| 摘要 |
Residue material (I) is hydrolysed to mannan oligomers (II) (DP1 to ca DP 10) as follows: (a) (I) is slurried in a liq. (to 5-60% (I), dry solids wt. basis); (b) an acid catalyst is added to pH 0.5-4; (c) the slurry is fed through a reactor at 160-260 deg. C in 6-60 sec./6-35 atmos.; (d) the slurry is discharged through an orifice so that the pressure is rapidly reduced to atmos.; (e) the slurry is neutralised; and (f) hydrolysed (I) is sepd. from the mannan oligomers (II) to leave these with purity above 80%. - (I) are coffee grounds that have been extracted at atmos. pressure, then thermally hydrolysed to remove most of the arabinogalactin. - Pref. step (a). Slurry pref. contains 5-20 wt.% by wt. (I) (dry basis) in H2O. Step (b). Acid is pref. H3PO4, HNO3, HCl, HOAc, or citric, tartaric, malic, adipic or fumaric acids, esp. H2SO4 (0.05-0.5% by wt. of slurry). Step (c). Reactor is pref. an extruder or plug flow reactor, and is esp. at 190-220 deg. C. Alternatively CO2 may be used as the catalyst, when it is injected into the reactor with the slurry.
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