Flavoring agents

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Flavoring agents
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Flavoring agents

• Flavor has a profound influence on the
  consumption of food
• three types of flavoring additives
• flavorings
• flavor enhancers
• (non-nutritive) sweeteners
• More than 1500 substances are used as food
  flavorings. The majority are of natural origin or
  are nature-identical

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• Only a few synthetic substances have been
  approved as food flavoring.
• Examples are ethylvanillin, ethylmaltol, and
  anisylacetone

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• The most widely used flavor enhancer is salt
  (sodium chloride, NaCl).
• It is also a preservative and a nutrient.
• Generally, it is primarily regarded as a food
  additive.
• A well-known toxic effect of NaCl is high blood
  pressure.

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• Flavor enhancers intensify or modify the flavor
  of food.
• They have no taste of their own.
• such as monosodium glutamate (MSG) and various
  nucleotides.
• These substances are present in Japanese seaweed
  (Laminaria japonica, traditionally used for
  seasoning), mushrooms, tomatoes, peas, meat, and
  cheese.

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• They are often used in soups, sauces and oriental
  food.
• No known adverse effects of flavor enhancers have
  been reported, except for the case of MSG.

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MSG

• It is also a synthetic product.
• MSG is an excitatory neurotransmitter. It has
  been shown to cause permanent lesions of the
  hypothalamus in newborn rats and mice.
• Presumably, this is attributable to immaturity of
  the blood-brain barrier.
• Further, in young mice and rats, lesions of the
  retina have been reported after large doses of
  glutamate.

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• Humans have also been found to be sensitive to
  food to which MSG has been added as a flavor
  enhancer.
• The symptoms, known as Chinese restaurant
  syndrome, include loss of feeling, general
  weakness, and heart palpitations.
• Humans have been described to be sensitive to
  food to which MSG had been added. The symptoms
  include numbness, general weakness, and heart
  palpitations

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Sweeteners

• Sweeteners present the consumer with one of the
  most important taste sensations.
• For nutritional and health reasons, however,
  there is a growing need for sugar substitutes in
  food that are non-nutritive, i.e., noncaloric,
  and noncariogenic.
• Two important noncaloric synthetic sweeteners are
  saccharin and aspartame.

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SACCHARIN

• In 1912 it was prohibited in the US on the basis
  of acute toxicity tests.
• Up to now, no mutagenicity has been found.
• However, long-term animal tests showed a higher
  incidence of bladder cancer.
• Although it is difficult to extrapolate from
  experimental animals to the human situation, the
  present average level involves risks of cancer.
• Therefore, the use of saccharin in food is still
  approved in the US and in Europe.

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ASPARTAME

• Aspartame was discovered in the early 1960s
• Aspartame is a dipeptide, consisting of the amino
  acids phenylalanine and aspartic acid.
• It is digested and absorbed by the body
• It is 200 times sweeter than saccharose and is an
  excellent sweetener for dry products.
• At high temperature and low pH, aspartame is
  gradually hydrolyzed, losing its sweetness.

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• It is suitable as table top sweetener, in chewing
  gum, in soft drinks, dairy products, ice cream,
  and dessert mixes.
• Results from toxicity tests suggest that
  aspartame has no adverse effects on humans even
  when extreme amounts of 8 mg/kg body weight are
  taken in. The ADI for aspartame is 40 mg/kg body
  weight.

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Preservatives

• Preservatives keep food edible for long periods
  of time by preventing the growth of
  microorganisms such as bacteria and fungi.
• Although the public perceives preservatives in
  particular as hazardous, they are not only
  harmless at the levels ingested but in fact
  beneficial in that they reduce or prevent the
  risks due to bacterial and fungal contamination

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Antimicrobial

• Common antimicrobial food additives are benzoic
  acid and benzoates, sorbic acid and sorbates,
  short-chain organic acids (acetic acid, lactic
  acid, propionic acid, citric acid), parabens
  (alkyl esters of p-hydroxybenzoic acid), sulfite,
  and nitrite.
• Most of these substances are believed to be safe
  for application in food.
• They are easily excreted and metabolized by both
  animal and man.
• An exception should be made for one of them,
  namely nitrite. The intake of nitrite can lead to
  the formation of nitrosamines, which are
  well-known carcinogens.

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• Nitrates and nitrites are used to preserve meats.
  
