MỤC LỤC
- Evaluate some factors affecting the pineapple vinegar production process - Developed a production process for pineapple vinegar.
Follow the work plan, provide timely supplementary instructions to suit the conditions of knowledge exchange activities from teachers in order to accumulate experience, carefully review the contents of preparing for the report and ask for opinions about problems that arise during the internship. - The research results of the topic will partly contribute to the study of the fruit vinegar production process that brings value, health and economy to the community.
The flesh of the fruit is pale yellow to white, less fragrant, sour, more watery.
According to statistics, the production of Smooth Cayene pineapple variety accounts for 70% of the world production and is mostly in canned form (about 95%) in so there has been pressure on investors to improve the Cayenne variety to provide a better form (Salewski and Scott, 2000). In Vietnam, according to research conducted by the Research Institute of Fruits and Vegetables, Cayenne have been gathered in our country including: Provinces with a large area of Cayenne pineapple such as Ninh Binh (700 ha), Nghe An (695 ha), Ha Tinh (438 ha), (Tuan and Tien, 2002).
Their growth rate is very fast, from one cell after 12 hours can reproduce into 17 million cells.In the process of growth and development form acetic acid, low acid concentrations will stimulate their growth [5]. Currently, in the world more than 20 species of Acetic bacteria have been found in the world, collectively known as Acetobacter: A fairly large bacillus belonging to the obligate aerobic type, the temperature range for their growth is from 20 - 40 OC. Bacterial strains of suboxydans, acetic acid is accumulated and retained in the environment without further oxidation, Species with high oxidizing capacity that continue to convert acetic acid are classified 13%.
Vinegar is produced from naturally fermented fruit, has the advantage that in addition to the main ingredient is acetic acid, there are other nutrients such as sugar, organic acids, amino acids, vitamins, inorganic salts. The output of these fruit products remains unresolved contribute to the enrichment and diversification of vinegar products and also the consumption direction, the output for fruit products is the production of vinegar contains a lot of nutrients. Present-day, the estimated potential market for fruit vinegar is quite limited because for-profit businesses often have no nutritional content, and may even be harmful to the health of users, so they produce vinegar.
Procedure: During the fermentation process, people usually put 1/5 of the acetic acid into the fermentation tank with a capacity of ẵ barrel volume, continue to give the grape juice so that the entire volume reaches 2/3 of the volume of the fermentation tank. The purpose of adding acetic acid is firstly to create conditions for fermenting bacteria to grow, on the other hand, to prevent other bacteria from growing, without being mixed with impurities, for fermentation at a temperature of 23-34OC. The air goes in the opposite direction from the bottom to make the fermenter rapidly metabolized by bacteria, so the fermenter is high enough, the operation is well controlled, only the fermenter is too low once to get a thick vinegar at the bottom of the device.
For anaerobic culture, the culture process does not require aeration, only stirring, and for aerobic microorganisms, it is necessary to continuously aerate the use of aqueous medium so that the surrounding surface is in contact with the liquid. Through the above methods, the application of submerged fermentation to the research topic of pineapple vinegar needs to be carried out in order to study the influence and optimize the new processes to bring about constructive results as well as community. The oxygen supply through the aerator is stopped (when the power is turned off) there is still no effect on the bacteria because at that time the ventilation valves in the device are opened and air enters through natural ventilation, so the micro membrane bacteria on the mattress still do not die.This method overcomes the advantages and disadvantages of the two methods above.
In vinegar production, a certain amount of vinegar is added to the initial substrate to acidify the medium in order to: prevent the growth of harmful microorganisms, and put a certain amount of cells in the fermentation solution. In order for the oxidation to occur rapidly in the fermentation solution, it is necessary to add some mineral salts: K2HPO4, KH2PO4, MgSO4.7H2O, FeCl3.6H2O, (NH4)2SO4, (NH4)2HPO4,..depending on specific needs body of each species. Vinegar is cloudy and reduces acidity: In production, two oxidation processes - Oxidation of C2H5OH to CH3COOH: The oxidation of C2H5OH to CH3COOH is a beneficial process for production.
Vinegar preservation: The fermentation process is still continuing, it means that the wine has not been fully converted into vinegar, the vinegar has not been imported into the warehouse. Mix well the jelly, bentonite with vinegar and then let it settle, use a siphon to suck the clear vinegar out of the bottle, do it slowly so that the residue in the bottle does not still rise. Suitable vinegar preservation materials: Materials wood, aluminum, glass, hard rubber, pressed wood or treated paper can be used to store vinegar because vinegar is highly corrosive, iron is easily corroded by vinegar, and zinc is damaged by vinegar.
- The Acetobactor acetic astrain was obtained at the laboratory of the Department of Biotechnology and Food Technology, Thai Nguyen University of Agriculture and Forestry. Research on the production process of vinegar from pineapple in laboratory scale and production environment.
The product is evaluated for the limit of bacterial contamination in food according to QCVN 8-3: 2012 / BYT - National Technical Regulation on microbial contamination in food. The product was determined microbiologically in food according to TCVN 4884-2: 2015 and Escherichia coli quantified according to TCVN 7924-1: 2008. Analysis of the composition and standard of benefits of the product product according to the national standard.
Survey of demand and sensory evaluation of products: Conduct a survey of consumption and demand for fruit vinegar products and sensory evaluation of pineapple vinegar products with different formulations.
The fermentation process is monitored every 24 hours after 7 days to determine the amount of acetic acid based on the appropriate brix to choose and apply to the fermentation process. Normally, the brix meter has been calibrated at the place of manufacture, so the measurement results very accurate, but you should still perform this step regularly to check the machine's operation. A pH meter to determine the fermented fruit juice, when measuring is done by inserting the tip of the electrode into the solution at least 30mm-50mm deep so that the permeable membrane can contact the solution, can be using 0.1N NaOH and 0.1N HCl to adjust the fermentation juice concentration to the required concentration.
The number of aerobic bacteria in 1 ml of the test food product sample was calculated from the number of colonies counted from the culture cartridges according to the dilutions. Sensory standards follow the tests of general or separate sensory criteria based on the criteria: color, smell, taste and state to evaluate product quality. Calculate the total weighted score of all sensory criteria and then look up the product quality level table according to the total weighted average score of the panel members.
The results obtained in Table 4.1 and Figure 4.1 show that the acetic acid content tends to gradually increase from the initial minimum brix of 5 to the brix = 6 with the largest acetic acid content. From the above comments, the indicator of fermentable sugar content is suitable for the growth of acetic acid bacteria because at low content bacteria will be difficult to grow, high content will limit the growth of this bacteria. The initial acetic acid content tends to increase from the smallest pH of 4.5 to the maximum at the most suitable pH of 5.5; then tended to decrease and the lowest acid content at the highest pH was 6.5.
From the table, it can be seen that when the pH changes, the acetic acid content also changes, and the acetic acid content tends to increase from the smallest pH of 4.5 to the maximum of 5.5 and then to decrease deeply. By observing the table and figure, it can be seen that the fermentation time is too short for the bacteria to grow and carry out the metabolic processes, the bacteria have enough time for their optimal growth and metabolic activities, if the fermentation time is prolonged, the bacteria will continue to metabolize, it will use the same amount of acetic acid created. - The quality of the product is commented on the evaluation ability of the evaluation board: The members of the sensory evaluation panel on the quality of pineapple vinegar products meet the requirements of the panel, respectively.
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