the chia ( salvia hispanica ) seed was used as an offering to the aztec gods , and , because of its religious use , it essentially disappeared for 500 years .
this is an annual herbaceous plant belonging to the lamiaceae or labiatae family . in pre - columbian times , it was one of the basic foods of several central american civilizations , less important than corn and beans , but more important than amaranth .
the chemical composition reports contents of protein ( 1525% ) , fats ( 3033% ) , carbohydrates ( 2641% ) , dietary fiber ( 1830% ) , and ash ( 4 - 5% ) .
chia seeds have been investigated and recommended due to their high levels of proteins , antioxidants , dietary fiber , vitamins , and minerals but particularly due to their oil content with the highest proportion of -linolenic acid ( -3 ) compared to other natural sources known to date .
chia seeds contain up to 39% of oil , which has the highest known content of -linolenic acid , up to 68% .
chia seed gum has the potential for industrial use because of its slimy properties , evident even at very low concentration , and because the plant , native to america , grows well in semiarid regions that have few practical plants .
chia gum begins to emerge from seeds as soon as they are placed in water .
the exudate is either partially cross - linked or is bound to the seed surface , since it is not easily separated from the seed .
separation can be accomplished by strong stirring , preferably in the presence of sand to aid in dislodgment or cleavage of insolubilizing bonds . for research purposes ,
gum has been removed by extraction of seeds with a 6  m urea solution .
chia gum is composed of -d - xylopyranosyl , -d - glucopyranosyl , and 4-o - methyl--d - glucopyranosyluronic acid unit in the ratio 2  :  1  :  1 . the polysaccharide seems to consist of a repeating unit .
extracted gum has a slimy , mucilaginous character at very low concentrations , giving it wide potential use in a variety of industrial applications , especially in certain foods and food preparations .
the objective of the present study was to determine the physicochemical properties of fatted and defatted gums from chia ( salvia hispanica ) seeds .
chia ( s. hispanica l. ) seeds were obtained in the yucatan state of mexico .
reagents were of analytical grade and purchased from j. t. baker ( phillipsburg , nj , usa ) , sigma ( sigma chemical co. , st .
louis , mo , usa ) , merck ( darmstadt , germany ) , and bio - rad ( bio - rad laboratories , inc .
seeds of chia were submitted to gum extraction with water at a 1  :  20 ratio ( w / v ) for 30  min and at a 50c temperature .
after that , the suspension was milled in a mixer and then it was boiled again at 50c under stirring for 15  min .
the crude mixture , containing water , gum , and seeds , was centrifuged at 9460  g at 15c for 3  h. the recovered gum ( fcg ) was dried at 40c for 24 hours and milled .
one portion of the recovered gum was partly defatted ( pdcg ) in a soxhlet .
standard aoac   procedures were used to determine nitrogen ( method 954.01 ) , fat ( method 920.39 ) , ash ( method 925.09 ) , crude fiber ( method 962.09 ) , and moisture ( method 925.09 ) contents in the fatted and defatted chia gums .
approximate water absorption capacity was first determined by weighing out 0.1  g ( d.b . ) of sample , adding water until saturation ( approximately 5  ml ) , and centrifuging at 2000  g for 10  min in a beckman gs-15r centrifuge .
approximate water absorption capacity was calculated by dividing the increase in sample weight ( g ) by the quantity of water needed to complete original sample weight to 15  g. water absorption capacity ( wabc ) was then determined by placing samples in four tubes , adding different quantities of water to bracket the measurement ( 1.5 and 0.5  ml water above original weight and 1.5 and 0.5  ml water below ; one in each tube ) , agitating vigorously in a vortex for 2  min , and centrifuging at 2000  g for 10  min in a beckman gs-15r centrifuge .
average water absorbed was calculated and the wabc was calculated , expressed as g water absorbed per g of sample .
briefly , 0.1  g ( d.b . ) of sample was placed in an equilibrium microenvironment at 98% relative humidity , generated by placing 20  ml of saturated potassium sulfate saline solution in tightly sealed glass flasks and placing these in desiccators at 25c .
