Zooming In and Out with VoiceOver On
The solution to the problem: Turn off the Voice-over with three clicks of the home button.
do the Pinch gestures .
turn on the Voice-over with three clicks.
And the growing possibility now appears possible match with sliding up and down from 0 to 100
With voiceover on, use the rotor (rotate with two fingers) until Zoom is selected. Works in Maps, for instance.
Then, a quick swipe down or up to zoom in or out respectively. Voiceover announces the zoom factor (e.g., 16x).