CN101869282A - Method for preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying - Google Patents

Abstract

The invention relates to a method for preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying. The method comprises the following steps of: mixing grease which contains polyunsaturated fatty acid, an emulsifier and water to obtain a mixture; homogenizing the mixture to obtain emulsion; atomizing the emulsion into liquid drops for spraying into a cool chamber filled with refrigerating fluid, wherein the temperature of the refrigerating fluid is lower than the eutectic point of the emulsion; and performing vacuum freeze drying on a material obtained by refrigerating so as to obtain the polyunsaturated fatty acid grease microcapsules. The method is implemented under a low-temperature and oxygen-free condition, so that the method has the advantages of capability of reducing oxidation of the polyunsaturated fatty acid to the greatest extent, difficult damage to nutrition constituents, no need of smashing in the entire preparation process of the microcapsules, simple process, uniform distribution of obtained polyunsaturated fatty acid grease microcapsules, high efficiency, short time and low energy consumption.

Description

A kind of method of preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying

Technical field

The present invention relates to a kind of method for preparing microcapsules, especially utilize atomizing freeze drying to prepare the method for easily oxidized polyunsaturated fatty acid grease microcapsules such as arachidonic acid (ARA) and DHA (DHA).

Background technology

Polyunsaturated fatty acid grease microcapsules such as arachidonic acid and DHA traditional spray-drying production commonly used at present.This method is in dry run, and the oxidation of heat sensitive material arachidonic acid or DHA is comparatively serious, thereby the gas flavour and the stability of microcapsule product is had a negative impact.There is a small amount of enterprise to use vacuum freeze-drying technique to produce arachidonic acid or DHA polyunsaturated fatty acid grease microcapsules in addition, this method is normally directly carried out vacuum freeze drying with the emulsion of arachidonic acid or DHA, and fragmentation obtains the finished product pulvis then.But this method energy consumption is big, and the time is long, and the very difficult control of the granularity of finished product pulvis evenly, and also may sneak into foreign matter in the shattering process.

The patent of application number 200710053378.8 has related to a kind of preparation technology and application of unsaturated fatty acid microcapsule.It may further comprise the steps: choose the wall material; The wall material is mixed by a certain percentage with water; Add the capsule material and carry out homogeneous and obtain emulsion; Obtain product after emulsion carried out spray-drying, cools off and sieve.This method uses traditional spray-drying mode to prepare unsaturated fatty acid microcapsules such as arachidonic acid, DHA, baking temperature height (about 200 ℃), make that unsaturated fat acid moieties such as arachidonic acid, DHA are oxidized, cause microcapsule product gas flavour and stability all relatively poor.

Application number is that the patent of 200810195187.X has related to a kind of method of using the low dew point gas atomization freeze drying powder process of low temperature, it is characterized in that the droplet that uses atomizer liquids to be dried to be turned to the 1-250 micron is low to moderate-60 ℃ in temperature, dew point is to be frozen into the ice powder in-70 ℃～-80 ℃ the gas, the eutectic temperature that then EAT is adjusted to material is hanged down 2～4 ℃ temperature, gas is by the orifice plate of fluid bed, the feasible ice pruinescence fluidization that rests on the fluidisation plate, the solvent of icing simultaneously in the powder is distilled, when the gas dew point until gas outlet is got back to-55 ℃～-60 ℃, lyophilization finishes, be warming up to 30 ℃～50 ℃ dryings 1～2 hour, the ice pruinescence is dried to 1～220 micron particles.

Finlay, W. and Wang, Z. patent WO2005061088 " Powder formulation by atmosphericspray-freeze-drying " has also related to a kind of method of utilizing the powder process of cryogenic gas atomizing freeze drying, it is characterized in that at first freeze drying chamber being cooled to below-50 ℃ by the gas of low temperature drying, to spray into the freeze drying chamber of the gas of the drying that is full of low temperature after the feed liquid atomizing then, the drop of atomizing is frozen the back and is collected in the bottom.

The patent of application number 200810189058.X has related to a kind of integrated atomizing freeze drying equipment and method.This equipment comprises the freeze drying chamber that is cooled off by refrigerating plant, and this freeze drying chamber is provided with vacuum pumping opening, liquid outlet, sprayer and refrigerant inlet, and this sprayer links to each other with the feed liquid mouth.This method has then comprised spray chilling process and freezing dry process, and described spray chilling process and freezing dry process are successively to carry out automatically in same equipment.