the sample was left in the microenvironment until reaching constant weight ( 72 h ) .
briefly , 0.1  g ( d.b . ) of sample was weighed and then stirred into 20  ml of distilled water or corn oil ( mazola , cpi international ) for one minute .
these fibrous suspensions were then centrifuged at 2200  g for 30  min and the supernatant volume was measured .
water - holding capacity was expressed as g of water held per g of sample , and oil - holding capacity was expressed as g of oil held per g of gum .
corn oil density was 0.92  g / ml . apparent viscosity was evaluated using an adaptation of the li and chang   method , using a brookfield viscometer model dv - ii ( brookfield engineering lab . , stoughton , ma ) with spindle 27 ( for small samples ) and share rate range from 2.5 to 100  rpm at 25c .
the samples were dispersed in water to 0.5 , 1.0 , 1.5 , 2.0 , and 2.5% ( w / v , db ) .
the results were expressed in pa.s and data was fixed to an ostwald - de waele model to determine the consistency index ( k ) and flow behavior index ( n ) .
this percentage was lower than reported by sciarini et al .   in gleditsia triacanthos seeds ( 11.934.16% ) .
however , the chia gum 's yield was higher than reported by oomah et al .   in flaxseed ( 3.68% ) .
the proximal composition ( table 1 ) showed that pdcg registered a higher content of protein , ash , and nfe than fcg .
the fiber content of fcg ( 28.96% ) was similar to that reported by vazquez - ovando et al .   in a fiber - rich fraction of chia seeds ( 29.56% ) .
the moisture content of both gums was similar to that reported by kader et al .   in acacia glomerosa ( 9.09% ) but lower than reported in guar gum ( 10.36% ) , xanthan gum ( 11.08% ) , and gleditsia triacanthos ( 14.08% ) .
with respect to the nfe content , both gums registered lower values than reported by vazquez - ovando et al .   in a fiber - rich fraction of chia seeds ( 34.52% ) .
however , the ash content of fcg and pdcg was higher than that reported by kader et al .   in arabic gum ( acacia senegal , 3.6% ) although lower than reported by sciarini et al .   in xanthan gum ( 9.35% ) .
the protein content of both gums was higher than registered in corn gum ( 5.1% ) and mesquite gum ( 5.8% ) , this last one with important emulsifying properties attributed to its protein content according to bosquez . in this respect ,
establish that hydrocolloids rich in protein , such as gelatin , arabic gum , and mesquite , are good stabilizers because they have sufficient hydrophobic groups to act as bonding points as well as hydrophilic groups that reduce surface tension in a liquid - liquid or liquid - gas interface . on the other hand , yadav et al .  
establish that the lipid content in the gums may also play an important role in stabilization of oil - water emulsions .
however , bosquez   established that carbohydrates avoid flocculation and coalescence of oil droplets to extend in the aqueous solution .
these findings suggest that fcg and pdcg could act as good emulsifiers and stabilizers in the food industry . 

water absorption capacity is indicative of a structure 's aptitude to spontaneously absorb water when placed in contact with a constantly moist surface or when immersed in water .
water adsorption capacity is the ability of a structure to spontaneously adsorb water when exposed to an atmosphere of constant relative humidity .
wabc was higher in fcg ( 44.08  g / g of sample ) than pdcg ( 36.2  g / g of sample ) .
the high values of wabc obtained here could be due to the proteins present in the gums , which would have a large number of exposed hydrophilic sites interacting with water .
the wabc of fcg and pdcg was higher than reported by vzquez - ovando et al .   in a fiber - rich fraction of chia seeds ( 11.73  g / g of sample ) , who establish
that fiber content is an important factor in the increment of this property for its capacity to form gels and to hold water ; this justifies the higher value of wabc in fcg .
on the other hand , pdcg ( 0.84  g / g of sample ) registered a higher value of wadc than fcg ( 0.27  g / g of sample ) .
