HO CHI MINH UNIVERSITY OF TECHNOLOGY AND EDUCATION
FACULTY OF HIGH QUALITY TRAINING

GRADUATION THESIS
CODE: 2021-17116013

SOFT CHEESE PRODUCTION USING
CITRIC ACID AND RENNET AS COAGULANTS

Advisor: PhD. PHAM THI HOAN
Student: PHAN NGUYEN NGOC KHANH
LE THI NGOC YEN

HO CHI MINH CITY - 12/2021

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Student ID: 17116013
17116045

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ACKNOWLEDGEMENTS
Firstly, we would like to express our heartfelt gratitude to all of the lectures at Ho
Chi Minh City University of Technology and Education in general and lecturers at the
Faculty of Chemical and Food Technology especially. We gained valuable knowledge and
skills regarding Food Technology throughout our four years at the school.
We would like to express our appreciation to PhD. Pham Thi Hoan - lecturer at the
Department of Food Technology, Faculty of Chemical and Food Technology, Ho Chi Minh
City University of Technology and Education. She was always enthusiastic in her support
and teaching us, mentoring and imparting knowledge and experiences from the idea to the
completed graduation thesis. We are truly grateful for that, and we will keep her teaching in
mind.
We would like to show our thanks to Ms Ho Thi Thu Trang, consultant in charge of
the Department of Food Technology laboratories and workshops. She had been supportive
and helpful with tools, machinery and equipment during our experimental research process.
We also would like to express our deep sense of gratitude to the instructors in charge of Food
Technology workshop 1, workshop 3, Microbiology laboratory, Biochemistry laboratory
and Sensory laboratory who d an ideal environment for us to complete this project.
We are very grateful to everyone who made my experience at Ho Chi Minh
University of Technology and Education very positive and enjoyable this experience would
not have been possible without my friends, family, fellow students and mentors. This project
has been one of the most challenging things we have done, but also one of the most enjoyable
and rewarding. It is impossible to prevent faults while implementing the thesis, so we look
forward to hearing your feedback on our thesis. Once again, we gratefully acknowledge you
and wish you all the best.

Best regards!

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TABLE OF CONTENT
GRADUATION PROJECT ASSIGNMENT ...................... Error! Bookmark not defined.
ACKNOWLEDGEMENTS ..................................................................
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The fat content in cheese was determined according to TCVN 8181:2009 (ISO

1735:2004). The sample is digested with hydrochloric acid followed by the addition of
ethanol. The acid-ethanol solution is extracted with diethyl ether and the pentane solvents
are removed by distillation or evaporation. The extract is weighed. This principle is usually
called the Schmid-Bondzynski-Ratzlaff principle.
The fat content of cheese was determined by the following steps. 3 grams of cheese
sample (with a precision of 1 mg) was diluted with 10 mL of hydrochloric acid in a 250-mL
erlen. The erlen was heated in a water bath until the sample was completely dissolved. The
erlen was subsequently boiled on the stove for about 10 minutes and cooled under tap water.
The sample mixture was transferred from the erlen to a separating funnel and the erlen was
rinsed with 10 mL of ethanol and shook well for 30 seconds. The erlen was continuously
rinsed with diethyl ether the top of the separating funnel was also rinsed with diethyl ether
and shook well for 90 seconds. The erlen was finally rinsed with 25 mL of pentane the top
of the funnel was also rinsed with pentane. The funnel was stood for 30 minutes to allow the
solvents to separate. After that, the light phase was collected to the petri dish. The solvent in
the dish was evaporated on the electric hot stove at ≤ 100 ± 1℃ until the solvent was almost
completely evaporated. The dish and fat were subsequently dried to a constant weight in a

drying oven at 102 ± 1 ℃. The dish was cooled to room temperature in the desiccator and
weigh. The experiment was triplicated
The lipid content in cheese is determined
W=

(???????? −???????? )−(???????? −???????? )
????????

× ????????????

With,
m0 is the sample weight (g).
m1 is the weight flask containing lipid and extracts (g).
m2 is the weight flask used to collected lipid (g).
m3 is the weight flask containing extracts in the blank test (g).
m4 is the weight flask used in the blank test (g).

APPENDIX 12: TESTED SAMPLE AND CONTROL SAMPLE COMPARISION
Sample Cheese yield Total solid in
%, w/w

Moisture

CSY

cheese

content

%, w/w

%, w/w

%, w/w

Cheese hardness, g

CS

18.83 ± 0.32a 29.67 ± 0.67b

70.33 ± 0.67a 37.26 ± 1.46a

195.33 ± 2.93a

RS

20.74 ± 0.20bc 36.51 ± 0.24ab

63.49 ± 0.34b

360.67 ±12.64c

50.46 ±0.46b

The different letters (a-d) in each column showed significant difference (p 0.05).
*RS: rennet – coagulated cheese (tested sample) and CS: acid – coagulated cheese (control sample)