The patent of application number 200610070156.2 has related to fluidized-bed normal pressure spray-freezing drying method and device, is formed by the freezing granulation of cold nebulization and the dry two kinds of process combination of fluidized-bed normal pressure air freezing.The twin fluid atomization device atomization refrigeration that the feed liquid raw material moves down through cryogenic conditions earlier, obtain tiny freezing particulate, be collected in the bottom of device fluid bed, utilize the low steam partial pressure of atmospheric freeze drying medium to satisfy the water sublimed condition again, by fluidization technology, the particulate that spray chilling is made becomes the split product at unified device inner drying.

Above patent and document or adopt high temperature drying to produce arachidonic acid and DHA, and the nutritional labeling of high temperature destructible product maybe need to prepare the device of cryogenic gas, apparatus and process more complicated.

Summary of the invention

Technical problem to be solved by this invention provides a kind of method of preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying.This method is carried out under the condition of low temperature, anaerobic, can farthest reduce the oxidation of polyunsaturated fatty acid, and nutritional labeling is difficult for being damaged; Whole process need not fragmentation, and technology is simple, the polyunsaturated fatty acid grease microcapsules even particle distribution that obtains; The efficient height, the time is short, and energy consumption is low.

For solving the problems of the technologies described above, the technical scheme that is adopted is: a kind of method of preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying is characterized in that: grease, emulsifying agent and the water that will contain polyunsaturated fatty acid mix, and obtain mixture; With the mixture homogeneous, obtain emulsion; Emulsion is atomized into drop sprays in the cool chamber that freezing liquid is housed, the temperature of freezing liquid is lower than the eutectic point of emulsion (temperature when free moisture is frozen into ice crystal fully in the material); The freezing material that obtains is carried out vacuum freeze drying promptly obtain polyunsaturated fatty acid grease microcapsules.

Press such scheme, described polyunsaturated fatty acid is arachidonic acid or DHA.These two kinds of polyunsaturated fatty acids are very easily oxidized in common microcapsules process, and polyunsaturated fatty acid is not oxidized and the sharpest edges of this method can adequately protect in process exactly.

Press such scheme, described mixture also comprises antioxidant, filler; Described mixture by weight percentage, its mixing match is: the grease 10～30%, emulsifying agent 2～30%, antioxidant 0～0.5%, filler 0～30%, the water 30～70% that contain polyunsaturated fatty acid; When the mixture that uses different ratios to prepare burden and obtain, its eutectic point that carries out the emulsion that homogeneous obtains can change, and general excursion is-10～-50 ℃.

Press such scheme, described emulsifying agent is one or more the mixing in vegetable protein, casein sodium, converted starch, lactalbumin, the food-grade glue; Described filler is one or more mixing of maltodextrin, glucose, sucrose; Described antioxidant is one or more mixing of sodium ascorbate, vitamin E, ascorbyl palmitate, Tea Polyphenols.

Press such scheme, described mixing temperature is preferably 30～80 ℃.

Press such scheme, described atomizing type is a kind of in pressure atomization, aerodynamic atomization, the centrifugal atomizing, and wherein pressure atomization and aerodynamic atomization are more convenient for implementing; The atomizing pressure of described pressure atomization is 0.5MPa～2MPa; The stream pressure of aerodynamic atomization is 0.01～0.2MPa.Compare with common freeze drying process, adopt finished product particle size range that this atomization condition obtains between 10～500 μ m, and be generally the spheric granules of rule, have splendid flowability.

Press such scheme, described freezing liquid adds in the cool chamber when drop is sprayed into the cool chamber that freezing liquid is housed continuously or off and on; Described freezing liquid is a kind of in liquid nitrogen, liquid argon, the liquid carbon dioxide.

Press such scheme, described freezing liquid stirs in drop being sprayed into the cool chamber process that freezing liquid is housed the time, and stir speed (S.S.) is 10～300rpm/min.Freezing liquid stirred the freezing particle that obtains be difficult for to be reunited, but mixing speed can not be too fast, to prevent to destroy the particle after freezing.

Press such scheme, the described freezing material that obtains is transferred in drop being sprayed into the cool chamber process that freezing liquid is housed and carries out vacuum drying in the vacuum freeze dryer, or after drop being sprayed into the cool chamber process end that freezing liquid is housed, be transferred to and carry out vacuum drying in the vacuum freeze dryer; The absolute pressure of described vacuum freeze drying is less than or equal to 300pa, and final baking temperature is less than or equal to 60 ℃.Dry run under the high vacuum can not only protect grease not oxidized effectively, and can remove the bad smell that may have in the grease simultaneously.

