FLAVORFlavor is the term used to describe the sensory impression offood, which is a combined effect of taste, odour and trigeminalimpressions in the oral and nasal cavities.Flavor is one of the three main sensory properties which isdecisive in the selection, acceptance and ingestion of food.Flavor compounds arise mainly from normal biosyntheticprocesses of animals and plant metabolism.These compounds exist as precursors and developcharacteristic flavoring effects during processing or cooking.
Apart from the food components that triggerthe taste, odor and trigeminal impressions,there are some components that are capableof supplementing, enhancing or modifying theflavor of food.Although they have little or no flavor of theirown at typical usage levels.These substances are commonly known asflavor potentiators.
FLAVOR POTENTIATORSFlavor potentiators are chemicals whichthemselves have little or no odor or taste.But yet intensify or enhance the flavour of foodat usage levels.The effect of flavor potentiators is accompaniedby changes in the mouth feel of the productthereby inducing a sensation of fullness orsatisfaction.
NATURALLY OCCURING FLAVOR POTENTIATORS IN FOOD FOODS AMOUNT(%) MSG IMP GMPBeef 0.013-0.088 0.163 0.002Cheese 1.333 NR NRCod 0.011 0.043 NRScallop 0.012-0.024 0.000 0.000Orange juice 0.015 NR 0.00002Nectarine 1.219 NR NRCorn 0.102 NR NRMushroom 0.177-0.635 NR 0.56Potato 0.254 NR 0.001Tomato 0.177 NR 0.001Tea, green 0.264-0.640 NR NR
COMPOUNDS USED AS FLAVOURPOTENTIATORS IN FOOD INDUSTRYMonosodium glutamateMonopotassium glutamateMonoammonium glutamateGuanosine 5´-monophosphateInosine 5´-monophosphateMaltolEthyl maltolDioctyl sodium sulfocuccinateN, N´ -di-o-tolylethylenediamine
MONOSODIUM GLUTAMATE Monosodium glutamate(MSG) is a neutral salt of L- glutamic acid which occurs naturally as one of the amino acids building blocks of food proteins. MSG was first isolated in a laboratory by a Japanese scientist in 1908 and subsequently patented by Ajinomoto Corporation of Japan in 1909. It heightens and intensifies natural flavor without adding significant flavor of its own. MSG draws out hidden flavor attributes and tends to enhance weaker flavor character.
There is practically no aroma associated withMSG.The functioning of MSG is pH dependent i.e. itmust exist in the food as monosodium salt.Therefore its use is limited to those foods thatare in the pH range of 5.0-8.0.It has the HS code 29224220 and the E numberE621.
CHARACTERISTICS OF MSG Coarsely crystalline substance. Molecular formula:C5H8NNaO4 5% solution of MSG has pH: 6.7-7.2 Melting point: 232° C Solubility at 25°C: 74.2g/100ml of water at 60° 101.4g/100ml of water C: Sodium content: 12.3% Bulk density: 11.0 to 13.8g/ cu in. Calories: 2.88 cal/ g
PRODUCTION OF COMMERCIAL MSGThe vast majority of MSG is produced through bacterialfermentation process.Bacteria of genera Corynebacterium glutamicum and Brevibacteriumare widely employed.Starch, cane and beet molasses are used as carbon source.Ammonium chloride, ammonium sulfate and urea are used asnitrogen source.Yields of 100 g/litre can be prepared in this way.
TOXICITY OF MSGMSG has low toxicity from an acute stand point.Injection of MSG has been shown to induce rapiddegeneration of neurons in the inner layers of retina.Degeneration of nerve cells in brain due tosubcutaneous injections of large doses of MSG havealso been observed in various species.
HEALTH CONCERNS MSG is called an “excitotoxin” by leading neuroscientists because of its degenerative and deadly effects on the brain and central nervous system. Monosodium glutamate has been associated with the Chinese Restaurant syndrome (CRS). The symptoms include:- Racing pulse Burning sensation in the back of neck Facial pressure Chest pain Sweating Headaches Hypertension Weakness & thirst.
Studies have found that typical CRS symptoms could notbe included in 99% healthy males given 5g of MSG.The symptoms of CRS are shown by highly sensitivepeople.Children, Unborn & Elderly are most vulnerable.
5´- NUCLEOTIDES 5´- Nucleotides are the building blocks of ribonucleic acid (RNA). It consists of a purine base, ribose and phosphoric acid linked to 5´- position of ribose. The most commonly used 5´- nucleotides as flavor potentiators are:-1. Guanosine 5´-monophosphate (GMP)2. Inosine 5´-monophosphate (IMP)
GUANOSINE 5´-MONOPHOSPHATE It is an ester of phosphoric acid with the nucleotide Guanosine and ribose sugar. Guanosine monophosphate is commercially available in the form of its salt “disodium guanylate”. The E number for disodium guanylate is E627. Molecular formula of Guanosine 5´-monophosphate is C10H14N5O8P.
