Long chain glycolipids useful to avoid perishing or microbial contamination of materials

Method of preservating a material or imparting antimicrobial properties to said material, said method comprising adding to said material an effective amount therefor of a compound of the formula I, or a mixture of two or more such compounds of the formula I,

• wherein m is 3 to 5, n is 2 to 5, o is 0 or 1 and p is 3 to 17, with the proviso that the sum m+n+o+p is not less than 14;
• and
• R is a carbohydrate moiety bound via one of its carbon atoms to the binding oxygen,
• and/or a physiologically, especially pharmaceutically or nutraceutically or cosmetically, acceptable salt thereof, or an ester thereof,
• where the compound may be present in open chain form and/or in the form of a lactone,
• where said material is selected from the group consisting of a cosmetic, a food, a beverage, a pharmaceutical, a medical device, and an active packaging material.