Food Mycotoxins: An Update

The Institute of Food Technologists has issued this Scientific Status Summary to update readers on the science of fungal toxins.     

速冻糯玉米粒加工工艺

以糯玉米为原料,经预冷、热烫(或不热烫)等处理后,进行速冻,制定技术标准并研究提出质量控制的工艺参数.     

Mycotoxins in foodstuffs

Summary The influence of variousa _w values (high, moderate and low, e.g. 0.92, 0.87, and 0.82) of cakes (Rührkuchen, made of wheat flour, sugar, eggs, fat and water) on the development and the mycotoxin production ofAspergillus flavus (aflatoxins),A. versicolor (sterigmatocystin),A. ochraceus (ochratoxin A),Penicillium chrysogenum (citrinin) andP. expansum (patulin) was investigated. None of the moulds was able to germinate at ana _w of 0.82. An increase of the water activity resulted in a pronounced growth of the five fungi. Citrinin was not formed on the cakes at all. The yields of the other mycotoxins were not markedly influenced by thea _w (0.92 or 0.87). During the development of the moulds thea _w of the substrate was lowered at first (water requirement during germination and initial growth) and subsequently increased (initiation of the secondary metabolism).All microorganisms need water for their development and the content of water in foodstuffs is best characterised by their water activity (a _w ) [1]. This term gives information on the amount of free water directly available to microorganisms and not bound to electrolytes and macromolecules.Most of the common bakery goods havea _w values in the range of 0.90–0.97 [2], and this provides good growth conditions for most of the spoilage moulds, which have a minimuma _w requirement for growth of 0.80 [3, 4]. There are some reports concerning the water requirements of the spore germination and the growth of mycotoxin producing fungi, especially of the aflatoxin forming strains ofAspergillus flavus andA. parasiticus [4–9]. Corresponding studies on the influence ofa _w on the formation of mycotoxins are lacking. All studies mentioned above were made using artifical media, but not with foodstuffs.As bakery goods could be spoiled by many fungi that maybe able to form mycotoxins [10] the influence of variousa _w values of cakes on the growth of moulds and the production of mycotoxins was studied.

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Mykotoxine in LebensmittelnXII. Der Einfluß der Wasseraktivität von Kuchen auf das Wachstum von Schimmelpilzen und die Bildung von Mykotoxinen

Zusammenfassung Der Einfluß verschiedenera _w -Werte (hoch, mäßig und gering, z. B. 0,92, 0,87 und 0,82) von Kuchen (Rührkuchen, hergestellt aus Weizenmehl, Zucker, Eiern, Fett und Wasser) auf die Entwicklung und die Bildung von Mykotoxinen vonAspergillus flavus (Aflatoxine),A. versicolor (Sterigmatocystin),A. ochraceus (Ochratoxin A),Penicillium chrysogenum (Citrinin) undP. expansum (Patulin) wurde untersucht. Keiner der Pilze entwickelte sich bei einer Wasseraktivität von 0,82. Eine Erhöhung der Wasseraktivität bewirkte ein ausgeprägtes Wachstum der fünf Pilze. Citrinin wurde auf keinem der verschiedenen Kuchentypen gebildet. Die Biosynthese der anderen Mykotoxine wurde durch die Wasseraktivität (0,92 oder 0,87) nicht wesentlich beeinflußt. Während des Wachstums der Pilze wurde dera _w -Wert des Substrates zunächst vermindert (Verbrauch von Wasser während Sporenkeimung und Anfangswachstum) und anschließend dann erhöht (Einsetzen des sekundären Stoffwechsels).

     

Mycotoxins in dairy products: A review

Milk and dairy products continue to raise concerns with regard to contamination with mycotoxins, most of which have a likely or confirmed carcinogenic status. Such concerns are more serious for certain cheeses due to their frequent contamination with high concentrations of mycotoxins from various sources, including the milk used as a raw material and moulds found as contaminants or purposely added for ripening. Different control measures have been suggested to prevent the formation or to remove mycotoxins in dairy products once formed therein. However, these methods either provide an insufficient degree of protection or are onerous to implement. This review surveys the main mycotoxins associated with dairy products and discusses their health significance. Attention is drawn to the lack of knowledge on the emerging and masked mycotoxins with relevance to dairy products. Known control measures are discussed from the perspective of their application while presenting their strengths and weaknesses.     

