Potato Extraction, Determination of End Point in Extraction of Free Amino Acids from Potatoes

Abstract

Procedure. Using infrared lamps, take 100-ml. samples of milk to dryness, ash at 500°to 550°C ., digest on water bath with 5 ml. of approximately 6 ' hydrochloric acid, together with a little water, and filter. Take the filtrate to dryness to remove most of the hydrochloric acid, dissolve in about 5 ml. of water, transfer to a 50-ml. centrifuge tube, and wash with about 10 ml. of water. Add 3 ml. of 10% HEEDTA and two drops of bromothymol blue, and titrate slowly with approximately 2.V ammonium hydroxide to the blue-green color. (The volume prior to addition of ammonium hydroxide is about 20 ml.) Centrifuge and transfer the supernatant to a 50-ml. beaker and set aside.Dissolve the precipitate in about 10 drops of nitric acid, add another 3 ml. of 10% HEEDTA, and repeat the precipitation of calcium phosphate. Centrifuge, add the second supernatant to the first, and take the whole to dryness under an infrared lamp. To the residue, add 15 ml. of nitric acid, cover with a Speedyvap, and take to dryness on the hot plate to remove ammonia. Add 10 ml. of the acid mixture and, when most of the nitric acid has been removed, POTATO EXTRACTION raise the hot plate temperature to ensure efficient oxidation by the perchloric acid. When the vigorous oxidation reaction is complete, allow the beaker to cool, wash down the Speedyvap and the sides of the beaker with distilled water and return to the hot plate at low temperature to evaporate off the water.When fuming starts, raise the temperature to fume off the bulk of the sulfuric acid, and finally flame the beaker.Cool beaker contents, add about 2 ml. of w'ater, bring to near boiling on the hot plate, and transfer to a 10-ml. graduated centrifuge tube. Add 3 ml. of the phosphoric-periodate solution, mix, immerse in boiling water, and keep just boiling for about 2 hours. The initial volume of about 10 ml. is reduced to about 6 ml. over this period. After cooling, centrifuge to remove water from the upper parts of the tube and to bring down the small amount of calcium sulfate, which usually occupies about 0.3 ml. Make the volume up to 6.3 ml.-i.e., 6 ml. over the volume occupied by the calcium sulfate, mix thoroughly, recentrifuge, and transfer to a 5-cm. cell for density determinations at 525 µ. ConclusionsRecoveries of manganese by this method appear satisfactory, taking into account the levels involved. Although not investigated, DTPA would probably behave in much the same way as HEEDTA. This method may well have application to other materials high in calcium and/or phosphorus, such as bone, teeth, phosphate rock, and limestone.

Potato Acids, Identification and Determination of the Major Acids of the White Potato

“…The results (Table III) show that most of the acids are obtained completely by two cold extractions, but that citric, phosphoric, and the unidentified acid require longer, or high temperature extractions. This is similar to the findings of Talley et al (23) with amino acids in potatoes, and indicates that incomplete extraction will give not only smaller amounts of acids but also a false picture of their abundance relative to each other.…”

Soxhlet extraction of acrylamide from potato chips

“…12 Also, static and batch extraction of amino acids, possibly related to acrylamide dissolution, from potatoes may be slow and complex processes. 13 Unfortunately, there is a lack of experimental investigations of extraction of food samples using modern techniques. However, there are analogous investigations of environmental samples.…”

“…The methods used should be verified thoroughly on each specific food for which they are to be used. 13 The verification should include significant variations of key parameters, for example: particle size, solvent volume to sample weight, temperature and extraction time.…”

Foodstuffs Analysis, Extraction of Nitrogenous Constituents from the Navy Bean Seed, Phaseolus Vulgaris

“…To the dialyzate. 4 volumes of absolute ethyl alcohol were added and the suspension was allowed to stand for about 16 hours at about 25°C. Subsequently the suspended matter was removed by filtration with Whatman 41H filter paper which had been washed with water and 80% ethyl alcohol, dried at 105°C.…”