The shelf life of fresh fruits and vegetables is determined by a combination of physical, physiological and microbiological factors that act throughout the supply chain, from harvest through transport and storage to retail display. These factors may be influenced – either positively or negatively – by the presence or absence of packaging.
Mechanical damage
Mechanical damage of fruits and vegetables may occur during transport, in retail display and during consumer handling (AESAN, 2023, OVAM, 2024). Typical forms of injury include abrasion, compression damage, cuts, and punctures. These injuries compromise structural integrity and may lead to cosmetic defects, physiological responses in the product itself, as well as microbiological spoilage by bacteria and fungi (AESAN, 2023).
Mechanical disruption of plant tissues breaks cellular compartmentalisation, allowing enzymes and substrates to interact, leading to enzymatic browning, as well as increasing metabolic activity, including respiration (AESAN, 2023, OVAM, 2024). Elevated respiration accelerates senescence, shortens shelf life and may also enhance ethylene production in climacteric produce, thereby promoting ripening and quality loss. Mechanical injury also facilitates microbial spoilage as damaged tissues provide entry points and nutrient-rich substrates for microorganisms, including pathogenic bacteria (AESAN, 2023). Trays, clamshells and top-sealed containers are commonly used packaging formats for protecting sensitive products against mechanical injuries (OVAM, 2024, White & Lockyer, 2020).
Water vapour exchange
Water loss is another important determinant of quality and shelf life in fresh fruits and vegetables (AESAN, 2023, Morya & Sharma, 2019, OVAM, 2024). After harvest, produce continues to exchange water vapour with the surrounding environment. Fruits and vegetables that are sold loose are directly exposed to ambient air in retail environments, where relative humidity is often lower than optimal. Water loss results in reduced turgidity, wilting and shrivelling (AESAN, 2023). This in turn may increase susceptibility to mechanical damage and microbial invasion. Products that have high surface area and delicate tissues – for example leafy vegetables, fresh herbs and berries – are especially susceptible to water loss (AESAN, 2023). Packaging can mitigate dehydration by creating a microenvironment with higher relative humidity around the product. Films and sealed trays reduce vapour diffusion and slow down transpiration (White & Lockyer, 2020). Such packaging also provides protection against mechanical damage.
Conversely, if humidity becomes too high, condensation may occur, which can negatively affect sensory quality and promote spoilage (OVAM, 2024). From a microbiological perspective, surface moisture increases the likelihood of spoilage bacteria and fungi to grow, especially in products with damaged tissues. For packaged products, materials and designs with appropriate water vapour permeability in relation to product characteristics and storage conditions should therefore be used (AESAN, 2023, OVAM, 2024).
Respiration rate
After harvest, produce continues to consume oxygen and produce carbon dioxide, using stored substrates to maintain cellular metabolism. The speed of this process influences the rate of senescence, loss of nutritional value and overall quality deterioration (Morya & Sharma, 2019, OVAM, 2024).
Respiration rates vary considerably between products. A non-exhaustive list of produce and their respiration rates is presented in OVAM (2024). Products such as broccoli, mushrooms and certain berry varieties exhibit comparatively high respiration rates, whereas others, such as apples (depending on variety) and cauliflower, show lower values. In climacteric fruits, respiration is closely correlated with ethylene production, which further regulates ripening processes (Hasan et al., 2024). Elevated metabolic activity therefore shortens potential storage life, particularly if temperature and atmospheric conditions are not optimally controlled.
Lower storage temperature may reduce the speed of respiration (Hasan et al., 2024, OVAM, 2024). Packaging may affect respiration indirectly by modifying gas exchange and the surrounding atmosphere. However, it is important that oxygen is not completely excluded from the packaging as it would lead to anaerobic conditions resulting in fermentation (OVAM, 2024). In certain types of packaging, the product’s own respiration is utilised to help protect and preserve the product. In passive modified atmosphere packaging (PMAP), the internal atmosphere develops naturally through the interplay between the respiration of the fresh produce and the gas permeability of the packaging material (Berk, 2013). This approach is commonly used for fresh, respiring products such as leafy greens and cut vegetables.