Jam is a product made from puree, juice or pulp with sugar, pectin and acid. During the concentration process, the dry matter content increases (dry matter content> 50%) and a gel forms on cooling. This product is preserved for a long time dueto their high sugar content, proper acidity and good coagulation. There are 3 kinds of jam: Jelly, Jam and Marmalade. Jelly is a jam made from juice. Jam is made from puree and Marmalade is made from whole or cut fruit. Product can be used in breakfast, tea, filling, served with bread.
These steps in fruit jam process are in following
Preparation of the fruit
Wash the fruit in clean water, peel it and remove stones and damaged parts. Chop large fruits into smaller pieces. The fruit should be as fresh as possible and slightly under-ripe. Over-ripe and/or bruised fruit will not make good jam as it has low levels of Pectin and/or acid
Preparation of the jars and lids
Wash the glass jars and lids and put them into a large saucepan. Fill the saucepan with water so that the jars and lids are covered and heat until the water boils for about 5 minutes. The lid is sterilized by soaking in an antiseptic solution
Heat treatment
To make jam, the fruit also needs to be softened (turned into pulp):
Place the washed fruit in a pan and heat over a low heat. This is to soften the fruit and allow the juice to be released. Next, add the sugar and continue to heat gently until all the sugar has dissolved. Add the pectin if you are using it. If you cannot buy pectin, you can use apples as these are a good source of pectin.
Return the pan with the pulp plus dissolved sugar and pectin to the heat to boil the mixture. The aim of boiling is to reduce the water content of the mixture and concentrate the fruit and sugar. The final Total Soluble Solids (TSS) content of a jam (also known as the “Degrees Brix” or “end-point of the jam”) should be 65 to 68%.
Filling and packaging
Cool the jam to about 85°C and pour into the hot sterilised jars. The jars should be hot when they are filled or they may crack. If the jam is hotter than 85°C, condensation will form under the lid. This can drop down onto the surface of the jam and dilute it, which may allow mould to grow. If the jam is colder than this, it will be difficult to pour.
Fill the jars to about 9/10ths of their volume. Place the clean lids onto the jars, fasten them loosely and invert the jars to sterilise the lid with the hot jam.
Storage
Jams and jellies that are made according to the correct recipe will have a long shelf life. Jam stored in glass jars will have a longer storage life (up to 12 months) than those packed in plastic bottles (up to 4 months). For the optimum storage time, jams should be stored in a cool dry place, away from direct sunlight.
REFERENCE
1. Lê Văn Tán, Nguyễn Thị Hiền, Hoàng Thị Lệ Hằng, Quản Lê Hà (2008), Công nghệ bảo quản và chế biến rau quả, NXB Khoa học và Kỹ thuật Tp Hồ Chí Minh.
2. Susan Azam Ali, 2008, HOME-BASED FRUIT AND VEGETABLE PROCESSING: A Manual for Field Workers and Trainers. BOOK 2: Practical Guidance and Recipes. FAO