Project funded by Sai Gon Technology University. This project published 1 article in the proceedings of Asia Food Conference 2017.
Project director: MSc. Tran Ngc Hieu
Implementing organizations: Saigon Technology University (STU)
1. General introduction
Along with the increase in world population, the demand for food is also constantly increasing. Nowadays, grain is the main source of food, with corn, rice and wheat providing 60% of the total energy for the world's population. In addition, this is a cheap source of protein. However, plant proteins often lack essential amino acids. For example, cereal proteins often lack lysine and tryptophan, legume proteins often lack methionine (Fatou Ba, 2016). Therefore, in recent years studies have begun to focus on food sources derived from aquatic organisms. Algae living in aquatic environments often grow so fast but their nutritional needs are low. Protein from algae can also provide a complete range of essential amino acids (Garcia-Vaquero M. 2016). Thus, algae species will be a source of nutrition in general and protein in particular, along with the development of the world.
Gutweed- Enteromorpha sp. is green algae, naturally occurring with very large biomass in brackish water such as extensive ponds, natural canals, etc. of Mekong Delta. Gutweed usually appears in the rainy season when the salinity of water is reduced by about 2 - 25 ‰. Studies on biochemical components have found that brakish gutweed has a protein content of 9-25%, is rich in essential amino acids and has a protein digestibility of up to 98% (Nguyen Thi Ngoc Anh, 2014).
2. Objectives of the project:
- Determing the ratio of 4 groups of proteins presenting in the material to guide the process of protein extraction appropriately.
- Finding out an effective process for obtaining protein from brackish gutweed, including extraction and precipitation stage. The research is also directed to an energy-efficient, cost-efficient and environmentally friendly process for exploiting protein .
- Determinating of the in vivo nutritional values of protein obtained from the results of experiments on white mice.
3. The main results of the project:
3.1. Determing the ratio of 4 groups of proteins
There are 4 groups of proteins, the ratio of these proteins is as follows:
- Proteins soluble in water - albumins: 29.7%
- Proteins soluble in saline solution-globulins: 13.3%
- Proteins soluble in alcohol- prolamins: 10.3%
- Proteins soluble in alkaline solution- glutelins: 48.7%
3.2. Determing the extraction conditions
- The appropriate solvent for the extraction stage is 0.4% NaOH and the extraction efficiency reaches 41.8%.
- The appropriate temperature for the extraction stage is 500C. The extraction efficiency at this temperature reaches 41.8%,which is equivalent to that at 600C.
- The ratio (solvent: material) is 25ml: 1g, which makes the extraction efficiency higher than other ratios.
- After the extraction process is repeated 4 times, 70.8% of the protein is be obtained. However, after only 2 times of extraction, 63.7% protein is obtained
3.3. Determing the precipitation conditions
- (NH4) 2SO4 helps precipitate proteins more effectively than alcohol 960.
- The efficiency of precipitation by salt reaches 66.3% while that of precipitation with alcohol only reaches 38.4%. The purity of protein preparations when using alcohol and salt reach only 40.4 and 46.8% respectively.
- Reducing the temperature of the precipitate to 10 ° C makes the precipitation efficiency increase sharply and reach 78%.
Flowchart of obtaining protein from gut seaweed
With this process, the extraction efficiency reaches 63.7%. 78% protein in the extract is precipitated, collected, dried into protein preparations. The protein content of this preparation is 48.3%.
3.4. Evaluating nutritional values of protein preparations
- Obtained protein contains 9 essential amino acids. The essential amino acid content of protein in the preparation is 1.47 times higher than the amino acid requirement for children aged 1-2 years and 1.66 times higher than the amino acid requirement of adults.
- There are 7 in 9 types of amino acids with AAS value higher than 1. Two amino acids with AAS less than one are lysine and histidine.
- PER value of protein in preparation reaches 1.67, NPR reaches 6.56
- The BV value of protein in preparation is 65.19 compared to that of the control soy protein 72.14
- The PDCAAS value of protein in preparation is 65.19 compared to the requiremnt for children 1-2 years old. This value reaches 58.67 compared to the recommended adult needs