Mycotoxins in foodstuffs

Summary Sterigmatocystin was formed on different kinds of bread (whole wheat bread, whole rye bread, whole rye bread with shredded wheat, whole wheat bread with wheat germs and whole wheat bread with linseed) by two strains ofAspergillus versicolor. The highest yields were in the range of 0,1–0,4 rg/g. The growth of the moulds and the toxin production were influenced by the total acid content (Säuregrad; must be less than approximately 9) and by the temperature (optimal growth temperature: 20–30° C, optimal temperature for toxin synthesis: 20° C). After 10 days of incubation most of the toxin was already formed.

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Mycotoxine in nahrungsmittelnVI. Bildung von Sterigmatocystin in Brot durch Aspergillus versicolor

Zusammenfassung Zwei Stämme vonAspergillus versicolor bildeten das Mycotoxin Sterigmatocystin auf verschiedenen Arten von Schnittbrot (Grahambrot, grobes Rheinisches Vollkornbrot, Felkebrot, Weizenkeimbrot und Leinsamenbrot). Die höchsten Toxinkonzentrationen lagen im Bereich von 0,1–0,4 g/g. Das Wachstum der Pilze und die Toxinbildung wurden beeinflußt durch den Säuregrad des Substrates (der Wert mu unter 9 liegen) und durch die Temperatur (Wachstumsoptimum: 20–30° C, Optimaltemperatur für die Sterigmatocystin-Produktion: 20° C). Bei den meisten Brotarten waren die höchsten Toxinkonzentrationen bereits nach einer Inkubationszeit von 10 Tagen nachzuweisen.

     

Mycotoxins in rice

Mycotoxin contamination in rice is usually lower as in wheat or corn. However, there are some reports that rice has been contaminated with mycotoxins such as aflatoxin B1, B2, G1, G2 (AFS), citrinin, deoxynivalenol (DON), fumonisin B1, B2, B3 (FMS), fusarenon-X (Fus.-X), nivalenol (NIV), ochratoxin A (OTA), sterigmatocystin (STE), and zearalenone. Rice in Japan is preserved in warehouses where moisture content and temperature are regulated. Therefore, mycotoxin contamination from post harvest fungal growth occurs very seldom. Trichothecenes, aflatoxins, and STE in rice were recently analyzed in our laboratory. In 1998, a typhoon struck before rice harvesting in Japan, and the unpolished rice was found to be stained brown. Samples were collected and analyzed for the presence of trichothecenes. Mycotoxins DON, Fus.-X, and NIV were detected and confirmed with GC-MS. The quantity of trichothecenes was determined using GC-ECD. STE is a carcinogenic mycotoxin produced by Aspergillus versicolor and some other fungi. STE contamination of rice was studied in our laboratory since 1973. GC-MS, LC-MS, LC-MS/MS, and LC-UV methods for STE determination were examined, giving good results for the LC-UV method using a photo diode array detector. Different techniques for the extraction of STE from rice were also studied. Finally, brown rice was ground, and the ground rice was extracted with acetonitrile-water. An Autoprep MF-A 1000 column was used to clean up AFS and STE. The cleaned-up extract was analyzed with HPLC-UV. Forty-eight brown rice samples were analyzed, and none of them were contaminated with STE. These rice samples were also analyzed for AFS and FMS, and none of the samples were contaminated. The Ministry of Agriculture, Forestry and Fisheries in Japan is making the appropriate Institutes develop analytical methods for mycotoxins and survey mycotoxin contamination on rice as well as wheat, corn, and some other cereals.     

Control of alcoholic fermentation in winemaking: Current situation and prospect

Winemaking fermentations aim to optimise product quality, which is very difficult to quantify. Control over fermentation kinetics generally has direct technological advantages, in terms of tank use optimisation in the winery and control over energy expenses for the regulation of temperature and is generally a prerequisite for controlling the characteristics of the wine. How new technologies can assist the winemakers to elaborate wines with predefined characteristics and improve process performances as well as hygienic properties? On-line fermentation monitoring is one promising way because: (i) it is much more accurate than manual measurements and (ii) it makes possible new control strategies with an optimal control tank by tank. Later, preventive control, based on modelling of the fermentation process, may be possible. New processes, such as cell immobilisation, may also be used as well as methodologies in the domain of data management and knowledge based systems.     

