processing of fruit jam docx

FST4826
LABORATORY FOR PROCESSING OF
PLANT AND ANIMAL PRODUCTS

EXPERIMENT 6
FRUITS AND VEGETABLES
Title
GROUP MEMBERS

: Processing of Fruit Jam
: CHUA CHIAO LEE
170512
LEW KAH WAI
167685
MOHAMMAD NAQIYUDDIN
169925 BIN MOHAMED
EHWAL

GROUP

: 1

LECTURER

: DR. NOR AFIZAH MUSTAPHA

OBJECTIVE
To evaluate the effect of jam composition/formulation on physiochemical properties and
organoleptic attributes of fruit jam.
INTRODUCTION
Fruits and vegetables do not have a long shelf life in their un-processed forms. Un-processed
fruits and vegetables are food commodities that are perishable. Thus, most kinds of fruits and
vegetables are usually processed into jam, juices, jellies or pickles in order to extend their
shelf life. According to Paul, the making of jellies and other preserves is an old and popular
process to keep fruits far beyond their normal storage life. (Singh, 2014).
Jams are thick, sweet spreads made by cooking crushed or ground fruits with sugar.
Jams tend to hold their shape, but it is generally less firm than jellies. [ CITATION Bar08 \l
2052 ]. Normally, jam is made of mixture of not less than 45 parts by weight of fruits or
fruits ingredient and 55 parts by weight of saccharine ingredient. Jams are usually sugaracid-pectin gels or low methoxyl pectin calcium gel and the main ingredients of jams are
including fruits, sugar, pectin and acid.
Different fruits will give each product its characteristic flavor and colour. Normally,

flavourful, just ripen fruits are used for producing better taste of jam. Acid is added into jams
for both gel formation and flavoring purpose. The amount of acids added varies among
fruints used for jam production. Usually, under-ripen fruits will need higher amount of acids.
Besides acids, sugar is also another important ingredient for jam production. This is because
sugars can help in preserving fruits, forming gel and also contributing in the flavor of jam.
[ CITATION Bar08 \l 2052 ].
Next, pectin is a naturally-occurring thickening agent that is most often used in the
jams and jellies products to help them gel and thicken. It is a carbohydrate found in and
around cell walls of plants. Pectin helps to bind the cells together. Most of the fruits contain
pectin. However, the amount of pectin contained in each fruit is varies widely. Apples contain
the most pectin, thus its pectin is used commercially to thicken many different types of
products. Pectin generally needs some acids and a high sugar content to activate. Thus, the

commercially available pectin will include citric acid as an ingredient to help ensure it is
working with the products successfully. Pectin can be in both powder and liquid forms.
(Anonymous, 2012).

MATERIALS AND APPARATUS
MATERIALS
1.

2.
3.
4.
5.

Fruits (Pineapples)
Sugars
Pectin A and B
Water
Citric Acid

APPARATUS
1. oBrix Meter
2. pH meter
3. Air Tight Containers
4. Thermometer
5. Cooking Utensils

PROCEDURE
The two whole pineapples are weighted.

The fruits are cut and the peel and core are removed.

The weight of the cut fruits is determined

The pH, oBrix and moisture content of fruits are noted.
Jam mixture is calculated as below:
For every 100g
45 parts fruits by weight
55 parts sugar (by weight)
Amount of pectin= ml of sugar/100

The mashed fruit is bought to slow boil and the temperature is noted.

The fruits are heated until 30 minutes with constant stirring.

Pectin with sugar is mixed thoroughly (1 part pectin to 15 part sugar) to the fruit for 30
seconds.

The remaining sugar is added and the mixture is bought to slow boil.

The mixture is measured from time to time until oBrix is within 65-68.

The weight of jam is recorded and the yield is calculated.

Citric acid is added until the mixture has a pH 3.2 (except group 4 and 5)

The containers are exhausted in hot water bath.

Hot filled jam (85oC) is poured into sterile containers.

The lid is tighten.

Containers are cooled to 40oC

RESULT AND DISCUSSION
Table 1: Physiochemical properties of fresh fruit and jam
Formulation(fruit/ 1
2 (50/50)
3 (60/40)
sugar)

(45/55)
(3.2)
(3.2)
(pH)
(3.2)

4 (45/55)

5 (45/55)

(?)

(?)