the wadc of dcg was also higher than registered by vzquez - ovando et al .   in a fiber - rich fraction of chia seeds ( 0.3  g / g of sample ) , similar to that reported in carrots ( 0.82  g / g of sample ) but lower than the value registered in beet bagasse ( 1.58  g / g of sample ) .
however , whc of both gums was higher than that reported by vzquez - ovando et al .   and baquero and bermdez   in a fiber - rich fraction of chia seeds ( 15.41  g / g of fiber ) and passion fruit peel ( 8.7  g / g of fiber ) , respectively .
a similar behavior was observed with orange waste ( 7.658.23  g / g of fiber ) . soluble fiber and the denaturalized proteins
may have increased the whc of both gums , thus enhancing the swelling ability , an important function of proteins in preparation of viscous foods such as soups , gravies , dough , and baked products . on the other hand
, fcg showed a higher ohc than pdcg , which might be related to its higher value of fat .
however , both gums registered higher ohc values than those registered in guar and xanthan gum ( 46  g oil / g fiber ) although similar to that reported in arabic gum ( 8 - 9  g oil / g fiber ) .
this functional property has been attributed to the physical entrapment of oil for molecules such as lipids and proteins . for the above mentioned
, the ohc registered in chia gums could be due to protein and fat contents as well as factors as particle size and the absence of hemicellulose .
chia gum seems to possess an adequate fat absorption capacity , allowing it to play an important role in food processing , since fat acts on flavor retainers and increases the mouth feel of foods . 

both gums showed a non - newtonian behavior where viscosity presented a relation directly proportional to the concentration and inversely proportional to the shear rate . the maximum viscosity reached between both gums
was registered by pdcg ( 55.4  pas ) at 2.5% . in general , pdcg registered a higher viscosity profile than fcg suggesting that the fat content was the principal factor that generated this behavior . at this respect ,
report that gums with higher oil absorption as arabic gum show less viscosity ( 2.34  pas at 3.8% ) . according to table 2 ,
the rheological behavior of the fcg and pdcg dispersions was a shear thinning or pseudoplastic type due to registered values of n < 1 .
the results suggest the use at low concentrations of dcg in products as yoghurts , sauces , toppings , and pastries among others that require high viscosity , whilst fcg could be used in sauces , mayonnaises , and meat products as emulsifying and stabilizer .
the results obtained here show that chia gums present interesting physicochemical properties for the food industry .
the partly defatted chia gum showed a very good ability to water holding ( 110.5  g / g ) ; however , their ability of oil holding ( 11.67  g / g ) and water absorption ( 36.26  g / g ) was minor compared to the fatted chia gum , which provided a greater retention of oil holding ( 25.79  g / g ) and water absorption ( 44.08  g / g ) .
rheological behavior of gums was shear thinning or pseudoplastic type . from a functional point of view
, chia gum also is an important food ingredient due its emulsifier and stabilizer potentials .
 chia ( salvia hispanica l. ) constitutes a potential alternative raw material and ingredient in food industry applications due to its dietary fiber content . 
 gum can be extracted from its dietary fiber fractions for use as an additive to control viscosity , stability , texture , and consistency in food systems . 
 the gum extracted from chia seeds was characterized to determine their quality and potential as functional food additives . 
 the extracted chia gum contained 26.2% fat and a portion was submitted to fat extraction , producing two fractions : gum with fat ( fcg ) and gum partly defatted ( pdcg ) . 
 proximal composition and physicochemical characterization showed these fractions to be different ( p < 0.05 ) . 
 the pdcg had higher protein , ash , and carbohydrates content than the fcg , in addition to higher water - holding ( 110.5  g water / g fiber ) and water - binding capacities ( 0.84  g water / g fiber ) . 
 the fcg had greater oil - holding capacity ( 25.7  g oil / g fiber ) and water absorption capacity ( 44  g water / g fiber ) . in dispersion trials , 
 the gums exhibited a non - newtonian fluid behavior , specifically shear thinning or pseudoplastic type . 
 pdcg had more viscosity than fcg . 
 chia seed is an excellent natural source of gum with good physicochemical and functional qualities , and is very promising for use in food industry . 