Alpizar, E.; Dechamp, E.; Espeout, S.; Royer, M.; Lecouls, A. C.; Nicole, M.; Bertrand, B.; Lashermes, P.; Etienne, H.
The possibility of rapid validation and functional analysis of nematode resistance genes is a common objective for numerous species and particularly for woody species. In this aim, we developed an Agrobacterium rhizogenes-mediated transformation protocol for Coffea arabica enabling efficient and rapid regeneration of transformed roots from the hypocotyls of germinated zygotic embryos, and the subsequent production of composite plants. The A. rhizogenes strain A4RS proved to be the most virulent. High transformation efficiencies (70%) were obtained using a 2-week co-cultivation period at a temperature of 15-18 degrees C. Using a p35S-gusA-int construct inserted in the pBIN19 binary plasmid, we could estimate that 35% of transformed roots were GUS positive (co-transformed). Using the GUS assay as visual marker, 40% composite plants bearing a branched co-transformed rootstock could be obtained after only 12 weeks without selection with herbicides or antibiotics. Transgenic coffee roots obtained with A. rhizogenes did not exhibit the 'hairy' disturbed phenotype and were morphologically similar to normal roots. PCR analyses demonstrated that all co-transformed roots were positive for the expected rolB and gusA genes. Transformed and non-transformed root systems from both susceptible and resistant varieties were inoculated with Meloidogyne exigua nematode individuals. Inoculation of composite plants from the Caturra susceptible variety resulted in the normal development of nematode larvae. Numbers of extracted nematodes demonstrated that transformed roots retain the resistance/sensibility phenotype of varieties from which they are derived.
CONCLUSIONS : These results suggest that composite plants constitute a powerful tool for studying nematode resistance genes.
Blanc, M.
Limitations of current sampling techniques used for analysis of contaminants (pesticides, mycotoxins, heavy metals, dioxins, etc.) in agricultural products are discussed, with the aid of examples demonstrating perceived weaknesses in sampling recommendations used as part of the EU system for ensuring food hygienic quality. Aspects considered include: recent EU regulations establishing low limits for various contaminants in agricultural products (e.g. cereals, oilseeds, coffee, spices and dried fruits); difficulties associated with obtaining a representative sample; practical demonstration of sampling difficulties (distribution of mycotoxins in different lots of peanuts, corn and cottonseeds); sources of error when sampling other food contaminants; sampling for GMO analysis; and recommendations for improving sampling operations.
Source : Molecular Nutrition and Food Research, 2006 vol. 50 (6), pp 473 - 479
Cilas, C.; Bar-Hen, A.; Montagnon, C.; Godin, C.
Yield capacity is a target trait for selection of agronomically desirable lines; it is preferred to simple yields recorded over different harvests. Yield capacity is derived using certain architectural parameters used to measure the components of yield capacity. METHODS: Observation protocols for describing architecture and yield capacity were applied to six clones of coffee trees (Coffea canephora) in a comparative trial. The observations were used to establish architectural databases, which were explored using AMAPmod, a software dedicated to the analyses of plant architecture data. The traits extracted from the database were used to identify architectural parameters for predicting the yield of the plant material studied.
CONCLUSIONS: Architectural traits are highly heritable and some display strong genetic correlations with cumulated yield. In particular, the proportion of fruiting nodes at plagiotropic level 15 counting from the top of the tree proved to be a good predictor of yield over two fruiting cycles.
Source : Ann Bot (Lond), 2006 vol.97 (3), pp 405 - 411
Cruz, L. P.; Gaitan, A. L.; Gongora, C. E.
