We have many guyabano trees when I was in high school. More than 100 plants if my memory serves me right. We love eating soursop especially the sweet variety. But slowly the trees are cut down one by one. The main reason is marketing. This fruit is very hard to market because of its very short shelf life. A ripe fruit today will be rotten by tomorrow.
The answer to this problem could be processing. For those who still have soursop plantation, you can follow these simple steps provided by Department of Agriculture.
1. Wash and peel guayabano. Remove core and seeds. Cut into small pieces. Mix two cups water for every three cups of pulp.
2. Pass guayabano pulp through a juice extractor or corn mill grinder. Add little by little so juice can be fully extracted.
3. Strain through a stainless steel strainer. Measure extracted pulp juice and add one cup of water for every two cups juice. Add one cup sugar for every 3” cups of pulp mixture.
4. Pass sugared mixture through a juice mixer or beat with a rotary egg beater. Place the mixture in an enamel casserole or a stainless steel kettle, and cook until it simmers (about 90 °C). Do not let it boil. Lower the heat and stir from time to time until mixture become thick.
5.Pour cooked mixture into tall tin cans while still hot, leaving 1/4 inch space on top of the mixture. Seal the cans and place them in a pressure cooker for 15 minutes at 10 pounds pressure.
Measure the following physico-chemical properties and and adjust accordingly to your set standard. This properties should be uniform every batch.
a. sugar content. Sugar concentration can be increased by adding sugar or can be lowered by adding water or pulp.
b. pH. This can be lowered by adding citric acid or can be increased by adding water or pulp.
c. titrable acidity. Same as in (a), just replace sugar with citric acid. Be cautious because citric acid affects both pH and titrable acidity.
Adjustments can be computed using Pearson’s Square formula.