lab mt203 new

Food Preservation ( MT 203)

Iman_Jan2011

MT 203 FOOD PRESERVATION

LABORATORY MANUAL

Food Technology Department Politeknik Sultan Haji Ahmad Shah


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Lab : 1 Title : Equipments Used In Processing Laboratory Objectives : At the end of the lab, students must be able to:

1) know the functions of specific equipments used in processing

laboratory.

2) operate the specific equipments.

Introduction : Food preservation is defined as any purposeful treatment or

processing of food which extends the keeping quality of raw material to a

period longer than its natural keeping quality. The processes involved in

protecting food against microbes and other spoilage agents to permit its

future consumption. The preserved food should retain a palatable

appearance, flavour, and texture, as well as its original nutritional value.

Preservation can be arbitrarily divided between temporary, a short term

preservation to keep product fresh while distributing to markets and

permanent, a longer term where products can remain in consumers

homes indefinitely until use

Materials and Equipment : Refractometer Fruit juice pH meter Rice Vernier caliper Can Micrometer Method :

1) Measure the sweetness of the fruit juice using refractometer.

Take the value of Brix.

2) Measure the pH value of the fruit juice using pH meter.

Take the pH value.

3) Using micrometer, measure the size of a rice( length, thickness).

4) Using vernier calliper, measure the size of a can ( diameter,

thickness, depth).


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Result :

1

2

3

4

5

6

average

Fruit Juice

Brix

pH value

Rice

Length

Thickness

Can

Thickness

Diameter

Depth

Discussion :

1) Specifically discuss the function and the manual procedure of each

equipments.

2) Discuss the advantages and the disadvantages of each equipments.

Conclusion : References :


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Lab : 2 Title : Fruits Canning Objectives : At the end of the lab, students must be able to:

1) operate fruits canning operation according to the right methods.

2) compare and determine the organoleptic values of canned fruits.

Introduction : Canning is a process of preserving food by heating and sealing it

in airtight containers. It is one of the easiest and fastest preservation

method which using thermal process. Heating destroys enzymes and

microorganisms. The sealing of can ensure no microorganisms and

oxygen can get in. Airtight containers make sure that no oxygen in the

containers for bacteria to live and chemical changes. The thermal process

is depends on the pH value of the food.

Materials and Equipment :

Pineapples Refractometer

Syrup pH meter

Citric Acid Jacketed Steam Pot

CMC Sealing Machine

Method :

1) Weigh a pineapple.

2) Clean the pineapple and peel it.

3) Cut it into cubes. Wash and weigh.

4) Blanch the pineapple for about 1 minute at 90C 99C.

5) Prepare the syrup( 18 20 Brix). Take the Brix and pH value.

6) Fill the pineapple and syrup into cans which have been sterilized.

The syrup must be about 82C( hot filling ). Close the cans quickly.

7) Seal the cans by using sealing machine.

8) Sterile the cans in boiling water (100C) for about 30 minutes.

9) Cool the cans immediately to 38C and dry it.

10) Label the cans and evaluate it after 1 week.


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Result :

Parameter Group

1 2 3 4 5

Initial syrup concentration

Final syrup concentration

Initial pH value

Final pH value

Cut out Brix

Initial weight

Net weight

Drained weight

% of yield

Discussion :

1) Specifically discuss and identify the importance of each methods in

the canning process.

2) Discuss the end product in chemical, physical and organoleptic

aspects.

3) Compare your end product (canned fruits) with the one in the

market.



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Lab : 3 Title : Examination of Can Double Seam Objectives : At the end of the lab, students must be able to:

1) inspect visually the external and internal of the can double seam

2) calculate the overlap percentage of the double seam

Introduction : Cans used in food processing should be properly constructed to

give the desired protection to food while being able to withstand the

severe treatment of heat and pressure. The double seam of a can should

be examined very carefully because the success of the canning depends

largely on the degree of perfection achieved in sealing the can

airtight.The external and internal conditions of the double seam should be

inspected visually and every measurements should be taken carefully to

judge the quality of the double seam.

