Conclusões

A irradiação afetou grande parte das propriedades, não apresentando efeito na morfologia dos grânulos e padrão de raios-X. A irradiação alterou de modo uniforme o tamanho dos grânulos, teor de amilose, teor de carboxilas e acidez do amido de ambas cultivares. A radiação gama induziu à degradação das moléculas

de amilose e de amilopectina, mas também gerou ligações cruzadas, o que levou os amidos das diferentes cultivares a apresentarem comportamentos distintos para a digestibilidade in vitro e para a cristalinidade ao longo das doses aplicadas. Para a cv. IAC 202 ocorreu redução do número das cadeias longas e aumento das cadeias curtas da amilopectina, enquanto para a cv. IRGA 417 ocorreu aumento das cadeias longas e redução das cadeias curtas, promovendo aumento na temperatura de gelatinização.

Referências

ABU, J. O.; DUODU, K. G.; MINNAAR, A. Effect of gamma-irradiation on some physicochemical and thermal properties of cowpea (Vigna unguiculata L. Walp) starch. Food Chemistry, Barking, v. 95, n. 3, p. 386-393, 2006.

ASSOCIATION OF OFFICIAL ANALYTICAL CHEMISTS - AOAC. Official methods

of analysis. 18. ed. Gaithersburg: AOAC International, 2005.

BAO, J. S.; AO, Z. H.; JANE, J. Characterization of physical properties of flour and starch obtained from gamma-irradiated white rice. Starch-Starke, Weinheim, v. 57, n. 10, p. 480-487, 2005.

BHAT, R.; KARIM, A. A. Impact of radiation processing on starch. Comprehensive

Reviews in Food Science and Food Safety, Hoboken, v. 8, n. 2, p. 44-58, 2009.

CHATTOPADHYAY, S.; SINGHAL, R. S.; KULKARNI, P. R. Optimisation of conditions of synthesis of oxidised starch from corn and amaranth for use in film- forming applications. Carbohydrate Polymers, Barking, v. 34, n. 4, p. 203-212, 1997.

CHAVEZ-MURILLO, C. E. et al. Starch of diverse Mexican rice cultivars: physicochemical, structural, and nutritional features. Starch-Starke, Weinheim, v. 64, n. 9, p. 745-756, 2012.

CHUNG, H. J. et al. Relationship between the structure, physicochemical properties and in vitro digestibility of rice starches with different amylose contents. Food

Hydrocolloids, Amsterdam, v. 25, n. 5, p. 968-975, 2011.

CHUNG, H. J.; LIU, Q. Effect of gamma irradiation on molecular structure and physicochemical properties of corn starch. Journal of Food Science, Chicago, v. 74, n. 5, p. C353-C361, 2009.

______. Molecular structure and physicochemical properties of potato and bean starches as affected by gamma-irradiation. International Journal of Biological

COOKE, D.; GIDLEY, M. J. Loss of crystalline and molecular order during starch gelatinisation: origin of the enthalpic transition. Carbohydrate Research, Amsterdam, v. 227, p. 103-112, 1992.

DUBOIS, M.; GILLES, K.A.; HAMILTON, J.K.; REBERS, P.A.; SMITH, F. Colorimetric method for determination of sugar and related substances. Analytical

Chemistry, Washington, v. 28, n. 3, p. 350-354, 1956.

ENGLYST, H. N.; KINGMAN, S. M.; CUMMINGS, J. H. Classification and measurement of nutritionally important starch fractions. European Journal of

Clinical Nutrition, Basingstoke, v. 46, p. S33-S50, 1992.

ENGLYST, K. N.; LIU, S.; ENGLYST, H. N. Nutritional characterization and measurement of dietary carbohydrates. European Journal of Clinical Nutrition, Basingstoke, v. 61, p. S19-S39, 2007.

FALADE, K. O.; IGHRAVWE, E.; IKOYO, S. S. Physico-chemical characteristics of non-irradiated and gamma-irradiated yams cultivars (Dioscorea rotundata, Dioscorea alata) and sweet potato (Ipomoea batatas (L) Lam). International Journal of Food

Science and Technology, Oxford, v. 46, n. 6, p. 1186-1193, 2011.

FAO. FAOSTAT. Database. Rome, 2011. Disponível em: <http://faostat.fao.org>. Acesso em: 03 fev. 2014.

GANI, A. et al. Characterization of rice starches extracted from Indian cultivars. Food

Science and Technology International, London, v. 19, n. 2, p. 143-152, 2013. GANI, A. et al. Modification of bean starch by gamma-irradiation: Effect on functional and morphological properties. Lwt-Food Science and Technology, Amsterdam, v. 49, n. 1, p. 162-169, 2012.

GIBSON, T. S.; SOLAH, V. A.; MCCLEARY, B. V. A procedure to measure amylose in cereal starches and flours with concanavalin A. Journal of Cereal Science, London, v. 25, n. 2, p. 111-119, 1997.

