The Influence of Robusta Coffee Grounds Proportion and Fermentation Time on The Quality of Bokashi

Abstract

This research aimed to study the influence of robusta coffee grounds proportion as a mixture of raw materials for bokashi production and fermentation time on the quality of the bokashi. This research was conducted using a Completely Randomized Design with two factors and two replications. The first factor was the proportion of coffee grounds (A; 0, 10, 20, 30%), and the second was fermentation time (F; 0, 10, 20 days). Fish bone meal was added constantly to each sample as much as 5%. The analysis carried out on bokashi included microbial properties (total colony counts; TCC), temperature, chemical properties (pH value, water content, C, N, C/N ratio), descriptive organoleptic test (texture, colour, aroma), and plant growth test. The results showed that bokashi, with the addition of coffee grounds had better pH value, C content, and plant height, while worse in N content and C/N ratio. However, the C/N ratio value still met the standard (<20). There was no difference in pH, C, N, C/N ratio, and plant height among coffee grounds addition of 10% to 30%. The organoleptic characteristics of bokashi generally tend to be improved with fermentation time, although there was no difference among F2 and F3. The two best bokashi, namely A2F3 (10% coffee grounds and 20 days of fermentation) and A3F3 (20% coffee grounds and 20 days of fermentation) had similar characteristics, but A3F3 was the best since it had very significantly better plant height. The best experimental condition for the production of the bokashi was 20% coffee grounds proportion with 20 days of fermentation time.