A method for at least partial deacetylation of a biopolymer comprising acetyl groups, including: a1) providing a biopolymer including acetyl groups; a2) reacting the biopolymer including acetyl groups with hydroxylamine (NH2OH) or a salt thereof at a temperature of 100° C. or less for 2-200 hours to form an at least partially deacetylated biopolymer; and a3) recovering the at least partially deacetylated biopolymer.