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Duenchay Tunnarut , Satit Ritlertchai and Rungnaphar Pongsawatmanit *

Freeze -Thaw Stability of Tapioca Starch Gels With and Without Xanthan Gum and Sucrose. Duenchay Tunnarut , Satit Ritlertchai and Rungnaphar Pongsawatmanit *. Department of Product Development, Faculty of Agro-Industry, Kasetsart University. Outline. Introduction. Objectives.

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Duenchay Tunnarut , Satit Ritlertchai and Rungnaphar Pongsawatmanit *

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  1. Freeze -Thaw Stability of Tapioca Starch Gels With and Without Xanthan Gum and Sucrose DuenchayTunnarut, SatitRitlertchai and RungnapharPongsawatmanit* Department of Product Development, Faculty of Agro-Industry, Kasetsart University

  2. Outline Introduction Objectives Materials and methods Results and discussion Conclusion

  3. 1. Introduction Freezing • Freezing is one of the most important preservation methods for foods. • Freezing is the unit operation in which the temperature of a food is reduced below its freezing point and a proportion of the water undergoes a change in state to form ice crystals (Fellows, 2000).

  4. 1. Introduction • Freezing process, when starch pastes or gels are frozen, phase separation occurs upon formation of ice crystals. Upon thawing, the water can be easily expressed from the dense network, a phenomenon known as syneresis or water separation (Karim et al., 2000). • When longer storage may enhance the changes in the product quality. Effect of freezing process on the change starch pastes or gels

  5. 1. Introduction • Many studies have reported the freeze-thaw stability of some starch pastes or gels could be enhanced by using biopolymers (Ferreroet al., 1994; Lee et al., 2002; Brennan et al., 2004) including xanthan gum (Xan) (Pongsawatmanit and Srijunthongsiri 2008) by measuring water separation or syneresis. Improvement of freeze-thaw stability

  6. 1. Introduction • Hydrocolloids are commonly used to improve the • texture and rheological properties of starch-based products (Shi and BeMiller, 2002), because they can be modified to have higher viscosity and less syneresis/water separation by using small quantities of hydrocolloids (Mali et al., 2003) Hydrocolloids • Hydrocolloids that are commonly used as a freeze-thaw stability such as xanthan gum (Xan), xyloglucan (XG), hydroxypropyl methylcellulose (HPMC), carboxymethyl cellulose (CMC), etc.

  7. 1. Introduction • This study selected Xan due to it’s provides an excellent stability in thermal and acid systems. Xanthan gum (Xan) β-D-glucose • Xan produced by Xanthomonascampestris • A backbone of 1,4-linked β-D-glucose with side chains consisting of two mannose molecules and one glucuronic acid. mannose glucuronic acid Fig. 1 Structure of xanthan gum Source: http://www.foodnetworksolution.com/wiki/word/1112/xanthan-gum

  8. 1. Introduction Tapioca starch (TS), • obtained from cassava roots • used as thickener agent in many foods products • it’s low cost product compared to other starches • Advantages • High viscosity • Clear appearance • Low production cost • Disadvantages • Low stability against heat or shear • During storage increase syneresis

  9. 1. Introduction • In general, food ingredients play an important role in determining final qualities of starch-based foods especially during storage. Sugar is another ingredient widely used in food formulation. Sugar • Sugars reduce water activity (Pongsawatmanitet al., 2002) • Sugars decrease water separation (syneresis) • The results of this study are expected to be useful for TS-based product development in the food industry.

  10. 2. Objectives • To determine the correlation between Xan, sucrose and water separation was investigated and proven to be a useful approach for predicting water separation at selected freeze–thaw cycles. • To investigate the freeze-thaw stability of 25% w/w TS gels with and without Xan and sucrose was determined at different freeze–thaw cycles.

