Francesca Vanara

Influence of agricultural practices on Fusarium infection, fumonisin and deoxynivalenol contamination of maize kernels

Mycotoxins in cereals are an economic and health problem. They are mainly produced in the field and are influenced by environmental conditions during ripening and by agricultural practices. The aim of this research was to evaluate the effect of combined agronomic techniques on fumonisins and deoxynivalenol contamination in maize kernels. Six experimental fields were prepared in North Italy from 2005 to 2007. Two hybrids with different maturity times and 6 different combinations of agricultural practices (sowing time, plant density, N fertilisation and European corn borer (ECB) control with insecticide) were compared for ECB incidence and severity, Fusarium ear rot incidence and severity, F. verticillioides and F. graminearum kernel infection and fumonisin and deoxynivalenol contamination. In temperate climates, where ECB attack is consistent, the production of maize kernels with a low fumonisin content can be enhanced by a correct insecticide application against second-generation ECB larvae and by an earl...

Determination of maize kernel hardness: comparison of different laboratory tests to predict dry-milling performance

BACKGROUND Numerous foods are produced from maize, and grain hardness has been described to have an impact on grain end-use value, and in particular for dry-milling performance. RESULTS Thirty-three samples of commercial hybrids have been analysed for test weight (TW), thousand-kernel weight (TKW), hard:soft endosperm ratio (H/S), milling time (MT) and total milling energy (TME) through the Stenvert hardness test, coarse:fine material ratio (C/F), break force (HF) and break energy (HWF) through the puncture test, floating test (FLT), kernel dimensions and sphericity (S), protein (PC), starch (SC), lipid (LC), ash (AC) content and amylose:amylopectin ratio (AS/AP).Total grit yield (TGY) has been obtained through a micromilling procedure and used to compare the efficiency of the tests to predict the dry-milling performance. TW, H/S, MT, TME, C/F, FLT, S, PC, SC and AS/AP were significantly correlated with each other. TW has been confirmed to be a simple estimator of grain hardness. Among the hardness tests, C/F was shown to be the best descriptor of maize milling ability, followed by FLT. A good correlation with TGY has also been observed with H/S, MT, TME and PC, while SC, S and AS/AP seem to play a minor role. The puncture test (HF and HWF) did not offer good indications on the impact of hardness on kernel grinding properties. CONCLUSION This study can be considered as a contribution towards determining kernel properties which influence maize hardness measurement in relation to the end-use processing performance.

Moniliformin analysis in maize samples from North-West Italy using multifunctional clean-up columns and the LC-MS/MS detection method.

A fast clean-up method has been developed to purify maize extracts and to detect moniliformin (MON) in maize samples from North-West Italy over a four-year period (2008–2011). The method is based on the use of MycoSep® 240 Mon clean-up columns (Romer Labs®). Samples were extracted using acetonitrile/water (84:16, v/v), and the extracts were purified with previously described clean-up columns. The liquid chromatography–tandem mass spectrography (LC-MS/MS) analysis has been carried out by means of hydrophilic interaction chromatography (HILIC), combined with negative electrospray mass spectrometry. The method has a recovery of 76–91% (relative standard deviation, RSD%: 6–14%), a limit of detection (LOD) of 1 µg kg–1 and a limit of quantification (LOQ) of 4 µg kg−1. Naturally contaminated maize (108 samples) was analysed for MON content. The average percentages of positive samples was 93% with the following ranges (µg kg−1): 33–2606 (2008);

Management of fumonisin contamination in maize kernels through the timing of insecticide application against the European corn borer Ostrinia nubilalis Hübner

The European corn borer (ECB), Ostrinia nubilalis, is the principal pest of maize in Central and South Europe. It is known to promote Fusarium verticillioides infection in maize grain, a recognized producer of fumonisins. Field experiments were performed in 2006 and 2007 in two sites in NW Italy to determine the effects of the timing of insecticide application on ECB damage, fungal ear rot and fumonisin contamination under natural conditions. Different insecticide application timings were compared, from maize flowering to approximately 15 days after the flight peak of adult ECB. At harvest, the ears were rated for incidence and severity of ECB damage, fungal ear rot symptoms and fumonisin (FB1 + FB2) contamination. In all years/sites, treatments applied at the beginning of consistent ECB flight activity were most effective in controlling insect damage on ears. Fungal ear rot and fumonisin contamination were significantly affected by ECB control. The efficacy of the best timing of insecticide application in controlling fumonisin contamination was, on average, 93% compared to the untreated control. Contamination levels of these mycotoxins increased with either an earlier or later treatment. Furthermore, an earlier insecticide application showed lower fumonisin contamination than a treatment applied after the adult flight peak. Production of maize kernels and maize-based foods that do not exceed the maximum international and EU permitted levels for fumonisins could be enhanced by appropriate insecticide treatment against second generation ECB. The optimum time for insecticide application is between the beginning of consistent adult flight activity and the flight peak.

