In a survey of nine carrot crops stored during four seasons 1978 -82, the major causes of wastage were spreading soft rots caused by Botrytis cinerea and Rhizoctonia carotae; rots caused by Sclerotinia sclerotiorum, Mycocentrospora acerina and StemphyIium radicinum were only of secondary importance. Storage weight losses were lower and roots remained turgid for up to 40 wk in an ice-bankcooled store at 0.5 "C, 97 -98% r.h., whereas carrots in conventionally-cooled stores at 2 -2.5 "C, 90 -95% r.h. became flaccid after a few months. In some crops, losses due to fungal spoilage were also lower in the ice-bank store. In two seasons' losses, mostly due to B. cinerea, were similar in hand-and machineharvested roots ; pre-storage washing of carrots grown on mineral soils increased the incidence of Botrylis rots, and reduced rotting by R. carotae, but had no effect on spoilage of roots from peat soils. Post-harvest fungicide treatment with benomyl or iprodione (0.5 g/litre a.i.) effectively reduced rotting by B. cinerea and S. sclerotiorum, but not by R. carotae. The recoveries of sound carrots after 23 -29 wk storage were consistently highest (mostly > 80%) from fungicidedipped roots stored under ice-bank conditions, but recoveries from all treatments were lower and more erratic after 35 -40 wk because of increased fungal spoilage.The practical applications of long-term ice-bank storage of UK-grown carrots are discussed. 0 1988 Association of Applied Biologists 504

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.

An experimental modified-atmosphere packaging system was used to compare the atmospheric compositions that developed within sealed packs made from a range offilms of differentpermeability properties. The effects of these conditions were then related to the primary quality attributes, i. e. background skin colour and flesh firmness, and the sensory quality of Discovery apples. Concentrations of CO, and 0, within packs were dependent on the permeability of the film and the holding temperature. In packs sealed with low density polyethylene films and held at 2PC, equilibrated atmospheres containing 3-5% CO, and 5 4 % 0, developed within 1-2 days. Softening and yellowing of fruit was markedly retarded. In packs sealed with some less permeable films, atmospheres containing 12-20% CO, and 0.94% 0, developed within 1-2 days, resulting in retarded softening and yellowing of the fruit but also a high incidence of tainting. Possible commercial applications, benefits and limitations of modifiedatmosphere packaging are discussed.