By Jennifer Bañuelos, MAS
Last week, we started a series about sensory development with a post about hearing. Today, in the second part of the series, we will cover another of the 5 senses, taste!Taste versus Flavor
In the medical dictionary, taste is defined as “the sense of perceiving different flavors in soluble substances that contact the tongue and trigger nerve impulses to special taste centers in the brain.” What does that mean to all of us non-doctors? It means that taste is basically a chemical reaction; when food (the soluble substance) hits our tongue, the chemicals in the food stimulate our taste buds, sending a message to our brain telling us if the food contains salty, sweet, sour, bitter, or umami compounds. Flavor, however, describes the perception about what is being consumed; it is the combination of 3 senses, what is tasted on the tongue, what is smelled with the nose, and the physical feeling of the food in the mouth (more on smell and touch in future posts). So, when we say something is “spicy” or “tastes like chicken” we are actually referring to flavor.
The Science of Taste
Although scientists have been studying taste for hundreds of years, they continue to discover new information. For example, it was originally believed that there were 4 basic tastes, sweet, salty, sour, and bitter, but over the last decade, scientists identified a 5th flavor, umami, described as a “pleasant savory taste.”(Umami Information Center) There is also new information about how the tongue and taste buds function and where they are located. Researchers have known that different areas of the tongue are more sensitive to specific flavors than others; the tip of the tongue is most sensitive to sweet, then along each side there are sensitive areas for salty, followed by sour, and bitter on the back of the tongue. The middle of the tongue was thought to be the least sensitive area. Recent research has indicated that our bodies may be much more complicated than described by this “tongue map.” There is now evidence that there may be taste receptors in other areas of the digestive tract, not just on the tongue! (Beauchamp 2011)
First Tastes
Babies’ first tastes occur long before birth. The amniotic fluid that surrounds a baby in the womb is affected by foods the mother consumes, so when the baby swallows this fluid, she is exposed to different flavors. In fact, studies have shown that babies may prefer flavors they were exposed to before they were born. (Beauchamp 2011) Maternal diet also affects the flavor of breast milk and studies indicate that babies who are breast fed may be more accepting of a variety of flavors once they start eating solid foods. (Beauchamp 2011; Maier 2008;)
Individual Taste
Some preferences are hard-wired into our brains. For example, babies are born with a preference for sweet and an aversion to bitter. (Beauchamp 2011; Schwartz 2009) Evolutionarily, this makes sense because foods that are sweet tend to by high in calories and bitter foods are often poisonous.
In a recently published study, researchers evaluated infant acceptance of the 5 tastes at 3, 6, and 12 months of age. By measuring both the volume consumed and facial expressions during consumption in the same infants at 3 different ages, they were able to present a more detailed picture of how taste preferences change with age compared to studies that only use 1 measurement. Much of what they found was consistent with previous findings; preference for sweet is present at birth and decreases with age, while acceptance of salty foods appears between 3 and 6 months of age. They also describe some novel findings. For example, for sour and bitter tastes, preference differed between the 2 methods of measurement; the consumption measurement indicated that the infants were indifferent to both tastes, but facial expressions expressed obvious rejection. They also found that as babies got older, they became more and more unique in terms of taste preference (once again, illustrating that all babies are different!). (Schwartz 2009)
Can you Teach Good Taste?
Although there is more to learn about exactly how our bodies sense tastes and flavors, using what is currently known, we have some suggestions to help parents promote a varied diet for their babies!
• Start when you are pregnant - Eating a varied diet while pregnant is good for you and will expose your unborn baby to all the flavors you love!
• Breastfeed – Continuing to provide a variety of flavors to your baby through your breast milk can increase acceptance of solid foods when your baby is old enough.
• Lead by example – If your baby sees you eating healthy foods, she’ll learn from you!
• Think outside the jar - Babies don’t need to be limited to rice cereal and applesauce. Although you should wait a few days before introducing a new food (to identify an allergy), babies can eat almost anything if it is prepared in accordance with their chewing and swallowing abilities.
• Be patient – Remember, babies’ preferences change over time. Also, studies have shown that it can take 10 to 15 times for a baby to learn to like a new food, don’t give up.
References:
Mosby's Medical Dictionary, 7th edition. Mosby Elsevier St. Louis, MO 2006
Umami Information Center, http://www.umamiinfo.com
Beauchamp G, Mennella J. Flavor Perception in Human Infants: Development and Functional Significance. Digestion (2011) 83(suppl 1):1-6.
Maier et al. Breastfeeding and experience with variety early in weaning increase infants’ acceptance of new foods for up to two months. Clinical Nutrition (2008) 27:849-857
Schwartz et al. Developmental changes in the acceptance of the five basic tastes in the first year of life. British Journal of Nutrition (2009) 102:1375-1385.
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