THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY LUONG NGUYEN CHINH ISOLATION OF LACTIC BACTERIA APPLY IN TOFU PRODUCING PROCESS BACHELOR THESIS Full name : Luong Nguyen Chinh Study mode: Full-time Major : Food Technology Falcuty : Advanced Education Program Batch : 2016 – 2020 Thai Nguyen, December 2020 Luan van ABTRACT Thai Nguyen University of Agriculture and Forestry Degree Program Bachelor of Food Technology Student name Luong Nguyen Chinh Student ID DTN1654190002 Thesis Title Isolation of Lactic Acid Bacteria apply in tofu producing process Supervisor (s) Dr. Luong Hung Tien Supervisor’s Signature Abstract: The aims of this study is isolating and screening the high acid producing ability LAB strains to apply in tofu’s protein coagulating and enhancing shelf life. We conducted to isolate LAB from natural ferment yogurt and tofu sour water, and we were isolated 11 LAB strains with the colony and cell’s morphology: round, milky-white color, rods shape. Totally, we are identified 4 LAB by Bergey’s Classification of Bacteria, by characteristics of sugar using, Gram dying method, oxidase and catalase activity.
Isolated strains were testing on soy milk ferment capacity by incubating condition at 41°C for 8 hours and comparing with control sample, protein coagulation capacity at 90 0C for 10 minutes. The results showed that DP3 have highest ferment capacity and good coagulation activity. Finally, DP3 strain was applied in tofu producing process to testing about tofu’s qualities, productivity, microbiological criteria and shelf-life characteristics. Keywords: Lactic acid bacteria, fermentation, soy beans, tofu Number of pages: 81 Date of 04/12/2020 Submission: Luan van ACKNOWLEDGEMENT During my studies and internship at Thai Nguyen University of agriculture and forestry, I have now completed my graduation thesis.
In order to complete this thesis, I have been guided by the devoted guidance of my supervisor, along with the help of Thai Nguyen University of Agriculture and Forestry, Faculty of Food Technology and Biotechnology and the Advanced Program Office. I also received the enthusiastic cooperation from colleagues, help and encouragement of my family members. In response to that sentiment, through here I would like to express my deep gratitude and respect to all collectives and individuals who created conditions to help me throughout the internship process. First of all, I would like to express my sincere thanks to the school management board, the Dean of the Faculty of Food Technology and the collective of teachers in the Faculty of Food Technology, Thai Nguyen University of Agriculture and Forestry that taught and mentored me during these time, as well as my graduation internship.
In particular, I sincerely thank for the attention and guidance of the instructing supervisor Dr. Luong Hung Tien, who directly guided me to implement this thesis successfully. Through this, I would also like to express my gratitude to family, relatives and friends for helping and encouraging me during my study and practice at school. Finally, I would like to respectfully send my sincere thanks and best wishes to the teachers and teachers in the evaluation committee.
Thank you sincerely! Thai Nguyen, December 2, 2020 Student LUONG NGUYEN CHINH Luan van TABLE OF CONTENT ACKNOWLEDGEMENT. iii TABLE OF CONTENT. iv LIST OF S .vii LIST OF TABLES. OVERVIEW OF SOYBEAN.
Characteristic of soybean. Acreage, yield and demand for soybeans. Chemical composition of soybeans. OVERVIEW OF TOFU.
Process of producing tofu from natural sour water. FUNDAMENTAL OF THE GEL PROTEIN FORMATION PROCESS OF IN SOY MILK. Mechanism of formation. Soy protein properties.
LACTIC ACID BACTERIA OVERVIEW. Common features of lactic acid bacteria. OVERVIEW OF HYDROPEROXIDE AND BACTERIOCIN DURING LACTIC FERMENTATION. OVERVIEW OF TOFU PRESERVATION.
RESEARCH SITUATION WORLDWIDE AND IN VIETNAM. Lactic acid bacteria. EQUIPMENT AND CHEMICAL REQUIRE FOR RESEARCH. LOCATION AND TIME PERIOD OF THE RESEARCH.
Content 1: Isolation of some strains of lactic acid bacteria that can be used in secondary production. Content 2: Selection of bacteria with good ferment ability for application in tofu production. DATA PROCESSING METHODS .RESULTS AND DISCUSSION. Results of isolation and selection of lactic acid bacteria.
Biological characteristics of lactic acid bacteria isolated. Experimental set up test for soy milk fermentation. Results of pH measurement. Sensory quality of fermented soy milk.
Carbohydrate metabolism of selected strain. Tofu production efficiency. Determine the storage time. Indicate quantification of total aerobic bacteria.
Indicate quantification for Coliforms. Quantify total molds. Results comparing sensory quality between common tofu and tofu produced with lactic fermented soy milk. 61 Luan van LIST OF FIGURES 2.
Traditional tofu production process in Vietnam. Different gel network structures of protein. The molecular structure of Glycinin. The molecular structure of Conglycinin.
Process of enumeration of total aerobic bacteria. Process of enumeration of Coliform. Process of enumeration of mold. Colony on MRS agar.
Representative characteristic of bacteria cell .4 Gram possitive bacteria .5 Gram negative bacteria. Total Number of aerobic microorganism in 2 types of tofu. Total number of coliforms in 2 types of tofu. Total number of mold in 2 types of tofu.
55 Luan van LIST OF TABLES Table 2. Soybean export volume of some major countries in the world in the crops of 2017/2018, 2018/2019 and 2019/2020 (thousand tons). Soybean production in Vietnam from 2011 to 2017. Production, supply and demand of soybeans in Vietnam.
