44 • Coffee & Cocoa Science • C&CI May 2013
field survey for coffee diseases in Kenya (Mugo et al. (2012) J. Agric. Sci. & Technol. A 2: 265-272) found that Coffee Berry Disease (CBD) and rust (CLR) were widely distributed in all coffee growing agro-ecological zones. Two other diseases, Fusarium Bark Disease (FRD) and Bacterial Blight of Coffee (BBC) were also present, though less common than the other two.
CBD (65 per cent incidence) and CLR (63 per cent) were the most commonly reported by farmers. CBD predominated in the Upper Midland 1 zone (72 per cent) and CLR in Upper Midland 2 (75 per cent). The survey found that these diseases have increased their altitudinal range in recent years. They also found that many farmers still prefer the disease susceptible SL varieties (42 per cent) compared to the disease resistant Ruiru 11 (22 per cent); some farmers stated that Ruiru 11 is less drought resistant. Less than half of farmers apply fungicides, with copper oxychloride and chlorothalonil the two most commonly used. The latter is a suspected carcinogen and highly toxic to fish and amphibians.
Costa Rican farmer survey
A study from the University of Copenhagen (Bosselman A.S. (2012) Ecological Economics 80: 79-88) surveyed 217 coffee farmer households in the Volcan Central Talamanca Biological Corridor in Cartago and Limón provinces in Costa Rica. The coffee area decreased steadily from 904 hectares in 2000 to 461 hectares in 2009, an annual reduction of about 7 per cent. The dominant replacement for coffee was pasture, comprising more than 40 per cent of the total converted area. Another 29 per cent was replaced with vegetables, sugar cane, or no crops, while 14 per cent was converted to fruit trees and banana. As the coffee area decreased, so too did the use of shade trees. Households that either reduced or eliminated their coffee fields removed an estimated 40,000 shade trees. The abandonment of coffee took place during a period of increasing coffee prices, rising from 44.4 US cents/lb in 2001 to 150 US cents/lb in mid-2009. In spite of this, the main problem in coffee production mentioned by farmers was low and fluctuating prices. This was linked to increasing costs of labour and agrochemicals, the second main problem mentioned by farmers.
What the papers say A
Dr Peter Baker looks at academic publications recently appearing on the CAB Abstracts database (
www.cabdirect.org)
Farmers in Costa Rica are switching to pasture because it requires less labour
Two frequent reasons for replacing coffee with less intensive land uses were given. First, by converting to pasture for example, family labour is freed and can be put to use elsewhere, often as day-labouring, thereby adding an activity to the income portfolio. Second, and this was often stated by older household heads, the younger members of the family had no intention of continuing labour intensive farming.
On the origin of CBD It had always been thought that CBD (Colletotrichum kahawae) evolved in East Africa by mutation from the cosmopolitan Colletotrichum gloeosporioides complex, a natural and non-aggressive component of the mycobiota associated with coffee. It was even thought that over-zealous use of fungicides to control CLR might somehow have provoked this new disease to emerge in the 1920s and spread aggressively from the 1960s. However, a new molecular study however (Silva et al., (2012) Mol. Ecol. 21: 2655-2670) suggests that the disease is not closely related to C. gloeosporioides and instead is much closer to an, as yet, unidentified disease that was isolated from field samples. It seems therefore that the disease may well have jumped from another host plant species. This story is quite similar to the appearance of another important African coffee disease – Coffee Wilt Disease – which also seems to have jumped from an unknown host.
Traditionally, high-quality red wines are matured in oak barrels. Compounds in the wood diffuse into the wine during the aging process and produce distinctive flavours depending on the type of oak, level of toasting and seasoning. But barrels are expensive, have a short lifetime and maturation is slow. Hence the maturation process is now often accelerated by adding toasted oak chips to wine kept in stainless steel tanks. A desired flavour profile can be selected depending on the toast level and type of oak used. For example “American oak medium toast plus” can impart chocolate and coffee notes.
Something completely different
Pinotage is a case in point; it is a South African red wine cultivar, cross-bred from Pinot Noir and Cinsaut (Hermitage) and this wine has been deliberately produced with a coffee flavour. It was derived from a particular combination of Pinotage, alternative toasted wood products and malolactic fermentation (lactic acid bacteria ferment the grape’s malic acid to lactic acid).
A recent paper (Naudé & Rohwer (2013) Journal of Chromatography A, 1271:176– 180) has identified the Pinotage coffee taste substances, which turn out to be a simple combination of furfural and 2-furanmethanol. This coffee perception is the result of a synergistic effect in which no individual compound was responsible for this particular aroma.
This cavalier but innovative attitude to wine-making is the antithesis of the purist and non-interventionist approach prevalent in the specialty coffee industry. But as finer coffees become more difficult to find, why not emulate?
Green coffee is famously adept at absorbing (unwanted) taints. So why not introduce some positive ones? Those of us who have attended Jorge Rivera’s sessions at SCAA meetings have been intrigued how a baggy Central can be transformed into something more exotic with a tiny squirt of citric or phosphoric acid. C&CI
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