Disclosed is a non- or substantially non-crystalline high trehalose content syrup, which is supersaturated in trehalose and which further comprises another dissolved saccharide in an amount at least as much as the amount of trehalose. The saccharide acts to prevent crystallization of trehalose. The saccharide may be a reducing monosaccharide, a non-reducing monosaccharide or an oligosaccharide. The supersaturated trehalose solutions are free from bacterial contamination even at ambient temperature.