• For example, they contribute to the prevention of
  growth of Clostridium botulinum, the bacterium
  that produces the well- known highly potent
  botulinum toxin.
• The adverse effects after intake of nitrates and
  nitrites are methemoglobinemia and carcinogenesis
  (from the formation of nitrosamines)

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Nitrite

• Nitrite oxidizes (ferrous) hemoglobin to
  methemoglobin, which cannot bind oxygen.
• This may lead to a state of anoxia.
• The consumption of meat with high levels of
  nitrate and nitrite as well as of other dietary
  nitrate sources, such as drinking water and
  spinach, has resulted in life-threatening
  methemoglobinemia, especially in young children.
• Newborns are (transiently) deficient in
  NADH-reductase, the major system responsible for
  methemoglobin reduction.

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• Nitrite (either ingested directly or indirectly
  via the reduction of nitrate) also reacts with
  secondary amines under the formation of a variety
  of nitrosamines, e.g., dimethylnitrosamine,
  diethylnitrosamine, and N-nitrosopyrrolidine.

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• Nitrosamine formation can take place in food and
  in vivo.
• The acidic conditions in the stomach favor
  nitrosamine formation.
• Nitrosamines are mutagens as well as carcinogens.
  
• They induce cancer in a variety of organs,
  including the liver, respiratory tract, kidney,
  urinary bladder, esophagus, stomach, lower
  gastrointestinal tract, and pancreas.
• Nitrosamines need biotransformation for their
  activation.
• The bioactivation of nitrosamines is mediated by
  cytochrome P-450.
• It involves oxidative N-dealkylation, followed by
  a sequence of rearrangements to yield the
  alkylating alkylcarbonium ions

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• It should be noted that a decrease in the
  incidence of botulism may be accompanied by an
  increase in the formation of carcinogenic
  nitrosamines, as a result of an increase in the
  nitrite level of the meat (products).

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• From a food toxicological point of view, three
  types of nitrosamines are of importance dialkyl
  nitrosamines, acylalkylnitrosamines, and
  nitrosoguanidines.
• Cyclic nitrosamines are similar to the dialkyl
  type. The nitrogen atom becomes part of the
  heterocyclic ring.
• Nitrosoguanidines are a special class of highly
  reactive nitrosamides.

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• One of the most effective inhibitors of
  nitrosation is ascorbic acid.
• This vitamin reacts rapidly with nitrite to form
  nitric oxide and dehydroascorbic acid. In that
  way, it can inhibit the formation of
  dimethylnitrosamine by more than 90.
• Other inhibitors of nitrosation are gallic acid,
  sodium sulfite, cysteine, and tannins.

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• Nitrosamine levels in food also depend on the
  temperature at which food is prepared.
• Cooking can increase the nitrosamine level in
  food.
• frying can increase the nitrosamine level in
  bacon quite considerably.
• Up to 135 C, cooking or frying does not result
  in detectable nitrosamine formation. Above 175C,
  however, the nitrosamine levels increase rapidly.

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• Nitrite addition to fresh meat and food products
  is still under discussion because of the
  toxicological hazards.
• Up to now, banning of this additive has been
  blocked by the food industry.
• It is stressed that so far no other antimicrobial
  agent has been found that can provide protection
  against Clostridium botulinum as effectively as
  nitrite.
• In some EU countries (but not in Germany and the
  UK) and the US, nitrite addition to fresh meat is
  allowed up to a maximum of 200 ppm.

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Antioxidants

• Antioxidants are used to protect oils, fats, and
  shortening against oxidative rancidity and to
  prevent the formation of toxic degradation
  products and polymers.
• Many foods may undergo oxidation, but
  particularly those containing fats are
  susceptible to changes in color, odor, taste, and
  nutritional value.
• Unsaturated fatty acids are readily peroxidized
  in the presence of molecular oxygen.

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• The peroxidation products may induce toxic
  effects.
• Also, in biological systems peroxidation of
  lipids may have severe adverse consequences.
• Peroxidation of polyunsaturated fatty acids is
  believed to be involved in disturbing the
  integrity of cellular membranes, the pathogenesis
  of hemolytic anemia, and pulmonary and hepatic
  injury.
• Secondary peroxidation products, e.g.,
  hydroxynonenal, can form adducts with DNA.