Kinetics of ochratoxin A destruction during coffee roasting

In the present study, Coffea arabica was artificially contaminated with spores of toxigenic Aspergillus westerdijkiae. The contaminated coffee was roasted in a vertical spouted bed roaster at four different temperatures (180 °C, 200 °C, 220 °C and 240 °C) and three different time periods (5, 8 and 12 min), in order to obtain more accurate results for the development of the kinetic model for ochratoxin A (OTA). Chlorogenic acids (CGA) content during coffee roasting was also evaluated to investigate the effect of the heat employed to destroy OTA in these health promoting compounds. Coffee treated with spouted bed roasting significantly reduced the OTA level from 8% to 98%. The spouted bed roasting proved to be a very efficient procedure for OTA reduction in coffee, and its reduction depended directly on the degree of roasting. OTA degradation during coffee roasting followed first order reaction kinetics. Using the apparent activation energy of OTA degradation and the temperature-dependent reaction rate, there was a compliance with the Arrhenius equation. This model was capable of predicting the thermal induced degradation of OTA and may become an important predicting tool in the coffee industry. The present study was also able to propose roasting conditions appropriate to destroy OTA and maintain most of the CGA at the same time.     

Effect of different roasting levels and particle sizes on ochratoxin A concentration in coffee beans

Contamination of roasted coffee with ochratoxin A (OTA) is directly related to the processing quality throughout the coffee production chain, from the farming to the roasting processes. The aim of this study was to evaluate the effects of roasting and particle size on the residual concentration of ochratoxin A in roasted and ground coffee. Coffee beans were artificially contaminated with Aspergillus ochraceus. The beans were roasted to three levels (light, medium and dark) and ground into three types (fine, medium and coarse) after an incubation period. OTA quantification was performed using high-performance liquid chromatography. The combination of dark roast and coarse particle size had the lowest concentration of OTA, 3.06 μg/kg with a 97.17% reduction. The results of this study show that roasting and particle size, rather than roasting alone, are critical for the residual concentration of OTA in roasted and ground coffee beans.     

Occurrence of Ochratoxin A in coffee beans,ground roasted coffee and soluble coffee and method validation

The purpose of this work was to determine the occurrence of Ochratoxin A (OTA) in coffee beans, ground roasted coffee and soluble coffee, which is imported by Argentina and manufactured in this country and also to perform a single laboratory validation for the analysis of OTA. Validation was done with certified reference material and with spiked samples. Certified material showed 104% of toxin recovery in the case of roasted coffee and 100% for green coffee. Spiked samples with levels from 1.98 to 10.18 μg/kg for soluble coffee had an average recovery rate of 79.4%. The limits of detection and quantification in coffee were 0.02 μg/kg and 0.05 μg/kg respectively. A good correlation (r = 0.9989) was found for this method. Fifty one samples were investigated to determine the presence of OTA, extracted by Ochraprep^® immunoaffinity columns for cleaning up and analysed by high performance liquid chromatography (HPLC). The results showed that a high percentage (69%) of the coffee was contaminated with OTA at different levels. The median obtained for green coffee was 2.7 μg/kg, for ground roasted coffee was 0.24 μg/kg and 0.43 μg/kg for soluble coffee. A possible exposure assessment was evaluated.     

Occurrence of ochratoxin A before bottling in DOC and DOCG wines produced in Piedmont (Northern Italy)

Italy is one of the countries where ochratoxin A (OTA) contamination in wine poses more risks. Previous surveys on the occurrence of OTA have poorly considered north Italian wines. In this study, 1206 red and white DOC and DOCG wines produced in Piedmont (Northern Italy) from 2000 to 2007 have been analyzed for OTA level (0.116 μg l⁻¹) and incidence (68.0%). The monitoring – the widest per number of Italian wine samples considered – analyzed the OTA contamination of wines in tanks just before bottling. OTA level and incidence were significantly higher in red (0.121 μg l⁻¹, 69.4%) than in white (0.086 μg l⁻¹, 61.3%) wines. Among the white wines, the incidence was significantly lower in the Moscato wines (7.3%), due to the different wine processing. The differences in the mean OTA level in the three main grapevine varieties of red wines could be related to the harvest period. Among the Nebbiolo appellations, a reduction of the OTA level was noticed with increasing the wood aging period. A significant effect of the vintage year was also registered.     

