Page 12 - Physicochemical properties of Indian plant gums- IINRG, Ranchi

Khair gcrrn (Acacia catechu)

General information
gtm' is ofvery good quality and is regarded as the best
The gtmftom Acacia catechu,k'hait
substitute for true gum arabic (,4' Seltega[1' Acacia catechu is.amoderar-sized deciduous
tree with a ligit feathery c,owo' o""t"ii"g thto"ghout India in dry types ofmixed forests
on a variety of geological formations anJsoils' Lac. can be successfirlly gawn on Khair
produc€d is similar in
trees. It is best used for raising the l ghani crop andthe €ncrustation
Ot"r,rq, Ot"llry to that produced"o nkus'trtt (Schleichera oleosa) Frexx,'T\ebark exudes
""4
a light gum. The t"ur. -uy b" u' lutge as 3cm in diameter and pale yellow to dark brown in
colour. It is not collectea separateiy"aod is generally mixed up with other Acacia gums' The
,rJ".'" .t"","ning tasteand is said to glve thicker and better mucilage lhan Dalul gum'

Physico-chemical Properties
Chemical nalare: Purified" exudates gum ftom fr'rat coltitls. ?gdlactose' L-arabinose'
L-rhamnose, and D-glucuronic acid in-a molar ratio of- 14'4:5'4:1'5: l The polysaccharide
'
aohydrouronic acid
.f tdt", ain (o.zay"), nitrogen (0.027o), methoryl (l '77o)' pH 4'8)' Hvdrolvsis
ii "iJ ***c J60 1c' o toz in acetate-bu.ffer'
"r"^naa rotation [tr]oE
(64'5770)' L-mabinose (24'21o/o)'
"rO gum showed that it is coiposed of D-galactose.
of the acid (l'1Vo
L-rhamnose (6'720/o) andD-glucuronic acid (4'037")' 4-O-methyl-glucruonic
Uf**""ic acid) is ul'o pt"'""t in the gum' The structure investigation of gum
"i,*J showed that main core of the gum is constituted of 1--+3 linked galactose
;il;;ffi
'orrit"to *tti"t u." attached side chains of galactose and arabinose by 1---+2 linkage'
Moteculat weighl: Ultra centrifugal analysis of polysac;laridS;howed its sedimentation
-;;;;; t" ;" ; 86 which conesponded to molecular weight of40'010'
Solubility & Wscosiry: Gum of l' catechu is soluble in cold water to a high degree'

Percentageofwater.Solubleportionin2Tosolution(ondrybasis)isreportedas94.2o/o
The viscosity determined
a St.g% for babul g"- u"a 99 'ZYo fot P- T1bt"'
""-n."i gnwerc 25 '0' 29 '6
with Redwood vis cometet of lJA,s%:oand 10% solutions of A'
^catechu
and 36.3 in Redwood ,""ondt '"tp""tiuely' The viscosity 1f-!lo' So/" and 10% solutions
of babul gum and gum arabic *"'i 2e'0' io'q * lg'l and 26'8' 31'1 & 36'5 in Redwood
seconds resPectivelY.
adhesive strength of l' catechu gan ndbabul gum were found to be
Adhesiveness:The
somewhat lower than that of gum arabic'

Olherstutlies:Differentialthermograms'infraredspectraandSEMstudiesweremadefor
identification of gum from A' catechu