Stability of mycotoxins during food processing

The mycotoxins that commonly occur in cereal grains and other products are not completely destroyed during food processing operations and can contaminate finished processed foods. The mycotoxins most commonly associated with cereal grains are aflatoxins, ochratoxin A, fumonisins, deoxynivalenol and zearalenone. The various food processes that may have effects on mycotoxins include sorting, trimming, cleaning, milling, brewing, cooking, baking, frying, roasting, canning, flaking, alkaline cooking, nixtamalization, and extrusion. Most of the food processes have variable effects on mycotoxins, with those that utilize the highest temperatures having greatest effects. In general the processes reduce mycotoxin concentrations significantly, but do not eliminate them completely. However, roasting and extrusion processing show promise for lowering mycotoxin concentrations, though very high temperatures are needed to bring about much of a reduction in mycotoxin concentrations. Extrusion processing at temperatures greater than 150 degrees C are needed to give good reduction of zearalenone, moderate reduction of alfatoxins, variable to low reduction of deoxynivalenol and good reduction of fumonisins. The greatest reductions of fumonisins occur at extrusion temperatures of 160 degrees C or higher and in the presence of glucose. Extrusion of fumonisin contaminated corn grits with 10% added glucose resulted in 75-85% reduction in Fumonisin B(1) levels. Some fumonisin degredation products are formed during extrusion, including small amounts of hydrolyzed Fumonisin B(1) and N-(Carboxymethyl) - Fumonisin B(1) and somewhat higher amounts of N-(1-deoxy-d-fructos-1-yl) Fumonisin B(1) in extruded grits containing added glucose. Feeding trial toxicity tests in rats with extruded fumonisin contaminated corn grits show some reduction in toxicity of grits extruded with glucose.     

Reduction of fumonisin B₁ in corn grits by twin-screw extrusion

Abstract: This study was designed to investigate the fate of fumonisins in flaking corn grits during twin‐screw extrusion by measuring fumonisin B₁ (FB₁) and its analogs with a mass balance approach. Food grade corn grits and 2 batches of grits contaminated with FB₁ at 10 and 50 μg/g by Fusarium verticillioides M‐2552 were processed with or without glucose supplementation (10%, w/w) with a twin‐screw extruder. Extrusion reduced FB₁ in contaminated grits by 64% to 72% without glucose and 89% to 94% with added glucose. In addition, extrusion alone resulted in 26% to 73% reduction in the levels of fumonisin B₂ and fumonisin B₃, while levels of both mycotoxins were reduced by >89% in extruded corn grits containing 10% glucose. Mass balance analysis showed that 38% to 46% of the FB₁ species detected in corn extruded with glucose was N‐(deoxy‐D‐fructos‐1‐yl)‐FB₁, while 23% to 37% of FB₁ species detected in extruded corn grits with and without added glucose was bound to the matrix. It was also found that the hydrolyzed form of FB₁ was a minor species in extruded corn grits with or without added glucose, representing <15% of the total FB₁ species present. Less than 46% of FB₁ originally present in corn grits could be detected in the fumonisin analogues measured in this study. Research is needed to identify the reaction products resulting from extrusion processing of fumonisin‐contaminated corn products. Practical Application: Twin‐screw extrusion is widely used in food industry for its versatility. This technology may reduce the level of fumonisins in corn particularly with added glucose.     