The development of an activated carbon from cherry stones and its use in the removal of ochratoxin A from red wine

The ability of activated carbon (AC) prepared from cherry stones (CS) by activation with H₃PO₄, ZnCl₂ or KOH to remove ochratoxin A (OTA) from two Italian red wines has been studied. AC was characterized in terms of texture and surface chemistry. OTA was analyzed by reversed-phase high-performance liquid chromatrography, using a fluorescence detector. The content of OTA in the starting wines is 7.38 and 2.36 μg/L. The adsorption of OTA is high only for one AC, which was prepared by KOH activation at 900 °C, using the 3:1 KOH:CS impregnation ratio. It possesses a large apparent surface area (S_BET = 1620 m²/g) and a high volume of large size macropores (1.84 cm³/g). It also contains narrow mesopores and intermediate size and wide micropores. Its content of acidic oxygen surface groups is low, whereas the content of basic groups is high (2.62 meq/g). The treatment of the wines with such an AC results in a decrease of the initial OTA content of more than 50%. However, the changes produced in the total polyphenolic index, color intensity, and hue are small (i.e. ～8%, ～5.5% and ～1.2%, respectively).     

Antimicrobial activity of clove (Syzgium aromaticum) oil in inhibiting Listeria monocytogenes on chicken frankfurters

The ability of Listeria monocytogenes to survive and grow at refrigeration temperature in some ready to eat (RTE) poultry products is a public health concern. The inhibitory effect of clove oil (1% and 2%, v/w) applied to the surface of RTE chicken frankfurters was determined on seven strains of L. monocytogenes inoculated at low (10²–10³ cfu/g) or high cell numbers (10⁴–10⁶ cfu/g), and stored at 5 °C for 2 weeks or at 15 °C for 1 week. All strains of L. monocytogenes survived and grew on control frankfurters at 5 °C and 15 °C but growth was inhibited under both storage conditions in the presence of either 1% or 2% clove oil. Depending on the sensory considerations, the addition of clove oil to frankfurters may be an effective strategy to control L. monocytogenes in chicken frankfurters.     

Skin damage,high temperature and relative humidity as detrimental factors for Aspergillus carbonarius infection and ochratoxin A production in grapes

This study investigated the impact of skin damage on Aspergillus carbonarius colonization and ochratoxin A (OTA) production in grapes at different temperatures and relative humidity. Four ochratoxigenic A. carbonarius strains isolated from wine grapes were used to inoculate artificially damaged and undamaged table grapes. Grapes were stored at three levels of relative humidity (80%, 90% and 100%) and at two temperatures (20 and 30 °C). After seven days, the infection percentage of A. carbonarius was recorded and OTA accumulation in berries was analysed. Damaged grapes were more commonly infected and development of colonies was higher than in undamaged ones; consequently more OTA was detected in the former treatment. Temperature and relative humidity had significant influences on both infection and toxin content. The amount of OTA detected at 30 °C was higher than at 20 °C in most of the treatments. The highest relative humidity (100%) led to maximum amounts of OTA while no significant differences were found between 90% and 80% in the OTA content. The implementation of preventive measures in order to minimise berry damage in the field by controlling pathogenic fungi and insects during grape growing and removing visibly damaged grapes at harvest may significantly reduce OTA contamination in grapes.     

Evaluating the combined effect of water activity,pH and temperature on ochratoxin A production by Aspergillus ochraceus and Aspergillus carbonarius οn culture medium and Corinth raisins

The objectives of this study were: (a) to evaluate the potential of the ELISA method in the determination of the produced OTA by Aspergillus ochraceus and Aspergillus carbonarius in malt extract agar (MEA) at different pH (3.9, 5.1, 5.9, 6.8), water activity (a_w) (0.87, 0.93, 0.99), and temperature (10, 15, 20, 25, 30, 40 °C) levels, providing a rapid screening for the optimum and marginal conditions of OTA production, (b) to comparatively evaluate the performance of ELISA and HPLC method, and (c) to evaluate the ability of A. ochraceus to produce OTA in rehydrated Corinth raisins during storage for 36 days. Two independent experiments were carried out to estimate OTA production on MEA and Corinth raisins. The produced OTA was evaluated qualitatively by the ELISA method and selected cases were verified by HPLC. The levels of OTA decreased with water activity, whereas pH seemed to have no specific effect. Furthermore, A. ochraceus produced maximum amounts of OTA on raisins at the 24th day of incubation, indicating that the endogenous microflora may restrictively affect OTA production. The knowledge of optimal and marginal levels of ecological factors in order to optimise post-harvest and storage of food products may significantly affect the production of OTA. Moreover, endogenous microflora of certain foodstuffs may cause OTA detoxification and consequently reduction of OTA levels; a fact that has to be taken into account in food commodities such as raisins, grapes, and wine.     

