In Miketz 42,2 it is written:
וַיֹּאמֶר--הִנֵּה שָׁמַעְתִּי, כִּי יֶשׁ-שֶׁבֶר בְּמִצְרָיִם; רְדוּ-שָׁמָּה וְשִׁבְרוּ-לָנוּ מִשָּׁם, וְנִחְיֶה וְלֹא נָמוּת
The translation according to Machon Mamre is
And he said: 'Behold, I have heard that there is corn in Egypt. Get you down thither, and buy for us from thence; that we may live, and not die.'
Why is corn called שבר? Isn't שבר something broken?
I am not looking for Midrashim based on the word, but rather for a direct etymological answer based on the word itself.