Alkali-based pre-treatment may prevent ochratoxin A in grapes

2016 ◽  
Vol 9 (4) ◽  
pp. 517-523 ◽  
Author(s):  
S. Özcan ◽  
V. Gökmen
Keyword(s):  
Ochratoxin A ◽  
Potassium Carbonate ◽  
High Performance ◽  
Elevated Temperatures ◽  
Alkali Treatment ◽  
Good Manufacturing Practice ◽  
Amide Bond ◽  
Aspergillus Ochraceus ◽  
Alkaline Conditions ◽  
Pre Treatment

In traditional raisin production process in Turkey, one of the major raisin producers in the world, grapes undergo an alkali treatment prior to drying. This procedure involves dipping grapes in a potassium carbonate solution for 10-15 seconds to remove the wax layer on the surface to accelerate the drying process. In this study, we aimed to investigate the effect of alkali treatment on ochratoxin A (OTA), an important risk factor for grapes and grape-derived products. First, the stability of the OTA was examined under variable pH (4-12), ion type (Na+, K+), ionic strength (0.1-10%) and temperature (4-60 °C). Then, Aspergillus ochraceus contaminated grapes were treated with an alkaline solution and a subsequent OTA analysis was performed through a high performance liquid chromatography-fluorescence detection. OTA started to decompose at pH values exceeding 10.0. The degradation followed a first order kinetics. Although both sodium carbonate and potassium carbonate solutions were at the same alkali pH and they both triggered the OTA degradation at increasing concentrations, potassium carbonate was more effective even at low concentrations. Elevated temperatures were also found to effect degradation. The degradation rate constant at 40 °C was approximately 5 times greater than the one at 25 °C. Furthermore, OTA levels dropped up to 50% in contaminated grapes after the alkali treatment. Our results confirmed that the amide bond of OTA rapidly hydrolysed to a non-toxic ochratoxin-alpha and phenylalanine under strong alkaline conditions. The results suggest that the alkaline pre-treatment unintentionally offers a great advantage to reduce OTA levels in raisins and it could be a viable approach for other dried fruits through the application of good manufacturing practice.

Ochratoxins A and B, Xanthomegnin, Viomellein and Vioxanthin Production by Isolates of Aspergillus ochraceus from Green Coffee Beans

1983 ◽  
Vol 46 (11) ◽  
pp. 965-968 ◽  
Author(s):  
MICHAEL E. STACK ◽  
PHILIP B. MISLIVEC ◽  
TURGUT DENIZEL ◽  
REGINA GIBSON ◽  
ALBERT E. POHLAND
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Ochratoxin A ◽  
High Performance ◽  
Toxin Production ◽  
Aspergillus Ochraceus ◽  
Average Level ◽  
Green Coffee ◽  
Green Coffee Beans ◽  
Coffee Beans

Isolates from Aspergillus ochraceus obtained from green coffee beans were cultured on rice and water. After 20 d of growth the cultures were extracted with chloroform and the extracts were analyzed by high performance liquid chromatography for ochratoxin A (OA), ochratoxin B (OB), xanthomegnin (X), viomellein (V) and vioxanthin (VX). Forty-three percent of the isolates produced OA at an average level of 397 μg of toxin/g rice, 17% produced OB at an average level of 312 μg/g, and 84% produced X, V, and VX at an average level of 281, 417 and 386 μg/g, respectively. The highest levels of toxin production were OA, 2088 μg/g; OB, 3375 μg/g; X, 1562 μg/g; V, 2514 μg/g; and VX, 2054 μg/g. VX has not previously been reported as an A. ochraceus metabolite.

In vitro effect of some fungicides used in cultivation of Capsicum spp. on growth and ochratoxin A production by Aspergillus species

2013 ◽  
Vol 6 (2) ◽  
pp. 159-165
Author(s):  
L. Santos ◽  
S. Marín ◽  
V. Sanchis ◽  
A.J. Ramos
Keyword(s):  
Ochratoxin A ◽  
High Performance ◽  
Fruit Production ◽  
Aspergillus Species ◽  
Aspergillus Ochraceus ◽  
Fungal Load ◽  
Capsicum Spp ◽  
Vitro Effect ◽  
Yeast Extract Sucrose

The present study aimed to assess the effect of some pre-harvest fungicides commonly used in Capsicum fruit production on growth and ochratoxin A production of three Aspergillus species found in Capsicum powder. Aspergillus tubingensis, Aspergillus ochraceus and Aspergillus westerdijkiae, previously isolated from paprika and chilli, were inoculated on yeast extract sucrose agar and paprika extract agar supplemented with different fungicides at their recommended dosage rates, and incubated at 20 and 30 °C during 7 days. Radial growth was measured after 3, 5 and 7 days and ochratoxin A production was determined by high-performance liquid chromatography with fluorescence detection on day 7. Dodine 40% and mancozeb 80% were the most effective fungicides in inhibiting growth and ochratoxin A production, regardless of the fungal strain tested or temperature conditions. Whereas the application of fungicides could be very attractive in reducing the mycotoxigenic fungal load, it can also stimulate ochratoxin A production in some cases.

