ISHS Acta Horticulturae 464: International Postharvest Science Conference Postharvest 96
EFFECT OF TEMPERATURE AND SIZE REDUCTION ON RESPIRATORY ACTIVITY AND SHELF-LIFE OF VEGETABLES |
| Authors: | J.P. Behrsing, R.B. Tomkins, J.M. Hutchin, P. Franz |
| Abstract:
The respiratory activity, maximum shelf-life and factors contributing to quality loss were determined for several fresh-cut vegetables stored at 1, 4.5 and 10°C in high humidity air. The respiration rates of broccoli florets, broccoli stem pieces, cauliflower florets, julienne and diced carrots, chopped red coral lettuce and chopped butter lettuce were compared to their whole counterparts. Respiratory activity of all products was reduced with lower storage temperature. The effect of size reduction of vegetable pieces on respiration rate varied with the product. Broccoli and cauliflower florets showed an initial rise in respiratory activity after chopping, but the equilibrium respiration rate was similar to that of intact heads. The respiratory activity of broccoli stem pieces equilibrated at a lower rate than whole broccoli following an initial increase after chopping. Chopped butter lettuce had a higher respiration rate compared to whole lettuce at each temperature (see Figure 1). Julienne and diced carrots showed a similar pattern, with respiration rate of julienne pieces being greater than that of diced product, which in turn respired more quickly than the intact roots. The major limit to shelf-life was microbial spoilage in broccoli stem pieces, cauliflower florets, julienne carrots, and cos lettuce. For broccoli florets, senescence and yellowing of the flower buds limited shelf-life at all temperatures, although microbial spoilage was also limiting at 10°C. Enzymatic browning was the major limiting factor for butter lettuce held at 1°C and 4.5°C, while at 10°C microbial spoilage contributed to loss of quality. The main causes of quality loss for diced carrot were desiccation and white blush. Storage temperature had a significant (p = 0.05) effect on quality loss. Depending on the product, shelf-life was increased between 48% and 154%, by storage at 4.5°C rather than at 10°C. This temperature range occurs during marketing and is often exceeded. Further increases in shelf-life of 12.5% to 85% were observed by storage at 1°C rather than at 4.5°C. | |
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