Fate of Fusarium mycotoxins in maize flour and grits during extrusion cooking

Extrusion technology is used widely in the manufacture of a range of breakfast cereals and snacks for human consumption and animal feeds. To minimise consumer exposure to mycotoxins, the levels of deoxynivalenol (DON) and zearalenone (ZON) in cereals/cereal products and fumonisins B₁ and B₂ (FB₁ and FB₂) in maize are controlled by European Union legislation. Relatively few studies, however, have examined the loss of Fusarium mycotoxins during processing. The behaviour of FB₁, FB₂ and fumonisin B₃ (FB₃), DON and ZON during extrusion of naturally contaminated maize flour and maize grits is examined using pilot-scale equipment. DON and ZON are relatively stable during extrusion cooking but the fumonisins are lost to varying degrees. There is some loss of ZON when present in low concentrations and extruded at higher moisture contents. The presence of additives, such as reducing sugars and sodium chloride, can also affect mycotoxin levels. Moisture content of the cereal feed during extrusion is important and has a greater effect than temperature, particularly on the loss of fumonisins at the lower moistures. The effects are complex and not easy to explain, although more energy input to the extruder is required for drier materials. However, on the basis of these studies, the relationship between the concentration of Fusarium toxins in the raw and finished product is toxin- and process-dependent.     

Extrusion Cooking Reduces Recoverability of Fumonisin B1 from Extruded Corn Grits

A split-split plot design was used to determine the effects of extrusion cooking on the recoverability of the mycotoxin Fumonisin B₁ (FB₁). Unextruded and extruded samples of spiked corn grits were analyzed for FB₁ by two methods, commercial enzyme linked immunosorbant assay (ELISA) and HPLC. Extrusion cooking resulted in more apparent loss of FB₁ with mixing screws than nonmixing screws. Losses of recoverable FB1 (p≤0.05) were observed at 120°C and 160°C with the mixing screws. A linear increase in loss of recoverable FB₁ was observed (with the nonmixing screws) as the moisture content increased.     

Reduced toxicity of fumonisin B1 in corn grits by single-screw extrusion

Corn grits spiked with 30 microg/g fumonisin B1 and two batches of grits fermented with Fusarium verticillioides (batch 1 contained 33 microg/g, and batch 2 contained 48 microg/g fumonisin B1), which were extruded by a single-screw extruder with and without glucose (10%, dry weight basis) supplementation were fed to rats. Control groups were fed uncontaminated grits. Extrusion with glucose more effectively reduced fumonisin B1 concentrations of the grits (75 to 85%) than did extrusion alone (10 to 28%). With one exception, the fumonisin B1-spiked and fermented extrusion products caused moderately severe kidney lesions and reduced kidney weights, effects typically found in fumonisin-exposed rats. Lesions in rats fed the least contaminated grits (batch 1) after extrusion with 10% glucose were, however, significantly less severe and not accompanied by kidney weight changes. Therefore, extrusion with glucose supplementation is potentially useful for safely reducing the toxicity of fumonisins in corn-based products and studies to determine the optimal conditions for its use are warranted.     

脱胚玉米在加酶挤压过程中化学成分的变化

为了研究添加酶制剂的脱胚玉米在挤压机内部化学性质的变化情况,将正常工作的挤压机急停,迅速左右分开套筒,沿螺杆分段采集样品,分析挤压物的化学组成及降解特性。脱胚玉米在螺纹推送下由松散状态逐渐被压实,在螺杆前端发生塑性形变进而熔融。挤压脱胚玉米和挤压添加酶制剂脱胚玉米中的淀粉、直链淀粉和脂肪含量沿物料输送方向降低,而糊化度、还原糖和抗性淀粉含量逐渐增加。添加酶制剂的挤压脱胚玉米与挤压脱胚玉米相比较,在相同取料部位,淀粉、直链淀粉、抗性淀粉含量和糊化度降低,而还原糖含量增加。挤压改变了脱胚玉米成分的含量以及淀粉糊化和水解特性,酶制剂在挤压过程提升了淀粉的水解特性,但缺降低了糊化度。然而由于挤压剪切的破坏,酶活性沿物料输送方向降低。通过对脱胚玉米挤压机理的研究,可以更好地为脱胚玉米挤压蒸煮系统的设计和参数选择提供科学依据和理论基础。     

Effect of industrial processing on the distribution of fumonisin B1 in dry milling corn fractions