Aflatoxin B1 and ochratoxin A in breakfast cereals from athens market: Occurrence and risk assessment

A method for aflatoxin B₁ (AFB₁) and ochratoxin A (OTA) determination in breakfast cereals is described using a simultaneous methanolic-aqueous extraction followed by immunoaffinity columns clean-up step and High Pressure Liquid Chromatography (HPLC) with Fluorescence Detector (FD). Recoveries were found to be 78% and 83% for AFB₁ and OTA, respectively, while the detection limit (DL) was 0.02 ng g^?1 for both mycotoxins. Both determinations were applied in fifty five samples of breakfast cereals purchased from Athens market. Results revealed the presence of AFB₁ in 56.3% of the samples examined (mean 1.42 ng AFB₁ g^?1). Seven samples (median 3.5 ng AFB₁ g^?1) were found to be contaminated at levels higher than the EU limit (2 g g^?1). OTA was detected in 60% of the samples (mean 0.18 ng g^?1). Nineteen samples were found to be contaminated by both mycotoxins. In addition in the present study the daily exposure to AFB₁ and OTA is discussed.     

Microbiological changes in farm reared freshwater prawn (Macrobrachium rosenbergii de Man) in ice

The microbiological changes in farm reared freshwater prawn (Macrobrachium rosenbergii de Man) during ice storage were studied. A total of 156 bacterial cultures from fresh and ice-stored farmed freshwater prawn were isolated and characterized. Total aerobic, mesophilic and psychrotrophic counts and hydrogen sulphide producing bacterial counts were determined. The total aerobic counts at 20 and 37 °C on fresh prawn was in the range of 4–5 log₁₀ cfu g⁻¹. Aerobic counts on M. rosenbergii at 20 °C and 7 °C exceeded 10⁷ cfu g⁻¹ by the end of storage, of which 40–52% were H₂S producers. Gram-negative bacteria constituted 73% of the total flora of fresh prawn and Enterobacteriaceae and Aeromonadaceae dominated. After 19 days of iced storage, more than 80% of the bacterial flora of prawn were Gram-negative. Pseudomonas, Aeromonas hydrophila, A. veronii boivar sobria and Shewanella putrefaciens were identified as the dominant spoilage organisms of farm reared M. rosenbergii stored in ice. This study confirms that freshwater prawn carry significant numbers of motile aeromonads capable of growth at low temperature. The results of the study indicated that the shelf-life of freshwater prawn as determined by microbiological data is 12–16 days. Immediate icing of harvested M. rosenbergii is essential to improve the microbiological stability.     

In vitro control of growth and ochratoxin A production by butylated hydroxyanisole in Aspergillus section Nigri species

This study was carried out to determine the efficacy of phenolic antioxidant butylated hydroxyanisole (BHA) under different interacting water activity (a_W) and temperature regimes on the lag phase and growth rate by Aspergillus section Nigri strains. In this experiment four A. section Nigri strains were used. Peanut meal extract agar (PMEA) was prepared at 2%. The a_W of the medium was adjusted to 0.995, 0.980 and 0.930, BHA at 1, 5, 10 and 20 mmol l^?1 was added to the basic medium. The plates were inoculated and incubated for 30 days at 18 and 25 °C. Radial growth rates (mm d^?1) and lag phase (h) were calculated. In control treatments, the growth rate decreased as water activity reduced in all strains assayed. At all a_W levels tested, BHA at 20 mmol l^?1 completely inhibited growth. In general, at 10 mmol l^?1 and 0.995 and 0.980a_W level, a significant reduction respect to control was observed. This antioxidant completely inhibited OTA production, at concentrations of 20 mmol l^?1, regardless of a_W used by all the strains evaluated.     

Microbial shelf-life extension of chilled Coho salmon (Oncorhynchus kisutch) and abalone (Haliotis rufescens) by high hydrostatic pressure treatment

This study was carried out to evaluate the effect of high hydrostatic pressure (HHP) treatment on microbial behavior and the shelf-life extension of Coho salmon and abalone during chilled storage at 4 °C. For salmon, HHP treatments were applied at 135, 170, and 200 MPa for 30 s, while abalone treatment consisted of 500 MPa for 8 min and 550 MPa for 3 or 5 min. Spoilage bacteria (Pseudomonas spp. and hydrogen sulfide-producing bacteria, mainly Shewanella putrefaciens), as well as aerobic mesophilic and psycrophilic microorganisms, were enumerated immediately after treatment and throughout subsequent storage at 4 °C. Results have shown that HHP treatment reduced the initial microbial counts of salmon from 3.16 to 2.2 log units, moreover abalone was reduced from 1.3 log to undetectable levels (<10 CFU g⁻¹). HHP-treatment used for salmon were not sufficient to extend their shelf-life. However, the shelf-life of abalone was extended from 30 (control samples) to >65 days irrespective of HHP treatment applied.     

