Rita Redaelli

Characterization of Maize Germplasm for the Chemical Composition of the Grain

The aim of this research was the evaluation of food grain quality-related traits in a collection of maize populations of different origins, currently used in the framework of breeding and genetic programs. A total of 1245 maize samples were scanned by near-infrared (NIR) spectroscopy to develop calibration equations to evaluate the content of crude protein, crude lipid, starch, and floatation area. The performances of the NIR equations developed in our study were assessed using the determination coefficient of cross-validation r(2) (ranging from 0.66 to 0.91) and the ratio of performance deviation (1.71-3.31) in flour starch and grain crude protein, respectively. Among the genotypes considered, 93 landraces belonging to the European Union Maize Landraces Core Collection (EUMLCC) were also analyzed for their content of lutein, zeaxanthin, and total carotenoids. Among the populations of the collection, several accessions, interesting from a nutritional point of view, were identified: VA25, VA158, VA282, VA284, VA285, VA567, VA572, VA814, VA950, VA1057, and VA1179. They showed protein and lipid contents ranging between 12.52 and 15.16% and 5.26 and 7.17%. The range of variation observed for antioxidants in the EUMLCC was quite large. Lutein varied between 1.03 and 21.00 mg kg(-1) dm, zeaxanthin varied between 0.01 and 35.00 mg kg(-1) dm, and total carotenoids ranged from 1.09 to 61.10 mg kg(-1) dm. Recently, a single cross-hybrid was developed from the ITA0370005 population; this hybrid had a high carotenoids content and is currently being used by the Italian food industry.

Use of near infrared reflectance and transmittance coupled to robust calibration for the evaluation of nutritional value in naked oats

A rapid accurate and precise method for simultaneous determination of β-glucan and protein content in naked oat samples, based on the coupling of near-infrared spectroscopy and chemometrics, is presented. In particular, three different spectroscopic approaches [near infrared reflectance (NIR) and transmittance (NIT) on flour and NIT on whole grains] and various spectral pretreatments were considered. To account for the possibility of outlying samples, a robust version of the PLS algorithm (namely partial robust M-regression) was used. All the models resulted as accurate as the reference methods, reflectance spectroscopy being the technique providing the best outcomes. Variable reduction by inclusion of the most relevant predictors only (as evaluated by VIP scores) resulted in simpler and, in one case, more parsimonious models, without loss in accuracy.

Development of a NIRS calibration for total antioxidant capacity in maize germplasm.

The feasibility of predicting total antioxidant capacity (TAC) in maize flours by NIRS was assessed in a set of 391 samples, comprising Italian and public inbred lines, F1 seeds, commercial hybrids and traditional varieties, using ABTS direct assay as reference value. A subset of 81 samples were also used to test the development of a calibration model for soluble phenolic content (SPC), whereas 101 samples were analysed by DPPH assay. The models obtained for TAC by ABTS in different genetic materials were characterized by a good stability of the regression coefficients and showed a RER>2, allowing to develop both global and specific predictive models for this trait. On the contrary, only specific models were developed for SPC, and no predictive models were obtained for TAC by DPPH assay. These results demonstrated that NIR spectroscopy could be applied efficiently to the screening of the genotypes currently selected for the food industry.

Effects of genetic and agronomic factors on grain composition in oats

The effects of genetic variability and agronomic practises on the chemical compounds of the grain were evaluated in a set of oat cultivars (16 naked and four husked) grown in different experiments in the years 2004–2008. In the first experiment, carried out for two years, β-glucan and Total Dietary Fibre (TDF) from eight oat cultivars, grown under three different levels of nitrogen fertilization and two seed doses, were considered. The second experiment, involving 12 cultivars for two years, explored the variation of β-glucan solubility and further characterized six cultivars for the content of TDF and arabinoxylans. In both experiments, genotype was found to exert the largest effect on the grain composition; nitrogen levels and seed doses had positive significant effects on protein and β-glucan contents, but did not affect fibre content. Among the naked cultivars, Irina, Abel, Luna, Hendon and Expression showed a good ability to accumulate the examined grain compounds. However, in general, the highest contents of protein and β-glucan were found in the groats of husked cultivars, suggesting that specific breeding programs are a crucial step to identify the suitable naked oat genotypes to produce foods of high nutritional value.

Evaluation of groat percentage in oats (avena sativa l.) by near infrared spectroscopy

In oats (Avena sativa L.), groat percentage (GP) is defined as the amount of hull-less kernels obtained after de-hulling, expressed as a percentage of the weight of the sample. GP is considered a good marker of milling yield in oats, but so far a quick and reliable method to define it has been lacking. In the present study, a group of oat cultivars, grown in Italy in 1998–2000, was used to develop near infrared (NIR) spectroscopy calibration equations for this parameter. The material for the analysis was represented by whole kernels. The coefficient of determination R2c was 0.80. The ability of the equation to predict GP was then verified using a separate set of oat samples. These preliminary results indicated that NIR spectroscopy could be considered a good tool to predict GP in oat cultivars; analysis of whole kernels allowed time to be saved by avoiding the grinding stage in sample preparation.

Gene sequences of vromindolines in Avena species

Vromindolines, a family of oat starch-bound proteins responsible for the extremely soft endosperm of this cereal, are characterized by a tryptophan-rich domain and ten conserved cysteine residues, as it was observed in the starch-bound proteins from other cereals, and proved to be specific of the genus Avena. Two-dimensional electrophoresis of vromindolines from different oat species, both cultivated and wild, revealed that they are present in all genomes and ploidy levels, with no major differences in their molecular weight and electrophoretic mobility. PCR amplification and sequencing of genes coding for VIN-2 and VIN-3 indicated that both proteins are strongly conserved across the species analysed. Some differences were found between diploid and polyploid accessions at specific amino acid positions along the protein. In particular the C-genome accessions (A. clauda, A. eriantha, A. ventricosa) differed from the A-genome diploids (A. canariensis, A. damascena, A. longiglumis, A. nuda, A. strigosa) for some peculiar sequences. Tetraploids (A. barbata, A. magna and A. insularis) showed two sequences each for both proteins; the variability observed in them was similar to that found in A. sativa. The characteristics of these genes could help to clarify the genetic relationship among the various species of the genus Avena. Moreover, the knowledge of the genetic control of these proteins represent an important tool for the modulation of oat endosperm texture.