Postharvest Biology and Technology 91 (2014) 9–24 Contents lists available at ScienceDirect Postharvest Biology and Technology jou rn al h om epage: www.elsevier.com/locate/postharvbio Bruise damage measurement and analysis of fresh horticultural produce—A review Umezuruike Linus Opara ∗ , Pankaj B. Pathare Postharvest Technology Research Laboratory, South African Research Chair in Postharvest Technology, Faculty of AgriSciences, Stellenbosch University, South Africa a r t i c l e i n f o Article history: Received 24 July 2013 Accepted 14 December 2013 Keywords: Fruit Mechanical damage Bruise susceptibility Bruise resistance Bruise index Instrumented sphere a b s t r a c t Bruising is the most common type of mechanical damage affecting fresh horticultural produce, and reduces quality to the consumer and income to fruit and vegetable industries. Bruising can occur during harvest and at all stages of postharvest handling, especially during packhouse operations, transport and storage, and is one of the major physical defects contributing to downgrading and postharvest loss of fresh horticultural produce. Understanding susceptibility or resistance of produce to bruising is important in developing strategies for reducing the problem. Bruise quantification can be carried out using destruc- tive manual measurements and subsequent analysis, or using a range of non-destructive techniques. Novel and emerging non-invasive technologies for bruise measurement of fresh horticultural produce include near infrared spectroscopy, hyperspectral imaging, thermal imaging and nuclear magnetic res- onance imaging. Various mathematical models used to estimate bruise size are discussed, including the use of instrumented spheres to characterise the bruise potential of postharvest handling systems. A wide range of indices based on mathematical expressions of the physical and mechanical properties of fruit, the bruised portion and the energy of the handling system causing the damage have been proposed and applied to quantify the intensity or potential to damage for different commodities and even for the same commodity. Standardisation of bruise measurement and analysis methods is warranted to permit com- parison of research results on the effectiveness of pre- and postharvest treatments to reduce bruising, as well as facilitate inter-laboratory traceability of data. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Consumer satisfaction with product quality is the main objective of the production, handling, storage and distribution of fresh horti- cultural produce. Consumers primarily judge fruit quality based on appearance, and even a moderate amount of bruising can reduce consumer acceptance (Fig. 1). With the long marketing chain of many fruit and vegetables that is currently in place, bruising is a common problem (Sablani et al., 2006), and is one of the major physical defects contributing to downgrading and postharvest loss of fresh horticultural produce (Opara, 2007). According to Kader (2002), visual quality plays a vital role (up to 83%) in consumer choice, and it is highly affected by the presence of defects. In another study, bruising was found to be a more important barrier to pur- chasing than price (Harker, 2009). With regard to horticultural pro- duce, bruising has been defined as damage to plant tissue by exter- nal forces causing physical change in texture and/or eventual chem- ical alterations of colour, flavour and texture (Mohsenin, 1986). ∗ Corresponding author. Tel.: +27 21 808 4064; fax: +27 21 808 3743. E-mail addresses: opara@sun.ac.za, umunam@yahoo.co.uk (U.L. Opara). The presence of bruising and other types of mechanical dam- age (cuts, puncture, split, abrasion) causes significant economic loss of fresh produce due downgrading or rejection of the appear- ance quality by the consumer (Van Zeebroeck et al., 2007c; Prusky, 2011). In addition, researchers have also demonstrated that the presence of mechanical damage also accelerates physiological pro- cesses which lead to senescence and spoilage as well as loss of nutritional value. For instance, studies by Wilson et al. (1995) showed that a single bad bruise on an apple increased the rate of moisture loss by up to 400%. In another study, sweet potatoes showed a 72% increase in the respiration rate after physical impact (Saltveit and Locy, 1982), while bruised tomato tissue was reported to have lower vitamin C content than unbruised tissue (Moretti et al., 1998; Sablani et al., 2006). Furthermore, fruit affected by bruising easily ferment, rot, or get mildewed, and infect other undamaged fruit during storage (Opara et al., 2007; Prusky, 2011; Lü and Tang, 2012). Research on a wide range of fruit and vegeta- bles has shown that up to 30–40% of produce may be affected by bruising and other types of mechanical damage from harvesting to market (Peleg and Hinga, 1986), amounting to significant financial losses in the fresh produce industry (Hyde et al., 1993; Funt et al., 2000; Storey, 2007). Given these substantial losses and potential 0925-5214/$ – see front matter © 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.postharvbio.2013.12.009