Post harvesting operationsWaxing fruits and vegetables : Post harvesting operationsWaxing fruits and vegetables By KHALID Sayed Mohammad Naim
SF2M-Master Student ISA Lille-France
Dec 2010 Food Processing homework 1 Table of contents: : Table of contents: Introduction
Advantages vs. Disadvantages
References Food Processing homework 2 Introduction : Introduction External appearance vs. 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. Food Processing homework 3 Fruits and Vegetables Benefited by Waxing : Fruits and Vegetables Benefited by Waxing Fruits:
tangerine Food Processing homework 4 Vegetables:
yam Advantages vs. disadvantages of waxing : Advantages vs. disadvantages of waxing Improve appearance
Prevent moisture loss
Longer postharvest Life(Cassava)
Reduced postharvest Decay
Reduce susceptibility to Chilling Injury
Reduce the weight loss.
Replace the natural wax.
Increase the freshness
Decrease the rate of transpiration
Reduce the shrinkage losses.
Inhibit mold growth
Prevent other physical damage Food Processing homework 5 Artificial Appearance
Wax Whiting (Chalking)
may trap certain pesticide Slide 6: Food Processing homework 6 Slide 7: Food Processing homework 7 How wax acts? : How wax acts? Food Processing homework 8 After waxing Slide 9: Food Processing homework 9 Sources ?
3 types PROPERTIES OF WAX : PROPERTIES OF WAX • Kneadable at 20° C.
• Easily emulsifiable.
• Should not impart undesirable odour.
• Should be economical.
• Efficient drying performance.
• Non-sticky or tacky.
• Should never interfere with the quality of fresh fruit / vegetable.
• Melts above 40° C without decomposition.
• Has relatively low viscosity.
• Capable of being polished by slight pressure.
• Translucent to opaque form but not like glass. Food Processing homework 10 Waxing methods: : Waxing methods: Liquid Paraffin wax method
Slab wax method
Dipping or cold wax method Food Processing homework 11 Waxing methods: : 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 material is used.
2. Slab wax method: (Roller Brushing)
In this case the wax is pressed against rapidly revolving brushes. But the efficiency is very less. Food Processing homework 12 Slide 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
Distance of fruit from the spray
Number of 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. Food Processing homework 13 Slide 14: Food Processing homework 14 Safety of waxes : Safety of waxes Food Processing homework 15 FDA ( it is generally accepted safe) conclusion : conclusion Coating improves product appearance 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 done by batch processing.
Safety of food product should be maintained in the coating operations. Food Processing homework 16 References : References Lisa Kitinoja and Adel A. Kader . Small-Scale Postharvest 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