Weaning is the process of gradually introducing an infant mammal to what will be its adult diet and withdrawing the supply of its mother’s milk. The process takes place only in mammals, as only mammals produce milk. The infant is considered to be fully weaned once it is no longer fed any breast milk (or bottled substitute) many cultures around the world, weaning progresses with the introduction of feeding the child food that has been preceded by the parent along with continued breastfeed, a practice known as premastication. The practice was important throughout human history in that it naturally gave a child a greatly improved protein source in addition to preventing iron deficiency. The preceding of food also gives the baby long-term immunological benefits through factors in the mother’s saliva. However, premasticated food from caregivers of lower socioeconomic status in areas of endemic diseases can result in the passing of the disease to the child. No matter what age baby food is introduced, it is generally a very messy affair, as young children do not have the coordination to eat “neatly Coordination for using utensils properly and eating with dexterity takes years to develop. Many babies begin using utensils between 10 and 14 months, but most will not be able to feed themselves sufficiently well until about 2 or 3 years of age.
Many mothers find breastfeeding challenging, especially in modern times when many mothers have to return to work relatively soon after the birth of their child. At this point, the mother tries to force the infant to cease nursing, while the infant attempts to force the mother to continue. From an evolutionary perspective, weaning conflict may be considered the result of the cost of continued nursing to the mother, perhaps in terms of reduced ability to raise future offspring, exceeding the benefits to the mother in terms of increased survival of the current infant.[This can come about because future offspring will be equally related to the mother as the current infant, but will share less than 100% of the current infant’s genes. So, from the perspective of the mother’s evolutionary fitness, it makes sense for her to cease nursing the current infant as soon as the cost to future offspring exceeds the benefit to the current infant. But, assuming the current infant shares 50% of the future offspring’s genes, from the perspective of the infant’s own evolutionary fitness; it makes sense for the infant to continue nursing until the cost to future offspring exceeds twice the benefit to itself (perhaps less, depending on the number of potential future offspring). Weaning conflict has been studied for a variety of mammal species, including primates and canines.
Breastfeeding in tandem
There are significant individual and cultural variations in regards to weaning.
Scientifically, one can ask various questions; some of the most straightforwardly empirical include:
- At what age do children self-wean?
- At what age do various societies normatively choose to wean?
- In comparison with other animals, especially similar primates, by various measures.
As there are significant ranges and skew in these numbers (some infants are never nursed, or only nursed briefly, for instance), looking at the median (half-way mark) is more useful than looking at the average.
Considering biological measures of maturity, notably investigated by Katherine Ann Dettwyler, yields a range of ages from 2 1/2 years to 7 years as the weaning age analogous to other primates – the “natural age of weaning”. This depends on the measure, for example: weaning in non-human primates is often associated with eruption of permanent molars (humans: 5 1/2 to 6 years); comparing duration of nursing to length of pregnancy (gestation time) yields a factor of about 6 in chimpanzees and gorillas (humans: 6×9 months = 54 months = 4 1/2 years); body weight may be compared to birth weight (quadrupling of birth weight yields about 2 1/2 to 3 1/2 years for humans; 1/3 of adult weight yields 5 to 7 years for humans); and similarly for other measures. The age at which children are normatively weaned can vary significantly between cultures, “from 6 months to 5 1/2 years”. In Islam the age of weaning is 2 years but can be less if the mother wants to. Other studies are possible, as in psychological factors. For example, Barbara Rogoff has noted, citing a 1953 study by Whiting & Child that the most distressing time to wean a child is at 13–18 months. After this peak, weaning becomes progressively easier and less distressing for the child, with “older children frequently weaning themselves.
Processing Techniques Suitable for Weaning Foods
Various food processing techniques and additives have the potential to enhance the nutrient bioavailability, nutrient density, food safety, storage stability, palatability, and convenience of supplemental foods suitable for weaning mixtures or to promote nutrition repletion following diarrheal episodes. Some of these are applicable for use at home, while others require the equipment and skills available in a small-or medium-scale food factory (Bressani et al., 1984).
