1 kg fruit- peel and seeds removed
1 kg sugar, white
10 ml (1 tbsp) calamansi juice or 1.25g (1/4 tsp) citric acid
5 tsp pectin powder (should be mixed with sugar)
1. Select ripe but firm fruits.
2. Wash them thoroughly under running water or through several changes of water.
3. Blanch the fruit by dipping them in hot water. Dipping will help reduce the microbial load.
4. Remove peel, seeds and core. Crush the by chopping or mixing in a blender.
5. Cook the fruits gently until soft. Fruits which break down readily, like berries, do not require additional water; but they are simmered for 15 minutes, before adding the sugar. Those requiring water needs boiling until the volume is reduced by about one-third.
6. Add acid to fruits with low acidity such as papaya, guava, and mango. For every kilogram of fruit, add 1 tbsp (10 ml) of calamansi or lemon juice or 1/4 tsp (1.25 ml) of citric acid.
7. Add sugar and boil until the setting point is reached. Temperature reaches 105-105oC or sugar concentration reaches 60-65oBrix.
8. Remove the jam from the heat immediately after setting point is reached. To keep the fruit from rising to the top of the finished product, stir the mixture for five minutes at frequent intervals after cooking. Stir gently to prevent air bubbles from forming in the jam.
9. Hot-filled the jam into sterile glass jars with lid. The temperature should be 82-85oC. If the filling temperature is too hot, the steam will condense on the inside of the lid and drop down onto the surface of the product. This will dilute the product’s surface making it vulnerable to microbial attack. Set them aside to cool undisturbed for proper gel formation.
The following physico-chemical properties can be measured for quality assurance purposes. Properties should be uniform every batch. Adjustments can be computed using Pearson’s Square formula. All artificial preservative can be omitted but will cause decrease in product shelf life.
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.