Caracterização dos compostos presentes na farinha de estigma de milho (Zea mays L.) como proposta alimentar

Abstract

For over five thousand years, maize domestication controlled by teosinte has taken place in the American continent enabling Zea mays to represent one of the most important vegetables for humankind. The monocotyledonous plant belongs to the genus Poaceae and has typical characteristics that give rise to technological, food and pharmaceutical-chemical applications. When its fruiting bodies are being developed, there is the formation of ears and their associated maize silks. Looking like hair strand, maize silk has several therapeutic applications associated with its phytochemicals. The current study, thus, has proposed the creation of a flour made of maize silk and the prospect of its components, considering its nutritional and technological importance, the antibacterial potential of protein extracts and its toxicity to Artemia franciscana. The flour was generated by lyophilization process followed by milling process. Physical and physical-chemical characterization methods were adopted along with the identification of macromolecules that are important in food matters. It was also carried out an evaluation of antinutritional factors occurrence, technological applicability (presence of proteases and starch, mainly) and protein profile in different aqueous extracts – obtained through the extraction of flour in water, sodium phosphate buffer, sodium chloride and glycine buffers. The generated flour showed good nutritional values compared to equivalent commercial products: 8.53% (± 0.37) of proteins, 4.042% (± 0.25) of ash, 0.8478% (± 0.01) of lipids, 8.46% of humidity and 78.12% of carbohydrates. All the resultant aqueous extracts showed different phytochemicals such as tannin, saponin, leucoanthocyanidin, flavone, flavonol and xanthan, but the absence of starch. Regarding the components of biotechnological applicability, the presence of proteases in the glycine extract (0,1mol.L -1 pH 2.0) and a lack of hemagglutinating activity with different types of the evaluated erythrocytes were identified. The extracts obtained from basic and acid glycine buffer showed the highest content of soluble proteins: 0.837 mgP/mL and 0.740 mgP/mL, respectively. For the acid extract, the results showed a pool of proteins revealing two relevant bands, ranging below 31 kDa. It was not possible to make a detailed identification for the basic extract. Protein-concentrated extracts did not demonstrate antibacterial activity for any of the evaluated strains, including the probiotic ones. The investigation about the toxicity to Artemia franciscana has indicated that the tested concentrations of extracts shows no mortality, overcoming 9 the survival rate when comparing it to the one from the control group. Thus, a flour made of maize silk proves to be nutritional rich, with the presence of proteases, becoming a possible candidate for biotechnological applications. Furthermore, protein extracts were not toxic when tested in the model organism Artemia franciscana, nor were they harmful to the development of lactic acid bacteria.