Wednesday, November 23, 2016

Post-harvest Management and Preservation of Pomegranates

If pomegranates are to be stored in packages, its storage capacity of totally dependent on proper peeling or pomegranate and quality of the arils. Storage becomes difficult if the arils/seeds are damaged during the process of peeling. There are various machines available in the market which helps in peeling and sorting pomegranate seeds. To continue with processing on such seeds, it is vital to disinfect pomegranate with the help of hydrogen peroxide. 

Ready-to-eat packages of pomegranate:

To prepare ready-to-eat packages of pomegranate, it is important to choose good quality fruit. They should be washed in clean and sterile water using chlorine. The seeds must be soaked in water with 100ppm chlorine and should later be cleaned in normal clean water. Chlorinated water used to clean seeds must have pH between 6 to 7. Usage of disinfected gloves during handling and entire process is recommended. 

Method:

Gently peel the pomegranate. Another enhanced option is to peel the seeds in clean and disinfected water. Keep aside broken or damaged kernel. Since pomegranate is acidic in nature, it is vital to remove broken or leaking seeds. In a package, acidic sap from such broken seeds can infect and rot other kernels resulting in foul smell. Transparent and turgid looking arils in good condition should be picked away. Stainless steel table or plastic containers disinfected by Food grade Hydrogen Peroxide should be used for sorting and collection. Pomegranate seeds should be disinfected by soaking for 5 minutes in a solution of 100 to 150 ppm sodium hypochlorite. Thus processed arils should be washed in clean water and then carefully be passed on a muslin cloth spread on a stainless steel table to dry the water. After the water is dried, they should be processed in a solution of lemon juice and water for 30 seconds. This solution should have 5% lemon juice extract. Lemon juice works as an antioxidant. It can be replaced by solution of ascorbic acid (5 gram per liter) or citric acid solution (5 gram per liter) or a mixture of both. If processed in these solutions for 30 seconds, they also work as antioxidants. 

The seeds after this process can be removed from the solution and they should be kept under cold blower (6to 8 degree Celsius) or high speed fan until all the water has dried out. The time required to drain the water depends on the blower speed and the thickness of layer of pomegranate arils. Depending on these factors, seeds are properly and completely dried out in 30 to 60 minutes. There are also machines available in the market to accelerate this process. Thus processed seeds can be packaged domestically. Packed ready-to-eat seeds stored at cold temperature which are suitable to launch in market. 4 to 6 degree Celsius is the ideal temperature to store such packed pomegranate seeds. Cold-chain plays an important role in increasing the shelf-life of processed arils.

Packaging:

Pomegranate arils packed using domestic machines and stored at 4 to 6 degree Celsius are edible for 3 to 4 days while those packed at 1 degree Celsius can stay till 6 days. Antioxidants and sanitizers used to process pomegranates should be checked for approval by the export countries. Generally used and almost globally approved chemicals are lemon juice, ascorbic acid, sodium hypochlorite and citric acid. The shelf life of these ready-to-eat pomegranate arils can be increased exponentially up to 14-16 days with the help of Modified Atmosphere Storage (MAP) by regulating the amount of nitrogen, oxygen and carbon dioxide in the atmosphere in which these packages are to be stored. This technology also maintains the desired microbial count for 14-16 days. 

Other natural substitutes like honey, lemon juice can also be used for processing which help in preserving the taste and turgidity along with increasing its shelf-life. Also, Food grade certified nano-silver and Hydrogen Peroxide along with MAP packaging help in maintaining the desired microbial count. Honey, citric acid and ascorbic acid work as antioxidants, increase product shelf-life and help in maintaining the medicinal value of the product thus increasing its market value.