Research on the origin, and on the impact of post-harvest handling and manufacturing on the presence of ochratoxin A in coffee.

The major risk factors and processing steps that can lead to contamination of green coffee with ochratoxin A (OTA) have been identified. Surveys of the green coffee production chain indicate that Aspergillus ochraceus and A. carbonarius are the most potent OTA producers on coffee. Both have been successfully grown in vitro on green coffee and coffee cherries, respectively, producing high amounts of OTA (5-13 mg kg(-1)). The so-called dry processing of coffee, which is cherry drying, was identified as one of the steps during which OTA formation can take place, particularly under humid tropical conditions. Cherries contain sufficient amounts of water to support mould growth and OTA formation during the initial 3-5 days of drying on the outer part of the cherries. Not surprisingly, after dehulling, husks can be highly contaminated with OTA, as also indicated by its enhanced concentration in soluble coffees adulterated with husks and parchment. A minimum water activity of 0.80 (about 14% MC) is required for in vitro OTA production on green coffee, a fact that does not rule out the possibility of OTA contamination due to improper transportation and storage of green coffee. However, this appears not to be a major route for OTA contamination of coffee. OTA contamination can clearly be minimized by following good agricultural practice and a subsequent post-harvest handling consisting of appropriate techniques for drying, grading, transportation and storage of green coffee; these procedures are well established.

Developmental variation of sugars, carboxylic acids, purine alkaloids, fatty acids, and endoproteinase activity during maturation of Theobroma cacao L. seeds.

The changes of mono- and oligosaccharides, carboxylic acids, purine alkaloids, and fatty acid composition, and of aspartic endoproteinase activity, were analyzed during seed development in two varieties of cacao (Theobroma cacao). The majority of the components examined either decreased or accumulated steadily in concentration during the second half of bean development. Sucrose is the major sugar in the mature embryo, whereas fructose and glucose are at higher concentrations in the endosperm tissue. Considerable amounts of malate are found in the endosperm, whereas citrate is the dominant carboxylic acid in the embryo. A major change in the fatty acid composition occurs in the young embryo when the proportion of stearic acid increases rapidly at the expense of linoleic acid, which is reduced from about 18 to 3%. Theobromine is the dominant purine alkaloid (ca. 80%), and caffeine appears only toward the end of seed maturity. Aspartic endoproteinase activity increases rapidly during embryo expansion, reaching a maximal activity before final maturity. The results are discussed in conjunction with physiological changes in developing seeds, and the potential contributions of the compounds analyzed for cocoa quality.

Production of ochratoxin A by Aspergillus carbonarius on coffee cherries.

Robusta coffee cherries collected before and during sun drying from two coffee farms in Thailand were examined for moulds producing ochratoxin A (OA). Aspergillus ochraceus was only detected in one sample, whereas Aspergillus carbonarius was isolated from 7 out of 14 samples. On gamma-irradiated coffee cherries, each of the six tested A. carbonarius strains produced OA. More than 4800 microg kg(-1) of toxin were detected under optimal conditions (25 degrees C, a(w) 0.99). OA production was strongly reduced (230 microg kg(-1)) at an a(w) of 0.94.

Development of ochratoxin A during robusta (Coffea canephora) coffee cherry drying.

The occurrence and formation of ochratoxin A (OTA) in Robusta coffee was studied for three consecutive seasons under tropical conditions in Thailand. Sun drying of coffee cherries consistently led to OTA formation in the pulp and parchment (husks) of the cherries. In replicated trials, dried coffee beans (green coffee) were shown to contain on average OTA concentrations that were approximately 1% of those found in husks. OTA contamination of green coffee depended on cherry maturity, with green cherries being the least, and overripe cherries the most susceptible. Defects, and in particular the inclusion of husks, are the most important source of OTA contamination. OTA contamination occurred independently of whether cherries were placed on concrete, on bamboo tables, or on the ground. The study suggests that better raw material quality, an appropriate drying and dehulling procedure combined with a reduction of green coffee defects can effectively contribute to the reduction of OTA in green coffee.

Definition of nonvolatile markers for flavor of tomato (Lycopersicon esculentum mill.) as tools in selection and breeding.

A methodology for flavor and composition assessment of processed tomato juice samples was developed using a wide range of commercial processing tomato varieties (Lycopersicon esculentum) grown in Spain and the United States. Fruitiness intensity was found by a trained panel to best describe overall tomato flavor. For two consecutive years, fruitiness intensity was significantly dependent on growing location and variety, and it was consistently linked to increased levels of glucose and reducing sugars and decreased glutamic acid content. Using the same procedure on a population of 176 breeding lines derived from the wild species of Lycopersicon pimpinellifolium, it was shown that tomato fruitiness intensity was significantly correlated to reducing sugars/glutamic acid ratio and glucose and glutamic acid contents. The definition of markers for tomato flavor of processed juice can provide the tomato breeder and processor with reliable analytical tools that can be applied in a straightforward way for the identification of raw materials that can be processed into juice with predictably high or low fruitiness.

Total fecal incontinence--a new method of gluteus maximus transposition: preliminary results and report of previous experience with similar procedures.

Since 1986, different procedures of gluteus maximus transposition have been performed, by one of the authors, in 10 patients with total anal incontinence not amenable to sphincter repair, due to congenital anomalies (four), sphincteric denervation (three) or after severe trauma (three). Variable degrees of long-lasting fecal control were obtained in all but one patient, with great improvement in six. Difficulties for achieving a closed anus without muscular tension of the neosphincter, together with the morbidity associated with anal wound infection, determined the reasons for the successive use of different techniques (Biström, Hentz, Schoamaker) until the authors, in 1990, designed a new procedure (Devesa). Although the reported experience with this technique described here is limited to only four patients, our impression is that the method is easier, has less morbidity, and achieves better short-term functional results, derived from a thick, tension-free neosphincter.

ß-Glucanases in developing cotton (Gossypium hirsutum L.) fibres.

Cotton fibres possess several ß-glucanase activities which appear to be associated with the cell wall, but which can be partially solubilised in buffers. The main activity detected was that of an exo-(1→3)-ß-D-glucanase (EC 3.2.1.58) but which also had the characteristics of a ß-glucosidase (EC 3.2.1.21). Endo-(1→3)-ß-D-glucanase activity (EC 3.2.1.39) and much lower levels of (1→4)-ß-D-glucanase activity were also detected. The exo-(1→3)-ß-glucanase showed a maximum late on (40 days post-anthesis) in the development of the fibres, whereas the endo-(1→3)-ß-glucanase activity remained constant throughout fibre development. The ß-glucanase complex associated with the cotton-fibre cell wall also functions as a transglucosylase introducing, inter alia, (1→6)-ß-glucosyl linkages into the disaccharide cellobiose to give the trisaccharide 4-O-ß-gentiobiosylglucose.