Encapsulation and Controlled Release of Food Ingredients - American

Chapter 17

Vitamin A Fortification in a High Stress Environment Harlan S. Hall

Downloaded by FUDAN UNIV on February 18, 2017 | http://pubs.acs.org Publication Date: March 24, 1995 | doi: 10.1021/bk-1995-0590.ch017

Coating Place, Inc., P.O. Box 930310, Verona, WI 53593-0310

Vitamin A deficiency is a primary cause of blindness in 500,000 children per year worldwide. Fortification requires a foodstuff that is widely used by the target population, is centrally processed (or packaged). The fortified foodstuff must be acceptable to the consumer. In Indonesia monosodium glutamate (MSG) was selected for fortification. MSG is a white crystalline material, vitamin A is bright yellow. The fortified product must retain potency and have a white appearance in the market. In 1983 work was initiated to develop an acceptable form of vitamin A for this application. The project started out simply to make vitamin A beadlets white so they would blend into the MSG. High ambient humidity and temperature, combined with MSG's tendency to absorb water create a stressful environment. A discussion of problems encountered, how they have been addressed and current status of the project will be presented.

The need to improve vitamin A consumption in many parts of the world is well documented (1, 2). World Health Organization (WHO) has estimated that more than 500,000 children per year become partially or totally blind due to a deficiency of Vitamin A in their diet. Several million have less severe health problems associated with vitamin A deficiency (3). In 1983 USDA/AID approached Coating Place to develop a "whitened" form of vitamin A beadlets. Vitamin A fortification of monosodium glutamate (MSG) had previously been tried with limited success. Hoffman 0097-6156/95/0590-0187$12.00/0 © 1995 American Chemical Society Risch and Reineccius; Encapsulation and Controlled Release of Food Ingredients ACS Symposium Series; American Chemical Society: Washington, DC, 1995.

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LaRoche vitamin A palmitate beadlets (250CWS) had been used in previous work in the Philippines but the small round beadlets segregated from the larger MSG crystals. This created problems in content uniformity and appearance. Appearance was also a problem because MSG is advertized and promoted as "pure, white crystals" much as Americans expect sugar or salt to be clean and white. Vitamin A is bright yellow. When the particles segregated the presence of a "foreign" material was obvious.


Early Results: The initial work was directed at devising a simple way to whiten the beads and to keep them from segregating from the MSG. This was accomplished by placing vitamin A beads in a Littleford mixer, wetting them with a titanium dioxide (Ti0 ) pigmented solution of hydroxypropyl cellulose (Klucel EF, Aqualon) dissolved in ethanol, mixing briefly, then adding a fine powdered form of MSG which was adhered to the whitened beads by the damp Klucel. This coated, agglomerated product was then dried. A more complete description of the procedure is provided given by Muhilal, et. al. (4). 2

By this method the vitamin A beads were covered with a thin white coating to which small white MSG crystals were adhered. The resulting particles were much lighter in color than the starting beads and also were slightly agglomerated, more closely approaching the particle size of the MSG to be fortified (Table I).

Table I. Particle Size Comparison: Beadlets. Coated Beadlets, MSG U.S. Mesh u Size Vit A Coated Vit A MSG Crystals > 18 mesh >1000/y ~ trace trace -18/+ 25 710-1000 80% RH @ > 8 0 ° F) moisture is able to permeate the packaging materials and attack the vitamin A beadlets. The packaging materials used are of good quality (MVTR = 5g/m724 hr @ 4 0 ° C , 90% RH), but due to the high surface

Risch and Reineccius; Encapsulation and Controlled Release of Food Ingredients ACS Symposium Series; American Chemical Society: Washington, DC, 1995.

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area of the package to mass of contents (26-35 mrrrVgram) water vapor transmission is significant. The smallest package contains approximately 600 mg product and may take up 0.1 mg/day (7).


The Klucel coating used above is not, and was not intended to be, a good moisture barrier. The 1989 trials made clear that we did not have a product that would meet all requirements under "real life" conditions. As a result of these findings additional development work was initiated, and changes were made in the test conditions. Samples are now tested at 3 5 ° C, 75% RH. Accelerated testing is now done at 3 5 ° C, 85% RH.