Effects of Zataria multiflora Boiss. essential oil and nisin on Bacillus cereus ATCC 11778

The effects of different concentrations of Zataria multiflora Boiss. essential oil (EO, 0.0%, 0.005%, 0.015%, 0.03% and 0.045%) and nisin (N, 0.0, 0.25, 0.5, 1.5 and 2.5 μg ml⁻¹), pH values (7.4, 6.5 and 6.0), temperatures (Ts, 10, 20 and 30 °C) and storage times (Ds, up to 43 days) on log₁₀ probability percentage of growth initiation (log P%) of one vegetative cell of Bacillus cereus in brain heart infusion broth were evaluated in a factorial design study. The log P% of the organism was significantly affected (P < 0.01) by the values of EO, N, pH, T and D.The combinations of T ⩾ 20 °C, EO ⩽ 0.03% and pH values (7.4, 6.5 and 6.0) could not obviously affect the growth of the organism in this study. Whereas, the strong inhibitory action was observed by increasing EO concentration to 0.045 at T ⩾ 20 °C and selected pH values (7.4, 6.5 and 6.0) and by decreasing temperature to 10 °C at EO ⩾ 0.015% and pH values used in this study. The inhibitory effect of N also was enhanced by decreasing storage temperature to 10 °C at the selected pH values (7.4, 6.5 and 6.0) in this study.The growth of the organisms was strongly affected by increasing EO concentration to 0.03% in combination with N concentrations used at the selected temperatures in this study. The growth of the organism was completely inhibited at combinations EO ⩾ 0.015%, N ⩾ 1.5 μg ml⁻¹, T ⩽ 30 °C and pH ⩽ 7.4 during 43 days of storage in this study. This synergistic effect of EO and N was enhanced in lower pH values (6.5 and 6.0) in the present study. The growth of organism was completely inhibited at combinations of EO ⩾ 0.005 and N ⩾ 1.5 μg ml⁻¹ at pH = 6.0, and EO ⩾ 0.03 and N ⩾ 0.5 μg ml⁻¹ at pH ⩽ 6.5 during the study at the selected Ts (30, 20 and 10 °C).     

Biological control of postharvest diseases of peach with Cryptococcus laurentii

Cryptococcus laurentii was evaluated for its activity in reducing postharvest gray mold decay, blue mold decay and Rhizopus decay of peach caused by Botrytis cinerea, Penicillium expansum and Rhizopus stolonifer respectively, and in reducing natural decay development of peach fruits. The concentrations of antagonist had significant effects on biocontrol effectiveness: the higher the concentrations of the antagonist, the lower the disease incidence. At concentrations of C. laurentii at 1 × 10⁹ CFU ml⁻¹, the gray mold decay was completely inhibited after 4 days incubation at 25 °C, while the control fruit had 50% decay, when inoculated with B. cinerea spores suspension of 1 × 10⁵ spores ml⁻¹; no complete control of the blue mold or Rhizopus mold was observed, when peach fruits were stored at 25 °C for 4 days (challenged with P. expansum) or 5 days (challenged with R. stolonifer) respectively, but the decay was distinctly prevented, the incidence of blue mold or Rhizopus mold was reduced by 78.6% or 80% respectively, compared with control, at challenged with P. expansum or R. stolonifer spores suspension of 5 × 10⁴ spores ml⁻¹, respectively. C. laurentii significantly reduced the natural development of decay and did not impair quality parameters of fruit following storage at 2 °C for 30 days followed by 20 °C for 7 days.     

Pressurized liquid extraction coupled to liquid chromatography for the analysis of ochratoxin A in breakfast and infants cereals from Morocco

A sensitive and reliable method using pressurized liquid extraction (PLE) and liquid chromatography (LC) has been developed for the analysis of ochratoxin A (OTA) in breakfast and infants cereals. Influence of several extraction solvents that affect PLE efficiency was studied. The selected PLE operating method was: 10 g of sample was packed into 22 ml stainless-steel cell and OTA was extracted with acetonitrile/water (80:20) at 40 °C, 34 atm in one cycle of 5 min at 60% flush. The mean recovery of OTA was 82 ± 4 at fortification level of 3 ng/g OTA. The limit of quantification (LOQ) of OTA was 0.25 ng/g. The proposed method was successfully applied to the analysis of 68 samples of breakfast and infants cereals products collected from different supermarkets and pharmacies in Rabat. Results showed that all analyzed infant cereals were free of OTA contamination. However, four samples of breakfast cereals were contaminated with OTA. Levels of OTA in positive samples ranged between 5.1 and 224.6 ng/g. All positive samples (5.8% of total samples) were above the maximum level set by EU regulations for OTA in cereal derivatives products.     

