Use chitosan to develop chocolate milk.

Chitosan and chitin are polysaccharide polymers containing more than 5000 glucosamine and acetylglucosamine units, respectively. Chitin is found in fungi, arthropods and marine invertebrates. Commercially, chitin is derived from the exoskeletons of crustaceans--shrimp, crab and other shellfish. Chitosan is obtained from chitin by a deacetylation process. Deacetylated chitin, or chitosan, is comprised of chains of D-glucosamine.

When ingested, chitosan can be considered a dietary fiber. Like dietary fiber, it is not digestible but may have beneficial effects on the gastrointestinal tract. Chitosan may also have an effect on the type of bacteria living in the intestines or on the action of these bacteria.

Modified chitosan--N-succinil-chitosan--is soluble in neutral and alkaline pH. It has the ability to form gels. Modified chitosan can find use as a thickening agent in chocolate beverages. The goal of Brazilian scientists was to develop a chocolate milk beverage using modified chitosan as a thickening agent, and to undertake a sensory and rheological evaluation of this product. They found that modified chitosan was effective as a thickening agent and helped create an acceptable new beverage. For the sensory evaluation, the researchers carried out an acceptance and comparative test with 50 local consumers, who tested the beverage as well as a commercial sample found on the Brazilian market. A hybrid hedonic scale was used. Investigators also performed a rheological evaluation using a commercial rotational rheometer.

Researchers found no difference between both beverages in terms of acceptance. Yet the developed beverage received better marks from consumers than the commercial beverage. Both showed a difference in viscosity, for which the developed beverage received a better rating.

The commercial drink fitted more to the Ostwald-de-Waale, Bingham and Casson flow and rheology models, and the developed beverage fitted better to the Ostwald-de-Waale model. The consistence index of the commercial beverage was 0.150, while that of the developed beverage was 1.590. This indicates a significant difference in their consistence characteristics. The flow index of the commercial beverage was 0.625, and the one for the developed beverage was 0.435.

Further information. Suzana Lannes, Department of Biochemical-Pharmaceutical Technology, University of Sao Paulo, Avenue Prof. Lineu Prestes, 580-B-16/Cidade Universitaria, Sao Paulo-SP, 05508-900 Brazil; phone: [phone]; URL: www2.usp.br/publishing/insite.cgi.