Beauveria bassiana is an entomopathogen widely used to control the coffee berry borer in Colombia, as part of an Integrated Pest Management strategy. Traditionally, the development of fungal insect pathogens as biocontrol agents in crop pests has been oriented towards the selection and formulation of elite clonal strains. Instead, we explored the potential application of genetic diversity in B. bassiana by determining the effect of strain mixtures on coffee berry borer mortality compared to clonal isolates. Genomic DNA from 11 strains was characterized using internal transcribed spacers and beta-tubulin sequences as well as amplified fragment length polymorphism markers. Cluster analysis produced three genetic groups and confirmed the low but significant intraspecific genetic diversity present among the strains. Single strain virulence towards the coffee berry borer under laboratory conditions, using 1x10(6) conidia ml(-1), ranged between 89.9 and 57.5%. All the inoculations with mixtures resulted in coinfection events. Combinations of genetically similar strains showed no significant differences when their virulences were compared. However, mixtures of genetically different strains led to both antagonism and synergism. The lowest virulence percentage (57%) was obtained by putting together the most virulent strain of each group, contrary to the highest virulence percentage (93%) that resulted from mixing the three least virulent strains. The results indicate the promising potential of designing strain mixtures as an alternative for the biocontrol of Hypothenemus hampei and other pests and provide tools for the understanding of the ecological dynamics of entomopathogen populations under natural conditions.
Source : Appl Microbiol Biotechnol, 2006 vol.71 (6), pp 918 - 926
Dussert, S.; Engelmann, F.
The present work establishes for the first time that tolerance of coffee seeds to liquid nitrogen (LN) exposure depends on the initial quality of the seedlot and on the rewarming regime employed. Seedlot quality was estimated by the parameters of a quantal response model of desiccation sensitivity developed previously. The percentage of seedlings recovered from cryopreserved seeds was very well correlated with the relative humidity (RH) at which 90 percent of the initial viability was retained, RH90, as estimated by the model. Whatever the cooling regime employed, rewarming the seeds slowly by exposing them to ambient air was highly detrimental. Slow rewarming-induced viability loss was not due to imbibitional damage since seeds pre-heated at 37 degree C after slow rewarming to 0 degree C exhibited a survival percentage lower than seeds thawed rapidly to 0 degree C before sowing. The optimal hydration status for coffee seed cryopreservation was also re-examined. Drying seeds in 81 percent RH provided survival percentages considerably higher than those obtained using the drying RH always employed until now, i.e. 78 percent. A new procedure for slowly precooling the seeds prior to immersion in LN was also established. It consisted of placing the vials containing the seeds in a dry ice-bath for 25 min. Using this procedure in combination with seed drying in 81 percent RH and rapid rewarming in a 37 degree C water-bath for 30 min ensured the highest survival percentages ever obtained with coffee seeds, i.e. 89 percent, a value which was not significantly different from the initial viability percentage.
Source : Cryo Letters, 2006 vol. 27 (3), pp 169 - 178
Pardo, E.; Marin, S.; Ramos, A. J.; Sanchis, V.
Studies on the effects of water activity and temperature on germination, mycelial growth and production of the mycotoxin, ochratoxin A, by ochratoxin-producing isolates of Aspergillus ochraceus and Penicillium verrucosum are reviewed. Differences between the species are noted. Predictive models for different stages of fungal development are presented. Results enable the identification of critical control points in the production, storage and distribution of foods, and implications for reducing spoilage of barley grain, coffee beans and grapes are discussed.
Source : Food Add Cont, 2006 vol. 23 (4), pp 398-410
Taniwaki, M. H.
It was originally thought that the roasting process would destroy any ochratoxin A that was present in raw coffee, but an improved detection method showed that ochratoxin A existed in commercial coffee samples. In this chapter the following topics are discussed; incidences of ochratoxin A in coffee samples worldwide; fungi producing ochratoxin A in coffee; the coffee production process and how it affects ochratoxin A; the effect of roasting on ochratoxin levels; and ochratoxin A consumption from coffee. It was shown that ochratoxin A is formed in raw coffee after harvest and can be minimised by appropriate postharvest handling. Preventative measures from tree to cup are the most effective way of preventing ochratoxin A contamination.
Source : Proceedings of the Fifth International workshop of Food Mycology, Samso, October 2003
Anese, M.; Manzocco, L.; Nicoli, M. C.
This work was addressed to study the secondary shelf life of ground roasted coffee. To this purpose, fresh dark-roasted ground coffee samples were equilibrated at increasing water activity (aw) values up to 0.44 and stored at 30 degrees C for up to 1 month. To simulate home storage conditions, the headspace atmosphere was periodically perturbed by opening for a short time and then closing the packaging. The changes of some chemical and physicochemical indexes of coffee staling were studied, and sensory analysis was carried out to determine the end point of coffee acceptability. The results showed that the volatile compounds in the headspace are representative indexes of the quality depletion of roasted ground coffee during home usage. The sensory and instrumental results were used to develop a mathematical model allowing to simply and quickly calculate the secondary shelf life of coffee on the basis of its aw value at a given temperature.
Source : J Agric Food Chem, 2006 vol. 54 (15), pp 5571 - 5576
Scheidig, C.; Schieberle, P.
This item discusses how raw coffee storage can influence the flavour, not only of the raw coffee, but also roast coffee and coffee drinks. Research used Colombian Arabica coffee beans, which saw negative changes in flavour during storage depending on water content of the beans and storage temperature.
Source : Lebensmittelchemie, 2006 vol.60 (3), 55-56 (no on-line content for this journal)
Knopp, S.; Bytof, G.; Selmar, D.
Effects of traditional dry and wet processing techniques were investigated on contents of low mol. wt. sugars in green arabica coffee (var. Acaia). A close correlation was observed between the nature of post-harvest treatment and contents of fructose and glucose. While in washed coffee beans (wet processing) only low amounts of both fructose and glucose were present, levels in unwashed coffee (dry processing) were significantly higher. Model-processing experiments in the laboratory confirmed these findings. Moreover, a comparison with the untreated control samples revealed that levels decreased after wet processing, but remained unchanged or even increased after dry processing. Other minor sugars were also affected by post-harvest treatment. Amounts of galactose, arabinose and mannose were affected in a similar way to glucose and fructose, although their overall concn. were approx. 100-fold lower. Sucrose, the major low mol. wt. sugar in green coffee beans, was not significantly affected by processing method. The potential influence of active seed metabolism on the concentration of sugars is discussed.
Source : Eur Food Res Techn, 2006 vol. 223 (2), pp 195 - 201
The processing of particles in rotating cylinders is affected by the types of flow regimes within the cylinders during rotation. Conventional industrial coffee roasting is performed in rotating cylinders, and coffee beans undergo physical and chemical changes during roasting. The types of flow regimes affect the uniformity of processing and the quality of roasting. In this study, a small-scale acrylic model of a cylindrical roaster was built and used to examine the different forms of transverse motion of a bed of coffee beans during rotating motion. The model allowed visualisation of the flow regimes and their transitions, giving information on the regimes required for the operation of conventional industrial roasters.
Source : J Food Eng, 2006 vol. 75 (1), 142-148
Clifford, M. N.; Knight, S.; Surucu, B.; Kuhnert, N.
The paper describes the use of LC-MS for the identification of chlorogenic acids in Robusta green coffee beans, 18 of which have previously been reported. The authors report that, during this study, 12 new chlorogenic-acid compounds were detected: three isomeric dimethoxycinnamoylquinic acids, three caffeoyl-dimethoxycinnamoylquinic acids, three diferuloylquinic acids and three feruloyl-dimethoxycinnamoylquinic acids. The proposed structures of these compounds, derived from LC-MS patterns of fragmentation and relative hydrophobicity, are presented.
Source : J Agric Food Chem, 2006 vol. 54 (6), 1957-1969
Girard, P.; Stober, P.; Blanc, M.; Prodolliet, J.
Carbohydrates are very good tracers for the authenticity assessment of soluble (instant) coffee. Total glucose and total xylose were determined in 1002 samples of commercial soluble coffees using high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) according to AOAC Method 995.13 and ISO standard 11292. The samples analyzed included both authentic and adulterated coffees but were all sold as 100% pure soluble coffee. The statistical model, called "mixture of distributions," was applied to all results and allowed to derive the maximum content of the 2 carbohydrates in the population of products corresponding to pure soluble coffee: 2.32% for total glucose and 0.42% for total xylose. The specification limits, above which a soluble coffee should be considered as adulterated, were calculated by adding the corresponding expanded measurement uncertainty to the maximum content. Specification limits of 2.46% for total glucose and 0.45% for total xylose were obtained. The data statistically confirm previously established criteria for the authenticity assessment of commercial soluble coffee.