The aim of this study was to investigate the distribution of fumonisin B1 in various corn milling fractions processed by an industrial plant. Corn kernels and six derived milling fractions (germ, bran, large and small grits, animal feed flour, and flour) were sampled. In addition, in order to evaluate the effect of cooking, samples of polenta were prepared starting from naturally contaminated flour obtained from the industrial processing cycle. The industrial plant worked continuously at a rate of 60 tons per day. Two sublots of 5 tons each were investigated with samples of derived products taken at regular time intervals. Due to a similar heterogeneous distribution of fumonisin B1 with other mycotoxins, such as aflatoxins, the sampling scheme was derived from the European Directive 98/53 for aflatoxins. Both lots of kernels showed fumonisin contamination at 4.54 and 5.09 mg/kg, respectively. Germ, bran, and animal feed flour showed contamination levels, namely 8.92 mg/kg (lot 1) and 9.56 mg/kg (lot 2), 7.08 mg/kg (lot 1) and 8.08 mg/kg (lot 2), and 9.36 mg/kg (lot 1) and 6.86 mg/kg (lot 2) higher than large and small grits and flour (0.39 mg/kg [lot 1] and 0.42 mg/kg [lot 2], 0.60 mg/kg [lot 1] and 1.01 mg/kg [lot 2], and 0.40 mg/kg [lot 1] and 0.45 mg/kg [lot 2], respectively). These results seem to account both for the industrial yields of the derived products and the distribution of fumonisin contamination in a kernel. The cooking of polenta in a domestic pressure cooker did not affect fumonisin contamination because the mycotoxin concentrations were similar to those of the starting flour (0.40 and 0.45 mg/kg).     

Loss of Fuminosin B1 in Extruded and Baked Corn-Based Foods with Sugars

The objective of this work was to determine the effect of added sugars on fumonisin B₁ (FB₁) levels in baked corn muffins and extruded corn grits. Muffins containing added glucose had significantly lower FB₁ levels than muffins with sucrose, fructose, or no added sugar. Extrusion cooking of the grits resulted in significant (p< 0.05) reductions of FB₁ in all treatments relative to unextruded controls, but use of glucose resulted in greater reductions of FB₁ (45.3 to 71%) than did the use of fructose (29.5 to 53%) or sucrose (19.2 to 39%). When extrusion conditions were optimized, 92.1% loss of FB₁ was found when grits were extruded with glucose. Adding glucose to thermally processed food can result in a substantial reduction in FB₁ levels.     

Stability of zearalenone during extrusion of corn grits

The effects of extrusion cooking on the stability of zearalenone (ZEN) in spiked (4.4 microg/g) food-grade corn grits were investigated using a twin screw extruder. A ground rice culture material containing a high level of ZEN was used to spike the corn grits. The extrusion variables were screw type (mixing and nonmixing), temperature (120, 140, and 160 degrees C), and moisture content (18, 22, and 26%). Both unextruded and extruded samples were analyzed for ZEN by high-performance liquid chromatography. Extrusion cooking of the corn grits resulted in significant reductions of ZEN in grits extruded with either mixing screws or nonmixing screws, but use of mixing screws was somewhat more effective (66 to 83%) overall than nonmixing screws (65 to 77%). Greater reduction of ZEN was observed at either 120 or 140 degrees C than at 160 degrees C. The moisture content of corn grits was not a significant factor affecting reduction of ZEN during extrusion with either mixing or nonmixing screws.     

