Ebla

ˀà-me-ṣu, ˀà-mi-ṣu-um - Sum. NINDA.AD₆ (‘leavened bread’) (VE 128; Conti 1990: 83)

PS
*ḥmṣ̂ - to be sour (Fronzaroli 1971: 623, 635, 641; Kogan 2011: 239)