Repeated exposure to cumin and lemongrass – novel flavours for over 65s – in potato soup containing monosodium glutamate (MSG) led to significant increases in consumption of the soup – but the participants continued to say they did not particularly like the flavours.
The researchers from the University of Reading were surprised by the findings. “We report here a serendipitous finding of conditioned intake in the absence of conditioned liking,” they said. “One interpretation of this dissociation is that it reflects separate processes inherent in the liking/wanting distinction.“
According to the study people can learn to like new flavours through increased exposure in two ways – either because the mind associates it with a liked taste such as sweetness, known as flavour-flavour learning, or because of the beneficial nutrients that are consumed, which is called flavour-consequence learning. The authors suggested that glutamate – a naturally occurring amino acid – was the nutrient involved in this process.
The study involved 40 elderly men and women between the ages of 65 – 80 who were assigned to one of two groups. Both groups were given two varieties of potato soup flavoured with cumin or lemongrass - one containing 5% MSG - to eat three times over six days.
Liking ratings for both cumin and lemongrass were low before the study and remained low (5.7 out of 9 for the first session and 5.4 for the last). However, there was an increase in mean consumption of the MSG soup from 123 g to 164 g compared with a slight decrease in the non-MSG group, with intake falling from 130 g to 121 g.
They suggested that this could be because of the higher sodium content in the MSG soup.
A tough crowd to please
While previous research has focused on conditioning liking in children and babies, the researchers chose to look at elderly people because they are generally less receptive to new flavours and at greater risk of malnutrition.
“One of the physiological factors that results in reduced food intake is the natural decline of taste and olfaction due to ageing or due to diseases and medication, which can lead to a reduced appreciation and interest in food.”
Malnutrition affects 60% of over-65s in care homes and hospitals according to Age Concern, and the researchers believe their findings could be of particular benefit to this populace.
Going beyond MSG
The researchers, led by Maria Dermiki, also said the findings were not limited to MSG but may be applied to other sources of glutamate - which would allow for sodium reduction.
“Since the glutamate rather than the sodium was responsible for the increased wanting, the use of other sources of glutamate apart from MSG may be preferable as a supplement to foods in such situations. The results may be generalisable to the use of natural food sources of glutamate and 5′ ribonucleotides.”
MSG has been linked to obesity and liver disease but according to the European Food Information Council the bad press is unfounded.
"Monosodium glutamate is one of the most extensively studied food ingredients in our food supply. Hundreds of studies and numerous scientific evaluations have concluded that [it] provides a safe and useful taste enhancer for foods."
Last year Givaudan filed a patent for an MSG-free umami, which it said was born of a consumer desire for umami alternatives.
"The presence of MSG in foodstuffs is not universally acceptable, and there is an interest in the achievement of umami taste with lower proportions of MSG than is normally the case,” it wrote in the European patent filing.
Source: Appetite Journal
Published online ahead of print, vol. 90, pp. 108–113 doi:10.1016/j.appet.2015.03.002
"Novel flavours paired with glutamate condition increased intake in older adults in the absence of changes in liking"
Authors: M. Dermiki, J. Prescott et al.