Gas packing milk powder with a mixture of nitrogen and hydrogen in the presence of palladium catalyst

Abstract

Whole and skimmed milk spray dried powders have been gas packed by two methods, and the chemical and physical changes taking place during storage at 17 and 37 °C for two years have been measured. The conventional method of double gas packing with nitrogen, with an interval of several days for desorption, was used as a control for a new method employing a single gas packing with a mixture of nitrogen (90 %) and hydrogen (10 %) plus the inclusion within the can of a solid catalyst pellet containing palladium.The new system was more effective in removing oxygen and in maintaining an almost oxygen free atmosphere within the cans. Used on a commercial scale it would have several important advantages over the conventional method, and both whole and skimmed milk powders packed in this way would probably be usable after storage for 10 years at normal temperatures. Because of the low general level of oxygen in all the cans packed by both methods and because of the low moisture content there was little difference in the keeping quality of the powders. What little there was, however, was in favour of the new method.The most effective method of extending the storage life of milk powder is to pack it in an airtight container from which the air has been removed and replaced by a chemically inert gas such as nitrogen, the process commonly known as gas packing. This is particularly true for whole milk powder where the storage life is governed by the rate of oxidation of the unsaturated fats and the consequent development of objectionable flavours (Lea, Moran & Smith, 1943). The advantage of gas packing skimmed milk powder of normal moisture content (about 3 %) is much less but it has been found to be worth while in preventing the development of stale flavours, especially where the storage period might be prolonged or the storage temperature high (Henry, Kon, Lea & White, 1948).The technique of gas packing is simple and, so long as the containers are airtight, the oxygen content can easily be reduced from the 21 % present in air to 1 % or less

Quality and Stability of Some Freeze‐dried Foods in “Zero” Oxygen Headspace

“…The recently developed method of gas displacement described by Hu and Breyer (1970) can achieve residual oxygen of the order of 0.1%. More effective still is the technique of removing traces of oxygen by reaction with hydrogen on a palladium catalyst described by Abbot et al (1961) and employed by Tamsma et al (1960) to increase the shelf life of whole milk. In the headspace of a package filled with 5% hydrogen in nitrogen (a nonflammable, nonexplosive mixture), residual oxygen quickly falls below 0.001%.…”