ABSTRACTDesorption isotherms at 25°C and 43°C and adsorption isotherms at 25°C were determined for salted and unsalted female roe of mullet (Mugil cephalus). Isotherms for ground white muscle of mullet were also determined for desorption at 25°C, 43°C, and 54.5°C, and for adsorption at 25°C. Adsorption‐desorption hysteresis was evident for the sigmoid shaped isotherms. At 45°C and 15 RH, and also at 45°C and 25 RH, mullet fillets dry almost four times faster than mullet roe. An air temperature lower than 45°C should be used to obtain an acceptable color for the roe.SUMMARYDESORPTION AND ADSORPTION isothems at several temperatures were determined for salted and unsalted female roe of mullet, and ground white muscle of mullet. All isotherms are sigmoid shaped, typical of isotherms for food products. Adsorption‐desorption hysteresis was also evident for salted and unsalted roe, and for ground white muscle. At any given temperature and relative humidity, the equilibrium moisture content for unsalted roe was always lower than that for salted roe.Under the conditions tested, mullet fillets dried almost four times faster than roe. Roe placed in an air stream did not dry faster than roe in still air at the same temperature and relative humidity. This indicated that the restriction to moisture removal was in the moisture migration within the roe rather than at the roe surface. Air temperature should be lower than 45°C to prevent excessive browning of the row. Browning began on the tips and continued toward the cen
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