Materials and Equipment : Screw gauge Seam Cutting Saw

Cutting Plier Magnifying Glass

Double Seam Can

Methods :

A. External Examination

1) Observe carefully all around the seam end, both on the body and lid.

2) Record the presence of defects if any such as V, droop, cut-over,

sharp seam etc.

3) Measure the seam length (L), seam thickness (T) and countersink

(CS) at 3-4 points by using screw gauge.

B. Internal Examination

1) Strip can end all around using plier and get a ring of the cover hook

portion.

2) Observe wave like wrinkle on inside surface of the cover hook and

record them.


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3) Cut seam section at 3-4 points and observe for hooking, overlapping

and clearance using magnifying glass.

4) Separate body hook (BH) and cover hook (CH), without altering the

shape and measurement of double seam and record their lengths.

5) Find out average value of body hook (BH) and cover hook (CH).

6) Measure the end plate thickness (EPT) and body palte thickness

(BPT).

7) Calculate the overlap (OL) percentage by using following formula.

% OL = BH + CH + EPT L X 100

L ( 2 EPT + BPT )

Where :

BH : body hook length

CH : cover hook length

L : length / seam width

EPT : end plate thickness

BPT : body plate thickness

OL : overlap

Result :

Seam cutting point

External Examination Internal Examination

L

T

CS

BH

CH

EPT

BPT

%OL

1

2

3

Average

Discussion :

1) Discuss your observation for external examination ( defects).

2) Discuss your observation for internal examination ( wrinkles).

3) Discuss the percent of overlap from your result.



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Lab : 4 Title : Heat Penetration in Canned Food Objectives : At the end of the lab, students must be able to:

1) calculate the heat penetration value in selected canned food

Introduction : Heating times and temperature for canned food are based on the

destruction of the spores of Clostridium botulinum, as this organism has

been known to survive an inadequate process and thereafter grow up,

producing toxins that can cause sickness and in instances, death. The

temperature required to process food is based on their pH. Low acid food

required high temperature of processing. Meanwhile high acid foods,

required low temperature process. This is because acidic food produce

natural preservatives to microorganism (microorganism cannot stand in

acid condition).

Materials and Equipment : Food sample Retort

Thermometer Can

Thermocouple Table of Thermal Death Time

Methods :

1) Put the thermocouple into the can.

2) Fill the can with the sample and seal.

3) Connect the thermocouple with a thermometer and put into the retort.

4) Fill in the table below with the data from the thermometer.

5) Calculate the Fo value using formula and the Thermal Death Time.

6) Stop the stim when the Fo is 12.

7) Cool the cans immediately and dry.


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Result : Fill in the data into the blank

Time of Processing (minute)

Temperature (C)

Thermal Death Time

Sum of Thermal Death Time

Calculate the Sterilizing Value (Fo) from the data

Sum of Thermal Death Time ( X ) = --------------------

Time Interval ( Y ) = --------------------

Sterilizing Value (Fo) = X x Y

= ----------------

Discussion :

1) Discuss the result of Sterilizing Value (Fo).

2) Discuss the effect of the Sterilizing Value (Fo) on food.



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Lab : 5 Title : Freezing Operation (Blast Freezer). Objectives : At the end of the lab, students must be able to :

1) describe the function of blast freezers compartments.

2) operate blast freezer.

Introduction : Air at -18 to - 40 C flows around packaged or unpackaged

product to freeze. The earliest freezing sharp freezing used still air

(no fans). This slow freezing process took 3 to more than 72 hours for

complete freezing - poor quality.

Now air blast freezing is used - rapid forced circulation of

air around product to get moderately fast freezing. Most common

arrangement is -29 C air moving at 2500 ft/min.

Materials and Equipment : Blast freezer

Sample

Methods :

1) Prepare the sample.

2) Determine each component of blast freezer and its functions.

