Ascorbic Acid from Walnut Hulls

Abstract

In studies on recovery of ascorbic acid from waste green hulls within the limits of error 0 natural sources of as-walnut hulls, an over-all yield of crystalline product of of the animal test. Spurious corbic acid is the immature 25 to 50% was obtained. Experimental details are previtamin C (or nonvitamin C walnut or its green hull. This sented for the following steps: extraction in dilute aqueous reductants which respond to fact was discovered by Ghersulfur dioxide solution; purification of the extract by abthe indophenol test) has been ghelezhiu in 1937 (2), and sorption on, and elution from, anion exchange resin;estimated by the method of several studies (8, ' 7, 9) have and crystallization from the concentrated, decolorizedWokes et al. (IO) to be less confirmed and extended the eluates. Pilot plant scale extraction operations were than 15% of the total aporiginal observations. The conducted. Economic analysis of the extraction process parent ascorbic acid measured immature walnut develops a indicates that the process is marginal unless other use photocolorimetrically. Analyses for ascorbic acid and maximum of 2 to 2.5y0 ascorother constituents of walnut bic acid on the wet basis (I6 hulls obtained from commerto 20% dry basis) just before hardening of the shell. From this maximum the concentration decia1 hullers over three harvesting seasons are given in Table 1. creases gradually to about 0.370 (wet basis) during the final 3Extraction and Stabilization Methods. LABORATORY SCALE months of ripening. Bukin ( 1 ) has reported a procedure for re-INVESTIQATIONS. Since most mechanical hullers break the hulls covery of ascorbic acid from whole immature walnuts, involving away in discrete pieces, the cellular structure is not damaged and four solvent fractionation steps and giving a 20% yield of very little loss of ascorbic acid takes place in the process of hullcrystalline product.ing. In the frozen state (0' F.) the ascrobic acid in the hulls is In recent years the Western Regional Research Laboratory has quite stable over periods of I year or longer. However, a t atmosconducted a project on possible utilization of waste walnut hulls pheric temperature the destruction of ascorbic acid is fairly rapid as a aource of ascorbic acid. At least 50,000 tons of hulls are proHulls held a t normal temperatures in open air lost more than two duced yearly in California alone. A considerable portion is availthirds of their ascorbic acid within 8 hours. When hulls were disable in central locations, because walnuts are harvested with hulls integrated in distilled water by means of a Waring Blendor, there intact and hulled by machin'es. A study of the development of was an 85% loss within 30 minutes. This rapid destruction is unascorbic acid in several commercial varieties of Persian walnut in derstandable from estimations of ascorbic acid oxidase in walnut central California during the growing sebson has been reported hulls, from which it has been concluded that, a t room temperature elsewhere (4).and pH 5, it should require not ...

Xylochemicals and where to find them

“…furan-2,5-dicarboxylic acid oxidation of hydroxymethylfurfural/methoxymethylfurfural (59%) [134][135] P benzene depol. of kraft lignin (175 g/kg), [136] wood combustion [137][138] P HO OH hydroquinone raw wv from Pinus tabulaeformis carr [127] green shell of walnuts, [139] citrus fruits [140] P Me O OH sorbic acid wv, [65] rowan berries [141][142] P O O Me parasorbic acid rowan berries (132 mg/100 g), [143] cranberry (0.12% of dry plant) [144] [86] growing wheat, [87] industrially through fmt. of sugars (up to 100%), [69,145] citrus juice and pineapple waste [69] and purification by esterification [146] S O O O cyrene green solvent alternative for DMF or NMP, from cellulose (from larch log, poplar wood, bagasse, corn cob, bilberry presscake), [147] via hydrogenation of levoglucosenone (up to 100%) [147][148]…”

Separation of Ascorbic Acid and 2-Keto-L-gulonic Acid

“…The separation and recovery of ascorbic acid by exchange with anion-exchange resins (1)(2)(3)(4)(5)(6) and the removal of ionic impurities from solutions of ascorbic acid by ion-exchange resins (7-10) were reported by some workers. However, there seems to be no available study on the separation of ascorbic acid and 2-keto-~-gulonic acid by molecular sorption on cation-exchange resins.…”

Título en español.

“…Klose, et al, (9) at the Western Utilization Research Branch, USDA, developed a more direct method for the isolation of ascorbic acid from green walnut hulls. Their experimental procedure may be summarized as follows: Extraction of the vitamin from the hulls using a dilute SO2 solution, purification of the extracts by absorption on, and the elution from anion-exchange resins; and crystallization from the concentrated, decolorized eluate.…”