Blanching is a cooking process used to destroy enzymatic activity in fruits and vegetables through methods like steam or hot water blanching. It has several objectives including tissue softening, preserving color and flavor, and reducing enzymatic damage. However, while blanching can enhance color and texture, it may also result in the loss of some vitamins and minerals depending on various factors.

1. BLANCHING
TOPICS TO BE COVERED
• FACTORS AFFECTING BLANCHING TIME
• OBJECTIVES OF BLANCHING
• METHODS OF BLANCHING
• EFFECT ON FOODS
PRESENTATION BY
UTKARSH JAIN

2. BLANCHING
 USED TO DESTROY ENZYMATIC ACTIVITY
 TEMPERATURE VARIES FROM 88-99 DEGREE CELCIUS.

3. FACTORS AFFECTING BLANCHING TIME
 TYPE OF FRUIT/VEGETABLE.
 SIZE OF PIECES OF FOOD
 BLANCHING TEMPERATURE
 METHOD OF HEATING

4. OBJECTIVES OF BLANCHING
 TO SOFTEN TISSUE TO FACILITATE PACKAGING
 TO AVOID DAMAGE TO PRODUCT
 TO ELEMINATE AIR FROM PRODUCT
 TO PRESERVE NATURAL COLOUR
 TO DESTROY UNDESIREABLE ENZYMES
 TO PRESERVE NATURAL FLAVOUR

5. METHODS OF BLANCHING
TWO MOST COMMON METHODS
 STEAM BLANCHING
 HOT WATER BLANCHING
 BOTH METHODS ARE RELATIVE SIMPLE AND INEXPENSIVE.

6. STEAM BLANCHING
 FRUITS/VEGETABLES ARE STEAMED FOR 30-90 SECONDS.
 VOLUME OF WASTE WATER IS LESS
 HIGHER NUTRIENT RETENTION

7. HOT WATER BLANCHING
 FRUIT/VEGETABLE DIPPED IN HOT WATER.
 TIME:B/W 1-5 MINS

8.  AFTER BLANCHING COOLING IS DONE BY COLD AIR OR COLD WATER.
 COOLING WITH RUNNING WATER.
 INCREASES LEACHING LOSS.
 GAINS WEIGHT BY ABSORBING WATER.
 COOLING BY AIR.
 NUTRIENT RETENTION.
 WEIGHT LOSS BY EVAPORATION.

9. EQUIPMENT FOR BLANCHING
STEAM BLANCHER
 CONSISTS OF MESH CONVEYER.
 CARRIES FOOD THROUGH STEAM ATMOSPHERE.
 RESIDENCE TIME :DEPENDS ON SPPED OF CONVEYER.

11. EQUIPMENT FOR BLANCHING
 HOT WATER BLANCHER
 RETAINS FOOD IN HOT WATER
 TEMPERATURE:70-100 DEGREE CELCIUS.
 THEN IT REMOVES IT TO A DEWATERING COOLING SECTION

12. EQUIPMENT OF BLANCHING
 MAIN DESIGNS OF HOT WATER BLANCHING
1.REEL BLANCHER.
 FOOD ENTERS A SLOWLY ROTATING MESH DRUM.
 IT IS PARTIALLY SUBMERGED IN HOT WATER.
 HEATING TIME : DETERMINED BY SPEED OF ROTATION.

13. 2. PIPE BLANCHER.
 FOOD IS IN CONTACT WITH HOT WATER.
 WATER RECIRCULATES THROUGH A PIPE.
 RESIDENCE TIME : DETERMINED BY
A. LENGTH OF PIPE.
B. VELOCITY OF WATER.

14.  IN CONVENTIONAL STEAM BLANCHING:
 THERE IS POOR UNIFORMITY OF HEATING.
 TO OVERCOME THIS
 INDIVIDUAL QUICK BLANCHING WAS INTRODUCED.

15. INDIVIDUAL QUICK BLANCHING
 INVOLVES 2 STAGES
FIRST STAGE
 FOOD IS HEATED IN SINGLE LAYER TO SUFFICIENTLY HIGH TEMPERATURE
SECOND STAGE
 DEEP BED OF FOOD IS HELD FOR SUFFICIENT TIME.
 THIS ALLOWS TEMPERATURE AT CENTRE OF EACH PIECE TO INCREASE TO NEEDED
TEMPERATURE OF ENZYME INACTIVATION.

17. EFFECT ON FOODS
NUTRITION
 SOME MINERALS,SOLUBLE VITAMINS AND OTHER COMPONENTS ARE LOST.
 LOSSES OF VITAMINS:MOSTLY BY LEACHING.
NUTRITION LOSS DEPENDS ON
 MATURITYAND VARIETY
 METHOD OF BLANCHING
 TIME AND TEMPERATURE OF BLANCHING
 METHOD OF COOLING

18. EFFECT ON FOODS
COLOUR
 BRIGHTENS THE COLOUR OF FOODS
 HOW??
 BY REMOVING AIR &DUST FROM SURFACE