Press such scheme, the particle diameter of the polyunsaturated fatty acid microcapsule product that the method for described preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying prepares is 10～500 μ m.

Beneficial effect of the present invention:

1, this method sprays into the drop that atomizes earlier and carries out the snap frozen granulation in the freezing liquid, carry out vacuum freeze drying then, whole process is carried out under the condition of low temperature, anaerobic, can farthest reduce the oxidation of readily oxidizable substances such as arachidonic acid and 26 carbon tetraenoic acids, nutritional labeling is difficult for being damaged, thereby improve the gas flavour of microcapsule granule, improve the quality of product, prolong the product shelf life.

2, production environment cleaning, do not need to carry out fragmentation in the whole process, need not to carry out post processing, technology is simple, the polyunsaturated fatty acid microcapsule granule that obtains is uniformly distributed in 10～500 μ m, and by the control atomization condition, can effectively control the size and the distribution of microcapsule granule, satisfy the different market demands;

3, compare with traditional vacuum freeze-drying technique, carry out the spray chilling granulation earlier before vacuum freeze drying, the increment charge level is long-pending greatly, thereby improves drying efficiency, shortens drying time, cuts down the consumption of energy;

4, the polyunsaturated fatty acid microcapsule product particle integrity that obtains, grease embedding rate height;

5, freezing liquid can be recycled, thereby reduces production costs greatly.

Description of drawings

Fig. 1 is the process chart of the method for preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying among the embodiment 1.

The specific embodiment

Embodiment 1

Table 1

Contain 44% arachidonic grease	Casein sodium	Pea protein	Maltodextrin	Sodium ascorbate	Water
						??10Kg	??3Kg	??3Kg	??24Kg	??0.4Kg	??50Kg

Material in the table 1 is mixed, shear under the rotating speed of 10000rpm/min, the pressure of 40MPa carries out homogeneous then, obtains emulsion; Adopt the mode of aerodynamic atomization that the emulsion atomizing is drop, directly spray in the cool chamber that liquid nitrogen is housed, wherein the pressure of aerodynamic atomization is controlled at 0.01～0.02MPa, the flow velocity of feed liquid is 3kg/h, liquid nitrogen temperature is-195.8 ℃, the emulsion eutectic point is-37 ℃, agitating device is equipped with in the cool chamber bottom, stir speed (S.S.) is that (stirring can make the freezing particle that obtains produce slight motion about 150rpm/min, thereby reduce the freezing intergranular reunion that obtains), the drop of atomizing can be frozen into the solid granulates of rule at low temperatures rapidly, meanwhile, continues to replenish liquid nitrogen in cool chamber, and the material that will freeze from cool chamber bottom simultaneously is transferred to and carries out drying in the vacuum freeze drier, and collect the nitrogen that volatilizes, it is compressed recasting obtain liquid nitrogen, recycling; After the spray process for the treatment of emulsion is finished, the freezing particle that obtains all transferred to carry out vacuum freeze drying in the vacuum freeze drier, keep the vacuum about 7Pa in the drying machine, ℃ dry 5h at first-40, in 15h, rise to 20 ℃ then from-40 ℃, last 20 ℃ of dry 5h, obtain particle diameter 50～380 μ m, moisture 3.94% (percetage by weight of water in the polyunsaturated fatty acid grease microcapsules product), grease embedding rate 99.5% (percetage by weight), the white arachidonic acid microcapsules of peroxide value 0.45mmol/kg.

Embodiment 2

Table 2

Contain 42% arachidonic grease	Casein sodium	Pea protein	Arabic gum	Glucose	Maltodextrin	Sodium ascorbate	Rope E supports one's family	Water
									??50Kg	??10Kg	??10Kg	??10Kg	??60Kg	??60Kg	??1Kg	??1Kg	??250Kg