Roasting describes a process that dry cooks a cereal, legume, or oil seed. The resulting dry ground products can be mixed with sugar and oil and moistened to form a ball that can be fed by hand to an infant or child. Roasting can be accomplished by shaking the grains in a heated pan or by immersing and agitating them in hot salt or sand… Roasting loosens the seed coats, making them easy to remove before the product is ground.
Soaked whole grams can be sprouted prior to cooking to increase vitamin levels, reduce the molecular weight of the carbohydrates that are present, and increase the availability of essential amino acids and relative nutritional value of the food. The amylases, released during germination hydrolyze starch to shorter-chain carbohydrates and sugars.
Milling, a spectrum of processes, cleans and separates the components of grains (germ, bran, and endosperm) and reduces their size. Mining has the beneficial effect of lowering fiber and bulk but it is at the expense of a lowered vitamin and mineral content in the remaining flour.
Cleaning steps associated with milling can remove insect and microbiological contamination of raw materials. The mined product, however, is more susceptible to insect damage if it is not protected in packaging that is puncture resistant and resealable Bacteriological growth is not a concern in mined products as long as they have less than a 15 percent moisture content.
Baking is used to produce nutritionally dense biscuits containing fat, sugar, and vegetable and animal proteins. Biscuits can be crumbled, and water or milk can be added to make a gruel. Older children eat biscuits directly as a ready-to-eat supplementary food. Individual biscuits provide a degree of portion control and can be very acceptable to children.
Cereal, legume, and oil seed based products are typically prepared by boiling in 70–90 percent water to completely cook and gelatinize the starch to form a thick paste. The gruels have a low nutrient density unless amylase (sprouted grains) is used to hydrolyze some of the starch to reduce the viscosity at higher solids concentrations. The use of ground beans instead of whole beans added directly to boiling water can reduce cooking time by a factor of 10 (Nelson et al., 1978).
The cooking or reheating of foods can destroy vegetative forms of enter pathogens. The temperature necessary depends on the time of exposure, with only a short interval (less than I minute beating temperature) at greater than 75°C are required. Even at these temperatures, however, heat-resistant spores survive. This is of concern when food is held between the time of cooking and serving. Foods held at temperatures between 20 and 50°C allow bacteria to multiply rapidly.
Water must be available for spore germination, microbial growth, and toxin production. Drying and the addition of solutes, such as NaCl or sucrose, to the food depress the water activity (aw) according to the nature of the solute. Water activity is defined as the ratio of the water vapor pressure of the food to that of pure water.
Extruded products are formulated from mixtures of cereals, legumes, and oil seeds and are completely precooked for easy reconstitution and use. They can be fortified with vitamin and minerals (Harper and Jansen, 1985). The process has been used successfully to produce nutritious foods that have been distributed in dry packaged form through both commercial and governmental programs.
A variety of fermentation processes have been used with cereals to increase digestibility, palatability, and shelf life. Some of these products have served as weaning foods (Steinkraus et al., 1983). These processes normally begin by soaking the whole grain for 24–72 hours. Wet grinding follows to remove some of the hull and gem. Fermentation at 30–50 percent moisture requires another 24–72 hours at approximately 30°C, using a mixed culture of acid-forming bacteria. Before consumption, water is added to give a 7–10 percent solids concentration, and the Mixture is brought to a boil to produce a gruel. These foods are most common in Africa, but similar processes are used in most countries.
Natural inhibitors of microbial growth, such as carbonyl, sulfur, or nitrogenous compounds; fatty acids; and other antimicrobial agents can be found in various foods. Their potential role as additives in controlling pathogens is poorly understood, and their potential toxic effects are unknown. No fully suitable food preservative is currently available.
Various bacterial organisms found in or added to food have been said to produce an intestinal microbial flora that protects the host against colonization with enteropathogens. These organisms, such as Lactobacillus acidophilus, Lactobacillus bulgaricus, and Streptococcus faecium, appear to survive passage through the stomach and remain in the upper small intestine for up to 6 hours (Clements et al., 1983). Although a protective effect has been found in some animal models, no preventive or therapeutic effect has been found in limited studies in humans.