United signed Henriquez from Universidad de Chile in 2012 and after finishing last season on loan at Wigan Athletic he scored on his senior debut for the English champions in this month's 1-1 draw at Swedish side AIK Fotboll in a pre-season friendly.
"Angelo has made a tremendous impact on the game in his short career so far," former United manager Alex Ferguson, now a director, said on the club's website (www.manutd.com).
"His pace is a great asset and he reads the game really well for someone of such a young age," he added.
Zaragoza finished bottom of the 20-team La Liga standings last term and are currently 14th in the second division, or Liga Adelante, after drawing their opening two games.
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(Reporting by Iain Rogers, editing by Ed Osmond)