  11. 3. Materials and methods • Tapioca starch • (Siam Modified Starch, Pathumthani, Thailand) • Xanthan Gum • (CP Kelco, San Diego, USA) • Sucrose (Ajax, Australia)

  12. 3. Materials and methods Preparation of TS/Xan/Sucrose gels Xan TS Distilled water Mixing and keeping for least 6 h 25% TS/Xan dispersion 25%TS 24.7% TS Mixing at room temp. for 2 h and adding sucrose 0% 10% 20% Mixing at room temp. for 30 min Fig. 2 Preparation of gels

  13. 3. Materials and methods Heating (˂65ºC) for 2-3 min Preparation of TS/Xan/Sucrose gels (Continue) Degassing under vacuum for 15-30 min Filling in case (250 x 22 mm) and sealing Heating at 95°C for 30 min Cooling in ice water for 10 min Keeping at 5°C for 24 h • Moisture content • Water activity • Freeze-thaw stability Fig. 2 Preparation of gels

  14. 3. Materials and methods TS and TS/Xan/Sucrose gels Freeze-thaw stability measurement Cutting into pieces and freezing at -25°C for 22 h Thawing at 40°C for 2 h Repeating for 9 cycles Water separation at cycle 1, 3, 6 and 9 weight of thawed starch gel and syringe after a centrifugation Water separation (%) = (wb – wa) x 100 ws weight of thawed starch gel and syringe before a centrifugation weight of thawed sample Fig. 3 The freeze-thaw stability experiment.

  15. 4. Results and discussion Table 1. Moisture content and water activity of 25%w/w TS gels with and without Xan and/or sucrose Mean ± standard deviation values (n = 3) followed by a different letters within the same column are significantly (p < 0.05) different by Duncan’s multiple range test. The (-) indicates no unit. • Moisture content and water activity values of freshly prepared TS and TS/Xan gels with and without sucrose were decreased with increasing sucrose (p<0.05) due to the higher solid content in the systems. - The water activity values of both TS and TS/Xan gels were about 0.985 and 0.982, respectively whereas those of gels containing 20% sucrose were 0.972 and 0.963, respectively.

  16. 4. Results and discussion (a) TS (b) TS/Xan Fig. 4 Water separation of 25% w/w TS (a) and TS/Xan (9.875/0.125) (b) containing different sucrose concentrations as a function of number of freeze–thaw cycles. The vertical bar represents the standard deviation.

  17. 4. Results and discussion Table 2. Correlation matrix between water separation at different freeze-thaw cycles of 25%w/w TS gels with and without Xan and sucrose * Correlation is significant at the 0.05 level (2-tailed), p < 0.05. ** Correlation is significant at the 0.01 level (2-tailed), p < 0.01. • Sucrose revealed negative significant correlations for p < 0.01 and higher values with higher number of freeze-thaw cycle indicating the high influence of sucrose on freeze-thaw stability in TS gels. • The effect of Xan on freeze-thaw stability in TS gels also showed negative correlation values (p < 0.05) but lower than those of sucrose.

  18. 4. Results and discussion • Since the water separation from freeze–thawed gels resulted from the retrogradation of starch biopolymers in the TS gels with and without Xan and/or sucrose, therefore, we derived an equation for predicting response/dependent variable (Y: water separation) from the explanatory/independent variables (X: Xan, sucrose and number of freeze–thaw cycles).

  19. 4. Results and discussion • The linear regression was conducted to relate the water separation with Xan, sucrose and number of freeze–thaw cycles as shown in Eq. for predicting water separation as shown below: Water separation (%) = 3.742 - 10.650(Xan) - 0.479(sucrose) + 1.368(cycle) • Then, we validated the Eq. by plotting another data set of experimental water separation values from TS gels with and without Xan and/or sucrose after repeating freeze–thaw treatment for one to nine cycles.

  20. 4. Results and discussion • A rather good predictability of water separation at various freeze–thaw cycles between the modeling dataset and testing dataset was obtained indicated by the corresponding correlation coefficient (R = 0.879) and small value of the root mean square error (RMSE = 3.021) values between them. Fig. 5 Predicted water separation using Eq. and experimental water separation from 25% w/w TS and TS/Xan (9.875/0.125) gels with and without sucrose (R = 0.879, RMSE = 3.021)

  21. 5. Conclusion • The addition of Xan and sucrose revealed better freeze-thaw stability of 25% w/w TS gels by reducing water separation in TS gels subjected to repeated freeze-thaw cycle. • The effect Xan and sucrose on water separation in TS gels revealed negative significant correlations for p < 0.05 and p < 0.01, respectively. The regression model performance in predicting water separation from specified freeze–thaw cycle revealed a good agreement with the experimental dataset.

  22. Acknowledgments • This study was based upon work supported by a grant from the Thailand Research Fund (TRF) under the Research and Researchers for Industries (RRI) project.

  23. Thank you for your kind attention

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