Solid-phase extraction and HPLC determination of Ochratoxin A in cereals products on Chilean market

Ochratoxin A (OTA) is a mycotoxin produced by different species of Aspergillus and Penicillium fungi. The presence of this mycotoxin in cereals-based products has relation with manufacturing practices, especially with storage conditions. An extraction procedure for OTA from wheat-based products was implemented in this study. The method uses an alkaline extraction with NaHCO₃, purification with Sep-Pak^® RP-18 cartridges; and quantitative analysis by high performance liquid chromatography with fluorescence detection. The presence of OTA was confirmed by the formation of Ochratoxin A methyl ester. The method shows good validation parameters with a rate of recovery rate over 95%, limits of detection and quantification of 0.6 and 2.1 μg kg^?1, respectively. Once the method was validated; 31 samples including, flour, corn starches and rice were analyzed. About 70% of flour samples, 50% of rice and 63% of corn starch samples resulted positives for OTA.     

ELISA and HPLC analysis of ochratoxin A in red wines of Croatia

Ochratoxin A (OTA) contaminates wine all round the world, and its consumption may significantly increase human exposure to this toxin. In this study, enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC) for OTA analysis were tested on must and wine samples collected in Croatia. The results of ELISA and HPLC analysis of OTA in naturally contaminated red wines correlated well (r = 0.821), and the correlation was better at higher OTA concentrations. In contrast to HPLC, ELISA could not detect very low OTA concentrations. OTA concentrations in must (range 19–50 ng/l) were higher than in the wines (range 0–21 ng/l). No must samples showed the presence of Aspergillus carbonarius, which is a common OTA-producing mould affecting grapes.     

Aflatoxins in bulk and pre-packed pistachios sold in Spain and effect of roasting

The occurrence of aflatoxins in national and imported pistachios available in Aragón (NE Spain), purchased from commercial outlets during 2007, was surveyed. Thirty-two samples of roasted pistachios were analyzed for aflatoxins by immunoaffinity cleanup with liquid chromatography and fluorescence detection using post-column photochemical derivatization. Results showed that the incidence of aflatoxin B₁ and B₂ in pre-packed pistachios was 19% and 6%, while in bulk pistachios was 50% and 12.5%, respectively. All positive samples originated from Iran, while pistachios from USA, Turkey and Spain tested negative for aflatoxins. The low degree of contamination ranged from 0.12 to 0.29 μg/kg, and no sample exceeded the maximum permitted level for aflatoxins in pistachio nuts. Naturally occurring aflatoxin B₁ was not noticeably reduced by commercial roasting at 120 °C for 20 min.     

Ochratoxin A in coffee beans (Coffea arabica L.) processed by dry and wet methods

The incidence of ochratoxin A was studied in different coffee (Coffea arabica L.) samples. A higher incidence of filamentous fungi was observed in the coffee swept from ground and floating coffee samples. The species Aspergillus ochraceus, Aspergillus sulphureus and Aspergillus sclerotiorum were ochratoxin A producing. In 128 (44%) samples ochratoxin A was not detected; however, in 89 samples (31%), ochratoxin A was detected at 0.1–5.0 μg/Kg levels. Other 25% samples presented contamination above 5.0 μg/Kg. This study showed that the fractions coffee swept from ground and floating coffee represents a serious risk of ochratoxin A contamination.     

The effect of air flow in coffee roasting for antioxidant activity and total polyphenol content

The objective of this study was to investigate the effect of air flow in coffee roasting for antioxidant activity and phenolic compound content. Roasting was conducted in various combinations of temperature (180–200 °C), time (13–17 min) and volume flow rate (VFR; −0.271–0.271 L/s) using Box-Behnken design. The results of DPPH, ORAC and total polyphenol content (TPC) were fitted to the response surface methodology models (R² = 0.9936–0.9869). Increasing temperature and time were negatively influenced for functional properties of roasted coffee with significances (P < 0.05). The quadratic effect of VFR was observed in DPPH and ORAC assays. Higher DPPH and ORAC values were shown in high or low VFR than the centre point of VFR at the same temperature or time. On the other hand, TPC was decreased from high to low VFR at the same temperature or time. The VFR was a significant parameter for antioxidant activity and TPC in coffee roasting. Manipulation of air flow by increasing or decreasing VFR can deliver higher antioxidants and phenolic compounds from the same amount of coffee beans to consumers.