Chemical composition of some kind of beans. Chemical composition of soybean. Non-substituting amino acids in soybeans compares to other important foods (g / 100g protein). Carbohydrate components in soybean.
Vitamin content in soybean. Mineral contents in soybean. Quality level specified standards. Tofu description scorecard.
Gram staining result. pH of fermented soy milk of 4 bacteria strains after 8h. Results of sensory evaluation of lactic fermented soy milk. Sugar fermentation test result of DP3.
Sensory score results between normal tofu and lactic fermented soy milk. 56 Luan van ABBREVIATIONS CS Calcium sulphate EMP Emble – Mayerhorf – Parnas FAS Foreign Agriculture Service FDA Food and Drug Administration LAB Lactic Acid Bacteria LDL Low Density Lipoprotein MAP Modified Atmosphere Packaging PAW Plasma Activated Water PP pathway Pento – phosphate pathway TI Trypsin Inhibitors TMC Trimagnesium Citrate TPA Texture profile Analysis USDA United State Department of Agriculture WHC Water Holding Capacity 1 Luan van PART I. Research rationale Tofu is an important food made from soy protein (Kohyma et al., 1995) This is an important traditional food for the people of Southeast Asia due to its high nutritional content and good digestibility (Tsai et al. The benefits of tofu to human health were recognized by the FDA in 1999.
Due to the recognized nutritional benefits of tofu, there has been an increase in tofu consumption among the western countries in the world in the recent years (Oboh, 2006). Talking about the benefits of tofu, many researchers believe that using tofu as well as soy products can reduce the number of chronic diseases such as cancer, heart disease, and osteoporosis. Soy protein contains isoplavolesterol and isoflavones, which are effective against atherosclerosis (Carrol, 1991). It is also thought that the consumption of soybean protein has a lower effect on total cholesterol, cholesterol, LDL, and triglycerides in serum compared to animal protein (Potter, 1998).
Isoflavones, aglycones, and proteins contained in tofu have antioxidant properties that protect against lipid oxidation (Jackson et al. Tofu brings many health benefits to consumers, tofu is a popular dish of both urban and rural residents, so it has a large consumer market and stability. However, in fact in Vietnam, tofu is mainly produced on a small scale, mainly on household scale with rudimentary technology, outdated equipment and machinery. Tofu products are made without quality registration, no packaging, short storage time which only lasts 1-2 days after production.
The short shelf life of tofu not only 2 Luan van causes waste product, but also limits the scope of the distribution and the time it takes to commercialize the product. On the other hand, the protein coagulation process in tofu is mainly using chemicals such as CaSO4, MgCl2, citric acid and CaCl2 Calcium sulphate (CS) (Murugkar, 2015),. which are used in food. Many tofu manufacturers use impure chemicals that lead to metal residues in the tofu product.
Moreover, the topic of lactic bacteria as well as a number of benefits related to the use of lactic bacteria in food technology are of great interest to many scientists. Several organic compounds produced during lactic fermentation are considered to be good antibacterial agents [7],[9],[16],[19]. Therefore, there are more and more researches applying lactic fermentation or extracting substances from lactic fermentation to be used as biological preservatives, reducing mycotoxins in food more and more and with many remarkable results receive [5], [6], [7], [12]. Therefore, I conducted the topic: " Isolation of lactic bacteria apply in tofu producing process".
Research objective Isolation and selection of lactic acid bacteria with good fermentation ability and application in tofu production process as a coagulant 1.3 Detail goals - Isolation some strains of lactic acid bacteria - Selection of bacteria with good fermentation ability apply for tofu production 1.4 Limitations 3 Luan van Limitation that are expected to be encountered throughout the study - Language barrier: Since this report is conducted in English, so the study would have some obstacles due to the difference of language. - Equipment and chemicals provided: This study is conducted in the Faculty of Food Biotechnology and Food Technology, Thai Nguyen university of Agriculture and Forestry. Therefore, there inadequacy of specialized machines that are required for the research process 4 Luan van PART II. OVERVIEW OF SOYBEAN 2.
Characteristic of soybean Soybeans are scientifically known as Glycine max Merril. According to Phạm Văn Thiều (1993), Book of “Soybean plant, cultivation and product processing techniques” [4], soybeans are legumes, short-term crops (80 ÷ 150 days), and its stem is about 30 to 80 cm high, depending on the variety. Soybean plants are relatively upright compared to other legumes. Soybean trees have fewer branching than other legume trees; fruit grows in brunch, about 2 to 20 fruits, and each tree has nearly 400 fruits.
One fruit has from 1 to 7 seeds. The soybean fruit is slightly curved, the average length of it is about 4 to 6 cm. Soybeans have many various shapes such as round, oval, long circle, and flat circle. Similarly, the color also varies, including yellow-green, gray, black, but mostly yellow.
Soybeans have three parts: the shell, cotyledons, and the embryo. Cotyledon is the part that reserve of nutrients. Not as in cereal grains, in soybean seeds, there is no aleurone layer; endosperm and embryo stand separately. The whole bean is a large embryo surrounded by a seed coat.
Therefore, compared with other legumes, soybeans contain less starch, while their protein and lipid content is much higher. Acreage, yield and demand for soybeans 2. Production situation in the world The homeland of soybeans is East Asia, but nearly 60% of the world soybean production is located in the Americas, in which the US and Brazil are the countries 5 Luan van with the largest production in the world. According to the latest data, Brazil has surpassed the US in soybean production, reaching 124 million tons in the first half of 2020 and nearly two-thirds of production is for export.
Some other major soybean producing countries such as, Argentina, China, India, Paraguay, Canada. Soybean export volume of some major countries in the world from 2017 to the first half of 2020 is shown in Table 2.