3) Operate it and collect the frozen product.

Result :

Parametres Group

1 2 3 4 5

Initial Temperature

Final Temperature

Initial Time

Final Time

Time Differential


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Discussion :

3) Specifically discuss the operation process of blast freezer and identify

the functions of each components.

4) Discuss the advantages and the disadvantages of blast freezer.

5) Discuss the suitable product that can be frozen using blast freezer.



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Lab : 6 Title : Oven Drying Objectives : At the end of the lab, students must be able to :

1) describe the function of oven and operate the oven.

2) determine a few factors affecting drying.

Introduction : Drying is one of the oldest methods of preserving food for later

use. It is simple, safe and easy. Drying removes the moisture from the

food so bacteria, yeast and mold can not grow and spoil the food. Drying

also slows down the action of enzymes (naturally occurring substances

which cause foods to ripen), but does not activate them. Because drying

removes moisture, the food becomes smaller and lighter in weight. When

the food is ready for use, the water is added back, and the food returns to

its original shape.

Materials andEquipment :

Oven

Potatoes

Methods :

1) Weight a few potatoes.

2) Peel the potatoes, cut into different size and shape.

3) Weight it again.

4) Blanch the potatoes for about 1 minute at 90C 99C.

5) Arrange the potatoes in a tray and dry it in an oven for about 4 - 5

hours at 60C.

6) After dried, weight the potatoes and get the moisture percent.

7) Evaluate the dried potatoes and determine the differences after dried.


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Result :

Parameter Group

1 2 3 4 5

Initial weight

Weight of cutting

% of cutting

Dried weight

% of drying

% of moisture content

Discussion :

1) Compare the changes of weight and the differences of drying

percentage among samples.

2) Discuss the physical changes in colour, texture, shape and size.

3) Discuss factors affecting drying and the quality of the dried product.



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Lab : 7 Title : Drum Dryer Objectives : At the end of the lab, students must be able to :

1) describe the function of drum dryers compartments.

2) operate drum dryer.

Introduction : Drum driers are hollow drums of iron or stainless steel heated

internally usually by steam. Food to be dried must be in the form of liquid

or slurry and is applied to outer surface of drum by dipping, splashing,

spraying, spreading devices, or feed rollers. Transfers heat to food by

conduction is direct contact of food with heating surface.

Hollow drums, heated internally with steam have smooth surfaces

of machined steel. Food applied to the drum in a form of slurry. Food is

dried as it is carried by the rotating drum to a point where it is removed by

a fixed scraper. Foods that can be dried using drum dryer are potato

flakes, instant cereals (e.g. baby food), and fruit leather.

Materials and Equipment : Drum dryer

Sample

Methods : 1) Prepare the sample.

2) Determine each component of drum dryer and its functions.

3) Operate it and collect the dried product.

Result :

Parametres Group

1 2 3 4 5

Initial weight

Final weight

% of drying


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Discussion :

1) Specifically discuss the operation process of drum dryer and identify


2) Discuss the physical changes in colour, texture, shape and size of

dried product.

3) Discuss the advantages and the disadvantages of drum dryer.

4) Discuss the suitable product that can be dried using drum dryer.



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Lab : 8 Title : Spray Dryer Objectives : At the end of the lab, students must be able to :

1) describe the function of spray dryers compartments.

2) operate spray dryer.

Introduction : Spray dryer is used for drying liquid products including milk,

coffee,and eggs.Initially developed for dairy products but has been used

for many food and pharmaceutical products.

Spray dryer using hot air for drying liquid food to become powder.

The liquid material is sprayed into the top of a chamber simultaneously

with hot air, which is also blown in at the top where it is in contact with a

stream of hot dry air. Dehydration is very rapid because of the large

surface area of droplets.

The cool, moist air exits near the bottom, and the dried particles

suspended in air flow move to separation equipment at the bottom and

are collected by gravity flow, or with the aid of scrapers that may also be

used to removed dried material from the walls or bottom. Cyclones

[conical-shaped collectors] may be used to collect particles escaping with

the exit air.