Source : J AOAC Int, 2006 vol. 89 (4), pp 999 - 1003
Preininger, M.
This chapter examines interactions of flavour components in foods, and presents information and discussion under the following main headings: interactions with lipids, including physical fundamentals - partitioning, flavour changes after fat reduction, fat type and fat affects basic taste; emulsions - effect of microstructure and emulsifiers; interactions with carbohydrates, including polysaccharides and sugars; interactions with proteins, including binding characteristics, dairy protein, soya protein and other proteins; interactions with fat replacers; interactions with coffee solids, water in citrus beverages, and salt; interactions with food packaging; and perceptual interactions of aroma, taste and texture.
Source : in Ingredient interactions: effects on food quality, ed. A. Gaonkar (2005)
Frank, O.; Zehentbauer, G.; Hofmann, T.
Information on the molecular basis for the typical bitter taste of coffee brews, which develops during the roasting of the beans, is currently fragmentary. This study applied taste dilution techniques to screen a roasted coffee beverage for its key taste compounds, and then isolated these compounds in order to study chemical structure and sensory impact. The results identified caffeoyl- and feruloyl-quinides, as well as more complex esters between quinides and cinnamoyl derivatives, as the most intense bitter taste compounds in roasted coffee. Bitter taste recognition thresholds were determined in the individual compounds and demonstrated that bitter threshold levels were strongly dependent on their chemical structure.
Source : Eur Food Res Techn, 2006 vol. 222 (5-6), pp 492-508
Anonym
It has been claimed that decaffeinated coffee may cause an increase in low-density-lipoprotein cholesterol concentration, thus having a negative effect on health. This article briefly discusses the evidence and in particular, the study on which these claims were based. In the study, levels of non-esterified fatty acids increased in participants consuming 3 to 6 cups of decaffeinated coffee per day but did not change in those drinking caffeinated coffee or the control group. Possible explanations for this finding are outlined, including confounding factors (e.g. body weight) and the lack of actual increase in cholesterol levels, and the sensational articles reporting the study results.
Source : Coffee and Cocoa International, 2006 vol. 33 (3), 32-34
Atanasov, A. G.; Dzyakanchuk, A. A.; Schweizer, R. A.; Nashev, L. G.; Maurer, E. M.; Odermatt, A.
Recent epidemiological studies demonstrated a beneficial effect of coffee consumption for the prevention of type 2 diabetes, however, the underlying mechanisms remained unknown. We demonstrate that coffee extract, corresponding to an Italian Espresso, inhibits recombinant and endogenous 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) activity. The inhibitory component is heat-stable with considerable polarity. Coffee extract blocked 11beta-HSD1-dependent cortisol formation, prevented the subsequent nuclear translocation of the glucocorticoid receptor and abolished glucocorticoid-induced expression of the key gluconeogenic enzyme phosphoenolpyruvate carboxykinase.
CONCLUSIONS : We suggest that at least part of the anti-diabetic effects of coffee consumption is due to inhibition of 11beta-HSD1-dependent glucocorticoid reactivation.
Bchir, F.; Dogui, M.; Ben Fradj, R.; Arnaud, M. J.; Saguem, S.
