|
Prepared at the 51st JECFA, published in FNP 52 Add 6 (1998) superseding specifications prepared at the44th JECFA (1995), published in FNP 52 Add 3 (1995). ADI "not specified" established at the 25th JECFA in 1981. |
|
SYNONYMS |
Locust bean gum, algaroba, carob gum, INS No. 410 |
DEFINITION |
Primarily the ground endosperm of the seeds from Ceratonia siliqua (L.) Taub. (Fam. Leguminosae) mainly consisting of high molecular weight (approximately 50,000-3,000,000) polysaccharides composed of galactomannans. The seeds are dehusked by treating the kernels with dilute sulphuric acid at high temperature or roasting the kernels, followed by milling and screening of the seeds to obtain the endosperm. The gum may be purified by washing with ethanol or isopropanol or dispersing in boiling water, followed by filtering, evaporation and drying. |
C.A.S. number |
9000-40-2 |
DESCRIPTION |
White to yellowish white, nearly odourless powder |
FUNCTIONAL USES |
Thickener, stabilizer |
CHARACTERISTICS | |
IDENTIFICATION | |
Solubility |
Soluble in hot water, insoluble in ethanol |
Gel formation |
Add small amounts of sodium borate TS to a solution of the sample; a gel is formed |
Viscosity |
Transfer 2 g of the sample into a 400-ml beaker and moisten thoroughly with about 4 ml of isopropanol. Add, with vigorous stirring, 200 ml of water and continue the stirring until the gum is completely and uniformly dispersed. An opalescent, slightly viscous solution is formed. Transfer 100 ml of this solution into another 400-ml beaker. Heat the mixture in a boiling water bath for about 10 min and cool to room temperature. There is an appreciable increase in viscosity (differentiating carob bean gum from guar gum). |
Test for galactose and mannose |
Passes test See description under TESTS |
Microscopic examination |
Disperse a sample of the gum in an aqueous solution containing 0.5% iodine and 1% potassium iodide on a glass slide and examine under microscope. Carob bean gum contains long stretched tubiform cells, separated or slightly interspaced. Their brown contents are much less regularly formed than in Guar gum. (Guar gum shows close groups of round to pear shaped cells. Their contents are yellow to brown). |
PURITY | |
Loss on drying |
Not more than 14.0% (105o, 5 h) |
Total ash |
Not more than 1.2% (800º, 3-4 h) |
Acid-insolublematter |
Not more than 4.0% Test 1.5 g of sample, accurately weighed |
Protein |
Not more than 7.0% Proceed as directed under nitrogen determination (Kjeldahl Method). The percentage of nitrogen determined multiplied by 6.25 gives the percent of protein in the sample |
Starch |
Not detectable by the following method: To a 1 in 10 solution of the sample add a few drops of iodine TS. No blue colour is produced |
Ethanol and isopropanol |
Not more than 1%, singly or in combination See description under TESTS |
Lead |
Not more than 2 mg/kg Prepare a sample solution as directed for organic compounds in the Limit Test and determine by atomic absorption spectroscopy |
Microbiological criteria |
Total plate count= Not more than 5,000 cfu/g E.coli= Negative by test Salmonella= Negative by test Yeasts and moulds= Not more than 500 cfu/g |
TESTS | |
| IDENTIFICATION TESTS | |
Test for galactose and mannose |
Boil a mixture of 100 mg of the sample and 20 ml of 10% sulfuric acid for 3 h. Allow to cool and add excess barium carbonate mixing with a magnetic stirrer until the solution is of pH 7, and filter. Evaporate the filtrate in a rotary evaporator at 30-50o in vacuum until a crystallized (or syrupy) residue is obtained. Dissolve in 10 ml of 40% methanol. This is the hydrolysate. Place 1 to 10 µl spots of hydrolysate on the starting line of two chromatoplates of silica gel and spots containing 1 to 10 µg of galactose and mannose expected to be present in the hydrolysate. Use two solvent systems, one for each plate: A. a mixture of formic acid, methyl ethyl ketone, tertiary butanol and water (15:30:40:15 by vol) and B. a mixture of isopropanol, pyridine, acetic acid and water (40:40:5:20 by vol) to develop the plates. After development, spray with a solution of 1.23 g anisidine and 1.66 g phthalic acid in 100 ml ethanol and heat the plates at 100o for 10 min. A greenish yellow colour is produced with hexoses, a red colour with pentoses and a brown colour with uronic acids. Compare sample with those for the solution of galactose and mannose. |
PURITY TESTS | |
Ethanol and isopropanol |
PrincipleThe alcohols are converted to the corresponding nitrite esters and determined by headspace gas chromatography.
Sample preparationDissolve 100 mg of sample in 10 ml of water using sodium chloride as a dispersing agent if necessary.
Internal standard solutionPrepare an aqueous solution containing 50 mg/l of n-propanol.
Standard alcohol solutionPrepare an aqueous solution containing 50 mg/l each of ethanol and isopropanol.
ProcedureWeigh 200 mg of urea into a 25-ml "dark vial" (Reacti-flasks, Pierce, Rockford, IL, USA, or equivalent). Purge with nitrogen for 5 min and then add 1 ml of saturated oxalic acid solution, close with a rubber stopper and swirl. Add 1 ml of sample solution, 1 ml of internal standard solution and simultaneously start a stop watch (T=0). Swirl the vial and recap with an open screw cap fitted with a silicone rubber septum. Swirl until T=30 sec. At T=45 sec inject through the septum 0.5 ml of an aqueous solution of sodium nitrite (250 g/l). Swirl until T=70 sec and at T=150 sec withdraw through the septum 1 ml of the headspace using a pressure lock syringe (Precision Sampling Corp., Baton Rouge, Louisiana, USA, or equivalent.
