A weighed quantity of sample is mixed with an equal weight of deionized water. The degree Brix is measured on a Brix hydrometer, corrected for temperature difference from 20°C, and multiplied by 2 to correct for the dilution. The results are reported in degrees Brix (or percent sucrose by weight). The true percentage of dissolved solids in the sample is usually several degrees lower than the apparent number obtained by this procedure.
This method determines the weight per volume of a sample by filling a measured cylinder with a representative sample, weighing, and calculating the bushel weight.
Caffeine is extracted with water and determined by HPLC.
Caffeine and Theobromine
Caffeine and theobromine are extracted from the sample and separated and detected by HPLC.
Calories by bomb calorimetry
A weighed portion of sample is ignited in a sealed, oxygen-filled metal bomb which is submerged in a bath containing a measured amount of water. The whole system is maintained at a constant temperature by a thermally-insulated water jacket to prevent heat loss from the water bath due to radiation.
Chloride is extracted from the sample with dilute nitric acid solution. Using an automated analyzer system, sample extracts and standard chloride solutions are treated with mercuric thiocyanate. Chloride ions displace the thiocyanate, which is reacted with ferric ion, forming a red colored complex, which is measured spectrophotometrically. Chloride content in the sample is quantitated from standards of known concentration that are taken through the procedure.
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Isoflavones AOAC saponification method
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Non-volatile organic acids
Nonvolatile organic acids (Pyruvic, Lactic, Oxalacetic, Oxalic, Methyl Malonic, Malonic, Fumaric, Succinic, & Sorbic acids) are extracted from the sample with a methanol solution. An aliquot of the extract is heated with sulfuric acid, forming methyl esters of the organic acids. The sample is diluted with water and the acid methyl esters are phased into chloroform. A portion of the chloroform extract is injected into a gas chromatograph (GC) equipped with a flame ionization detector. Nonvolatile organic acid concentrations are quantitated from a set of standards of known concentration that are taken through the method.
Phytic acid, ion exchange
Phytic acid is extracted with dilute hydrochloric acid solution, and separated from inorganic phosphates on an anion exchange column. Phytate is eluted with a sodium chloride solution. The eluate is digested with sulfuric/nitric acid, freeing phosphorus, which is reacted with ammonium molybdate and sulfonic acid solutions, forming a blue color complex which is measured spectrophotometrically. Phosphorus concentration is quantitated from a set of standards of known concentration that are taken through the color reaction. Values are converted to phytic acid based on molecular weight equivalence.
Screen, Alpine or Brinkman
This method physically separates a sample into a particle size distribution that is dependent on the mesh size of the screens selected for the test.
Volatile Organic Acids
Volatile organic acids (Acetic, Propionic, Isobutyric, Butyric, Isovaleric, Valeric, Isocaproic, Caproic, & Heptanoic acids) are extracted from the sample with a mixture of phosphoric acid, water, and alcohol. The extract is filtered and a portion of filtrate is injected onto a gas chromatograph (GC) equipped with a flame ionization detector. Acid concentration is quantitated from a set of standards of known concentration that are injected into the GC under identical conditions.