HENRY, F.; COSTA, L. C.; AYMES-CHODUR, C. Influence of ionizing radiation on physical properties of native and chemically modified starches. Radiation Physics

and Chemistry, Oxford, v. 79, n. 1, p. 75-82, 2010.

INSTITUTO ADOLFO LUTZ. Métodos físico-químicos para análise de alimentos. São Paulo, 2008. 1020 p.

JANE, J. Effects of amylopectin branch chain length and amylose content on the gelatinization and pasting properties of starch. Cereal Chemistry, Saint Paul, v. 76, n. 5, p. 629-637, 1999.

JULIANO, B. O. A simplified assay for milled-rice amylose. Cereal Science Today, Minneapolis, v. 16, n. 10, p. 334-340, 1971.

KANG, I. J. et al. Production of modified starches by gamma irradiation. Radiation

Physics and Chemistry, Oxford, v. 54, n. 4, p. 425-430, 1999.

KONG, X. L. et al. Effect of gamma irradiation on the thermal and rheological properties of grain amaranth starch. Radiation Physics and Chemistry, Oxford, v. 78, n. 11, p. 954-960, 2009.

LAWAL, O. S. et al. Rheology and functional properties of starches isolated from five improved rice varieties from West Africa. Food Hydrocolloids, Amsterdam, v. 25, n. 7, p. 1785-1792, 2011.

LEE, Y.-J. et al. Physicochemical properties of gamma-irradiated corn starch.

Journal of Food Science and Nutrition, Busan, v. 11, n. 2, p. 146-154, 2006.

LIU, T. Y. et al. Modifications of structure and physicochemical properties of maize starch by gamma-irradiation treatments. Lwt-Food Science and Technology, Amsterdam, v. 46, n. 1, p. 156-163, 2012.

NARA, S.; KOMIYA, T. Studies on the relationship between water saturated state and crystallinity by the diffraction method for moistened potato starch. Starch/Stärke, Weinheim, v. 35, p. 407-410, 1983.

PATINDOL, J. et al. Properties of flours and starches as affected by rough rice drying regime. Cereal Chemistry, Saint Paul, v. 80, p. 30-34, 2003.

ROMBO, G. O.; TAYLOR, J. R. N.; MINNAAR, A. Irradiation of maize and bean flours: effects on starch physicochemical properties. Journal of the Science of

Food and Agriculture, London, v. 84, n. 4, p. 350-356, 2004.

SINGH, N. et al. Relationships between physicochemical, morphological, thermal, rheological properties of rice starches. Food Hydrocolloids, Amsterdam, v. 20, n. 4, p. 532-542, 2006.

SINGH, S. et al. Effects of gamma-irradiation on the morphological, structural, thermal and rheological properties of potato starches. Carbohydrate Polymers, Barking, v. 83, n. 4, p. 1521-1528, 2011.

SODHI, N. S.; SINGH, N. Morphological, thermal and rheological properties of starches separated from rice cultivar's grown in India. Food Chemistry, Barking, v. 80, n. 1, p. 99-108, 2003.

SONG, Y.; JANE, J. Characterization of barley starches of waxy, normal and high amylose varieties. Carbohaydrates Polymers, Amsterdam, v. 41, p. 365-377, 2000.

WANG, J.; YU, Y. Effect of gamma-ray irradiation on the physicochemical properties of flour and starch granule structure for wheat. International Journal of Food

WANG, L. et al. Study on the granular characteristics of starches separated from Chinese rice cultivars. Carbohydrate Polymers, Barking, v. 87, n. 2, p. 1038-1044, 2012.

WANI, A. A. et al. Physico-chemical, thermal and rheological properties of starches isolated from newly released rice cultivars grown in Indian temperate climates. Lwt-

Food Science and Technology, Amsterrdam, v. 53, n. 1, p. 176-183, 2013.

WILCOX, D. et al. Image tool for Windows, version 3.0. San Antonio: The University of Texas, Health Science Center, 2002.

WONG, K. S.; JANE, J. Effects of pushing agents on the separation and detection of debranched amylopectin by high-performance anion-exchange chromatography with pulsed amperometrico detection. Journal of Liquid Chromatography, New York, v. 18, n. 1, p. 63-80, 1995.

WOOTTON, M.; DJOJONEGORO, H.; DRISCOLL, R. the effect of gamma-irradiation on the quality of Australian rice. Journal of Cereal Science, London, v. 7, n. 3, p. 309-315, 1988.

YOON, H. S. et al. In vitro digestibility of gamma-irradiated corn starches.

Carbohydrate Polymers, Barking, v. 81, n. 4, p. 961-963, 2010.

YU, Y.; WANG, J. Effect of gamma-ray irradiation on starch granule structure and physicochemical properties of rice. Food Research International, Essex, v. 40, n. 2, p. 297-303, 2007.

YUN, S. H.; MATHESON, N. K. