Effects of modified atmospheres on textural and cell wall changes of asparagus during shelf‐life

Abstract

Spears of asparagus cultivator (cv) Regal harvested from a commercial crop on 16 May, 30 May, and 6 June, 1989 were packaged in rigid PVC trays (300g per pack) over-wrapped with non-perforated 15 p stretch PVC (Auto RMF-A), a similar micro-perforated film or with a highly perforated control film. Packs were held at 8°C for 1 d, then transferred to 20°C to simulate commercial cool chain distribution and ambient display. Respiration rates as mg C 0 2 production kg-' h-' were determined for each harvest, and changes in the pack atmosphere composition and weight losses were monitored during shelf-life. On the day of harvest, and after 3 and 6 d shelf-life, shear forces required to cut through spears and visual quality were determined, and cooked samples were assessed for tenderness, stringiness, flavour, and bitterness by a trained sensory panel. At these intervals, samples of asparagus from each treatment were also extracted for alcohol-insoluble residues (AIR'S), from which the composition of sugars and cell wall phenolics were also determined.Rates of respiration and the extent of pack atmosphere modification were similar for each harvest; in non-perforated packs, C 0 2 increased to > 11% and O2 fell to < 2% and in microperforated packs, C 0 2 equilibrated to ca 5 6 % and O2 decreased to a minimum of ca 6-7%. The shear forces needed to cut stems increased during 6 d shelf-life; this increase was greatest for control-packed spears and least for those from non-perforated packs. Regrowth (elongation of the stem and opening of bracts) was almost eliminated in non-perforated packs, and much reduced in micro-perforated packs. Asparagus in micro-perforated packs became slightly less tender and more stringy, whereas control-packed spears became much tougher and stringier during shelf-life; changes in flavour and bitterness were slight. Levels of most cell wallsugars changed little, although some obvious changes were detected during shelf-life; galactose decreased in all treatments, arabinose decreased and xylose content increased considerably (67%) in control-packed spears. Similarly, the lignin content of asparagus increased by >400% in control, by 200% in micro-perforated and by < 100% in non-perforated packs.The relationships between instrumental and sensory methods for assessing textural changes in asparagus and the changes in cell wall composition, and the effects of modified pack atmospheres on these changes are discussed. The possible benefits and limitations of modified atmosphere (MA) packaging to retard post-harvest deterioration, particularly textural changes in asparagus are also discussed.

Evolution of Quality Characteristics of Minimally Processed Asparagus During Storage in Different Lighting Conditions

“…The change in texture of asparagus has been related to fibrousness and can be attributed to lignification, but different studies have shown that other modifications of the cell wall composition could also be related to this alteration (Everson and others 1992; Rodríguez and others 2004; Albanese and others 2007). In our case, minimally processed asparagus underwent gradual softening during storage which made cutting more difficult and meant an increase in the effort necessary to complete it ( A 2 in Figure 4).…”

“…The speed with which changes occur in the attributes of color and texture in minimally processed asparagus is clearly affected by the conditions of storage and display. Several studies have concentrated on the influence of storage temperature on the shelf life of this product or packaging film permeability (Everson and others 1992; Siomos and others 2000). However, few studies have analyzed the influence that the unavoidable exposure to light during the time they are on sale has on the evolution of the quality parameters of this product (Nilsson 2000; Siomos and others 2000).…”

Effect of a prestorage treatment with 6-benzylaminopurine and modified atmosphere packaging storage on the respiration and quality of green asparagus spears

“…The technology of MAP can extend the shelf-life of asparagus spears (Baxter & Waters, 1991;Everson, Waldron, Geeson, & Browne, 1992). Some researches showed that keeping green or white asparagus in non-perforated polyethylene bags at 1°C or polyethylene bags at 2°C, the shelf-life can reach 8-35 days (GarciaGimeno, Castillejo-Rodriguez, Barco-Alcala, & ZureraCosano, 1998;Lill, 1980;Osuna, Zurera, & Garcia, 1995).…”

Characterization of Asparagus Lignin by HPLC

“…The chemical basis of hardening is related to modifications of the cell wall composition and has traditionally been associated with lignification (Salunkhe and Desai 1984; Smith and Stanley 1987; Everson and others 1992). The presence of lignin is confined to vascular plants, where it is mainly deposited in cell walls of tissues involved in mechanical support or in water conduction such as xylem, sclerenchyma, phloem fibers, and periderm.…”