Lecture 4 - Part 2
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What are the ingredients for jams and jellies?
Fruit or fruit juices (source of acid) Sugar Heat (extract pectin, cook the fruits) Pectin (Natural or Commercial) Acid (Natural or Commercial) -Sometimes already enough acid in them so no need to add extra source
Which fruits contain enough pectin and acid and only require sugar to be added?
Apples Grapes Blackberries Plums Citrus Fruits
What fruits need to have commercial pectin added?
Apricots Peaches Raspberries Strawberries
What is pectin?
Pectin fouund between cell walls of plant cells, act as cenet to hold everything together
When and what type of pectin forms a gel?
Proto Pectin (Unripe fruit) (No Gel) Pectin (Gel) Pectic Acid (Over ripe fruit) (No Gel)
What is the optimum pH for gelation?
3.2 pH < 3.0 …… Weak Gel pH > 3.5 … No Gel
What are the different tests you can do to see if there is enough pectin in your fruit?
Cook Juice + Sugar > Gel Formation indicates presence of Pectin 2) 1 Part Juice + 2 parts Alcohol> Precipitation of pectin indicates presence of Pectin 3) Jel-meter to measure viscosity
What is galacturonic acid and its relationship to galactose?
Galacturonic Acid: Building block of Pectin -structured similarly to galactose except for on C6 there is HO-C=OH
What happens to galacturonic acid in high pH?
Repel one another and both negative charce, so no gel
What happens to galacturonic acid in too much water?
Too much water and anot enooug =h sugar, and not enough carboxylic acid, it will H oond to water instead of carboxylic acid
What happens to galacturonic acid at pH 3-3.5?
Good gel formaiton
What happens when there is Ca present?
Can heve gel formaiton with Ca Resonance structure resutls in gel formation
What happens when sugar crystallization happens?
jelly failure because: Too much sugar Not enough acid Over cooking
What happens when the mix fails to gel?
jelly failure because: Lack of proper balance between sugar/acid/pectin Lack of acid/pectin in fruit Over cooking
what happens when mould forms on jelly mix?
jelly failure because: Jelly glasses not sterilized Jelly stored in warm, damp place Jelly not completely sealed
How do you get proper jelly, jam, marmalade, and conserves?
Jelly Juice + Sugar > Heat> Proper Consistency 2) Jams Small fruits or small pieces of fruit + Sugar> Heat > Proper Consistency 3) Marmalade (Jelly like product that contain thin slices of fruit) Sliced Fruit + Water > Cook > Sugar > Gel Formation 4) Conserves (Similar to Jams) (Fruit + Nut + Raisin) + Sugar > Cook > Proper Consistency