browning presentation

8/3/2019 Browning Presentation

1/15

Click to edit Master subtitle style

5/5/12

SBK3023FoodScience andNutrition

GROUP 3BROWNINGPREVENTION

NORFAZILAHBT

ZAINUL

(D20091035128)

AZIRENSANTHARAN

(D20091035141)

TUANZAKIAHBTTUAN

MAHMOOD

(D20091035112)

NURULIZZATIBT

MUSA20091035121

)


2/15

5/5/12

WHY SOME

FRUITS ANDVEGETABLES TURN

BROWN WHENCUT PEELED ????

?

??


3/15

5/5/12

This is due tobrowning

enzymaticreaction!!


4/15

5/5/12

When fruits or vegetable

are peeled or cut,

enzymes in the plant

tissue, POLYPHENOL

OXIDASE are exposed tothe air.

In the presence of


5/15

5/5/12

METHOD use to PREVENT browning enzymaticreaction..

Several methods can be applied to avoid enzymatic browning, based onINACTIVATING THE ENZYME (heat) or by REMOVING ESSENTIALCOMPONENTS (most often oxygen).


6/15

5/5/12


7/15

5/5/12

SET A (CHANGE PH)

HERE, WE HAVE USED 3 DIFFERENT BROWNINGPREVENTING AGENT WHICH ARE LEMON JUICE,VINEGAR AND SALT SOLUTION.


8/15

5/5/12


9/15

5/5/12

ACTIVITY:1)CUT THE LEMON AND SQUEEZE THEM

2)PREPARE THE SALT SOLUTION

3) MEASURE 20 ML OF THE LEMON JUICE, VINEGAR AND

SALT SOLUTION BY USING THE MEASURING CYLINDER.

4)PUT EACH OF THE MEASURED SOLUTION INTO 4

LABELLED BOWL A,B ,C AND D RESPECTIVELY.

5) CUT THE APPLE INTO 4 SLICE.

6)SOAK THE APPLE SLICE INTO THE 3 LABELLED BOWL

RESPECTIVELY TAKING ONE AS A CONTROL FOR 20

MINUTES.

7) TAKE OUT THE APPLE SLICE AND SEE THE TIME

TAKEN FOR IT TO TURN BROWN.


10/15

5/5/12

APPLE SLICES BROWNING

PREVENTING

AGENT

COLOUR CHANGE

AFTER 1 NIGHT

A LEMON JUICE WHITEB VINEGAR BROWN

( DUE TO

DAMAGE)

C SALT WATER SLIGHTLY BROWN

D (CONTROL) - DARK BROWN

RESULTS

ACTIVITY 1


11/15

5/5/12

HOW LEMON JUICE KEEP APPLE FROM

BROWNING?

Lemon juice helps keep the apple from browning, because it is full of ascorbic

acid (Vitamin C) and it has a low (acidic) pH level.

Low pH levelPolyphenol oxidase works best when the pH level

is between 5.0 and 7.0. However, below a pH level

of 3.0, the enzyme becomes inactivated. The pH

of lemon juice is in the 2.0 range, making it very

effective against browning.

Antioxidant

Ascorbic acid (vitamin C) acts as an antioxidant.Oxygen is more likely to react with the ascorbicacid, rather thanwith the phenolic compounds inthe fruit or vegetable.Browning does not proceeduntil most of the ascorbic acid is used up in the

reaction.


12/15

5/5/12

HOW VINEGAR WORKS ON APPLE?

Like lemon juice, vinegar prevent browning of apple by loweringthe pH of the

Although vinegar can prevent the browning of

apple, but too large amount of it will cause

damage to the apple.

Why did this happen?

As vinegar undergoes the fermentation process,

it is a lot stronger when compared with lemonjuice. So, it is actually the mildness of acid in

lemon juice that is the key to prevent apples

from turning brown.


13/15

5/5/12

SET 2(DEHYDRATION)

WE ARE GOING TO USE THE SALT SOLUTION OF 3 DIFFERENT

CONCENTRATION.

ACTIVITY:1)PUT THE SALT INTO A MEASURING CYLINDER UP TO 1 ML.THEN PUT 20 ML OF

WATER AND STIR THEM.

2)REPEAT STEP 2 BY REPLACING THE 1 ML LEVEL WITH 3 ML AND 6 ML.

3) PUT THE THREE SOLUTION INTO 3 DIFFERENT LABELLED BOWL.

4)CUT THE APPLE INTO 4 SLICES

5)SOAK THE APPLE SLICE INTO THE 3 LABELLED BOWL RESPECTIVELY TAKING

ONE AS A CONTROL FOR 20 MINUTES.


14/15

5/5/12

HOW SALT WATER PREVENT BROWNING OF

APPLE?

The Polyphenol Oxidase enzyme needs sufficient water

to be active. Salt water will lower water activity in the

apples by adding water-binding chemicals (sodium

chloride). But dehydrating the apple, will only inhibited

the enzyme but not destroy it.

APPLE SLICES CONCENTRATION OF SALTWATER

IN 20 ml WATER

COLOUR CHANGEAFTER 1 NIGHT

A Salt(up to 1 ml of measuring

cylinder)

LIGHT BROWN

B Salt(up to 3 ml of measuringcylinder)

WHITE

C Salt(up to 6 ml of measuring

cylinder)

WHITE

D (CONTROL) - DARK BROWN


15/15

5/5/12

.THE END

browning presentation

Documents