On-Line Determination of Water Activity at the Lean Surface of Meat Products During Drying and Its Relationship with the Crusting Development

Abstract One of the main problems in drying of meat products is the surface hardening or crusting. The crusted surface layer is harder and less permeable than the inner part of the product. A dramatic increase of hardness during drying in dry-cured meat products has been found when the water content reaches a critical value. The water content can be related with the water activity by sorption isotherms. Therefore, an on-line measurement of the water activity at the surface (aws) could be used by the control system in order to avoid the crusting problem. The aim of this study was to evaluate a methodology for the on-line water activity determination at the lean surface of raw or salted meat during drying and relate this determination with the crusting development. Water activity at the surface was estimated from the heat balance (aws h) in salted meat slices and in unsalted and in salted loin samples. The proposed methodology was able to monitor the aws in both products. The estimated aws h was related with the crusting development in loin samples, showing its potential application in control systems for avoiding the crusting development during the drying of meat products.