Shelf life assessment of green asparagus packaged in polypropylene macro-perforated and micro-perforated

The very short shelf-life of asparagus (Asparagus officinalis, L.) is mainly related to its high respiratory activity which continues after harvesting. The perishable nature of the product poses the challenge to develop effective storage methods to extend its post-harvest life. The loss of quality is mainly perceived by consumers in the wrinkling of stems, hardening, loss of the green colour and brightness. The aim of this study was to evaluate the quality of green asparagus ('Vegalim') packaged in polypropylene macro-perforated with a piercing density of 7 holes/cm2 and micro-perforated coextruded PP with a row of central holes spaced each 3 cm having an oxygen transmission rate of 38800 cc/m2. The quality evaluation of asparagus was assessed by measuring changes in the main physical-chemical parameters and by visually monitoring the product, during a period of 32 days of cold storage. Weight loss, instrumental texture and colour degradation were measured. Data were analysed with a specific testing software. Image analysis was performed. The weight loss of the samples, which is mainly due to moisture loss, was 16% in macro-perforated film, while it was negligible in micro-perforated film (mean value 0.4%). Maximum shear force and cutting energy were measured cutting asparagus spears into three parts: tip (0-6 cm, measured from the apex of the spear), middle portion (6-12 cm) and base (12-18 cm). For samples packaged in the macro-perforated film, hardness increased in all three parts throughout the experimental period. Shear force of the middle portion of samples packaged in micro-perforated film did not change during the 32 days of the experiment. Hue and Chroma were similar in both samples. The shelf life of refrigerated green asparagus could be extended to 32 days with packaging in micro-perforated film. In literature temperatures of 5°C were considered adequate for keeping the shelf life of asparagus about 11-14 days, it is relevant how the utilization of the correct plastic film to wrap asparagus is the goal for any companies producing this vegetable to significantly extend their marketability.