CA2070706C

CA2070706C - Pulverulent products composed of a water-insoluble core substance and of a protective covering

Info

Publication number: CA2070706C
Application number: CA002070706A
Authority: CA
Inventors: Joachim U. Schneider; Gerhard Schwarz; Paul Grafen; Wolfgang Bewert; Horst Schumacher
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1991-06-25
Filing date: 1992-06-08
Publication date: 1999-11-23
Anticipated expiration: 2012-06-08
Also published as: JPH05200273A; JPH0714474B2; CA2070706A1; US5290567A; EP0525333A1; DE4120918A1

Abstract

Pulverulent products composed of a water-insoluble core substance and of a protective covering, are obtainable by - dispersing the core substance in an aqueous solution of amylose or a starch with an amylose content of more than 40 % by weight as film-forming polymer for the protective covering, - spraying this dispersion using hydrophobic silica as auxiliary and - subsequently drying the sprayed particles.

Description

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.: , O.Z. 0050/42495 Pulverulent products composed of a water-insoluble core substance and of a protective coverina The present invention relates to pulverulent products composed of a water-insoluble core substance and of a protective covering, obtainable by - dispersing the core substance in an aqueous solution of amylase or a starch with an amylase content of.
more,than 40 ~ by weight as film-forming polymer for the protective covering, - spraying this dispersion using hydrophobic silica as auxiliary and - subsequently drying the sprayed particles.
The present invention also relates to a process for preparing the pulverulent products composed of a water-insoluble core substance and of a protective covering.
Pulverulent products composed of a water-insoluble core substance such as, in particular, vitamins and carotenoids and of a protective covering are general-ly known and are used in pharmaceutical processing and in the hwnan and animal food sectors.
US--A 3 499 962 discloses pulverulent products composed of water-insoluble core substances such as perfumes or vitamins and of a protective covering com-r posed of starch with an amylase content above 40 ~ by weight, and GB-A 10 72 795 describes the use of amylase as film--forming polymer for encapsulating vitamins.
However, the disadvantage is the conversion of the dispersion .into the pulverulent products, whi~rh either is ~0 too industrially elaborate or provides particles which are too small.
EP-A 00 74 050 discloses the preparation ~f dry powders by spraying a dispersion with the addition of hydrophobic silica as aux:~liary and subsequent drying.
It is an object of the present invention to provide pulverulent products of the said type which are P
r - 2 - O.Z. 0050142495 more easily obtainable industrially and have better technical properties than the preparations hitherto disclosed.
We have found that this object is achieved by the pulverulent,products, defined in the first paragraph, composed of a water-insoluble core substance and of a protective covering, and by a process for preparing these pulverulent products.
Film-forming polymers to be used according to the invention are starch. with an amylose content above 40 ~S
by weight ar, preferably, amylose, which are generally employed in amounts of from 30 to 99 ~ of the weight of the pulverulent product.
The amylose can be obtained from corn starch which contains from 20 to 30 ~ by weight of amylose in addition to from 80 to 70 ~ by weight of amylapectin.
Starch with an amylose content of at least 40 ~ by weight can be obtained from novel varieties of corn with high amylose contents or from marrowfat peas.
The amylose or. starch with a high amylose cowtent to be used according to the invention has the advantage that it is soluble in water only at elevated temperature and separates out as water-insoluble film on cooling.
Protective coverings of this type are therefore dis-tinguished by high thermal and mechanical stability and resistance to faster. The products prepared in 'this way can thus be processed even in very stressful ways such as extrusion or compression.
A solution of the film-forming polymers can be produced either batchwise at from 150 to 160°C in an autoclave or, preferably, continuously with steam under from 5 to 10 bar by means of a heated nozzle (jet heater).
Suitable and preferred water-insoluble core substances are pharmaceutical agents, flavorings and, i.n particular, vitamins and caratenoids.. Further suitable examples are fats, oils and perfumes.