1. Weight
Whole fruit

2378.22
g

2145.00g

2261.00g

2295.00g

2327.80g

Peeled fruits

1238.30
g

1135.00g

1200.00g

1305.00g

1355.00g

Jam

2090.00
g

1880.00g

1560.00g

2120.00g

1590.00g

% yield of jam

87.88

87.65

69.00

92.37

68.33

pH of fresh fruit

3.77

3.81

3.76

3.77

3.78

pH of jam

3.20

3.30

3.05

3.34

3.67

°Brix in fresh fruit

9.7

9.0

9.8

9.6

9.0

°Brix in jam

65

66

65

72

65

3. Viscosity of jam

5.53

5.91

66.63

19.70

7.45

2. Chemical

Table 2: Time taken for mixture to form gel
Formulatio
1
2
n
Time to
form gel
55.45
47.00
(min)

Table 3: Sensory evaluation of jam product
Sample
1 (45/55)
2 (50/50)

3

4

5

51.00

45.00

35.00

3 (60/40)

4 (45/55)

5 (45/55)

Color

1.69 ±
0.58

2.06 ±
0.59

2.17 ±
0.71

1.91 ±
0.66

1.37 ±
0.55

Aroma

2.11 ±
0.53

1.63 ±
0.65

1.83 ±
0.71

2.17 ±
0.57

2.77 ±
0.49

Taste

1.86 ±
0.43

1.66 ±
0.68

1.54 ±
0.51

2.26 ±
0.61

2.40 ±
0.69

Acceptabili
ty

1.86 ±
0.36

1.80 ±
0.58

1.71 ±
0.46

2.14 ±
0.49

2.37 ±
0.60

In this experiment we try to evaluate the effect of jam formulation on physiochemical
properties and organoleptic attribute of fruit jam. We were using five different formulation
which differ in the ratio of fruit and sugar, type of pectin and pH value. The yield of jam from
group formulation 4 is the highest (92.37%). The fresh fruit used for every formulation is
different from each other. The yield might be varies due of the way we cut off the pineapple
skin, some group may cut the pineapple deep into the flesh cause the yield of jam will be
decrease. The formulation or specifically the volume of sugar added into the mixture also one
of the factor. In this experiment we used two different pectin, the slow setter pectin and the
fast setter pectin. Only formulation 5 were used fast setter pectin while the rest four
formulation used the slow setter pectin. Addition of pectin had no significant effect on the pH
of the finished jam. Sufficient pectin levels however improved the texture, gel formation and
enhanced spread ability of the jam ( Emmanuel 2006).
All pH value of the pineapple dropped when in processed into jam. The pH of the jam
for sample 1, 2 and 3 were fixed to be around 3.2 using acid. Fast setting pectin believes to
have higher pH value (3.67) compared to the other sample where it used slow setting pectin
(3.20, 3.30, 3.05, 3.34). Optimum firmness is achieved within definite pH ranges for the
particular pectin used. Slow-set pectin often are used in commercial jelly manufacture and
attain a maximum firmness at pH 3.0 to pH 3.15. Rapid-set pectin are used for jams and
preserves because they set at a higher temperature before fruit components float to the top of
the jar and attain maximum firmness at pH 3.30 to 3.05. The upper limits for successful gel
set are pH 3.4 and pH 3.6 for slow set and rapid set pectin respectively (Smith 2006).
A degree Brix (°Brix) is a unit of measurement for the sugar concentration of liquids.
It can be measured by both the density and the refractive index (nD). In this experiment °Brix
for all formulation were increases as we add sugar into making jam. It could be seen that the
sugar concentration in a fresh fruit quite low between 9.0 to 9.8 °Brix. As we added sugar
into the mixture to make jam the °Brix increases till around 65 to 72 °Brix. Biswal and
Bozorgmehr (1991) reported that maximum sucrose concentration that can be achieved in the

liquid phase of the jam product is 67.89%. However, higher total sugar quantities (up to 70 to
72%) found in products is explained by increased reducing sugar solubility, resulting from
sucrose inversion.
The viscosity of the jam happen to be highest (66.63) in the formulation 3 with 60/40
fruit to sugar ratio. There are many factor that influence this figure and one of it is the pH of
the jam. This agree with the findings by Egan et al. (1985) which reported that pH that near to
or below 3.0 might result in hard gels.
After sensory evaluation were conducted jam from formulation 5 happen to score
highest in each attribute besides color. But in term of color jam from formulation 3 become
the most desirable. In term of overall acceptability the jam from formulation 3 score lowest
compared to the others. This may due to sugar used in the formulation which is lower than
the others.

