Abstract: Disclosed herein are a process for producing mixed crystals of disodium 5?-guanylate and disodium 5?-inosinate which comprises precipitating mixed crystals of disodium 5?-guanylate and disodium 5?-inosinate (I+G mixed crystals) by adding an aqueous mixed solution of disodium 5?-guanylate and disodium 5?-inosinate and a hydrophilic organic solvent at the same time into a crystallization vessel in such manner that the ratio of the hydrophilic organic solvent to the liquid phase in the crystallization vessel is maintained in a range of 30 to 70 vol %, as well as such process for producing I+G mixed crystals wherein said producing of I+G mixed crystals is carried out by seeding crystallization wherein crystals of 5?-IMP2Na or/and I+G mixed crystals are used as seed crystals.

Abstract: Purine nucleotide derivative disodium crystals having a minimized amount of remaining alcohol such as methanol, ethanol or a mixture thereof are produced by overdrying purine nucleotide derivative disodium crystals containing the alcohol; and bringing the overdried purine nucleotide derivative disodium crystals into contact with an aqueous solution containing a hydrophilic organic solvent to control the humidity of the purine nucleotide derivative disodium crystals under a high humidity condition.

Abstract: Disclosed herein are a process for producing mixed crystals of disodium 5′-guanylate and disodium 5′-inosinate which comprises precipitating mixed crystals of disodium 5′-guanylate and disodium 5′-inosinate (I+G mixed crystals) by adding an aqueous mixed solution of disodium 5′-guanylate and disodium 5′-inosinate and a hydrophilic organic solvent at the same time into a crystallization vessel in such manner that the ratio of the hydrophilic organic solvent to the liquid phase in the crystallization vessel is maintained in a range of 30 to 70 vol %, as well as such process for producing I+G mixed crystals wherein said producing of I+G mixed crystals is carried out by seeding crystallization wherein crystals of 5′-IMP2Na or/and I+G mixed crystals are used as seed crystals.

Abstract: Purine nucleotide derivative disodium crystals having a minimized amount of remaining alcohol such as methanol, ethanol or a mixture thereof are produced by overdrying purine nucleotide derivative disodium crystals containing the alcohol; and bringing the overdried purine nucleotide derivative disodium crystals into contact with an aqueous solution containing a hydrophilic organic solvent to control the humidity of the purine nucleotide derivative disodium crystals under a high humidity condition.

Abstract: The present invention relates to a double packages for preventing caking of powders or granules which comprises an inner container having high water vapor permeability for packaging article, an outer container having no or low water vapor permeability for packing said inner container, and desiccants placed between said inner container and said outer container.

Abstract: A process for recovering a high-purity L-amino acid from a fermentation liquor obtained by fermentation or an enzymic method, which comprises removing the impurities contained in said fermentation liquor by passing said fermentation liquor through an ultrafilter membrane and then through an ion-exchange or adsorbent resin; concentrating or cooling the effluent thus obtained to result in crystallization of said L-amino acid, and isolating said crystalline L-amino acid from said fermentation liquor.

Abstract: A process for recovering a high-purity L-amino acid from a fermentation liquor obtained by fermentation or an enzymic method, which comprises removing the impurities contained in said fermentation liquor by passing said fermentation liquor through an ultrafilter membrane and then through an ion-exchange or adsorbent resin; concentrating or cooling the effluent thus obtained to result in crystallization of said L-amino acid, and isolation said crystalline L-amino acid from said fermentation liquor.

Abstract: L-glutamine is purified by concentrating a fermentation liquor containing at least 40 g/l or more of L-glutamine, or a solution obtained therefrom by filtering off microbial cells, at pH 5.6.+-.0.5, or by cooling the fermentation liquor or the solution after concentration or without concentration at a temperature in the range of 2.degree. to 30.degree. C., thereby giving a slurry of L-glutamine crystals of 70 g/l or higher concentration; (2) separating the crystals from the mother liquor and then dissolving the separated crystals in a water; and (3) bringing the solution thus obtained into contact with an OH-type anion-exchange resin, thereby removing impurities through adsorption.

Abstract: A method for recovery of optically active tryptophane, which comprises filtering a solution of optically active tryptophane containing impurities through a semi-permeable membrane; adding a lower alcohol or a ketone to the filtrate; maintaining the solution containing the lower alcohol or ketone at an alkaline pH and a temperature higher than the .alpha./.beta. crystalline transition point; adding acid to the solution, thereby causing crystals of optically active tryptophane to form in the solution; and separating the crystals from the solution containing impurities, is disclosed. This method avoids the use of resins in the purification steps.