Postharvest Handling of Berries

Abstract

Strawberries, raspberries, and blackberries are highly appreciated fruits due to their unique taste and high content in antioxidant and bioactive compounds. They are rich in phenolic compounds, mostly lavonoids and anthocyanins, which are responsible for fruit color and can exert antioxidant, antimicrobial, anti-inlammatory, anticancer, and cardioprotective efects. However, berries have a short storage life, as a result of their high respiration and softening rate, and susceptibility to mechanical damages and decay. As berries are considered non-climacteric fruit, they must be harvested at, or near to full maturity, because they will not continue to ripen normally once detached. At this stage, the fruit presents appropriate organoleptic atributes but may become softer and more sensitive to mechanical damage. Thus, it is crucial to be extremely careful during harvest and postharvest handling and to sort, grade, and pack the berries in the ield, avoiding excessive manipulation of the fruit. The most extended methods to maintain quality during the postharvest period are prompt precooling and storage at low temperatures. Modiied and controlled atmospheres with up to 20-kPa CO 2 and 5-10-kPa O 2 reduce microbial growth and delay senescence but can afect bioactive compounds with a cultivar-dependent response observed for these technologies.

Recent advances in postharvest technologies to extend the shelf life of blueberries (Vaccinium sp.), raspberries (Rubus idaeus L.) and blackberries (Rubus sp.)

“…Similarly, the same treatment reduced Salmonella by 3 log CFU g -1 in inoculated raspberries [66]. The feasibility of this technology, however, could be limited by the residual surface moisture left on berries, which can encourage microbial growth [27].…”

“…[26]. As discussed below, management of fungal disease is hindered by a current lack of practical sanitisation treatments [27].…”

“…Postharvest loss of moisture alters fruit appearance, texture and flavour, and reduces marketable weight [33]. Raspberries and blackberries are more prone than blueberries to dehydration due to the lack of epicuticular wax, with a maximum acceptable moisture loss of 6% [27]. In blueberries, moisture loss of >2-8% (depending on the cultivars) reduces the waxy bloom [33], causes loss of firmness and leads to shrivelling [34].…”

“…In general, sanitisation by washing is not recommended for berries as it can promote mechanical damage and residual surface moisture, particularly in raspberries owing to their hollow structure [27]. The few studies that have reported the efficacy of sanitisers mostly examined blueberries with a focus on food safety rather than fruit quality and control of fungal decay.…”

“…In contrast, enclosed punnets to replace vented clamshells could allow CO 2 accumulation during storage, but observed levels were insufficient to control fungal decay in blackberries [118]. In addition, the resistance of plastic packaging to water vapour permeation prevents water vapour due to produce transpiration escaping from the packaging and leads to moisture condensation that favours mould growth [27]. Perforated MAP could aid by accelerating gas exchange and increasing the permeability to water vapour.…”