CONCLUSION
In conclusion, the ratio of fruit to sugar could affect the desirable attribute in jam
product and also the physiochemical properties of the jam. The pectin used in the
formulation, pH and the °Brix of the jam effect the gel strength of the jam. Also the specific
pectin have their own pH that will result in jam desirable attribute. Texture of jam is a
composite property related to a number of physical properties such as, pH, sugar
concentration, viscosity and elasticity, and their relationship is complex.

QUESTIONS
1. What is the function of pH in jam making?
Low pH around 3.0 to 3.2 is the suitable pH for jam making. Low pH is required to enable
the pectin to set the jam or jelly and convert some of the sugar into invert sugar to prevent the
jam or jelly from crystallizing. If the pH is not low enough a gel will not form. If it is too

high, the jelly will weep or lose liquid. At low pH the concentration of the hydrogen ion is
higher which tend to repress the ionization of the galacturonate carboxyl group. The tendency
of the negatively charged carboxyl groups to repel each other is eliminated.
2. What is the effect of °Brix on the gel strength of the jam?
°Brix refer to the sugar concentration inside the solution, higher °Brix means higher sugar
concentration and resulted decrease in water that available to keep pectin from interacting.
The result was increase in gelling and possibly some crystal formulation due to lowered water
concentration.
3. How does the selection of pectin type affect the quantity, processing time and
quality of the product?
Pectin are increasingly identified by their degree of methylation (DM). Slow-set refers to a
pectin within the 60 to 65 DM range, while rapid-set refers to pectin within the 68 to 75 DM
range. The rapid- set pectin cause the jam yield will be lower than the slow-set pectin. Rapidset pectin will be causing the mixture to turn into jam faster compared to slow-set pectin. In
term of the quality of product the rapid-set pectin will give better quality compared to slowset, but other variable have to be taken into consideration such as the pH, temperature and the
sugar concentration of the jam.

4. How did the consistency of jam change when the ration of pectin to sugar was
altered? Explain what caused the behavior observed?
Sugar and pectin are interrelated in the jam making. When sugar is too low the jam will be
syrup and not set and it goes the same if not enough pectin used in the making. The pectin
chemical structure is a 6 carbon ringed compound with methyl ester groups attached. It can
link with each other and form a straight chain of pectin molecules. This chain can further
react with other pectin chain by forming junction zones between their hydrogen and oxygen
molecules. This junction traps water and form gel. Sugar is needed to remove water shell
from pectin. If the sugar concentration is too low the gel will not be able to form because the
pectin molecule will be surrounded by water and will not be able to make contact with each
other. If the sugar is too high the solution will begin to crystalize.

REFERENCES
1. Emmanuel Ohene Afoakwa, Dorinda Nartey, Joseph Ashong, and George Annor.
"Effect of Sugar, Pectin and Acid Balance on the Quality Characteristics of Pineapple
(Ananas Comosus) Jam. " Proceeding of the 13th World Food Congress. . Nantes,
France, pp 1405-1406, September 17-21, 2006.. Sep. 2006. Available at:
http://works.bepress.com/georgeamponsahannor/7
2.

Smith, D. (2006) Food Jellies: Food Processing for Entrepreneur Series. Retrieved
from : http://www.ianrpubs.unl.edu/pages/publicationD.jsp?publicationId=418

3. Egan H, Kirk RS, Sawyer R (1985). Person’s chemical analysis of foods. Churchill
Livingston, Edinburgh London, pp. 9-10
4. Biswal RN, Bozorgmehr K (1991). Equilibrium data for osmotic concentration of
potato in NaCl-water solution. J. Food Process. Eng., 14: 237-245.
5. Anonymous. (2012, August 10). What is Pectin? Retrieved November 10, 2014, from
Baking Bites: http://bakingbites.com/2012/08/what-is-pectin/
6. Ingham, B. H. (2008). Making Jams, Jellies and Food Preserves. Retrieved 11 7,
2014, from Winconsin Safe Food Preservation Series:
http://learningstore.uwex.edu/assets/pdfs/B2909.pdf
7. Singh, R. P. (2014). Fruit preserves, jams, and jellies. Retrieved November 7, 2014,
from Encyclopedia Britannica:
http://global.britannica.com/EBchecked/topic/221114/fruit-processing/50259/Fruitpreserves-jams-and-jellies