TW201635910A - One processing method for krill oil - Google Patents

Abstract

Krill oil contains a lot of long-chain polyunsaturated fatty acids (LCPUFAs, such as: DHA, EPA) attached to the phospholipid and rich in astaxanthin. It is easier to be absorbed by the human body. The fresh krill must be freeze-dried to remove moisture before oil extraction and to avoid autolysis. Microwave freeze-drying krill can provide sublimation energy of frozen krill by microwave and overcome the heat transfer resistance in a freeze-drier with heat plate. Microwave vacuum freeze-drying can retain the quality of dried krill and avoid lipid oxidation, and it can save drying time and energy consumption. Further, the use of ethanol as solvent for microwave extraction microwave krill oil has a high extraction yield, fast and less energy consumption. Because microwave heating can rapidly increase temperature and pressure in the cells to cause krill cells rupture and the krill oil and active components can be dissolved in the ethanol to increase oil extraction yield. Moreover, if the microwave extraction system is operated at vacuum condition, then the temperature of the extract solution will be lower and also avoid lipid oxidation. Ethanol can be evaporated by microwave vacuum system to concentrate krill oil. Compared with supercritical carbon dioxide extraction, it can extract non-polar lipid without residual solvent, but the supercritical extraction equipment is expensive, time-consuming. The equipment of conventional solvent extraction is cheap, but it needs take a few hours to accomplish and may have organic solvent residues. However, the traditional freeze-drying and extraction take very long time to accomplish. The method is to apply microwave in freeze-drying krill and extraction of krill oil. It can improve processing efficiency and significantly decrease operation time and energy consumption.

Description

Method for producing krill oil

The invention technology can be divided into three parts, the first is to use the microwave vacuum freeze-drying technology to dry the krill to save time and energy; then use ethanol as the extraction solvent to rapidly extract the krill oil by microwave vacuum, wherein the phospholipid is connected to the long Chain polyunsaturated fatty acids (such as DHA, EPA), and contains very high resistance to astaxanthin, this process can improve efficiency and reduce operating time and energy, and finally use microwave vacuum heating to evaporate ethanol to concentrate krill oil.

Antarctic krill is distributed in planktonic crustaceans in the Antarctic waters. The individual mass is about 1~2g, the head is 45%, the shrimp body is 55%, and the muscle part is 40%. The main component is crude protein about 16.3%. The crude fat is about 1.3%, the water is about 75%, and the ash is about 2.8%. The protein of Antarctic krill is rich in essential amino acids, which are ideal proteins, but there are a variety of proteases in the body that accelerate the degradation and digestion of autologous decomposition and digestion (Wang et al., 2012). Therefore, the Antarctic krill used for human consumption needs to be processed within 3 hours after the capture. As the animal bait, it needs to be processed within 10 hours, so the processing technology is extremely demanded (Chen et al., 2009).

The oil of Antarctic krill is mainly concentrated in the head, the oil content is 0.4%~3.6%, and the unsaturated fatty acid is 49.1~67.6% of the total fat content. The ratio of EPA and DHA in omega-3 to unsaturated fat content 79.1 to 89.2%, which is higher than about 15% of EPA and DHA in fish oil. In addition, Antarctic krill has high antioxidant activity of astaxanthin and contains phospholipids accounting for about 40% of total oil (Wang et al. 2012). Antarctic krill oil has been successfully developed internationally for human health care.

The process of processing Antarctic krill is mostly freeze-dried to maintain its quality. However, in 1997, US Patent (US 5,672,370) used defrosted krill to dry under microwave vacuum or dry air with air flow. Low-temperature extraction of shrimp oil (re-refining), and the extracted dried shrimp powder directly as animal feed, or enzymatic decomposition to obtain hydrolyzed peptone, and the shrimp shell can be further processed to produce health foods such as chitin and glucosamine ( Wang et al. 2012). In addition, the US patent (US8624046 B2) in 2014 also mentions the use of protease treatment and then pressing to increase the amount of shrimp oil. In the 2007 world patent (WO2007080514 (A)), the fresh krill is directly crushed into shrimp, and then heated at 90 ° C for 45 minutes, the water layer and the oil layer can be obtained in the liquid, and then the oil layer is separated. Although this method does not use organic solvents at all, it takes a long time to heat, is easy to oxidize, and the extraction effect of shrimp oil needs to be improved.