Materials and Equipment : Spray dryer

Milk

Methods : 1) Prepare the sample.

2) Determine each component of spray dryer and its functions.

3) Operate it and collect the dried product.

Ingredient Weight (gram)

Milk Powder 400

Water 3000

Dextrin 30


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Result :

Parametres Group

1 2 3 4 5

Initial weight

Final weight

% of drying

Discussion :

1) Specifically discuss the operation process of spray dryer and identify


2) Discuss the physical changes in colour, texture, shape and size of

dried product.

3) Discuss the advantages and the disadvantages of spray dryer.

4) Discuss the suitable product that can be dried using spray dryer.



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Lab : 9 Title : The Effects of Food Additive On Food Objectives : At the end of the lab, students must be able to :

1) determine the suitable limit for food additive.

2) evaluate the effects of food additive on food.

Introduction : Food Additives , natural and synthetic compounds added to food

to supply nutrients, to enhance color, flavor, or texture, and to prevent or

delay spoilage. Some additives can inactivates or kill micro-organisms,

retard chemical spoilage. All food additives are carefully regulated by

federal authorities and various international organizations to ensure that

foods are safe to eat and are accurately labeled.It is important to note that

food additives are not all bad. There are often good and proper reasons

for using additives in the commercial preparation of foods. Unfortunately,

additives have received a bad press because they are used on occasions

to disguise inferior products.

Materials and Equipment: Dried Chilli - 1 kg

Water - 2.5 L

Natrium Benzoat

Methods :

1) Weigh the chilli.

2) Cut and wash the chilli.

3) Boil in boling water 10 minutes.

4) Blend the chilli with water.

5) Divide the mixture into 7 portion.

6) Put each portion with 0.2%, 0.15%, 0.125%, 0.1%, 0.075%, 0.05%

and 0% of Natrium Benzoate.

7) Check pH value for each portion.

8) Store each portion in a plastic container for 2 weeks.

9) Observe the containers and check the pH value every 2 days. Record

the observation and the pH value.


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Result :

Day Observation

2

4

6

8

10

12

14

Discussion :

1) Discuss your observation for every 2 days.

2) Discuss your observation after 2 weeks.

3) Discuss the function of Natrium Benzoat.



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Lab : 10 Title : Food Fermentation ( Preparation of Tapai Pulut ) Objectives : At the end of the lab, students must be able to :

1) Describe the fermentation process of Tapai Pulut.

2) determine the organoleptic characteristics of Tapai Pulut.

Introduction : Fermentation is the use of biological processes to make products.

Its major uses are in the production or preservation of food. Fermentation

is not new. For many centuries fermentation has used micro-organisms to

make beer, yogurt and cheese.

The basis of the fermentation process is the conversion of sugar

(glucose) to alcohol or to lactic acid by enzymes. Fermentation acts as a

preservation method by producing an acid which lowers the pH of the

product, converting a perishable food into one that has a longer shelf-life.

Materials and Equipment: Beras pulut - 500g

Ragi - 1g

Water - 450ml

Plastic container

Methods :

1) Clean the beras pulut. Wash and soak it for about 15 minutes.

2) Pour the water and wash again.

3) Cook the rice with 450ml water for about 5-10 minutes.

4) Cooled the rice to 400C on a clean plastic after cooked.

5) Spread the ragi on the rice.

6) Mix the ragi and the rice carefully.

7) Put the rice into the plastic containers.

8) Close it and ferment for about 45 hours.


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Result : Sensory evaluation of final product for the organolleptic characteristics ( scoring test).

Discussion :

1) Specifically discuss each step in preparing tapai pulut and identify the

importance of each step.

2) Discuss the end product in chemical, physical and organoleptic

aspects.

3) Compare your end product with the other group.



Iman_Jan2011

lab mt203 new

Documents

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short term preservation

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