Foods: Dairy products Ethanol

Acetonitrile precipitation has been the subject of some papers dealing with the analysis of mono- and disaccharides in milk and dairy products, oligosaccharides in soybeans, and general methods for sugars in foods (23). Aqueous ethanol has also been frequently utilized in the extraction of lipids as undesirable components along with the carbohydrates. A further treatment with chloroform will free the hydroalcoholic extract from the lipids. 

Protein-rich foods can also be specially treated. According to Saag (135), in order to extract colorants from fish, samples are boiled, filtered, washed, with an ammonia solution to displace proteins, and then washed through Sephadex LH-20 with water. The colored zones are collected for HPLC analysis. Dairy products (ice cream, cheese, yogurt) are first mixed with acetone or ethanol to precipitate the protein, which is ground up with sea sand and Celite, and the slurry is placed in a column from which dyes are eluted with a solution of ammoniacal methanol (135,162). 

In materials in which there are strong interactions between the lipids and the matrix, methods involving alkaline or acid pretreatment may be required. ExtractabUity decreases with samples of high water content and therefore freeze-drying may be required before extraction. Incomplete extraction particularly of polar lipids can be overcome to some extent by including polar co-solvents such as ethanol. Extraction of nonfat material, including water, can also be a problem. In spite of the potential problems, it has been shown for several foods, including meat and some bakery and dairy products, that extraction is as efficient as conventional methods. 

The farm industry supports the production of corn-based ethanol, although the food industry opposes it, because the increased demand for corn is raising the cost of animal feed and, therefore, the cost of dairy, poultry, and other products. 

Most polysaccharides used today are of plant origin. However, also bacteria produce polysaccharides. Especially extracellular polysaccharides (eps s) produced by lactic acid bacteria may find application in foods. Lactic acid bacteria are food-grade organisms and the eps s produced offer a wide variety of structures. The presence of eps is considered to contribute greatly to texture and structure of fermented milk products. An exopolysaccharide produced by Lactococcus lactis ssp. cremoris B40 was chosen as a subject of study. The eps was a gift from the Dutch Institute of Dairy Research (NIZO), Ede, the Netherlands. The eps had no gelling properties, could not be precipitated in plates by ethanol or cetylpyridinium chloride and did not show interaction with Congo red. 

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