A new preparative method for simultaneous purification of ochratoxin A and ochratoxin B from wheat culture inoculated with Aspergillus ochraceus

2016 ◽  
Vol 9 (1) ◽  
pp. 31-40 ◽  
Author(s):  
Z.Y. Zhao ◽  
N. Liu ◽  
L.C. Yang ◽  
A.B. Wu ◽  
Z.L. Zhou ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Ochratoxin A ◽  
High Performance ◽  
Gel Permeation Chromatography ◽  
Preparative Method ◽  
Aspergillus Ochraceus ◽  
Potential Health ◽  
Ochratoxin B ◽  
Purity Analysis

Ochratoxins are a mycotoxin family frequently found in agricultural commodities worldwide and pose a potential health risk to humans and animals. To obtain large amounts of high-purity ochratoxins for food safety monitoring and toxicological research, a novel and effective method was established for simultaneous purification of ochratoxin A (OTA) and ochratoxin B (OTB) from a wheat culture inoculated with an ochratoxin-producing Aspergillus strain. The inoculated wheat culture was first extracted with methanol:water (80:20, v/v), followed by one or two cleanup procedures involving acid-assisted liquid-liquid extraction and gel permeation chromatography. Subsequently, target analytes were separated and collected using preparative high performance liquid chromatography. Finally, a combined approach of ultra-high performance liquid chromatography, ultraviolet spectrophotometry and mass spectrometry was applied for purity analysis and structural identification of the obtained toxins. As a result, 100 g of an inoculated wheat culture yielded 69 mg of OTA and 6 mg of OTB with purities greater than 98%. This proposed method might serve as a valuable reference to obtain expensive ochratoxin standards. To the best of our knowledge, this is the first report on simultaneous preparation of OTA and OTB from artificially inoculated wheat culture.

Occurrence of Ochratoxigenic Fungi and Ochratoxin A in Green Coffee from Different Origins

2004 ◽  
Vol 10 (1) ◽  
pp. 45-49 ◽  
Author(s):  
E. Pardo ◽  
S. Marin ◽  
A. J. Ramos ◽  
V. Sanchis
Keyword(s):  
Fungal Infection ◽  
Ochratoxin A ◽  
High Performance ◽  
Limit Of Detection ◽  
Aspergillus Ochraceus ◽  
Green Coffee ◽  
Agar Plug ◽  
Coffee Beans ◽  
Different Origins ◽  
Positive Results

Fungal infection and ochratoxin A (OTA) contamination were determined in green coffee samples from different origins, in which OTA-producing fungi were also identified. About 72% of the beans analysed by direct plating presented fungal infection, including species of Aspergillus, Penicillium and Rhizopus. The genus Aspergillus was presented in more than 90% of infected coffee beans. Aspergillus ochraceus and Aspergillus section Nigri isolates represented 2.8 and 65.4%, respectively from the total number of isolates from the coffee beans. The capacity to produce OTA was determined in 260 isolates of A. section Nigri and 19 of A. ochraceus by the agar plug method, giving positive results for 6% of the A. section Nigri isolates and 16% of the A. ochraceus. OTA production was analysed by high performance liquid chromatography. OTA contamination of green coffee beans was analysed by enzyme immunoassay. OTA levels in all samples analysed were above the limit of detection (0.6 mg/kg), with a mean OTA concentration of 6.7 mg/kg.

ALCOA 351 SUPRACAST

Alloy Digest ◽  
2020 ◽  
Vol 69 (7) ◽  
Keyword(s):  
Physical Properties ◽  
Tensile Properties ◽  
Copper Alloy ◽  
High Performance ◽  
Elevated Temperatures ◽  
Heat Treating ◽  
Aluminum Silicon

Abstract Alcoa 351 SupraCast is a heat-treatable aluminum-silicon-copper alloy that also contains small amounts of magnesium, manganese, vanadium, and zirconium. It is designed for components exposed to elevated temperatures in high performance engines. This datasheet provides information on composition, physical properties, and tensile properties as well as fatigue. It also includes information on heat treating, machining, and joining. Filing Code: Al-466. Producer or source: Alcoa Corporation.

BERYLCO 25S

Alloy Digest ◽  
1952 ◽  
Vol 1 (3) ◽  
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Precipitation Hardening ◽  
Elevated Temperatures ◽  
Heat Treating ◽  
Good Resistance ◽  
Subzero Temperatures ◽  
Endurance Strength ◽  
Wear And Corrosion ◽  
Resistance To Wear

Abstract Berylco 25S alloy is the high-performance beryllium-copper spring material of 2 percent nominal beryllium content. It responds to precipitation-hardening for maximum mechanical properties. It has high elastic and endurance strength, good electrical and thermal conductivity, excellent resistance to wear and corrosion, high corrosion-fatigue strength, good resistance to moderately elevated temperatures, and no embrittlement or loss of normal ductility at subzero temperatures. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Cu-3. Producer or source: Beryllium Corporation.

Ultra-thin two-dimensional molecular crystals grown on a liquid surface for high-performance phototransistors

2021 ◽  
Author(s):  
Shuyuan Yang ◽  
Yu Zhang ◽  
Ying Wang ◽  
Jiarong Yao ◽  
Lijuan Zhang ◽  
...  
Keyword(s):  
Organic Semiconductor ◽  
High Performance ◽  
Elevated Temperatures ◽  
Liquid Surface ◽  
Molecular Crystals ◽  
Two Dimensional ◽  
Poor Solubility

Bilayer 2D molecular crystals of an organic semiconductor with poor solubility were grown on a liquid substrate at elevated temperatures. The molecularly thin crystals exhibited superior mobility and photoresponse.

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