NOVELTY - A viscous fluid (F1) comprises at least 75 wt.% carbohydrate, 2-25 wt.% water, 0-25 wt.% of second organic solvent and 10-55 wt.% HCl, which second organic solvent is indicated by at least one of: having polarity related component of Hoy's cohesion parameter 0-15 MPa1/2; having Hydrogen bonding related component of Hoy's cohesion parameter of 0-20 MPa1/2; and having solubility in water of less than 15%, and forming heterogeneous azeotrope with water, where weight/weight ratio of solvent to water is 5-0.2, and solubility of water in solvent is less than 20%.    USE - As viscous fluid; as lignin composition; for the production of carbohydrate composition; for processing of lignocellulosic material (claimed); in the production of biofuels, chemicals, food ingredients and industrial products such as monomers for the polymers industry (e.g. lactic acid); and for forming food or feed ingredient such as citric acid, lysine or monosodium glutamate.    ADVANTAGE - The viscous fluid viscosity as measured at 80 degrees C by the Brookfield method is less than 150cP. The carbohydrate composition produced by using the fluid provide attractive and environmentally friendly substrate as the carbohydrates are obtained from renewable sources. The carbohydrates can be produced at costs that are lower than those of the food carbohydrates. The low cost carbohydrates open the way for much greater production of biofuels and industrial products such as monomers. The carbohydrates and co-products are of high quality, are free of HCl, and have minimal moisture and HCl content that is fluid enough for low-cost spray-drier based removal of residual HCl.    DETAILED DESCRIPTION - A viscous fluid (F1) comprises at least 75 wt.% carbohydrate (as calculated by 100 times carbohydrate weight divided by the combined weights of the carbohydrate and water), 2-25 wt.% water, 0-25 wt.% of a second organic solvent and 10-55 wt.% HCl (as calculated by 100 time HCl weight divided by the combined weights of HCl and water), which second organic solvent is indicated by at least one of: (a2) having a polarity related component of Hoy's cohesion parameter 0-15 MPa1/2; (b2) having a Hydrogen bonding related component of Hoy's cohesion parameter of 0-20 MPa1/2; and (c2) having a solubility in water of less than 15%, and forming a heterogeneous azeotrope with water, where the weight/weight ratio of the second organic solvent to water is 5-0.2, and where the solubility of water in the organic solvent is less than 20%. INDEPENDENT CLAIMS are included for the following:    (1) a method (M1) for the deacidification of a first aqueous solution involving: i) providing a first aqueous solution comprising carbohydrates, HCl and water, where the wt./wt. ratio of carbohydrates to water is 0.4-3 and where the wt./wt. ratio of HCl to water is 0.17-0.50; ii) contacting the first aqueous solution with a second organic solvent to form a second evaporation feed, which second organic solvent forms a heterogeneous azeotrope with water and is indicated by at least one of (a2), (b2) and (c2) and forming a heterogeneous azeotrope with water, where the wt./wt. ratio of the second organic solvent to water is 5-0.2, and where the solubility of water in the organic solvent is less than 20%; and iii) evaporating water, HCl and a second organic solvent from the second evaporation feed at a temperature below 100 degrees C and at a pressure below 1 atm, where a second vapor phase and the viscous fluid (F1) are formed;    (2) a lignin composition comprising 10-50 wt.% lignin, less than 8 wt.% water, 50-90 wt.% of a first organic solvent and less than 10 wt.% HCl (on an as is basis), which first organic solvent is indicated by at least one of: a1) having a polarity related component of Hoy's cohesion parameter of 0-15 MPa1/2; b1) having a Hydrogen bonding related component of Hoy's cohesion parameter of 0-20 MPa1/2; and c1) having a solubility in water of less than 15%, and forming a heterogeneous azeotrope with water, where the wt./wt. ratio of the first organic solvent to water is 5-0.2, and where the solubility of water in the organic solvent is less than 20%;    (3) a method (M2) for the deacidification of a second lignin stream;    (4) a method (M3) for the production of a carbohydrate composition;    (5) a method (M4) for the production of lignin;    (6) a method (M5) for processing a lignocellulosic material and for the production of a carbohydrate composition; and    (7) a hetero-oligosaccharides composition comprising tetramers composed of glucose and at least two sugars selected from mannose, xylose, galactose, arabinose and fructose.