Screening of maize germplasm for nutritional and technological parameters

In many countries maize is largely grown as food for humans, whereas in Italy it is mostly used for animal feed or industrial uses. However, the diffusion of gluten intolerance or celiac disease among consumers in recent years suggested introducing larger amount of maize, a gluten-free cereal, into diets. In this context, it is important to identify the characteristics which contribute to the identification of the most suitable raw materials, from a nutritional and technological point of view. Consequently, a set of 28 maize inbreds (comprising both old and recent Italian inbred lines and public line B73) were chosen for a preliminary screening of maize genotypes. The lines were multiplied in Bergamo during 2014 and reproduced by self-pollination. After harvest, their ears were dried, shelled and ground with a laboratory mill by a 0.5 mm sieve. Chemical analyses were carried out for the following parameters: crude protein, crude lipid, total starch, soluble phenols (SPs) and total antioxidant capacity (TAC), as measured by ABTS assay. Pasting properties and calorimetry analyses were also carried out, in order to evaluate the potential value of these flours for the food industry. The results of the chemical descriptors indicated the presence of a large variability among the lines for all the considered parameters. The older inbreds and the two amylose extender genotypes were characterized by the highest percentages of protein and lipid, whereas public line B73, which has almost black kernels, showed the highest values for SPs and TAC. Even the rheological properties showed a high variability among the samples. The most interesting characteristics, in terms of pasting properties (MicroViscoAmilograph test), were observed for lines Lo1481 and Lo1530. These samples showed the highest values for peak viscosity and setback indices, suggesting the formation of hard gels that make the flours suitable for pasta making. On the contrary, flours from lines Lo1501 or Lo1550 presented lower setback and could be used as an ingredient for bread and biscuits. The two amylose extender flours were characterized by an unusual trend, without viscosity increase and gelatinization peak. In general, the genetic variability present in maize germplasm for many compounds and technological parameters can be exploited, through the activation of specific breeding programs, for the selection of raw materials with a potential, innovative application in the food industry.