Lecture 4 - Part 2

Question 1

What are the ingredients for jams and jellies?

Answer 1

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

Question 2

Which fruits contain enough pectin and acid and only require sugar to be added?

Answer 2

Apples
Grapes
Blackberries
Plums
Citrus Fruits

Question 3

What fruits need to have commercial pectin added?

Answer 3

Apricots
Peaches
Raspberries
Strawberries

Question 4

What is pectin?

Answer 4

Pectin fouund between cell walls of plant cells, act as cenet to hold everything together

Question 5

When and what type of pectin forms a gel?

Answer 5

Proto Pectin
(Unripe fruit)
(No Gel)

Pectin
(Gel)

Pectic Acid
(Over ripe fruit)
(No Gel)

Question 6

What is the optimum pH for gelation?

Answer 6

3.2

pH < 3.0 …… Weak Gel

pH > 3.5 … No Gel

Question 7

What are the different tests you can do to see if there is enough pectin in your fruit?

Answer 7

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

Question 8

What is galacturonic acid and its relationship to galactose?

Answer 8

Galacturonic Acid: Building block of Pectin

-structured similarly to galactose except for on C6 there is HO-C=OH

Question 9

What happens to galacturonic acid in high pH?

Answer 9

Repel one another and both negative charce, so no gel

Question 10

What happens to galacturonic acid in too much water?

Answer 10

Too much water and anot enooug =h sugar, and not enough carboxylic acid, it will H oond to water instead of carboxylic acid

Question 11

What happens to galacturonic acid at pH 3-3.5?

Answer 11

Good gel formaiton

Question 12

What happens when there is Ca present?

Answer 12

Can heve gel formaiton with Ca

Resonance structure resutls in gel formation

Question 13

What happens when sugar crystallization happens?

Answer 13

jelly failure because:
Too much sugar
Not enough acid
Over cooking

Question 14

What happens when the mix fails to gel?

Answer 14

jelly failure because:

Lack of proper balance between sugar/acid/pectin

Lack of acid/pectin in fruit

Over cooking

Question 15

what happens when mould forms on jelly mix?

Answer 15

jelly failure because:

Jelly glasses not sterilized
Jelly stored in warm, damp place
Jelly not completely sealed

Question 16

How do you get proper jelly, jam, marmalade, and conserves?

Answer 16

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