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大綱

Postharvest Browning of Litchi Fruit by Water Loss and its Prevention by Controlled Atmosphere Storage at High Relative Humidity Y.M. Jiang and J.R. Fu

Introduction Postharvest browning of litchi was thought to be a rapid degradation of the red pigments by polyphenol oxidase (多酚氧化酵素), forming brown-colour byproducts

Introduction    Water loss results in a series of  biochemical and physiological changes, including substrate-enzyme (酵素基質) contact.

Introduction   Scott et al., and Underhill and Simons reported that : browning of litchi fruit, due to skin desiccation, was highly correlated with weight loss.

The objectives of this study investigated the relationship between water loss in controlled RH environment and fruit browning in relation to anthocyanin(花青素), polyphenol oxidase(多酚氧化酵素), pH, and membrane permeability

The objectives of this study  To control litchi fruit browning during controlled atmosphere storage

Materials and Methods

Materials and Methods    Fruit from the first lot were stored at various RHs at 20C and water loss, browning index, anthocyanin content, polyphenol oxidase activity, pH value, and relative leakage rate monitored through the experimental period.

Storage conditions Constant pressure air supply was divided into two streams, one dried to about 35%, and the other  humidified to  > 95% RH.

Storage conditions These streams were then ecombined, via metering values, to give the desired RHs(60, 70, 80, or 90%) and   flow rate (1 L/min).

Storage conditions  The RH sensor calibrated within an appropriate humidity range using saturated salt solutions

Browning assessment Sum of browned area on pericarp scale : 1 = no browning (excellent quality) 2 = slight browning 3 =< 1/4 browning 4 = 1/4-1/2 browning 5 => 1/2 browning (poor quality)

Controlled atmosphere storage    Controlled atmosphere :    (3-5% O 2 & 3-5% CO 2 at 1C)    Continuous flow : (100 mL/min, about 90% RH)

Results

Conclusion

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Reference