A prototype impact system for firmness sorting of fruits (TOUCHLINE), developed initially by Chen and Ruiz-Altisent (Paper presented at AgEng 96, Madrid, Paper no. 96F-003), has been modified and installed in an experimental fruit packing line. The system consists of a lateral impact sensor with a control electronic circuit, a control software and an ejection system with three outlets regulated by a microcontroller. The lateral impact sensor detects the presence of fruit by means of an optical sensor and impacts it. Impact signal is obtained by an accelerometer and sent to a PC where it is processed by specific software to yield a firmness index. According to this index the software gives an order to the microcontroller of the ejection system and fruit is sent to its corresponding outlet. Several tests were carried out with spherical balls of cork, tennis and rubber, showing a good performance of the sorting system. (C) 2002 Elsevier Science Ltd. All rights reserved.