The extraction of krill oil from Antarctic krill using supercritical carbon dioxide is based on non-polar triglycerides rather than phospholipids. In addition, if supercritical carbon dioxide is used to extract lyophilized Antarctic krill, the extraction rate is three times that of acetone and ethanol (Tian et al., 2011). The freeze-dried Antarctic krill was extracted with acetone and ethanol for 2 h, and the solid-liquid ratio was controlled at 1:12. The extracted oils accounted for 20.4-32.7% of phospholipids and 64-77% of polar non-phospholipids. Small molecules Triglyceride accounts for 1-3.2%, low cholesterol content and high antioxidant capacity, and the residual protein is partially dissolved in water, and then the isoelectric point is used to obtain shrimp protein, which can also reduce the content of ash and fluorine. . (Gogiliott et al ., 2009)

Since most of the krill oil extraction methods require lyophilization of Antarctic krill to increase the extraction rate, Tian et al. (2011) pointed out that it is necessary to develop new extraction methods when considering the time and energy consumption of freeze-drying large quantities of krill. It indicates that the current production of freeze-dried krill is also a bottleneck process. Extraction technology is the key technology for the production of Antarctic krill oil, so many companies apply for international specialization. Canada's Neptune company first uses acetone to dehydrate and extract the oil of Antarctic krill, and then extracts the remaining oil with ethyl acetate. However, this solvent has low ignition point and is prone to gas explosion, and if there is residual solvent, it is easy to involve food safety. . Norwegian companies or Chinese companies use microwave-assisted supercritical fluids to extract phospholipid-rich krill oil, only supercritical carbon dioxide mainly extracts non-polar substances, and the time of one batch extraction is several hours, based on operating cost considerations. Competitiveness.

The invention is based on the use of microwaves to provide sublimation heat of frozen krill in a vacuum system, which overcomes the traditional heat conduction barrier, so that the freeze drying time can be shortened from several days to several hours, not only saving energy but also producing Dried krill. In addition, using ethanol as an extraction solvent, the freeze-dried krill is at atmospheric pressure or Microwave extraction under vacuum, extraction is achieved in a few minutes, and the ethanol is quickly heated and evaporated by microwave vacuum concentrator to concentrate the krill oil. Therefore, the microwave vacuum system has greatly improved in extraction and concentration efficiency and energy saving. .

The krill is firstly packaged for freezing, then placed in a microwave freezing vacuum dryer, and then the system is evacuated, the pressure of the system is controlled below the triple point of water (4.5 mmHg), and then the low power microwave is turned on. Energy, so that the ice crystals in the krill can be sublimated, and the microwave freeze-dried krill can be obtained in about 1 hour. The drying time is related to the microwave power. The higher the microwave power, the faster the drying rate and the shorter the drying time. And the temperature of the krill in the microwave freeze-drying process should not be too high (Fig. 1). Compared with the traditional freeze-drying time, the microwave freeze-drying time is obviously shorter (Fig. 2), and the freezing system that needs dehydration due to the freeze-drying process will The sublimated water vapor freezes rapidly into ice, which prevents water vapor from entering the vacuum pump to maintain a constant vacuum system. Therefore, the longer the freeze-drying time, the compressor in the refrigeration system and the pump in the vacuum system need to consume energy, so the microwave The rapid sublimation of krill ice crystals can save approximately 90% of energy (Table 1). In the microwave extraction of krill oil, the freeze-dried krill can be placed in an extraction vessel, and several times (4-50) of ethanol can be added as an extraction solvent, or a vacuum system can be used to reduce the extraction temperature and prevent krill oil. Oxidation, then adjust the microwave power (300~1000W) for heating extraction, and extract the krill oil in about 5~20 minutes. The microwave vacuum concentration system is used again, and the microwave is used as a heat source to rapidly heat the extract. The evaporated ethanol can be condensed and recovered within 5 to 30 minutes, and the concentrated collection of krill oil is completed, which contains a large amount of EPA and DHA (Fig. 3).

In the analysis and analysis of the krill oil composition, the quantitative extraction extract was placed in a test tube, and a methanol solution of potassium hydroxide and an internal standard were added. After the test tube was sealed, it was heated at 80 ° C for 20 minutes for saponification, and then hydrochloric acid was added. Neutralize with methanol solution and use BF ₃ methanol solution as catalyst, heat at 80 ° C for 20 minutes to carry out methyl esterification reaction, finally add n-hexane, shake the test tube vigorously to extract fatty acid methyl ester in methanol phase, and let stand. After stratification, the supernatant liquid is aspirated, and anhydrous sodium sulfate is added to adsorb water, which can be placed in a sample bottle and sealed for use. The quantitative sample was injected into a gas chromatograph, and the analytical column was a CP7864 column (60 m*0.32 mm, 0.25 μm, Supelco); the analysis conditions were that the initial temperature was set at 150 ° C and the temperature was continuously raised to an end temperature of 250 ° C. The detection temperature is 280 ° C, and the flame ion detector (FID) is used as the detector. The saponification and esterification of krill oil was injected into the fatty acid composition map of GC analysis (Fig. 4), in which EPA and DHA accounted for more than 30% of the extracted oil.