Material in the table 2 is mixed, shear under the rotating speed of 10000rpm/min, 50MPa pressure carries out homogeneous then, obtains emulsion; Adopt the mode of aerodynamic atomization that the emulsion atomizing is drop, directly spray in the cool chamber that liquid nitrogen is housed, wherein the pressure of aerodynamic atomization is 0.015～0.025MPa, the flow velocity of feed liquid is 6kg/h, liquid nitrogen temperature is-195.8 ℃, the emulsion eutectic point is-39 ℃, and the drop of atomizing can be frozen into the solid granulates of rule at low temperatures rapidly; After the spray process for the treatment of emulsion is finished, the freezing particle that obtains all transferred to carry out vacuum freeze drying in the vacuum freeze drier, keep the vacuum about 10Pa in the drying machine, at first at-40 ℃ of dry 5h, under 20 ℃ and 0.1MPa, keep 3min then, at last at-40 ℃ of dry again 25h, obtain particle diameter 60～400 μ m, moisture 3.53% (percetage by weight of water in the polyunsaturated fatty acid grease microcapsules product), grease embedding rate 98.6% (percetage by weight), the white arachidonic acid microcapsules of peroxide value 0.31mmol/kg.

Embodiment 3

Table 3

The grease that contains 42% DHA	Converted starch	Lactalbumin	Maltodextrin	Sucrose	Ascorbyl palmitate	Tea Polyphenols	Water
								??100Kg	??40Kg	??50Kg	??100Kg	??120Kg	??1Kg	??1Kg	??400Kg

Material in the table 3 is mixed, shear under the rotating speed of 10000rpm/min, the pressure of 60MPa carries out homogeneous then, atomized liquid; Utilize the pressure type spray gun that the emulsion atomizing is drop, directly spray in the cool chamber that liquid nitrogen is housed, wherein atomizing pressure is 1.0～1.1MPa, and liquid nitrogen temperature is-195.8 ℃, the emulsion eutectic point is-35 ℃, and the drop of atomizing can be frozen into the solid granulates of rule at low temperatures rapidly; After the spray process of emulsion is finished, disposable the transferring to of the freezing particle that obtains carried out vacuum freeze drying in the vacuum freeze drier, keep the vacuum about 120Pa in the drying machine, at first at-30 ℃ of dry 12h, in 15h, rise to 15 ℃ then from-30 ℃, last 15 ℃ of dry 6h, obtain particle diameter 30～450 μ m, moisture 4.96% (percetage by weight of water in the polyunsaturated fatty acid grease microcapsules product), grease embedding rate 98.3% (percetage by weight), the white DHA microcapsules of peroxide value 0.23mmol/kg.

Embodiment 4

Table 4

Contain 40% arachidonic grease	Converted starch	Casein sodium	Maltodextrin	Glucose	Ascorbyl palmitate	Rope E supports one's family	Water
								??100Kg	??40Kg	??20Kg	??150Kg	??100Kg	??2Kg	??2Kg	??500Kg

Material in the table 4 is mixed, shear under the rotating speed of 10000rpm/min, the pressure of 70MPa carries out homogeneous then, obtains emulsion; Utilize centrifugal atomizer that the emulsion atomizing is drop, directly spray in the cool chamber that liquid argon is housed, wherein the centrifugal pan rotating speed of centrifugal atomizing is 3000～4000rpm/min, the liquid argon temperature is-185.9 ℃, the emulsion eutectic point is-32 ℃, agitating device is arranged at the cool chamber bottom, stir speed (S.S.) is controlled at about 100rpm/min that (stirring can make freezing particle produce slight motion, thereby reduce the freezing intergranular reunion that obtains), the drop of atomizing can be frozen into the solid granulates of rule at low temperatures rapidly; After the spray process of emulsion is finished, disposable the transferring to of the freezing particle that obtains carried out vacuum freeze drying in the vacuum freeze drier, keep the vacuum about 5Pa in the drying machine, at first in 1h, rise to-30 ℃ from-40 ℃, in 7h, rise to 0 ℃ then from-30 ℃, then in 6h, rise to 40 ℃ from 0 ℃, at last at 40 ℃ of dry 2h, obtain particle diameter 10～150 μ m, moisture 2.78% (percetage by weight of water in the polyunsaturated fatty acid grease microcapsules product), grease embedding rate 98.8% (percetage by weight), the white arachidonic acid microcapsules of peroxide value 0.30mmol/kg.

