CN114657022A - Deodorization method for improving quality of microalgae oil rich in DHA - Google Patents

Abstract

The invention relates to the field of oil and fat extraction, and discloses a deodorization method for improving the quality of DHA-rich microalgae oil. The deodorization method is as follows: firstly, DHA is fermented by Schizophyllum, and then DHA-rich oil is obtained by cell lysis and centrifugation, and pre-refined to obtain decolorized oil. The deodorized oil is deodorized, wherein the ionized water used for deodorization is heated to boiling first, and the gas and steam separated from the water are discharged and then pumped into the steam generator. The pre-deoxygenated water is further heated to form steam. Then deodorize. The method effectively reduces the peroxide value and p-anisidine value of the oil by reducing the negative influence of oxygen, and finally obtains a high-quality product that meets the market demand.

Description

A kind of deodorization method for improving the quality of DHA-rich microalgal oil

technical field

The invention relates to the technical field of microalgal oil processing, and mainly relates to a deodorization method for improving the quality of DHA-rich microalgal oil.

Background technique

Docosahexaenoic acid (DHA, 22:6n-3) is an important long-chain polyunsaturated fatty acid (PUFA) that plays an important role in human health. Traditionally, marine fish have been the main source of DHA, but due to the increasing scarcity of marine resources, DHA-rich microalgal oils have received extensive attention.

One of the main problems with the use of DHA-enriched oils on the market is their strong unpleasant taste. DHA-rich microalgal oil contains nearly 70% polyunsaturated fatty acids, and oils with a high proportion of polyunsaturated fatty acids are easily oxidized during processing and storage to form hydroperoxides (primary oxidation products) and odor components such as Aldehydes and ketones (secondary oxidation products).

Oil refining process is usually used to improve oil quality, and deodorization is usually the last and key process to break down oxides and remove odorous components, and oxygen is an important cause of oil rancidity because it is the starting material of oxidation, which can generate hydrogen peroxide . Therefore, the quality and stability of DHA-enriched oils can also be adversely affected if the oils come into contact with oxygen during deodorization. The water vapor used in the existing deodorization process will cause rancidity and affect the quality of the oil. This study developed an effective deodorization method by reducing the negative effects of oxygen, developing an effective and simple method for deodorizing and improving the quality of DHA-enriched microalgal oil. The method presented in this study provides a simple method for the deodorization of oils and an alternative to the deodorization of DHA-enriched microalgal oils, resulting in high-quality final products that meet market demands.

SUMMARY OF THE INVENTION

The present invention provides a high-efficiency deodorization method for microalgae oil, which is used to solve the technical problems mentioned in the above background art.

To achieve the above object, the present invention provides the following technical solutions: a deodorization method of DHA-rich microalgal oil, comprising the following steps:

(1) Pre-refining process of DHA-rich microalgal oil

After fermentation of DHA by Schizophyllum, DHA-enriched oil was obtained by cell lysis and centrifugation. The crude oil is pre-refined by washing, caustic soda refining and bleaching, and the resulting decolorized oil is used in the next deodorization process.

(2) Oil deodorization process

Deodorizes DHA-enriched microalgal oil. Equipment includes steam generators, cooling tanks and vacuum pumps. Vacuum is provided by a vacuum pump connected to the deodorizer.

① Send about 60kg of DHA-rich oil obtained after decolorization into the deodorant. The vacuum was maintained at 100 kPa.

②Use heat transfer oil to heat the test box to 180℃ and keep it at this temperature for 4 hours.

③ The total consumption of stripping steam in the whole deodorization process is adjusted to about 9L.

④After deodorization, the oil is pushed into the cooling tank with pure _N2 , and cooled by cold water circulation under the protection of _N2 .

⑤ First, heat the deionized water to boiling, discharge the gas and steam separated from the water, and pump the pre-deoxygenated water into the steam generator.

⑥ The pre-deoxygenated water is further heated to form steam for deodorization.

Compared with the prior art, the beneficial effects of the present invention are:

1. Due to the high temperature of the decolorization process, many secondary products of hydrogen peroxide are produced in the oil. The primary oxidation product, hydrogen peroxide, is stable at room temperature. However, under high temperature conditions, such as the deodorization process at 180 °C, it is easily decomposed into aldehydes, ketones, acids, etc., which are secondary oxidation products and have a strong bad odor. Reducing oxygen levels can greatly reduce the formation of secondary lipid oxidation products.