The detailed manufacturing process is shown in Figure 1. It includes the following steps:

a. After the krill is divided into bags, it is placed in a freezer for freezing.

b. First, turn on the compressor of the condensing and dehydrating device in the microwave freeze dryer to lower the temperature of the condenser to -20 ° C ~ -80 ° C. After the set temperature of the condenser is reached, the frozen krill is placed. In a dry chamber container. After the container is sealed, the vacuum pump is turned on immediately so that the pressure of the freeze-drying system is lower than the triple point of the water.

c. After the freeze-drying system reaches the vacuum, turn on the microwave and adjust the microwave output power to provide the sublimation heat of the frozen krill ice crystals, and monitor the temperature of the krill. If the temperature of the krill is higher than the room temperature, the microwave is indicated. Freeze drying has been completed. At this point, the vacuum pump is turned off and the vacuum is drained before the freeze-dried krill is removed from the container and the dried krill is vacuum packed.

d. The freeze-dried krill can be first ground to increase the surface area of the extraction. The dried krill is placed in an extraction vessel and 4 to 50 times of solvent is added. To take into account food safety, 95% ethanol is used as an extraction solvent. Connect the top of the extractor to the condenser and pass cold water to the low temperature, which will condense the evaporated solvent and recycle it.

e, turn on the microwave, adjust the appropriate microwave power, microwave extraction of krill oil, can also be combined with the vacuum system, so that the temperature of the extract is reduced, and the extract is not susceptible to oxidative damage, microwave extraction of phosphorus in about 5 to 20 minutes Shrimp oil, cooled, can be filtered or centrifuged to separate the upper extract and the lower extract residue.

f. The upper extract, which contains krill oil and ethanol, is placed in a microwave vacuum concentrator vessel, the microwave is turned on to rapidly heat the ethanol, and the evaporated ethanol solvent is cooled by the condenser, and the higher boiling krill oil concentration is obtained. It will be quickly increased. Finally, nitrogen will be blown in to remove residual ethanol and sealed off. This will prevent the oxidation of EPA and DHA polyunsaturated fatty acids in krill oil, and may also add antioxidants to increase the stability of krill oil. Li Baozang.

Figure 1 is a flow chart of the method of the present invention.

Claims (4)

The invention relates to a method for preparing krill oil, which comprises a method for microwave freeze-drying krill, microwave vacuum extraction krill oil and microwave vacuum concentrated krill oil, which can quickly obtain freeze-dried krill for storage, and can utilize microwave. The krill oil is quickly extracted, and the extraction solvent is evaporated by microwave heating to concentrate and purify the krill oil. The method for preparing krill oil according to claim 1, wherein the microwave freeze-drying the krill, the krill is first placed in a plastic bag and placed in a freezer, and stored in a freezer for storage. When operating the microwave freeze-drying device, the dehydration needs to be started first. The system's refrigeration compressor is cooled to -20 ° C ~ -80 ° C, then the frozen krill is placed in the microwave drying chamber, after the system is sealed, the vacuum pump is turned on to vacuum below 1 ~ 4mmHg, and then the microwave is turned on. The heating system regulates the microwave output power (50~300W) to provide the sublimation heat of the ice crystals in the frozen krill. When it is completely dry, the freeze-dried krill can be taken out and vacuum packed for use. The method for preparing krill oil according to claim 1, wherein the microwave vacuum extraction of krill oil refers to dried krill, which can be firstly ground and then placed in an extraction bottle, and added 5 to 50 times 95%. After the ethanol solvent, the extraction bottle is placed in a microwave oven, and the ice water condenser is connected above it. In order to avoid excessive extraction temperature and oxidation of the oil during the extraction process, the system can also be vacuumed, and finally the microwave output power is adjusted (300~1000W). ), to quickly heat the extract, microwave extraction of krill oil after about 5 to 30 minutes. The method for preparing krill oil according to claim 1, wherein the krill oil is concentrated under microwave vacuum, and the upper krill oil and the lower krill residue are separated by centrifugation or filtration after microwave extraction, and then the krill oil is removed. The ethanol extract is placed in a microwave vacuum concentrator to control the microwave power (300~1000W) and vacuum to reduce the evaporation temperature of the ethanol extraction solvent, and evaporate the ethanol by microwave heating, and condense and recover the ethanol solvent to obtain a concentrated Krill oil, filled with nitrogen for subsequent storage.