Levels of total fumonisins in maize samples from Italy during 2006–2008

We analysed a total of 2258 grain samples over a 3-year period (2006–2008) from 93 storage centers in the principal maize cultivation area of Italy to establish the levels of fumonisin contamination. Fumonisin concentrations were measured using ELISA (RIDASCREEN) fumonisin test kits. Mean levels of contamination were remarkably high in each year, with the highest value in 2006 (10.9?mg/kg) and the lowest in 2008 (4.8?mg/kg). Similarly, for each year, variations were quite large: from <LOQ to 77.0?mg/kg, <?LOQ to 26.3, and 0.1 to 19.0?mg/kg, respectively, in 2006, 2007 and 2008. The highest fumonisin concentration was found in samples harvested in Veneto (11.1?mg/kg) and Friuli Venezia Giulia (8.9?mg/kg), while the lowest were recorded in Emilia Romagna and Piemonte (4.6?mg/kg).     

Effect of Processing on the Physico-Chemical Characteristics of Quinoa Flour (Chenopodium quinoa,Willd)

The nature and extent of the modification of starch in quinoa, caused by various processes like cooking and autoclaving of the seeds, drum drying of the flour and extrusion of the grits was investigated by measuring the physico-chemical properties - the water absorption, water solubility, swelling power, viscosity and degree of gelatinisation - of the processed samples. Autoclaved samples showed the lowest degree of gelatinisation (32.5% by DSC) of the starch, while the degree of gelatinisation of the precooked/drum dried samples was found to be 97.4% by DSC method. Higher polymer degradation was observed in cooked samples than in autoclaved samples as seen in the gel chromatographic separation. The water solubility in cooked samples (5.44 to 15.58) and in autoclaved samples (7.02 to 9.64) increased with the process time. In the extrusion process, the moisture content as well as the compression ratio was found to affect the degree of starch modification significantly (p <0.01).     

Extrusion Cooking in Enzymatic Liquefaction of Wheat Starch

Wheat starch was treated for gelatinization, partial liquefaction, and subsequent further hydrolysis by extrusion cooking together with a thermostable Bacillus licheniformis α-amylase followed by batch incubation of the extrudates at 80°C. The degree of hydrolysis depended on the extrusion feed moisture content, enzyme concentration, mass temperature during extrusion cooking, and the length of the counter screw elements. The degree of hydrolysis was followed both by dextrose equivalent and by molecular weight distribution pattern as determined by high performance gel permeation chromatography. A reaction velocity model was shown to fit well to the kinetic data obtained. The enzyme was only incompletely inactivated by mercuric chloride suggesting the presence of also other than sulfhydryl dependent amylase.     

Fusaria and fumonisins in maize from Ghana and their co-occurrence with aflatoxins

Fifteen maize samples from four markets and processing sites in Accra, Ghana were analysed for fumonisins B1, B2, and B3. All samples contained fumonisins. Total fumonisin levels for 14 samples ranged from 70 to 4222 microg kg(-1). One sample of visibly mouldy kernels contained 52 670 microg kg(-1) total fumonisins. Mycological examination of the samples showed Aspergillus spp. as the most dominant fungi (76.4%) followed by Penicillium spp. (19.9%). Fusarium formed 2.6% with Fusarium verticillioides as the predominant Fusarium species. Thirty-two Fusarium strains representing five species isolated from the maize samples were tested for the production of fumonisins in maize substrates. From 95% (21 of 22) of the F. verticillioides strains tested, all three types of fumonisins were produced. Total fumonisin levels ranged from 127 to 11 052 microg g(-1). Additional studies on maize samples from 15 processing sites in Accra revealed a co-occurrence of both fumonisins and aflatoxins in 53% (8 of 15) of the samples.     

A comparison of the retention of vitamins B1, B2 and B6, and cooking yield in pork loin with conventional and enhanced meal-service systems

In this study different simulated meal-service systems were compared with respect to vitamin B₁, B₂ and B₆ retention, and cooking yield in pork roasts. Initially the roasts were cooked traditionally or sous vide. No significant differences were observed between cooking methods. Further processing included warm-holding, conventional cook-chill, modified atmosphere packaging (MAP) and sous vide. Compared to retention in the freshly cooked samples, vitamin B₂ retention remained unaffected, irrespective of the meal-service system used and storage period. As regards vitamin B₁ and vitamin B₆, retentions declined significantly, by 14% and 21% respectively during 3 h of warm-holding, and by 11% and 19% respectively after 1 day of storage and subsequent reheating (cook-chill, MAP and sous vide). Vitamin B₁ retention declined by an extra 4% during storage for 14 days (sous vide) (not significant) It is concluded that conventional and enhanced meal-service systems produce roasts with similar quality attributes. Adjustment factors of 15% and 20% for vitamin B₁ and B₆ respectively are suggested, in addition to the losses caused by the initial heat treatment.     

