Determination of puncture injury susceptibility of tomatoes Miche `le Desmet *, Jeroen Lammertyn, Nico Scheerlinck, Bert E. Verlinden, Bart M. Nicolaı ¨ Laboratory/Flanders Centre of Postharvest Technology, Katholieke Universiteit Leuven, W. De Croylaan 42, B-3001 Leuven, Belgium Received 9 January 2002; accepted 26 June 2002 Abstract Puncture injury leads to large qualitative and quantitative losses of loose tomatoes (Lycopersicon esculentum Mill.) when they pass through handling operations. Some cultivars are less susceptible to puncture injury, which is a desirable characteristic for tomato quality. It is, therefore, important that the puncture injury susceptibility of a new tomato cultivar is known, prior to commercialisation and large-scale production. In this research, a pendulum was designed to evaluate the puncture injury susceptibility of tomato cultivars in an objective way. Logistic regression was used as a statistical tool to model the influence of the impact energy on the incidence of puncture injury. This methodology was applied to two cultivars with different susceptibilities to puncture injury, ‘Tradiro’ (less susceptible) and ‘Blitz’ (very susceptible). Their susceptibilities to puncture injury were measured as a function of storage time and colour stage. It was found that: (i) tomatoes at harvest were less susceptible to puncture injury than after storage for several days; and (ii) colour at harvest had no effect on the susceptibility for puncture injury. This research revealed that the pendulum test in combination with logistic regression is a suitable method and a promising measurement tool to determine the puncture injury susceptibility of tomato cultivars. # 2002 Elsevier Science B.V. All rights reserved. Keywords: Puncture injury; Tomato; Impact; Pendulum; Logistic regression 1. Introduction Today’s markets demand high quality and fresh tomatoes with premium colour texture and fla- vour. Quality can be viewed as the absence of defects or a degree of excellence (Shewfelt, 1999). External damage on food products will not satisfy the consumers. To reduce damage, fruits and vegetables must be handled and distributed with care. The distribution chain in Belgium of fresh market tomatoes, grown in greenhouses, starts by harvesting the tomatoes by hand to minimise the damage. In the co-operative auctions, quality experts visually evaluate the colour at the blossom end of the tomato, using a colour card (V.B.T., Leuven, Belgium). The colour is expressed as a value from 1 (green) to 12 (very red). Normally tomatoes are harvested between colour 5, when the tomatoes are not directly consumed, and colour 9, * Corresponding author. Tel.:  /32-16-322376; fax:  /32-16- 322955 E-mail address: michele.desmet@agr.kuleuven.ac.be (M. Desmet). Postharvest Biology and Technology 27 (2003) 293  /303 www.elsevier.com/locate/postharvbio 0925-5214/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved. PII:S0925-5214(02)00115-1