Fermentation as a Method of Food Processing

Fermentation as a Method of Food Processing production of organic acids, pH-development and microbial growth in fermenting cereals Peter Sahlin May 1999 Department of Applied Nutrition and Food Chemistry Fermentation as a Method of Food Processing production of organic acids, pH-development and microbial growth in fermenting cereals Licentiate thesis May 1999 Peter Sahlin Division of Applied Nutrition and Food Chemistry Center for Chemistry and Chemical Engineering Lund Institute of Technology Lund University 2 Preface In developing countries, one tenth of the children under five years of age dies due to dehydration. The dehydration is mainly caused by too many of severe incidences of diarrhoea. The main cause for getting diarrhoea is the ingestion of food not having the appropriate standard regarding the hygienic condition. The hygienic standard of a food is based on the processing and handling of the food, as well as on the conditions of the raw materials. A food item prepared with water contaminated with pathogenic microorganisms will successively become contaminated, and a health risk. It is known that pathogenic microorganisms normally found in food will not be able to grow in an acid environment, that is at pH below four. This acidity is normally found in lactic acid fermented food. This thesis deals with the production and properties of lactic acid fermented food. At the beginning of the fermentation step, the food is vulnerable to contamination since it does not have any acidity. This work has followed the development of the acidity by measuring the rise in lactic acid content during the process. In addition, the ability of the acid environment to suppress pathogenic bacteria has been studied. The studies have been made on cereal-water slurries, a common base for the production of gruels, pancakes, porridges, puddings and other food items. It takes 12 to 24 hours for the type of food studied to reach an acidity level that is safe regarding common pathogenic microorganisms. It is also shown that a strain of enterotoxinogenic Escherichia coli can not withstand the acidic environment produced in this process. This work was financially supported by Sida/SAREC. 3 ... - tailieumienphi.vn