Physical Properties of Amino acid:-

Solubility: Amino acids are readily soluble in water, slightly soluble to insoluble in ethanol and insoluble in ether. Tyrosine  is soluble  in  hot water but only sparingly soluble  in cold water. Cysteine with difficulty is soluble in  only hot water. Proline and hydroxy proline are soluble in alcohol and ether.

Amino acids  are generally soluble  in  acids and  bases  and form salts. Tyrosine  is moderately soluble  in  acids and bases.  Cysteine is soluble  in  strong mineral  acids (HCI) but slightly soluble in acetic acid and dilute ammonia.

Melting Points: Amino acids have a high melting points in the range of 200 - 300°C.

Taste: Amino acids are  usually  sweet, tasteless  or bitter. Eg. Gly, Ala, Val,  Pro, hydroxy-Pro, Ser, Try and His are sweet; Leu  is tasteless, whereas, Ile and Arg are bitter in taste.

Sodium  salt  of  glutamic acid  (Monosodium  glutamate,  MSG,  also  known  as Ajinomoto)  is valuable as a flavouring agent  for certain foods  and  sauces since  it imparts and enhances the flavour (also for meat and meat products). MSG  is being used since 1908 when a ~apbese  Chemist Kikunae Ikeda discovered that MSG could improve the flavour of the food products. However, tests on animals have shown that it  can cause brain  damage  and cancer. It has not  been proved  to  be  dangerous to humans. However,  food experts  do  not approve its use  for  infants and pregnant women. The acceptable daily intake of MSG  for a person weighing about 60 Kg is approximately 7.2 gms.