Role of the European corn borer (Ostrinia nubilalis) on contamination of maize with 13 Fusarium mycotoxins

The European corn borer (ECB) plays an important role in promoting Fusarium verticillioides infections and in the consequent fumonisin contamination in maize grain in temperate areas. The objective of this study was to evaluate whether the ECB feeding activity could also affect the occurrence of emerging mycotoxins in maize kernels. During the 2008–10 period, natural infestation of the insect was compared, in field research, with the protection of infestation, which was obtained by using an entomological net. The ears collected in the protected plots were free from ECB attack, while those subject to natural insect attacks showed a damage severity that varied from 10% to 25%. The maize samples were analysed by means of an LC-MS/MS-based multi-mycotoxin method, which led to the detection of various metabolites: fumonisins (FUMs), fusaproliferin (FUS), moniliformin (MON), bikaverin (BIK), beauvericin (BEA), fusaric acid (FA), equisetin (EQU), deoxynivalenol (DON), deoxynivalenol-3-glucoside (DON-3-G), zearalenone (ZEA), culmorin (CULM), aurofusarin (AUR) and butenolide (BUT). The occurrence of mycotoxins produced by Fusarium spp. of Liseola section was affected significantly by the ECB feeding activity. The presence of ECB injuries increased the FUMs from 995 to 4694 µg kg–1, FUS from 17 to 1089 µg kg–1, MON from 22 to 673 µg kg–1, BIK from 58 to 377 µg kg–1, BEA from 6 to 177 µg kg–1, and FA from 21 to 379 µg kg–1. EQU, produced by F. equiseti section Gibbosum, was also increased by the ECB activity, by 1–30 µg kg–1 on average. Instead, the content of mycotoxins produced by Fusarium spp. of Discolor and Roseum sections was not significantly affected by ECB activity. As for FUMs, the application of a strategy that can reduce ECB damage could also be the most effective solution to minimise the other mycotoxins produced by Fusarium spp. of Liseola section. Graphical Abstract

Fumonisin Distribution in Maize Dry-Milling Products and By-Products: Impact of Two Industrial Degermination Systems

In temperate areas, the main limitation to the use of maize in the food chain is its contamination by B-series fumonisins (FBs) during cultivation. Since the content of this group of mycotoxins may be distributed unevenly after milling, the aim of this study was to compare the distribution of FBs in maize fractions derived from two industrial dry-milling processes, that is, a dry-degermination (DD) system and a tempering-degermination (TD) system. Grain cleaning reduces FBs by about 42%. The germ of the two degermination processes showed a similar FB content of kernel after cleaning. Conversely, an animal feed flour resulted in a FB content that was two times higher than whole grain before cleaning. A significant FB reduction was observed in the milling fractions in both processes, with a higher reduction in the TD system than in the DD one. The average decontamination respect to uncleaned kernels in the DD process was 50%, 83% and 87%, for maize flour, break meal and pearl meal, respectively, while it was 78%, 88% and 94% in the TD process for small, medium and flaking grits, respectively. Among the milling fractions, the flaking grits with the highest particle size resulted in the highest FB reduction.

Influence of Agricultural Management on Phytochemicals of Colored Corn Genotypes (Zea mays L.). Part 1: Nitrogen Fertilization

In this study, the influence of nitrogen (N) fertilization (170 versus 300 kg of N/ha) on the content of bioactive compounds of whole-meal flour of 10 different colored corn genotypes was investigated. Considerable differences in antioxidant capacity and phytochemical concentrations were observed among genotypes. Higher N fertilization rates significantly ( p < 0.05) increased the content of both total cell-wall-bound phenolics and xanthophylls (lutein and zeaxanthin). Nevertheless, the main phenolic acids (ferulic, p-coumaric, and sinapic acids) as well as the antioxidant capacity and content of β-cryptoxanthin, β-carotene, and total anthocyanins did not show significant differences as far as the N fertilization rate is concerned. For corn cultivation, the application of high N fertilization rates, generally carried out to obtain higher grain yields, could positively influence the content of some bioactives particularly in years characterized by high rainfall levels responsible for N leaching from the soil.