白藜芦醇的研究现状及应用前景

介绍了白藜芦醇的资源分布及化学结构,阐述了其生理、药理活性及相应的营养保健功效及其在食品、化妆品及药品方面的应用,提出开发富含白藜芦醇的植物,加快其有效地分离和纯化技术,增加临床应用,注重实用产品的研制,具有重要意义。     

高能见度纺织品的研究现状

高能见度纺织品在交通安全装饰领域的应用广泛。文章从单根纤维的回归反射、玻璃微珠的制造和排列、反光涂层三个方面介绍了高能见度纺织品的研究现状。     

Mycotoxins in spices]

Since antiquity, spices have been used for flavoring foods and beverages and for medication. They play an important role in the national economy of several of the producing, exporting and importing countries. Tropical climatic conditions under which spices are grown offer a favorable environment for the fungal and mycotoxin contamination. This review summarized information from 44 reports on the occurrence of mycotoxins (aflatoxins, ochratoxins zearalenone, fumonisins, trichothecenes) and their levels in different spices. Aflatoxins which are highly carcinogenic compounds, produced by A. flavus and A. parasiticus, are the leading toxins present in red peppers (paprika, chilli, cayenne) nutmeg, mustard, ginger, black and white peppers, coriander. Ochratoxins have been reported also as a natural contaminants in many spices. Although the levels of mycotoxins are generally low when compared with other food products, the testing of spices (imported and domestic) by regulatory agencies seems to be in need of expansion.     

出入境农产品中真菌毒素的污染、检测及控制

<正>真菌毒素(Mycotoxin)是一类由真菌产生的毒性二次代谢产物,广泛污染农作物、食品及饲料等植物源性产品。目前已知的有200多种,按其主要产毒菌种可分为曲霉菌毒素(如黄曲霉毒     

Mycotoxins in dairy products

Certain fungi produce chemical substances that cause toxic symptoms when food containing them is ingested by man or animals. These compounds are referred to as mycotoxins. Mycotoxins may contaminate dairy products by moulds growing on them, or by the carry-over of mycotoxins occurring in animal feedstuffs ingested by dairy cattle. An example of the first mentioned category is sterigmatocystin, a carcinogenic mycotoxin sometimes occurring on hard cheese. An example of the second category is aflatoxin M₁, a compound strongly suspected to be carcinogenic, which often occurs in milk. Due to the fact that processing of milk does not decrease the aflatoxin M₁ content, aflatoxin M₁ occurs in various dairy products. Sensitive methods of analysis for the determination of mycotoxins in dairy products have been developed in the last 10 years, most of them are based on TLC- or HPLC-separation procedures, followed by fluorimetric measurement.The most fundamental way to tackle the problem of mycotoxin contamination of dairy products is to prevent fungal growth on the dairy products or, in the case of carry-over of mycotoxins, in the crop before, during and after harvest. If measures to prevent fungal growth and mycotoxins production are not taken or fail, one can sometimes resort to physical or chemical methods to eliminate mycotoxins.     

Sampling Foods for Mycotoxins

It is difficult to obtain precise and accurate estimates of the true mycotoxin concentration of a bulk lot when using a mycotoxin-sampling plan that measures the concentration in only a small portion of the bulk lot. A mycotoxin-sampling plan is defined by a mycotoxin test procedure and a defined accept/reject limit. A mycotoxin test procedure is a complicated process and generally consists of several steps: (1) a sample of a given size is taken from the lot, (2) the sample is ground (comminuted) in a mill to reduce its particle size, (3) a subsample is removed from the comminuted sample, and (4) the mycotoxin is extracted from the comminuted subsample and quantified. Even when using accepted test procedures, there is uncertainty associated with each step of the mycotoxin test procedure. Because of this variability, the true mycotoxin concentration in the lot cannot be determined with 100% certainty by measuring the mycotoxin concentration in a sample taken from the lot. The variability for each step of the mycotoxin test procedure, as measured by the variance statistic, is shown to increase with mycotoxin concentration. Sampling is usually the largest source of variability associated with the mycotoxin test procedure. Sampling variability is large because a small percentage of kernels are contaminated and the level of contamination on a single seed can be very large. Methods to reduce sampling, sample preparation and analytical variability are discussed.     

新疆乳品工业的现状和前景

论述了新疆乳品工业的发展现状、特点及其在全国所处的地位;介绍了新疆乳品工业的技术亮点和创新点;分析了存在的主要问题和发展优势以及有利条件。笔者认为,新疆是我国奶业大省和重要的奶源基地,自然环境优越,奶类资源丰富,现代化奶牛养殖业和乳品加工业已经初具规模,少数民族居民素有饮奶和食用乳制品传统,周边国家多,市场潜力大,具有发展乳品工业得天独厚的条件,随着中央和自治区一系列方针政策的贯彻、落实,新疆乳品工业前景光明。     

生物质燃料成型技术研究现状

主要论述了生物质燃料成型技术的发展历史、现状、成型原理、影响因素、工艺类型、成型机型、成型方法等,并提出了成型技术存在的主要问题以及发展前景。