Science Snippets!

Coffee (Coffea arabica or canephora) is typically sold in bags and exported by sea in metal containers. Ochratoxin A can be a problematic mycotoxin for the coffee industry when levels are too high. A study by Palacios-Cabrera et al. (2007) investigated the effect of temperature and relative humidity on ochratoxin A content during transport of coffee from Brazil to Italy. The authors were interested in the formation in condensation in the metal containers and if this condensation water would affect ochratoxin A content in coffee beans. The authors shipped bags of coffee in two types of containers: e.g. regular 20-foot container (5.88 x 2.32 x 2.19m), and a custom made very small container (about 6-foot or 1.86 x 0.73 x 0.73m). The authors studied also whether the container location in the ship would affect condensation. They placed the different sized containers on the deck, first-floor, and in the hold (5 m below sea level) in stacks of three high. All containers were equipped with temperature and moisture probes. Temperature and moisture were measured continuously during sea transport. Transport took place from Brazil to Italy, leaving the end of January and arriving two weeks later. Thus the coffee beans were transported from a warm South-American climate to an Italian winter climate.

The authors found the top containers placed in the hold had the highest increase in moisture content (3.0%), while the top containers on deck showed an increase of 2.0%, and the ones placed on the first floor showed a moisture increase of 0.7%. The environmental readings indicated significant temperature and relative humidity changes in the top containers. Containers located on the ship’s first floor and hold showed condensation due limited ventilation. The authors also found that the smaller containers showed similar variations in moisture content as with the conventional containers.

Ochratoxin A was found (7.9 to 13.1 µg/kg) only in the coffee which bags were exposed to condensation water, while no evidence of ochratoxin A was found at the time of loading. The authors conclude that during container transport condensation can form, and that the location of the containers is very important as to how much condensation is being formed. The authors also speculate that longer sea transport might result in even more condensation and thus potentially to higher ochratoxin A content. Palacios-Cabrera et al. (2007) suggest, among others, it is important to avoid direct sun exposure of containers with coffee (e.g. by putting other containers with other products on top), to have ventilation holes in the containers, and to use direct shipment if possible.

Reference:

Palacios-Cabrera, H.A., H. C. Menezes, B. T. Iamanaka, F. Canepa, A.A. Teixeira, N. Carvalhaes, D. Santi, P.T.Z. Leme, K. Yotsuyanagi, and M. H. Taniwaki. 2007. Effect of temperature and relative humidity during transportation on green coffee bean moisture content and Ochratoxin A production. Journal of Food Protection. 70:164-171.