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3 - O.z. 0050/42495 The amount of the water-insoluble cure substance to be encapsulated is usually from ~, to 40 ~ of the weight of the pulverulent product.
To prepare the dispersion, the core substance is dispersed in an aqueous solution of the film-forming polymer, i-t~being possible for the dispersion to contain additives such as antioxidants, emulsifiers and/or preservatives, plasticizers, stabilizers, complexing agents or further film-formats.
The subsequent spraying of the dispersion is carried out with the aid of ~n auxiliary, and hydrophobic silica is used according to the invention (Die Mi~hle and Mischfuttertechnik, 114, (1977) 3). Hydrophobic silica comprises silica particles whose free hydroxyl groups on the surface have been reacted with a hydrophobic compound such as, in particular, a haloalkylsilane, for example dimethyldichlorosilane.
The introduction of the spraying auxiliary and its atomization are carried out with air at about 2 5 m3/kg of auxiliary, the amount of auxiliary required being only from 0.02 to O.IS times that of the dispersion.
It is preferable to use a spraying tower and to in-troduco the hydrophobic. silica, with simultaneous dispersion, into the spraying chamber at from 25 to 30°C.
It is expedient to introduce the spraying auxili-ary above the atomizing device, for example it .i.s pos-sibl~ to use nozz).es or high-speed atomizing disks.
The temperature of the dispersion to be atomized is not critical. It is normally from 60 to 90°C.
The direct introduction of the hydrophobia silica into the spraying zone substantially avoids mechanical stress on the particles. The thin hydrophobic film of the spraying auxiliary formed during the spraying stabilizes the particles so that agglomeration of the particles on contact in the non-solidified state .is prevented and immediate drying ~.s~ possible in a subsequent fluidized ~'~i 4 - 0.~. 0050/42495 bed drier in a conventional manner.
The drying is generally carried out at from 30 to 80°C because with air at this temperature the excess hydrophobic silica escapes.
The .pulverulent products which can be obtained in a straightforward manner by the process according -to the invention are distinguished by high stability, such as .insolubility in hot water, and are composed of particles with a satisfactory surface. The spraying procedure is such that, in a conventional manner, the particles have an average particle size of from 100 to 600 Vim, in particular from 180 to 350 ~~m. Powders with this particle size range ensure adequate protection of the encapsulated core substance and are particularly suitable for process-ing, for example to human or animal foods.
EXAMPLES
Preparation of pulveru.lent products A suspension of a ~ by weight of a film-forming polymer P in b ~ of water was heated at T1°C for t minutes and, after a further 20 minutes, cooled to 80°C aver the course of 90 minutes. The mixture was then mixed with a solution of c ~ by weight of'additive A in d ~ by weight of water and maintained at 80°C for 10 minutes.
Subsequently a ~ by weight of core substance K
were added and stirred into the solution over the course r of 10 minutes.
Subsequently the dispersion was sprayed under f bar and at 80°C in air loaded with hydrophobic silica.
10 kg of silica were added per h, and 80 kg of aqueous dispersion were sprayed per h. Conventional drying in a fluidized bed at 30°C {Examples 1 to 4) or 60°C
{Example 5) provided the powder with a residual water content of g ~ and an active substance content of h IU/g or i ~.
The particles were assessed by determining the particle size distribution by ASTM screen analysis.
Particles with sizes from 100 to 600 gym, with a ~~''~
- O.Z. 0050/2495 pea3c at about 180 - 350 Vim, were obtained in every case.
Details of the experiments are to be found in Tables 1 and 2.
leanings of the abbreviations in the tables 5 Polymer P
P/1 corn starch with an amylose content of 70 P/2 marrawfat pea starch with an amylose cowtent of 75 ~
Additive A
A/1 preswelled gelatin (film-former) A/2 glucose syrup (plasticizer) Care substance K
K/i vitamin .~. acetate (2.23 x 106 TU/g), stabilized with ethoxyquin K/2 vitamin A acetate (2,.12 x 106 IU/g), stabilized with ethoxyquin R/3 vitamin E acetate (24.7 R/4 citranaxanthin (33.2 ~) R/5 vitamin A acetate (2,15 x 106 Itl/g), stabilized with ethoxyquin 6 -- O.Z. OOSOl42~9~
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Claims

1. A pulverulent product consisting of particles composed of a water-insoluble core substance and of a protective covering, said particles having an average particle size of from 100 to 600 µn and being obtained by - dispersing the core substance in an aqueous solution of amylose or a starch with an amylose content of more than 40 % by weight as film-forming polymer for the protective covering, - spraying this dispersion using hydrophobic silica as auxiliary and - subsequently drying the sprayed particles.

2. A pulverulent product composed of a water-insoluble core substance and of a protective covering as claimed in claim 1, containing vitamins or carotenoids as water-insoluble core substance.

3. A pulverulent product composed of a water-insoluble core substance and of a protective covering as claimed in claim 1 or 2, obtained by using from 2 to 15 % by weight of hydrophobic silica, based on the aqueous dispersion.

4. A process for preparing a pulverulent product consisting of particles composed of a water-insoluble core substance and of a protective covering, said particles having an average particle size of from 100 to 600 µm and being obtained by dispersing the core substance in an aqueous solution of a film-forming polymer, spraying this dispersion with the aid of an auxiliary and subsequently drying wherein use is made - amylose or starch with an amylose content of more than 40 % by weight as said film-forming polymer and - hydrophobic silica as said spraying auxiliary.