How to convert points to a raster in QGIS (rasterize does not show z field)?

How to convert my points into a raster along the z attribute and a resolution of 5 minutes or 10 km

First I import the data as a .txt file and then I convert to a vector (shapefile). then I do: Raster> Conversion> rasterise (vector to raster). but the problem in the attribute fields I not find the z column, only the x, y coordinates. I do not know why?

x   y   z
2.88334 42.8458 350169
2.96667 42.8458 350169
2.88334 42.9292 352666
2.96667 42.9292 352666
3.05000 42.9292 352666

2.88334 43.0125 352666
2.96667 43.0125 352666
3.05000 43.0125 352666
2.80000 43.0958 353292
2.88334 43.0958 353292
2.96667 43.0958 352666
3.05000 43.0958 352666
2.80000 43.1792 353292
2.88334 43.1792 353292
2.96667 43.1792 352666

3.05000 43.1792 352666
3.13334 43.1792 353292
2.80000 43.2625 353292
2.88334 43.2625 353292
2.96667 43.2625 353292
3.05000 43.2625 353292
3.13334 43.2625 353292
3.21667 43.2625 353292
3.30000 43.2625 353293
2.71667 43.3458 353292

2.80000 43.3458 353292
2.88334 43.3458 353292
2.96667 43.3458 353292
3.05000 43.3458 353292
3.13334 43.3458 353293
3.21667 43.3458 353293
3.30000 43.3458 353918
3.38334 43.3458 353918
3.46667 43.3458 353918
3.55000 43.3458 353918

2.71667 43.4292 353292
2.80000 43.4292 353292
2.88334 43.4292 353293
2.96667 43.4292 353293
3.05000 43.4292 353293
3.13334 43.4292 353293
3.21667 43.4292 353293
3.30000 43.4292 353918
3.38334 43.4292 353918
3.46667 43.4292 353918

3.55000 43.4292 353918
3.63334 43.4292 353918
3.71667 43.4292 353918
2.80000 43.5125 353293
2.88334 43.5125 353293
2.96667 43.5125 353293
3.05000 43.5125 353293
3.13334 43.5125 353293
3.21667 43.5125 353293
3.30000 43.5125 353918

3.38334 43.5125 353918
3.46667 43.5125 353918
3.55000 43.5125 353918
3.63334 43.5125 353918
3.71667 43.5125 355171
3.80000 43.5125 355171
3.88334 43.5125 355171
2.88334 43.5958 353293
2.96667 43.5958 353293
3.05000 43.5958 353293

3.13334 43.5958 353293
3.21667 43.5958 353918
3.30000 43.5958 353918
3.38334 43.5958 353918
3.46667 43.5958 353918
3.55000 43.5958 353918
3.63334 43.5958 353918
3.71667 43.5958 355171
3.80000 43.5958 355171
3.88334 43.5958 355171

3.96667 43.5958 355171
2.96667 43.6792 353293
3.05000 43.6792 353293
3.13334 43.6792 353293
3.21667 43.6792 353293
3.30000 43.6792 353918
3.38334 43.6792 353918
3.46667 43.6792 353918
3.55000 43.6792 353918
3.63334 43.6792 353918

3.71667 43.6792 355171
3.80000 43.6792 355171
3.88334 43.6792 355171
3.96667 43.6792 355171
3.05000 43.7625 353293
3.13334 43.7625 353293
3.21667 43.7625 353293
3.30000 43.7625 353918
3.38334 43.7625 353918
3.46667 43.7625 353918

3.55000 43.7625 353918
3.63334 43.7625 353918
3.71667 43.7625 355171
3.80000 43.7625 355171
3.88334 43.7625 355171
3.96667 43.7625 355797
4.05000 43.7625 355797
3.13334 43.8458 353293
3.21667 43.8458 353293
3.30000 43.8458 353918

3.38334 43.8458 353918
3.46667 43.8458 353918
3.55000 43.8458 353918
3.63334 43.8458 353918
3.71667 43.8458 353918
3.80000 43.8458 353918
3.88334 43.8458 355797
3.96667 43.8458 355797
3.38334 43.9292 353918
3.46667 43.9292 353918

3.55000 43.9292 353918
3.63334 43.9292 353918
3.71667 43.9292 353918
3.80000 43.9292 353918
3.88334 43.9292 355797
3.46667 44.0125 353918
3.55000 44.0125 353918
3.63334 44.0125 353918
3.71667 44.0125 353918
3.80000 44.0125 355797

3.63334 44.0958 353918

Answer

You could to use "Raster Interpolation" (in Raster menu). Add your data using "Add Delimited Text Layer". (Menu Layer >> Add Layer >> Add Delimited Text Layer.

In Raster Interpolation you could to use Interpolation Method (TIN or IDW), and you could adjust the Cellsize.