A Further Insight into the Practical Applications of Exopolysaccharides from Sclerotium rolfsii (poster)

S.C. VIÑARTA; L.I.C. FIGUEROA; O.E. MOLINA; FARIÑA JI

New Orleans

Congreso; 104th GENERAL MEETING OF THE AMERICAN SOCIETY FOR MICROBIOLOGY; 2004

ASM

Starch is a widely distributed component in foodstuffs. The spontaneous separation of liquid from a gel or colloidal suspension due to the contraction of the gel (syneresis) is experienced by starch-containing products through cold storage and constitutes an undesirable phenomenon. It negatively affects the functional and sensory properties of foods and efforts are focused to minimize this effect without modifying the native properties of the product. The addition of exopolysaccharides (EPSs) to starch cooked pastes has been suggested to induce modifications on viscosity, gelling properties and syneresis. The present research aims to determine the influence of EPSs produced by fermentation with the fungus Sclerotium rolfsii ATCC 201126 at different cultivation times (EPS I: 48 h, EPS II: 72 h) on the syneresis of cooked starch pastes (corn and cassava starch, 2 and 3% w/v). The extent of syneresis was estimated by measuring the length of the liquid phase h separated above the sedimented phase. The degree of syneresis was represented by h/ho, where ho stands for the initial height of the sample dispersion. Measurements were daily performed throughout storage at 5°C. Different [starch : EPS] proportions varying between [9.90 : 0.10] and [9.00 : 1.00] were assessed against control starch. Up to day 20 of refrigeration and for the highest tested proportion [9.00 : 1.00], the EPS II was able to inhibit syneresis completely, while for the EPS I syneresis was detected only after 16 days of storage reaching a final value of 9% compared to the control (2% w/v corn starch w/o EPS) which represented the 100% syneresis. The other proportions showed a lower ability to reduce and/or slow down syneresis, being the decrease proportional to the reduction of EPS amount in the mixture, both for EPS I and II. The results indicated that the EPSs from S. rolfsii were successful on preventing the syneresis experienced by starch pastes during cold storage. This protective effect might be associated to the high water holding capacity of the EPSs and would retard the retrogradation of corn starch even for small amounts of polysaccharide, being more effective in the case of EPS II.