Gas chromatographyInsert syringe needle in the injection port; precompress the sample, then open the syringe and inject the sample. Use the following conditions
Column- material: glass - length: 90 cm - inner diameter: 4 mm - packing: first 15 cm packed with chrompack (or equivalent) and the remainder with Porapak R 120-150 mesh (or equivalent) Carrier gas: nitrogen Flow rate: 80 ml/min Detector: flame ionization Temperatures - injection port: 250º - column: 150º isothermal
CalculationQuantify the ethanol and isopropanol present in the sample by comparing the peak areas with the corresponding peaks obtained by chromatographing the headspace produced by substituting in the procedure 1 ml of Standard alcohol solution for 1 ml of Sample solution. |
Microbiological criteria |
Total plate count: Using aseptic technique, disperse 1 g of sample into 99 ml of phosphate buffer and use a Stomacher, shaker or stirrer to fully dissolve. Limit dissolving time to about 10 min and then pipette 1 ml of the solution into separate, duplicate, appropriately marked petri dishes. Pour over the aliquot of sample in each petri dish 12-15 ml of Plate Count Agar previously tempered to 44-46°. Mix well by alternate rotation and back and forth motion of the plates, allow the agar to solidify. Invert the plates and incubate for 48±2 h at 35±1°.
After incubation count the growing colonies visible on each plate and record the number of colonies. Take the average of both plates, and multiply by the sample dilution factor, 100. Where no colonies are visible, express the result as less than 100 cfu/g.
E. coli determination: Using aseptic technique, disperse 1 g of sample in 99 ml of Lactose broth using either a Stomacher, shaker or stirrer to fully dissolve the sample. Limit the dissolving time to about 15 min and then lightly seal the container and incubate the broth for 18-24 h at 35±1°. Using a sterile pipette, inoculate 1 ml of the incubate into a tube containing 10 ml GN broth. Incubate for 18-24 h and then streak any GN broths showing positive growth or gas production onto duplicate plates of Levine EMB agar. Incubate the plates for 24±2 h at 35±1° and then examine for colonies typical of E. coli i.e. showing strong purple growth with dark centre and a green metallic sheen sometimes spreading onto the agar. Record any typical E. coli colonies as presumptive positive, otherwise negative.
Streak any well isolated suspect colonies onto a plate of PCA and incubate for 18-24 h at 35±1°. Perform a Gram stain on any growth to confirm it is Gram negative. If so, disperse any colony growth into a small volume of 0.85% saline and perform chemical tests to confirm the identity of the bacterial growth. This can most conveniently be done by using API 20E or Micro ID strips or equivalent systems.
After completion of the tests, identify the organism from the Identification manual of the system used and record the final result.
MediaGN Broth (Gram Negative Broth)
Peptone 20.0 g Dextrose 1.0 g Mannitol 2.0 g Sodium citrate 5.0 g Sodium deoxycholate 0.5 g Potassium phosphate (dibasic) 4.0 g Potassium phosphate (monobasic) 1.5 g Sodium chloride 5.0 g
Make up to 1 litre with distilled or de-ionised water, pH 7.0±0.2 at 25°.
Salmonella determination: Using aseptic technique, disperse 5 g of sample into 200 ml of sterile Lactose broth using either a Stomacher, shaker or stirrer to maximise dissolution over a 15 min period. Loosely seal the container and incubate at 35±1° for 24±2 h.
Tighten lid and gently shake incubated sample mixture; transfer 1 ml mixture to 10 ml Selenite cystine broth and another 1 ml mixture to 10 ml Tetrathionate broth. Incubate 24±2 h at 35o. Mix (vortex, if tube) and streak 3 mm loopful incubated Selenite cystine broth on Bismuth sulfite (BS) agar, Xylose lysine desoxycholate (XLD) agar, and Hektoen enteric (HE) agar. (Prepare BS plates the day before streaking and store in dark at room temperature until streaked.) Repeat with 3 mm loopful of Tetrathionate broth. Incubate plates 24±2 h at 35o. Continue as indicated on pages 221-226 of the Guide to Specifications, FAO Food and Nutrition Paper 5 Revision 2, Rome 1991, "Examine plates for presence of colonies _".
Yeasts and moulds: Using aseptic technique, disperse 1 g of sample into 99 ml of phosphate buffer and use a Stomacher, shaker or stirrer to fully dissolve. Limit dissolving time to about 10 min and then pipette 1 ml of the solution into separate, duplicate, appropriately marked petri dishes. Pour over the aliquot of sample in each petri dish 15-20 ml of Potato dextrose agar (either acidified or containing antibiotic) previously tempered to 44-46°. Mix well by alternate rotation and back and forth motion of the plates, and allow the agar to solidify. Invert the plates and incubate for 5 days at 20-25°.
After incubation, count the growing colonies visible on each plate using a colony counter and record the number of colonies. Separate the yeasts from the moulds according to their morphology and count them separately. Take the average of both plates and multiply by the sample dilution factor, 100. Where no colonies are visible, express the result as less than 100 cfu/g. |