The present study investigated pharmacokinetic and electroencephalographic responses to caffeine (140 mg) in two groups of healthy volunteers reporting, or not, caffeine-related sleep disturbances. Significant differences in caffeine consumption and smoking habits were observed between the two groups. Plasma samples were taken from each subject before (T0) and after caffeine intake at 0.5, 1, 2, 4, 6 and 24 h. Three pharmacokinetic parameters: half-life (t1/2), maximum time (Tmax) and maximum plasma concentration (Cmax) were calculated from caffeine plasma concentration measurements determined by reversed phase HPLC analysis. Caffeine-sensitive subjects showed significantly greater half-life values when calculated on 24 h after the administration than tolerant subjects (p<0.05). Since the elimination kinetics were similar on the first 6 h after caffeine administration, the increased caffeine clearance observed overnight, when smoking was resumed in the control group, may indicate a short delay for the induction of hepatic cytochrome, reported here for the first time. Electrophysiological responses to caffeine, including vigilance and cortical activity, were assessed by ambulatory electroencephalographic (EEG) recorded during a period of 6 h before and after caffeine consumption. Following caffeine intake, the caffeine-intolerant subjects presented an increase in vigilance levels with faster peak alpha, beta frequency and lower delta and theta power when compared to tolerant subjects. Pharmacokinetic parameters and EEG data showed significant differences between sleep-sensitive and control subjects. These variations may be, in part, explained by cigarette smoking and the higher caffeine intake observed in the subjects of the control groups while caffeine sleep-sensitive subjects have a significantly lower caffeine intake, as already reported in previous studies on patients with sleep disturbances.
Bech, B. H.; Autrup, H.; Nohr, E. A.; Henriksen, T. B.; Olsen, J.
Cytochrome P4501A2 (CYP1A2) and N-acetyltransferase 2 (NAT2) are key enzymes in the metabolism of caffeine. The polymorphism of these genes facilitates the detection of fast and slow metabolizers, and if caffeine is causally related to stillbirth, we expect slow metabolizers to have a higher risk of stillbirth at any given intake of caffeine. Gluthatione S-transferase alpha1 (GSTA1) may also be active in the metabolism of caffeine as it conjugates glutathione to aromatic amines. Our study, therefore, included analyses of the association between GSTA1 and stillbirth. METHODS: A nested case non-case study among women who participated in the Danish National Birth Cohort: 142 cases of singleton stillbirths and 157 controls of singleton live births. RESULTS: Slow oxidizer status (CYP1A2), slow acetylator status (NAT2), and low activity of GSTA1 were not individually associated with the risk of stillbirth [odds ratio (OR) = 1.06, 95% confidence interval (95% CI) 0.67-1.67, OR = 0.95, 95% CI 0.60-1.51, and OR = 1.42, 95% CI 0.88-2.28, respectively]. We did, however, observe that subjects with a combination of slow CYP1A2, slow NAT2, and low GSTA1 genes had almost a 2-fold risk of stillbirth compared with subjects with other combinations of genotypes.
CONCLUSIONS: We found no link between any single genotype and the risk of stillbirth. An association between a combination of genotypes and stillbirth was discovered. Caffeine may be causally related to stillbirth, but larger studies using Mendelian randomization are needed to verify this.
Fiebich, B. L.; Valente, P.; Ferrer-Montiel, A.; Candelario-Jalil, E.; Menthe, J.; Luecker, P.
Coffee, one of the most excessively used beverages worldwide, commences the risk of gastroesophageal reflux (GER), which may lead to gastric ulcers and increase the risk of gastric cancer. Many attempts have been made by the coffee industry to diminish the irritating effect on mucosa by means of altering the extraction methods concerning gerbic acids and the roasting processes. This paper describes the effect of differently produced coffees involving two brands of Darboven and two brands of other coffee roasters. The aim of this study was to prove the results of gastric potential measurements we found in literature by using human AGS gastric epithelial cells (human adenocarcinoma). All four coffee extracts tested differentially affected the membrane resting potential of AGS cells. Coffees no. 1 and no. 2 depolarized the cells, presumably by increasing the cation entry into the cytosol. In marked contrast, coffee no. 4 hyperpolarizes the cells, possibly by H(+) extrusion and/or Cl(-) influx, suggesting that this coffee might increase acidity in the stomach, which might negatively affect the stomach, especially in people with gastroesophageal reflux symptoms. Overall, our data suggest that different roasting methods of coffees affect the membrane potentials of AGS stomach cells, resulting in increased influx of H+ possibly resulting in decreased stomach acidity and thus reducing GER. These results are in good accordance with clinical pharmacological results from potential difference measurements in healthy volunteers we found in the literature.
Source : Methods Find Exp Clin Pharmacol, vol. 28 (6), pp 369 - 372
Rauh, R.; Burkert, M.; Siepmann, M.; Mueck-Weymann, M.
