1. Post harvesting operationsWaxing fruits and vegetables
By KHALID Sayed Mohammad Naim
SF2M-Master Student ISA Lille-France
Dec 2010
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2. Table of contents:
Introduction
Advantages vs. Disadvantages
Wax action
Sources
Properties
Application methods
Safety
Conclusion
References
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3. Introduction
External appearancevs. quality vs. market acceptance
It is the first attribute.
Shiny and glossy appearance.
Various types of waxes and edible surface coatings may be applied to fruits and vegetables to improve the cosmetic features (shine, color) of the product.
Waxing is recommended only for good quality products
Waxing consists of applying a thin layer of edible wax to the outer surface of the product.
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4. Fruits and Vegetables Benefited by Waxing
Fruits:
avocado (pear)
breadfruit
carambola
coconut
guava
grapefruit
Lemons, lime
mango
orange
papaya
passion fruit
pineapple
tangerine
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Vegetables:
bitter melon
cassava
cucumber
eggplant
peppers
Pumpkins
sweetpotato
tomato
yam
5. Advantages vs. disadvantages of waxing
Improveappearance
Preventmoistureloss
Longer postharvestLife(Cassava)
ReducedpostharvestDecay
Reduce susceptibility to Chilling Injury
Reduce the weight loss.
Replace the natural wax.
Increasethe freshness
Decrease the rate of transpiration
Reduce the shrinkage losses.
Inhibitmoldgrowth
Prevent other physical damage
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ArtificialAppearance
AddedCost
Surface Burn
Wax Whiting (Chalking)
Off-flavordevelopment
maytrap certain pesticide
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8. How wax acts?
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After waxing
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Sources ?
3 types
10. PROPERTIES OF WAX
Kneadableat 20 C.
Easilyemulsifiable.
Should not impart undesirable odour.
Shouldbeeconomical.
Efficient drying performance.
Non-sticky or tacky.
Should never interfere with the quality of fresh fruit / vegetable.
Melts above 40 C without decomposition.
Has relativelylowviscosity.
Capable of being polished by slight pressure.
Translucent to opaque form but not like glass.
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11. Waxing methods:
Liquid Paraffin wax method
Slab wax method
Spray method
Dipping or cold wax method
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12. Waxing methods:
1. Liquid Paraffin wax method:
In this method fruits and vegetables are dipped in hot paraffin. Some times resins are added. The main disadvantage of this method is too much of coating materialisused.
2. Slab wax method: (Roller Brushing)
In this case the wax is pressed against rapidly revolving brushes. But the efficiencyisveryless.
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13. 3. Spray method:
Spraying of melted wax on the fruit, which is subsequently brushed mechanically until a film of desired thickness is obtained. The wax is dissolved in a suitable solvent. This depends on,
The pressure employed
Volume of wax used
Wax temperature
Distance of fruit from the spray
Numberof spray nozzles.
4. Dipping or cold wax method:
Fruits and vegetables are washed and then without being dried are dipped into a wax emulsion of proper concentration. They are dried before packing. Purified wax is odour less, tasteless and nontoxic and it can be heat- sealed.
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15. Safety of waxes
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FDA ( it is generally accepted safe)
16. conclusion
Coatingimprovesproductappearance and colour,
coating is an effective method of value addition and preservation for the food product
Continuous Mechanization is not available for various coating operations. Till now, many of the coating operations are doneby batch processing.
Safety of food product should be maintained in the coating operations.
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17. References
Lisa Kitinoja and Adel A. Kader . Small-ScalePostharvest Handling Practices: A Manual for Horticultural Crops. ( Nov 2003). UCDAVIS. Postharvest Horticulture Series No. 8E
WAXING FRUITS AND VEGETABLES. ( June 2004). Postharvest Handling Technical Bulletin No. 33. http://pdf.usaid.gov/pdf_docs/PNACY849.pdf
Preservation of fruits and vegetables by wax coating. (Aug 2006). http://www.techno-preneur.net/information-desk/sciencetech-magazine/2006/aug06/Preservation.pdf
http://chillibreeze.in/rate-articles-get-your-writing-rated/feature-article/waxing-of-fruits-and-vegetables/