Further developments: At one time it was felt that simply applying a water resistant coating onto the vitamin A beadlets would suffice to provide 6 month stability. The above field data showed that the product would retain potency (>50%) and appearance for 6 weeks in the market place and longer in storage. Pharmaceutical applications have a long history of using water resistant coatings for controlled release, i.e. controlling water permeation rates. In these applications it is common to extend release by a factor of 5 or 10 (see figure 3). It was hoped that by using a water resistant coating a factor of 4 or 5 improvement in stability could be achieved. A major flaw in this concept is that the original coating never did provide 6 weeks stability. A significant portion of the stability was due to the time required for sufficient water to permeate the package and increase the water content of the MSG. Once the moisture content of the MSG reaches a significant level moisture is available to attack the coated beadlet. The time for the original beadlet alone to fail when water is available is very short. Once water is inside the packet and available even a good moisture barrier is somewhat permeable and will fail eventually. It turned out that even doubling the shelf life of the fortified MSG by improved coating composition alone was very difficult. The coating that has currently been developed is a good moisture barrier within the limitations imposed by the following criteria: 1) Must be food approved and not violate dietary restrictions. 2) Must be water resistant. 3) Must be stable up to 6 0 ° C. 4) Must be bioavailable. 5) Must be white or near white.


HALL

Vitamin A Fortification in a High Stress Environment Vitamin A Retention - Field 1989 Product

120 100 Bogor 80 60 40

20 Π 4

1 1 8 6 Weeks Exposed

1

Γ 12

10

Figure 1. Chemical stability of vitamin A . EQUILIBRIUM MOISTURE CONTENT - MSG 18 16

MSG

14 12

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10

ater


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8 6 4 2 0 0

I I I I

10 5

15

20 2 5

I I

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40

I

50

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60

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70 7 5

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80

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Figure 2. Water absorption isotherm for M S G . RELEASE RATES vs. COATING COMPOSITION Ethyl vs. Hydroxypropyl

Cellulose

Figure 3. Change in release of soluble salt vs. coating composition.


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This work has resulted in a white coating that can be applied onto commercially available vitamin A palmitate beadlets and provides improved moisture barrier properties as well as whiteness. Further improvement in stability has been achieved by development of an improved bead by Hoffman La Roche. Both visual and chemical stability are vital to a successful product. It is possible to have either chemical or visual stability without the other. A product that has good chemical stability but is discolored is unacceptable to the consumer; a product with good cosmetic properties but little potency has no value. The white coating presently in trial was developed after it was determined that improved barrier properties were required. This turned out to be a very difficult problem. The vitamin A beadlets are approximately 250// in size. For purposes of achieving high potency and of controlling cost it is desirable to keep the coating level relatively low, however maximum barrier properties require higher coating levels (greater film thickness). 30% coating levels result in an approximate film thickness of 15/y. Although this improved barrier coating does improve the stability of the product, it actually works in concert with the packaging materials to provide the necessary stability. The current whitened beads made using the improved barrier coating and the improved beadlets are currently in test in the field. At three months the visual properties are good. Analytical results regarding potency retention are not available at this time. Resumption of large scale fortification trials are dependent upon current product remaining field stable for at least 6 months, a determination that the improved beadlet can be made commercially, and a determination by the Indonesian government and other funding agencies to continue the work.

Acknowledgements: I wish to recognize and thank the following for their roles in the reported work. This is a very large project that could not be conducted without the assistance, leadership and persistence of many people. Mr. Rod Crowley (retired), Helen Keller Foundation, U.S. Department of Agriculture, Dr. Muhilal and all at the Indonesian Ministry of Health, Dr. Patricia Murphy, Iowa State University, Dep't of Food Technology, Dr. Ben Borenstein, Β & Β Consultants and Hoffman La Roche.


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Vitamin A Fortification in a High Stress Environment

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Literature Cited: (1) (2) (3)


(4) (5) (6) (7)

Sommer, Α.; Nutritional Blindness: Xerophthalmia and Keratomalacia; Oxford University Press: NY; 1982 Thylefors, B.; The Challenge of Preventing Childhood Blindness in Developing Countries; World Health Organization; 1988 DeMaeyer; Vitamin A Deficiency and Its Consequences: Blindness in Childhood; World Health Organization; 1988 Muhilal, et. al.; Am J Clin Nutr; 1988,48,1265-1270 Murphy, et. al.; Iowa State University; unpublished report, 1987 Murphy et. al.; Iowa State University; unpublished report; 1989 Muhilal, et. al; A Pioneering Project for Combatting Vitamin A Deficiency and Xeerophthalmia with MSG; Unpublished report; 1986

RECEIVED September 13,1994


Encapsulation and Controlled Release of Food Ingredients - American

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