• THE-COFFEE-GUIDE.gif 
  • QA 108
    Question:
    What is the conversion ratio of fresh cherry to green bean (clean coffee)?
    Background:
    We have a plan to do a contract for coffee processing with small farmer and we need to find out Green Bean Equivalent (GBE) from FRESH RED Cherry to green bean. The only info I found out is just GBE from dried cherry & parchment to green bean. Thanks a lot for your help and look forward to get the answer.
    Asked by:
    Roaster - Indonesia
     
    Answer:

    There is no established standard. For arabica coffee we would consider a ratio of 1:6 (6 kgs fresh cherry produce 1 kg green bean) acceptable. Below 6 may be considered good whereas 1:7 is poor. All things being equal then robusta ratios are usually better: probably closer to 1:5. But, outturns as low as 1:7 are also possible…

    Much depends on the variety of coffee that is grown, and the quality of cherry that is received. Conversion ratios do vary between varieties whereas heavy cherry produces more and better quality green bean than light cherry. In Brazil for example conversions are based on litres of cherry (volume) to kilos of green coffee (weight). The potential conversion range is equally large. Good years (or irrigated coffee) can mean conversions as low as 300 litres cherry for 60 kgs of green coffee (one bag), whereas poor growing conditions can result in conversions as high as 500 litres, showing the impact of lower cherry density…

    Failure to separate lights and heavies can also negatively influence the conversion ratio, particularly when the cherry intake is not homogeneous. This is often the case with smallholder coffee. Conversion also varies with climatic conditions: a dry season usually means poor ratios. Moisture content plays a role as well - make sure all green bean is dried to the required standard moisture content.

    Our recommendation would be to establish an average outturn ratio for coffee from the area you intend to cover, based on the same processing method as will be used commercially. *  If subsequently commercial outturns are worse than that average then some of the potential causes worth checking would include cherry quality, inadequate separation of light and damaged cherry, incorrect weighing, theft, and wastage (green beans allowed to escape together with cherry pulp and skins). Obviously good record keeping for all daily functions and adequate security are essential. Of course, conversion ratios will vary from season to season, and during a season as well.

    Cherry sorting (removing green, damaged and overripe cherries etc) before pulping will improve both conversion and quality. It is our experience that as long as growers still receive some sort of payment for those rejects then objections to the sorting procedure are less likely.

    For more on primary processing and coffee quality generally, including what to look out for in wet processing, see chapter 11 of the Guide - Coffee Quality, covering both arabica and robusta. Chapter 12 deals with quality control issues, including issues relating to the prevention of mould in coffee. Other conversion ratios are found in topic box 01.01.02. If your project involves producing washed robusta for use in espresso then we particularly recommend reading also topics 12.09.04 and 05!

    * The Indonesian Coffee and Cocoa Research Institute - www.iccri.net or iccri@iccri.net - may be able to assist you here.

    Related chapter(s):
    Related Q & A:
    QA 069; QA 053; QA 008