Occurrence of the C-series fumonisins in maize from the former Transkei region of South Africa

Fumonisins are a group of structurally related mycotoxins produced mainly in maize by Fusarium verticillioides and F. proliferatum. The most abundant naturally occurring analogue is fumonisin B(1) (FB(1)), with lesser amounts of fumonisin B(2) (FB(2)) and fumonisin B(3) (FB(3)) occurring. The C-series fumonisins (FCs) are structurally analogous to the B-series but lack the C-1 methyl group. Good and mouldy subsistence-grown maize samples were collected from the Centane and Bizana districts in the former Transkei region of South Africa. After extraction with methanol/water and clean-up on strong anion exchange solid phase extraction cartridges, FB(1), FB(2), FB(3), FC(1), FC(3) and FC(4) were determined by reversed-phase LC-MS/MS using positive ion electrospray ionisation. FB(1) levels in both good and mouldy maize from Centane (means (±SD) 2.75 ± 2.24 and 23.4 ± 12.5 mg kg(-1), respectively) were higher than the corresponding levels in maize samples from Bizana (means 0.056 ± 0.157 and 3.71 ± 5.01 mg kg(-1), respectively). Similarly, FC(1) levels in both good and mouldy maize from Centane (means 0.107 ± 0.099 and 0.814 ± 0.391 mg kg(-1), respectively) were higher than in Bizana, where FC(1) was detected in only one (0.018 mg kg(-1)) of 19 good maize samples and occurred in mouldy maize with a mean of 0.102 ± 0.135 mg kg(-1). A significant correlation (r=0.982, p<0.01) was observed between FB(1) and FC(1) levels in all samples, with FC(1) levels at 3.3% of the corresponding FB(1) levels. FC(4) levels were similar to FC(1), whereas only low amounts of FC(3) were detected.     

Distribution of fumonisins in dry-milled corn fractions in Argentina.

Corn samples and different dry-milled fractions collected from an industrial mill in Argentina were analysed. Average contaminations were FB(1) 1540 microg kg(-1), FB(2) 716 microg kg(-1) and FB(3) 152 microg kg(-1) in whole corn; FB(1) 135 microg kg(-1), FB(2) 39.1 microg kg(-1) and FB(3) 10.2 microg kg(-1) in corn grits; FB(1) 358 microg kg(-1), FB(2) 122 microg kg(-1) and FB(3) 45.9 microg kg(-1) in 'C' flour; FB(1) 148 microg kg(-1), FB(2) 52.5 microg kg(-1) and FB(3) 28.3 microg kg(-1) in corn meal; and FB(1) 4210 microg kg(-1), FB(2) 2010 microg kg(-1) and FB(3) 447 microg kg(-1) in germ and bran together. The fumonisin contamination level was approximately three times higher in germ and bran than in whole corn, 13 times higher than in 'C' flour and 29 times higher than in corn meal and corn grits. Taking into account the distribution of fumonisins in commercial dry-milled corn fractions and corn meal consumption in Argentina, a theoretical whole corn level of 6640 microg kg(-1) maximum of total fumonisins could be processed to obtain products considered safe for human health.     

