The following descriptions and data are reproduced from projects to provide technology transfers for infant rusks in China, Indonesia and Vietnam.
Weaning is the process, which begins when the infant is first introduced to non-milk solid foods and ends when mother's milk or cow's milk ceases to be the main component of the diet. Usually weaning commences around three to four months of age and continues until eighteen months.
The whole of the weaning process is a particularly vulnerable period in a child's life. Nutritional requirements need to be fully satisfied by foods which can be readily assimilated by the child's immature physiology. Nutrient density (amount of nutrient per 100 kcal) has to be significantly higher than that of food for the rest of the family. This is because most adult foods are too bulky and indigestible for the young infant. In the absence of affordable, safe, easily digestible nutritionally balanced weaning foods, children often fail to achieve sufficient micronutrients for their development. Care must also be taken to ensure that weaning foods are free from microbial contamination. The infant's ability to fight infection is not equal to that of older children.
Taking these factors into account, it is not surprising that nutrient deficiencies and infant deaths during weaning are one of the world's serious health issues. The problem was world-wide, but the introduction in some countries of programmes to improve the status of infant foods has resulted in a great reduction of nutrient deficiencies and infant deaths and an improvement in the children's physical and mental development. Technologies are now available for the industrial production of nutrient-rich weaning foods. Such technologies can make a significant contribution to the health status of young people.
There are two main types of commercial weaning foods, cereal porridge and infant rusk. The rusk has many advantages. It is a dry piece product, like a biscuit, and is resistant to microbiological contamination. When wrapped at the point of production, it is safe and wholesome with a shelf life of 12 months. The rusk is pre-weighed and delivers an exact known quantity of vitamins and minerals. It can be formulated to deliver the correct daily recommended allowance of micro-nutrients for a child in one or two pieces. The content of vitamins and minerals can be easily modified to meet the specific requirements in each country.
FIG 1: Infant rusk consumption for children
For infants, it can be broken into soup, broth or milk for immediate consumption, or chewed as an aid to teething. The rusk can be eaten as a snack or part of a meal by older children. The rusk can therefore provide essential vitamins and minerals to children from weaning to school age and help to ensure good mental and physical development.
FIG 2: Infant rusks
Normally micronutrients are added so that one rusk delivers the recommended daily allowance for an infant under one year of age and half the daily allowance for an infant over one year of age. There is considerable flexibility to adjust the micronutrient formulation to suit regional requirements. One rusk (10gm) will normally provide 35 – 40 calories and protein in addition to the micronutrients.
The rusk can be fed in a wide variety of ways, from total dispersion in a fluid, to a soft porridge, to direct feeding of the crunchy rusk. The same product is suitable for infants of under 6 months up to school age children of 4-6 years.
FIG 3: Infant rusks dispersed in a warm fluid
The rusk softens rapidly in warm fluid and can be thinned to the required consistency. Softened rusk can be fed to the infant by spoon. As teething develops, the rusk can be dipped in fluid to soften it and then it is fed to the infant. Later the child can be given a rusk to chew. In this way the nutritional input can be maintained over a period of years with a product that adapts to the changing needs of the child. Because the rusk is easily prepared, the risk of spoilage, compared to a product which is made up in advance, is greatly reduced.
FIG 4: Children eating rusks
When the rusk is baked, it is sterile. It may be immediately packaged by machine after cooling, two rusks to a pack. This is the best arrangement for conventional distribution, protecting the product until its consumption.
When the rusk is distributed at a clinic, bulk packing can be used to reduce costs. Care must be taken at the factory and clinic to protect the rusks from contamination and humidity during packing and distribution.
The infant rusk is made on a cookie line. It is a continuous automated process. It is flexible, allowing different sizes and shapes of product to be made by the use of alternative dies and machine adjustments.
The main ingredients of the rusk are wheat flour, sugar and vegetable fat.
Flour and sugar
For small scale production, the flour may be delivered and stored in sacks near the mixing area. During production, the operator will open the sacks, sift the flour to remove any foreign matter and feed a pre-weighed quantity of flour to the mixer. Sugar may be handled and fed in the same way.
The fat may be supplied in blocks and kept in a refrigerated store. The fat will be pre-weighed and kept in plastic containers for feeding manually to the mixer as required.
Other ingredients will be pre-weighed and held in plastic containers until fed to the mixer manually.
Mixing the dough
A high-speed horizontal mixer is used. All the ingredients are fed to the mixing bowl for an "all in" mix. The mixer will be started at slow speed (30rpm) to thoroughly disperse the ingredients. The mixing action will ensure a good dispersion of all ingredients including the small quantities of micronutrients. After the ingredients have been fully incorporated, the mixer will be switched to high speed (60 rpm) for developing the dough to the required consistency. The mixing time should be as short as possible to develop a homogeneous dough. The temperature of the dough should be kept cool by circulating chilled water in the bowl jacket.
FIG 5: Baker Perkins horizontal mixer
After the mixing cycle is complete, the dough is tipped into a mobile tub to be transported to the wire-cut machine.
The dough may be stood for up to 30 minutes, particularly if it is sticky. The dough is then fed to the hopper of the wire-cut machine, ensuring a consistent, even level of dough in the hopper. Alternatively, an automatic metered dough feed system may be used.
The dough pieces are formed by a wire-cut machine. The dough is fed from the hopper through a pair of rolls which force the dough through a die plate. The die plate has apertures through which the dough is extruded. Below the die plate, a reciprocating wire cuts the dough pieces, which are deposited directly onto the steel baking band.
FIG 6: Wire cut depositor
FIG 7: Dough pieces being cut and deposited on the oven band
The die apertures determine the diameter of the dough piece and the weight is adjusted by altering the speed of the feed rolls. Between the feed rolls and the die apertures, the dough is controlled through a filler block, ensuring an even pressure of dough at each die aperture.
The dough pieces are carried directly through the baking chamber on a steel band. The speed of the band will be adjusted to maintain the optimum baking time, between 10 – 12 minutes. The baking process is slow and at low temperatures to avoid damaging the vitamin supplements.
An Indirect Radiant oven providing gentle radiant heat transfer is ideal. The automatic temperature control will provide a heat profile from 170 – 190 degrees C. The exact temperatures are dependent on the heat transfer system and will be adjusted to achieve the required colour and moisture content of the rusk. The top and bottom heat ratio will be adjusted to ensure even moisture content and colour.
FIG 8: Baker Pacific Indirect Radiant oven
After baking, the rusks remain very soft and they will be transported on the long run out of the oven band to receive some pre-cooling, before being stripped from the oven band.
The cooling process should allow sufficient time for the rusks to cool and for the moisture to become evenly distributed through each rusk. Normally the cooling time will be 1.5 times the baking time, about 15 – 18 minutes. After cooling the rusks may be stacked onto a packing table. A gentle form of stacking is preferred such as "flip stacking" by the use of differential speed conveyors.
The rusks will be conveyed along the packing table in stacked formation. The operators will pick up the rusks and transfer them to the infeeds of the packaging machines. Normally the rusks are packed in Flowpack style pouches, each containing two rusks.
FIG 9: Packing table
FIG 10: Infant rusk pack from Vietnam
|Weight per rusk:||10.0 gms (+ 1gm – 0gm)|
|Dimensions:||diam 58-60mm Height: 14-15mm|
|Shape:||round and domed|
|Surface:||smooth, slightly cracked|
|Texture:||open and porous|
|Taste:||Sweet, mild, rapidly softening in the mouth|
|Dissolving:||20 – 30 seconds in hand-hot water|
|Ferric ammonium citrate||0.280|