CHEMICAL STRUCTURE OFGUANOSINE 5´-MONOPHOSPHATE
INOSINE 5´-MONOPHOSPHATE Inosine 5´-monophosphate is commercially available in the form of its salt “disodium inosinate”. The E number for disodium inosinate is E 631 Molecular formula of Inosine 5´-monophosphate is C10H11N4Na2O8P.
COMMERCIAL PRODUCTION OF 5´- NUCLEOTIDESDegradation of RNA by 5´-phospho-diesterase.Fermentation to produce nucleotides followed bychemical phosphorylation to produce the 5´-nucleotides.Direct fermentation to yield 5´-nucleotides.Chemical decomposition of RNA to produce nucleotidesfollowed by chemical phosphorylation to produce the 5´-nucleotides.
TOXICITY OF 5´-NUCLEOTIDES Administration of lethal doses of 5´-nucleotides causes temporary depression, clonic convulsions and dyspnea. Dietary intake of 2% of total diet or less 5´-nucleotides have not been found to cause observable effects in any species of animals in long term feeding studies. Studies suggest that there are no significant toxicity concerns in humans for 5´-nucleotides in the diet.
MALTOLMaltol occurs naturally in many plants and is formed inroasted malt, baked goods etc.It was introduced as a flavor potentiator in 1942.The E number for maltol is E636.Toxicity of maltol is not known.It is commercially produced by the fermentation ofsoyabean proteins or glutinin.
ETHYL MALTOLEthyl maltol is derived from maltol (E636) byreplacing one methyl group with an ethyl group.Ethyl maltol is 4 to 6 times stronger than maltol.The E number of ethyl maltol is E637.It has no known effect.
OTHERSDioctyl Sodium Sulfosuccinate is used as aflavor potentiator in canned milk where itimproves and maintains the flavor andfreshness of the sterilized milk duringstorage. N, N´ -di-o-tolylethylenediamine is also usedas a flavor potentiator in dairy industry.
MODE OF ACTIONThe means by which flavor potentiatorsenhance flavor is poorly understood.However some indirect evidence has beengathered which supports some basictheories, which will be discussed briefly.
Strong (1968) suggested that flavor potentiators mayfunction by either increasing the amount of flavorcompounds actually arriving at the olfactory cells or byincreasing the magnitude of the signal generated by theflavor compoundSchinneller et al. (1972) suggested that 5´-nucleotidesunmasked certain flavor receptor sites, hence makingmore receptor sites available for reaction with thestimulus.Saint-Hilaire and Solms (1973) proposed that flavorpotentiators interacted with collagen like proteins at thereceptor sites. This would create an improvedenvironment for taste receptor stimulation.
APPLICATIONS OF FLAVOR POTENTIATORSFlavor potentiators find wide usage in foodproducts.Vegetables, sauces, meats and other savoryfoods constitute the major food application.The ability of flavor potentiators to impartviscosity, drying and fullness is a useful propertyin soups, gravies, sauces and juices.
USAGE LEVELS OF MSG AND 5´-NUCLEOTIDES IN VARIOUS FOOD PRODUCTS FOODS USAGE LEVELS % MSG% 5´NUCLEOTIDES (50/50 IMP &GMP) %Dehydrated soups 5-8 0.10-0.20Canned soups 0.12-0.18 0.0022-0.0033Canned asparagus 0.08-0.16 0.003-0.004Canned fish 0.10-0.30 0.003-0.006Sausages 0.30-0.50 0.002-0.014Sauces 1.0-1.2 0.010-0.030Ketchup 0.15-0.30 0.010-0.020Mayonnaise 0.40-0.60 0.012-0.018Snacks 0.10-0.50 0.003-0.007Vegetable juices 0.10-0.15 0.005-0.010Processed cheese 0.40-0.50 0.005-0.010
USAGE LEVELS OF MALTOL AND ETHYL MALTOL IN VARIOUS FOOD PRODUCTS FOODS USAGE LEVELS (ppm) MALTOL ETHYL MALTOLBaked goods 75-250 25-150Beverages 2-250 1-100Candies 3-300 1-100Chocolate foods 30-200 5-40Dairy products 10-150 5-50Desserts 30-150 10-75Jams 40-200 15-60
REFRENCESAshurst. P. R.(1999), Food flavourings, 3rd edition, Aspen publications, Pp367-394.Heath. H.B.(1981), Source book of flavors, 1st edition, Springer publications,Pp 323-325.Heath. H.B., Reineccius. G.(1999), Flavor chemistry and technology, 2ndedition, CBS publishers, Pp 318-329.Reineccius. G.(1994), Source book of flavors, 2nd edition, Aspenpublications, Pp 642-647.http://www.crcnetbase.com/doi/abs/10.1201/9780203485347.ch11http://www.msgtruth.org/NEWUNIFIEDTHEORY.pdf