During the last years, heart rate variability (HRV) has become a promising risk factor for cardiovascular events. However, the effect of caffeine on HRV in habitual caffeine consumers has barely been investigated. Therefore, we treated 30 male habitual caffeine users in a randomized double-blinded crossover study design with either placebo, 100 or 200 mg caffeine orally and determined parameters of HRV under resting conditions and metronomic breathing. As result, we could not detect significant differences in HRV parameters up to 90 min after drug ingestion. We conclude that modest amounts of caffeine do not reveal negative nor positive effects on HRV within the first 90 min after drug ingestion in young and healthy habitual caffeine consumers. However, further research is necessary to determine the effects of caffeine on HRV in habitual caffeine users, healthy as well as suffering from diabetes, hypertension and postmyocardial infarction.
Source : Clin Physiol Funct Imaging, 2006 vol. 26 (3), pp 163 - 166
Riksen, N. P.; Zhou, Z.; Oyen, W. J.; Jaspers, R.; Ramakers, B. P.; Brouwer, R. M.; Boerman, O. C.; Steinmetz, N.; Smits, P.; Rongen, G. A.
We studied whether caffeine impairs protection by ischemic preconditioning (IP) in humans. BACKGROUND: Ischemic preconditioning is critically dependent on adenosine receptor stimulation. We hypothesize that the adenosine receptor antagonist caffeine blocks the protective effect of IP. METHODS: In vivo ischemia-reperfusion injury was assessed in the thenar muscle by (../../99m.jpg)Tc-annexin A5 scintigraphy. Forty-two healthy volunteers performed forearm ischemic exercise. In 24 subjects, this was preceded by a stimulus for IP. In a randomized double-blinded design, the subjects received caffeine (4 mg/kg) or saline intravenously before the experiment. At reperfusion, (../../99m.jpg)Tc-annexin A5 was administered intravenously. Targeting of annexin was quantified by region-of-interest analysis, and expressed as percentage difference between experimental and contralateral hand. In vitro, we assessed recovery of contractile function of human atrial trabeculae, harvested during heart surgery, as functional end point of ischemia-reperfusion injury. Field-stimulated contraction was quantified at baseline and after simulated ischemia-reperfusion, in a paired approach with and without 5 min of IP, in the presence (n=13) or absence (n = 17) of caffeine (10 mg/l). RESULTS: Ischemic preconditioning reduced annexin targeting in the absence of caffeine (from 13 +/- 3% to 7 +/- 1% at 1 h, and from 19 +/- 2% to 9 +/- 3% at 4 h after reperfusion, p = 0.006), but not after caffeine administration (targeting 11 +/- 2% and 16 +/- 3% at 1 and 4 h). In vitro, IP improved post-ischemic functional recovery in the control group, but not in the caffeine group (8 +/- 3% vs. -8 +/- 5%, p=0.003).
CONCLUSIONS: Caffeine abolishes IP in 2 human models at a dose equivalent to the drinking of 2 to 4 cups of coffee. (The Effect of Caffeine on Ischemic Preconditioning; ; NCT00184912).
Watanabe, T.; Arai, Y.; Mitsui, Y.; Kusaura, T.; Okawa, W.; Kajihara, Y.; Saito, I.
Chlorogenic acids (CGA) in green coffee bean extract (GCE) reduce blood pressure in spontaneously hypertensive rats and humans. The authors examined the blood pressure-lowering effect and safety of CGA in patients with mild hypertension through a placebo-controlled, randomized clinical trial. Subjects (n = 28) were randomized to receive treatment with CGA (140 mg/day) from GCE or placebo. Blood pressure, pulse rate, body mass index, routine blood test, hematochemistry, urinalysis, and subjective symptoms were recorded throughout the study. In the CGA group, but not the placebo group, blood pressure (systolic and diastolic) decreased significantly during the ingestion period. There was no difference in body mass index and pulse rate between groups, nor were there any apparent side effects. Thus, CGA from GCE is effective in decreasing blood pressure and safe for patients with mild hypertension.