Embodiment 5

Table 5

The grease that contains 40% DHA	Casein sodium	Lactalbumin	Maltodextrin	Tea Polyphenols	Water
						??200Kg	??40Kg	??150Kg	??450Kg	??5Kg	??700Kg

Material in the table 5 is mixed, shear under the rotating speed of 10000rpm/min, the pressure of 80MPa carries out homogeneous then, obtains emulsion; Utilize the pressure type spray gun, under the atomisation pressure of 2MPa, the emulsion atomizing is drop, directly spray in the cool chamber that liquid carbon dioxide is housed, wherein the liquid carbon dioxide temperature is-78.5 ℃, the emulsion eutectic point is-28 ℃, agitating device is arranged at the cool chamber bottom, stir speed (S.S.) is controlled at about 200rpm/min that (stirring can make freezing particle produce slight motion, thereby reduce the freezing intergranular reunion that obtains), the drop of atomizing can be frozen into the solid granulates of rule at low temperatures rapidly, meanwhile, in cool chamber, continue to replenish liquid carbon dioxide, and the material that will freeze from the cool chamber bottom simultaneously is transferred to and carries out drying in the vacuum freeze drier, and collect the carbon dioxide that volatilizes, it is compressed recasting obtain liquid carbon dioxide, recycling; After the spray process for the treatment of emulsion is finished, the freezing particle that obtains all transferred to carry out vacuum freeze drying in the vacuum freeze drier, keep the vacuum about 300Pa in the drying machine, at first in 2h, rise to-20 ℃ from-40 ℃, in 12h, rise to 40 ℃ then from-20 ℃, at last at 40 ℃ of dry 3h, obtain diameter 10～200 μ m, moisture 1.85% (percetage by weight of water in the polyunsaturated fatty acid grease microcapsules product), grease embedding rate 98.9% (percetage by weight), the white DHA microcapsules of peroxide value 0.43mmol/kg.

Claims (10)

1. the method for a preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying is characterized in that: will contain grease, emulsifying agent and the water mixing of polyunsaturated fatty acid, and obtain mixture; With the mixture homogeneous, obtain emulsion; Emulsion is atomized into drop sprays in the cool chamber that freezing liquid is housed, the temperature of freezing liquid is lower than the eutectic point of emulsion; The freezing material that obtains is carried out vacuum freeze drying promptly obtain polyunsaturated fatty acid grease microcapsules.

2. the method for preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying according to claim 1, it is characterized in that: described polyunsaturated fatty acid is arachidonic acid or DHA.

3. the method for preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying according to claim 1 is characterized in that: described emulsifying agent is one or more the mixing in vegetable protein, casein sodium, converted starch, lactalbumin, the food-grade glue.

4. the method for preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying according to claim 1, it is characterized in that: described mixture also comprises antioxidant, filler; Described mixture by weight percentage, its mixing match is: polyunsaturated fatty acid grease 10～30%, emulsifying agent 2～30%, antioxidant 0～0.5%, filler 0～30%, water 30～70%; The eutectic point of the emulsion that described mixture homogeneous obtains is-10～-50 ℃.

5. the method for preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying according to claim 4 is characterized in that: described filler is one or more mixing of maltodextrin, glucose, sucrose; Described antioxidant is one or more mixing of sodium ascorbate, vitamin E, ascorbyl palmitate, Tea Polyphenols.

6. the method for preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying according to claim 1, it is characterized in that: described mixing temperature is 30～80 ℃.

7. the method for preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying according to claim 1 is characterized in that: described atomizing type is a kind of in pressure atomization, aerodynamic atomization, the centrifugal atomizing; The atomizing pressure of described pressure atomization is 0.5MPa～2MPa; The stream pressure of aerodynamic atomization is 0.01～0.2MPa.

8. the method for preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying according to claim 1, it is characterized in that: described freezing liquid adds in the cool chamber when drop is sprayed into the cool chamber that freezing liquid is housed continuously or off and on; Described freezing liquid is a kind of in liquid nitrogen, liquid argon, the liquid carbon dioxide.

9. the method for preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying according to claim 1, it is characterized in that: the described freezing material that obtains is transferred in drop being sprayed into the cool chamber process that freezing liquid is housed and carries out vacuum drying in the vacuum freeze dryer, or after drop being sprayed into the cool chamber process end that freezing liquid is housed, be transferred to and carry out vacuum drying in the vacuum freeze dryer; The absolute pressure of described vacuum freeze drying is less than or equal to 300pa, and final baking temperature is less than or equal to 60 ℃.

10. the method for preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying according to claim 1, it is characterized in that: the particle diameter of the polyunsaturated fatty acid microcapsule product that the method for described preparing polyunsaturated fatty acid grease microcapsules by spray freeze drying prepares is 10～500 μ m.

Images