Thursday, November 3, 2011


Chinese bullet trains were recently in the news for a wrong reason, the safety of foods served being questioned. People in India are too familiar with the low quality and uncertain safety of foods served in trains under the India Railways and therefore are not surprised that such things happen in China also. However the issue is of a different nature and the controversy had a technical flavor to it. The issue was how can any one serve food packets with 6 months shelf life on a train which obviously have no pantry cars and even if cooking facilities are available it may be too difficult to cook hot foods when the trains are moving at such high speeds. It is forgotten that the classical canned foods with which every body is familiar have shelf life of 1-2 years and both World Wars of the last millennium were fought by soldiers dependent on such long life tinned foods. Modern food technology has evolved suitable processing conditions for the manufacture of long life foods using other packaging materials also that include multi-layer plastics and plastic trays. In India Retort pouched foods of various varieties, mainly traditional preparations, are in the market with  6-12 months product life. Viewed against this backdrop, Chinese Railways serving foods with 6 month life is no surprise at all

"An investigation carried out by Shanghai Morning Post last week found two such box lunches produced a month ago. One of the lunches had a guarantee of 90 days and the other six months. Sold at around 30 yuan ( $ 4.7) each, the box lunches contained rice, beef, potatoes, eggs and carrots, and the labels stated that no additive has been used. the paper sent the two samples to a laboratory in Shanghai for testing. The results of the test showed that the food had not deteriorated and there were no illegal additives. A spokesperson with the Shanghai Railway Bureau, who insisted on anonymity, explained that they offered such box lunches with long guarantee periods only on long distance trains. "some trains leave (to Shanghai) the next day. We are afraid the safety of food purchased in places outside Shanghai (for the return trip) is unsafe", adding fresh box lunches are supplied on short distance trains". 

Foods which are preserved by processing at high temperatures as happening in the retorts used for sterilization, safety is never a problem as long as the package integrity is ensured by appropriate handling and storage. Such products, however can have some quality problems in terms of sensory properties. Naturally food products containing different chemical substances like proteins, carbohydrates, fats and other reactive moieties can always undergo chemical reactions, generating artifacts and the extent of such changes is dependent on temperature of storage and presence of oxygen inside the pack. Therefore it may be too much to expect that such heat processed foods will have same eating quality as that of their freshly prepared counterparts. Chinese passengers complaining about eating quality of the foods served in Bullet Trains may have some truth.   


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