Lecture
Flavour (aroma) enhancers (modifiers) enhance (modify) a person's perception of taste and aroma by stimulating
54
the endings of the taste nerves. At the same time, the enhancers themselves may have neither
their own odour nor taste. They enhance, restore and stabilise
the taste and aroma or their individual components, which are lost during raw material processing and storage of the finished product. They can also soften
certain undesirable components of taste and aroma [2, 5].
Glutamic acid (E620) (3.5) and its salts (E621-E625) are widely used in the food industry. They enhance the natural
flavour properties of foods and also restore these properties when weakened by processing and storage. The human taste organs detect the presence of monosodium glutamate when dissolved in water at a ratio of
1:300. Monosodium glutamate is a finely crystalline white powder that dissolves easily and readily
and completely in water.
In recent years, data have been published on the ability of monosodium glutamate
to cause headaches, muscle weakness, accelerated heartbeat, and to trigger allergic reactions and other symptoms. These manifestations
are grouped under the name of the so-called «Chinese restaurant syndrome». The mechanism of the toxic action of glutamate is still unknown. Therefore, although
sodium glutamate is a food additive naturally present in a number of foods (meat, fish, cheese), its use in food products is regulated at a level of 10,000 mg/kg of the finished product and is subject to control.
Japanese scientists have established that monosodium glutamate in large doses causes
blindness in rats. The amount consumed by humans is, of course, considerably
lower. However, in the opinion of researchers, there is a possibility that glutamate
may affect vision, especially if consumed over many years.
Of this group of flavour modifiers, only E621 has authorised use permitted in Ukraine, and it is restricted. It is believed that glutamic acid and its salts should not
be added to baby food products. The ADI of glutamic
acid is 120 mg/kg.
5'-Guanylic acid (E626) and its salts (E627-E629), 5'-inosinic
acid (E631) and its salts (E631-E635) are widely used as flavour enhancers. The maximum permissible level of these additives for food products is 500 mg/kg, and for seasonings – the ADI in the required amount
of these compounds is not limited. Since 2004, Ukraine has authorised the use
55
of only disubstituted sodium 5'-guanylate (E627) and disubstituted sodium 5'-
inosinate (E631).
Glycine (E640) is used as a flavour and aroma modifier.
Glycine participates in the detoxification of benzoic acid through the process of
synthesis of hippuric acid and in the formation of conjugates of compounds with bile
acids. It participates in the metabolism of carbohydrates and fats, in the synthesis of substances important in physiological terms: creatine and glutathione.
Glycine, as a food additive, has not been granted the status of authorisation in Ukraine.
Quinine C20H24O2N2 – the principal alkaloid of cinchona bark. Quinine
solutions are distinguished by a very bitter taste. It is interesting that quinine exerts not only an antimalarial action but also an antipyretic effect, caused by a direct action on the nerve centre that regulates body temperature. In large doses quinine is quite toxic. Therefore the MPL for tonic soft drinks must not exceed 100 mg/L.
The MPL of diacetyl – a flavour and aroma modifier – for margarine is 150 mg/kg, and for toffee – 6 mg/kg. Diacetyl gives products a pleasant milky aroma. Ukraine permits the limited use of diacetyl.
In addition, in Ukraine the following have not been granted the status of authorisation as flavour and aroma modifiers:
the amino acid L-leucine (E641) and some other compounds.
3.7. Toxicology of sweeteners and sugar substitutes
Excessive consumption of sugar and sugar-containing products causes, besides
obesity, systematic overexcitation of the insular apparatus of the pancreas
gland, may be a cause of its disorder, considerably increases the risk of diabetes, as well as of dental caries, hypertension, and atherosclerosis. Therefore, many countries around the world have organised the production and search for new sweeteners
and sugar substitutes [2, 5].
Food products containing a sweetener must carry the corresponding information
on the label, and for aspartame – a special warning
notice. Baby food products must not contain sweeteners.
Synthetic sweeteners are represented by saccharin, aspartame, its analogues, cyclamates, acesulfame potassium, etc.
Saccharin (3.6) and its sodium, potassium or calcium salts (E954)
– benzoic acid sulfamide C7H5NSO3, is 300-
500 times sweeter than sucrose.
Saccharin passes through the digestive tract relatively quickly, and 98% of it
is excreted in the urine. A large amount of saccharin in the diet has caused
the development of urinary bladder tumours in 60% of rats. It has now been established that daily consumption of saccharin over a long period is dangerous. According to the World Health Organization, no more than 5 mg/kg of saccharin may be used, and in dietary products – up to 25 mg/kg. In
Ukraine, the use of saccharin (E954) is authorised.
56
The use of the artificial sweetener cyclamate (3.7) and its
sodium, potassium or calcium salts (E952) is restricted in Ukraine – they
are permitted only as sweeteners in combination with saccharin. In the countries
of the European Community it is used to a limited extent in flavoured low-calorie soft
drinks and desserts. In the USA, cyclamate and its derivatives are not permitted for consumption.