2. The unsaponifiable lipid squalene can be removed by the deodorization process. However, in this study, we did not observe significant removal of squalene. The deodorization process using deoxygenated steam did not affect the DHA content in the oil, thereby preserving the nutritional value of the microalgal oil and making it edible.

3. The decolorized and deodorized oils using strategy I showed higher values after 7 days than the deodorized oils using strategy II according to the TBARS test.

4. This work provides a simple strategy to improve the efficiency of the DHA-enriched oil deodorization process, emphasizing the importance of pre-deoxygenation of water used to generate deodorized steam. Using this strategy, high-quality DHA-rich microalgal oil with zero peroxide value and very low p-anisidine value can be obtained, which can meet the high-quality requirements of the market. After the deodorization process, the losses of oil and DHA were about 6% and 3%, respectively. 30%, respectively, which did not significantly reduce the nutritional value of DHA-enriched microalgal oil. In addition, the authors propose other oxygen removal methods, such as nitrogen replacement or membrane treatment, to remove oxygen from the steam.

Detailed ways:

Specific implementation one:

Deodorization of DHA-enriched microalgal oil with steam generators, cooling tanks and vacuum pumps. Vacuum is provided by a Roots vacuum pump connected to the deodorizer. About 60kg of decolorized oil after decolorization is sent to the deodorant. The vacuum is kept at 100kpa. Heat the test chamber to 180°C using heat transfer oil and keep it at this temperature for 4 hours. During the whole deodorization process, the total consumption of stripping steam is adjusted to about 9L,

Specific implementation two:

After deodorization, the oil is pushed into the cooling tank with pure nitrogen, and cooled by cold water circulation under nitrogen protection: deionized water at room temperature is injected into the steam generator, and the water is heated to form steam for deodorization.

Specific implementation three:

The difference between this embodiment and the second embodiment is that the deionized water is first heated to boiling, the gas and steam separated from the water are discharged, and the pre-deoxygenated water is pumped into the steam generator. The pre-deoxygenated water is further heated to form steam for deodorization. Other steps are the same as in the second embodiment. Specific implementation four:

Each deodorization method was repeated three times.

Claims (3)

1. Develop a deodorization method for improving the quality of DHA-rich microalgal oil, which is used to solve the problem of oxidative rancidity in contact with oxygen during the deodorization process of DHA-rich microalgal oil, reducing the quality of oil and fat, and producing products that meet market demand , including the following steps: Step 1: after DHA is fermented by Schizophyllum, cell lysis and centrifugation are used to obtain DHA-rich oil; crude oil is pre-refined by washing, caustic soda refining and bleaching, and the obtained decolorized oil is used for the next deodorization process; Step 2: Deodorize the DHA-rich microalgae oil, add about 60kg of decolorizing oil to the deodorant, keep the vacuum at 100kPa, use heat transfer oil to heat the test chamber to 180°C, and keep at this temperature for 4h , the total consumption of stripping steam in the whole deodorization process is adjusted to about 9L; Step 3: After deodorization, the oil was pushed into the cooling tank with pure nitrogen, and cooled by circulating cold water under nitrogen protection. Two different deodorization processes were tested; Strategy 1: Inject deionized water at room temperature into a steam generator to heat the water to form steam for deodorization; Strategy 2: First, heat the deionized water to boiling, discharge the gas and steam separated from the water, and pump the pre-deoxygenated water into the steam generator, and the pre-deoxygenated water is further heated to form steam for deodorization; Each deodorization method was repeated three times. 2. a kind of deodorization method that improves the quality of DHA-rich microalgal oil according to claim 1, is characterized in that in step 2, at 100kPa, 180 ℃ of temperature are kept for 4h. 3. a kind of deodorization method that improves the quality of microalgae oil rich in DHA according to claim 1, is characterized in that in step 3, two kinds of deodorization processes are deionized water, in strategy one, deionized water directly injects steam However, in strategy 2, the deionized water is pre-deoxygenated first, and then enters the steam generator to be heated to form steam.