PROCESS FOR RETAINING PERICARP COLOUR AND
EXTENDING SHELF LIFE OF LITCHI 

A sequential surface chemical dip combination process has been developed at BARC for retaining attractive pinkish-red color of litchi fruit during prolonged storage (45 days) at low temperature (4 ºC). The treatment helps in retaining major color pigments (anthocyanins) of litchi pericarp and inactivates the enzyme (polyphenol oxidase) responsible for its browning. The treatment also kills microbes (bacteria, yeast and mold) present on the fruit. All these changes result in quality maintenance of litchi during prolonged storage without adversely affecting its sensory and nutritional properties as the fruits are dip treated with GRAS (Generally Recognized As Safe) chemicals.

INTRODUCTION

Demand for litchi fruit is quite high due to its delicious taste, unique aroma, and juicy nature, but supply is very limited due to its highly perishable, and non-climacteric (ripens on the tree itself) nature apart from localized cultivation and seasonal availability. The color of the fruit turns brown soon after harvest. Fruits also get spoiled soon after harvest due to physiological and microbiological changes. Although India is the second largest producer of litchi, a commercially viable technique is not available here for its shelf life extension. Non-availability of a proper technique is the biggest barrier for ambitious vendors involved in trade of fruits. The technology developed offers a practical solution to the difficulties associated with litchi trade.

PRODUCT CHARACTERISTICS

• Retention of attractive color (anthocyanins), nutritional quality, and complete inhibition of post-harvest browning.
• Almost complete microbial decontamination.
• No chemical residues, No harmful effect.
• The product is organoleptically acceptable for more than 45 days.

ADVANTAGES

• Market availability of processed fruits for prolonged period after harvest season.
• Processed fruits are of high quality and have a very good export potential through sea and air route.
• Have industrial potential as many secondary products can be prepared viz; Juice, Fermented beverage such as wine, Shelf stable dried litchi fruit, Fruit jam, squash, marmalade, blends with ice-creams, custards and jellies.

ADDITIONAL COMMERCIAL ADVANTAGES

• Highly profitable with less investment.
• The entire procedure can be scaled up as per the requirement from small to industrial scale.
• It does not require any costly instrument and much technical expertise, and hence can be operated by providing minimum training to the personnel.
• Longer shelf life can facilitate greater market coverage.
• The product can be supplied in packed and sealed condition.
• Requires less man power and energy, Minimum waste generation.
• A consumer can keep the processed-packed fruit in the refrigerator and can consume for more than a month.

INFRASTRUCTURE REQUIREMENTS

Materials and Equipments

• Heating facility (viz. LPG stoves/ Electric heater)
• Thermometer (scale 40-80ºC)
• Stainless steel container
• Plastic tubs
• Hand held sieve
• Low density polythene packets (LDPE)
• Heat sealer
• Muslin cloth
• Hand gloves
• Clean water

Space

• Hygienic working area: (Approximate area required - 1500 sq. ft.)
• Cold storage or refrigerator facility [temperature 4(±2) ºC] for preserving the processed fruits
  

Power

• As per requirement

Manpower

• One unskilled workers and one supervisor