 : 2,5; 5; 7,5% b/v) dan inokulum (X 2 : 2, 4, 6% v/v), digunakan untuk menentukan titik optimum proses fermentasi. Fermentasi dilakukan dengan sistem tumpak dengan volume media 100 mL dalam fermentor berupa labu Erlenmeyer 250 mL. Kultur diinkubasi pada goyangan 150 rpm dan suhu 37 C, selama 72 jam. Selanjutnya, asam laktat hasil analisis digunakan sebagai respon penentuan titik optimum variabel proses fermentasi. Hasil penelitian menunjukkan bahwa rendemen proses penepungan kulit pisang yang dihasilkan adalah 23,02% dengan karakteristik kimia memiliki kadar pati, gulatotal, asam total, dan serat kasar secara berturut-turut adalah 5,35; 1,36; 0,61; dan 1,54 % (b/b). Titik optimum konsentrasi substrat dan inokulum, yaitu 4,71% dan 6,61%, menghasilkan konsentrasi biomassa yang optimum sebesar 5,99 g/L, sedangkan titik optimum variabel X 1 dan X 2 dengan konsentrasi substrat dan inokulum sebesar 4,31% dan 4,64% menghasilkan nilai optimum konsentrasi asam laktat sebesar 7,06 g/L, yang merupakan hasil produksi asam laktat terbaik pada penelitian ini.

No abstract

Coffee is one of the many favorite drinks of Indonesians. In Indonesia there are 2 types of coffee, namely Arabica & Robusta. The classification of coffee beans is usually done in a traditional way & depends on the human senses. However, the human senses are often inconsistent, because it depends on the mental or physical condition in question at that time, and only qualitative measures can be determined. In this study, to classify coffee beans is done by digital image processing. The parameters used are texture analysis using the Gray Level Coocurrence Matrix (GLCM) method with 4 features, namely Energy, Correlation, Homogeneity & Contrast. For feature extraction using a classification algorithm, namely Naïve Bayes, Tree, Support Vector Machine (SVM) and Logistic Regression. The evaluation of the coffee bean classification model uses the following parameters: AUC, F1, CA, precision & recall. The dataset used is 29 images of Arabica coffee beans and 29 images of Robusta beans. To test the accuracy of the model using Cross Validation. The results obtained will be evaluated using the confusion Matrix. Based on the results of testing and evaluation of the model, it is obtained that the SVM method is the best with the value of AUC = 1, CA = 0.983, F1 = 0.983, Precision = 0.983 and Recall = 0.983.

Processing coffee from kepok banana peel is an option in diversifying food preparations and providing non-caffeine coffee. This study aims to study the characteristics of banana peel coffee based on fruit maturity and oven duration. In addition, it also analyzes total phenol and its antioxidant activity. The study design used a factorial randomized design with the first factor of fruit maturity (unripe and ripe) and the second factor of oven length (5, 10, and 15 minutes). Banana skin coffee has a yield ranging from 8.6 to 11.6%. Bulk density ranges from 0.43-0.48g/ml. Water content ranges from 3.9-6.39%. Ash content ranges from 0.92-6.79%. The content of phenol ranges from 0.6 to 2.46 mg PE/g. The coffee phenol content of ripe banana peel is larger than unripe. The longer oven increases the phenol content. IC50 and EC50 decrease with increasing phenol. The antioxidant activity of ripe banana peel coffee is larger than unripe