No harmful effect of cyclamates on the liver, kidneys
or other human organs has been found. The metabolic products of cyclamates are removed from the body fairly
quickly. At the same time, from 0.1 to 0.9% of cyclamate is metabolised to cyclohexylamine, which has high toxicity, and to the carcinogenic dicyclohexylamine. It has been shown that cyclamates in large doses cause bladder cancer in test animals. The widespread use of cyclamates in food products requires further study of their biological activity.
The sweetener aspartame (E951) (3.8) is suitable for use in
food products whose preparation does not require heat treatment, for example ice cream and creams. It loses its sweet taste when held at
150°C for 45 minutes. For this reason aspartame is poorly suited for use in food products that are manufactured at high temperatures and then stored for a long time (sterilised compotes, beer).
In the body aspartame breaks down into the L-amino acid (phenylalanine) and methanol, which are fully metabolised. As a side reaction, diketopiperazine may be formed, with its own ADI. The content
of phenylalanine may be harmful to patients with phenylketonuria (phenylketonuria – a very rare (1:15000) genetic defect requiring a special diet). Subject to these conditions, all clinical studies conducted in
France and the USA on children and adults have shown no undesirable
side effects.
57
In Ukraine the ADI of aspartame is up to 40 mg/kg, and its MPL in food products (desserts based on fermented milk with added fruit fillers, yoghurts with added fruit fillers, kefir with
added fruit fillers, curd cheeses with added fruit fillers) – 1000 mg/kg. The labelling of food products manufactured with
the use of aspartame (E951), or the joint use of aspartame
(E951) and acesulfame-K (E950), must necessarily contain the following warning: "Aspartame is a source of phenylalanine. The product is not recommended for patients with phenylketonuria and children under seven years of age" (Resolution of the Ministry of Health
of Ukraine and the Chief Sanitary Physician of Ukraine No. 42 of 28.12.2002).
Acesulfame potassium (acesulfame-K (E950)) (3.9) is a stable sweetener both in dry form and in aqueous solutions over the pH range
3-7. Its flavour profile is similar to the flavour profile of sugar. It is predominantly
is used for the preparation of beverages, dairy products, and confectionery.
Since acesulfame potassium dissolves quickly in water, it is well
suited for instant beverages and table sweeteners. It is usually used as part of blended sweeteners together with aspartame. In this case not only quantitative but also qualitative synergism is manifested. Each substance separately is about 200 times
sweeter than sugar, while in the mixture – 300 times. The sweetness of acesulfame potassium is felt
instantly but does not last very long, whereas the sweetness of aspartame, by contrast, is not felt
right away but persists for a long period of time.
Pharmacokinetic studies conducted on humans have shown that
orally administered doses of acesulfame potassium were fully absorbed and
rapidly excreted unchanged in the urine.
The ADI of acesulfame potassium is up to 15 mg/kg, and its MPL in food products (desserts based on fermented milk with added fruit fillers, yoghurts with added fruit fillers, kefir with
58
added fruit fillers, curd cheeses with added fruit fillers) is 350 mg/kg. When sweeteners are used together, the MPL of aspartame (E951) will be 500 mg/kg, and of acesulfame-K
(E950) – 175 mg/kg (Resolution of the Ministry of Health of Ukraine and the Chief Sanitary
Physician of Ukraine No. 42 of 28.12.2002).
The following have not received absolute authorisation status: sucralose (E955),
thaumatin (E957), glycyrrhizin (E958), neohesperidin dihydrochalcone (E959)
and some other sweeteners.
Among monosaccharides, an important place is occupied by fructose, which is absorbed
slowly in the body (2.3 times more slowly than glucose) and has little effect on the blood sugar level. Its metabolism takes place without the participation of insulin,
which opens up possibilities for using fructose in the diet of patients with
diabetes mellitus. Fructose has a limited cariogenic effect compared with sucrose and glucose. It can enhance the taste and aroma of products and
forms aromatic and coloured compounds.
Xylitol (E967) – a five-carbon alcohol C5H12O5 – is found in some
fruits and vegetables. Xylitol has a pleasant sweet taste and in sweetness
is close to sucrose. The utilisation of xylitol does not depend on insulin. Xylitol
has an anti-ketogenic action, caused by its conversion into glycogen, and
is able to reduce the accumulation of acetyl coenzyme A in the liver, which is a source of formation of ketone bodies. Xylitol has been shown to have an anti-caries action.
Its consumption in large doses can cause diarrhoea. Ukraine authorises the use of xylitol (E967).
In addition, Ukraine authorises the use of sorbitol and sorbitol
syrup (E420), mannitol (E421), isomaltitol (E953), maltitol and maltitol syrup (E965), otizon and sakharol.
Comments