Distribution of fumonisins and aflatoxins in corn fractions during industrial cornflake processing

The aim of this study was to investigate the distribution of fumonisins (B(1) B(2,) and B(3)) and total aflatoxins (B(1), B(2), G(1), and G(2)) in various corn processed fractions. 92 batches of whole corn and derived dry-milled fractions (animal feed flour, flaking grits, corn flour and corn meal) and cooked and roasted cornflakes fractions were industrially obtained. Samples were analyzed for both groups of mycotoxins by enzyme-linked immunosorbent assay (ELISA). Dry milling of corn led to a heterogeneous distribution of the two groups of mycotoxins in the different parts of the grain, with increased levels in fractions processed from outer layers (animal feed flour and corn flour) and decreased levels in fractions processed from inner portions, such as corn meal and flaking grits. Levels of fumonisins in cornflakes were lower than 400 microg/kg, the maximum tolerable limit set by the EU. By contrast, three samples of final product were found to exceed the aflatoxin maximum tolerable limit of 4 microg/kg. Animal feed flour showed concentration factors of 317 and 288% for fumonisins and aflatoxins, respectively. Food traceability system was used by the industrial companies which processed corn into breakfast cereals. Nevertheless, even though the use of food traceability, which is defined as the ability to trace any food, feed, food-producing animal or substance that will be used for consumption through all stages of production, processing and distribution, only initial fumonisin contamination of whole corn and contamination of animal feed flour and corn flour were found to be correlated.     

Occurrence of fumonisins B1 and B2 in broa, typical Portuguese maize bread

Fumonisin B(1) (FB(1)) and fumonisin B(2) (FB(2)) are mycotoxins mainly produced by Fusarium verticillioides, and Fusarium proliferatum, fungi species most commonly isolated from maize. The natural occurrence of FB(1) and FB(2) in broa, typical Portuguese maize bread, was evaluated in 30 samples. Twenty five were found positive with levels ranging from 142 to 550 microg kg(-1). The limit established by the European regulations was exceeded by 27% of the samples. The tolerable daily intake for fumonisin B(1), and B(2), alone or in combination, for all of the analysed samples, was lower than 2 microg kg(-1) body weight per day established by the European Commission.     

EXTRUSION BEHAVIOUR AND PRODUCT CHARACTERISTICS OF BROWN AND MILLED RICE GRITS

ABSTRACT

Extrusion behaviour of milled and brown rice grits obtained from six rice cultivars (Jaya, IR-8, PR-103, PR-106, Pusa No.1 and Basmati 385) was investigated using Brabender single screw extruder. Feed moisture of the grits was adjusted to 16%, and extrusion cooking was done at barrel temperature of 150°C and screw speed of 100 rpm. The milled and brown rice grits from different rice cultivars differed significantly with respect to extrusion behaviour and extrudate characteristi cs. Extrudates obtained from milled rice grits showed higher die pressure, expansion, water absorption index (WAI) and water solubility index (WSI) as compared to those from brown rice. WSI of extrudates varied from 3.38 to 10.5%, WAI from 5.20 to 6.90, die pressure from 6068 to 9325 kPa and expansion from 7.52 to 11.30 respectively. The grits from cultivars which had lower length-breadth ratio and mealy endosperm resulted into more expanded extrudates and hence were found to be more suitable from extrusion.     

Reduction of Moniliformin in Corn by Heat Processing

The effects of autoclaving, baking, extrusion, frying, and roasting on the stability of moniliformin (MON) in spiked (5 μg/g of MON) corn‐based food products were investigated. Roasting corn meal at 218 °C for 15 min had the most significant effect (p ≤ 0.05) on the reduction of MON (44.6%). Autoclaving creamed corn at 121 °C for 65 min resulted in only 10% reduction of MON. Reductions of MON ranging from 5.4 to 28.9% were observed when corn chips were prepared from spiked masa. MON was reduced by 42.2% when corn muffins were baked and by 26.7% when corn grits were extruded. Overall, MON showed heat stability similar to or greater than other Fusarium mycotoxins such as deoxynivalenol and fumonisin B₁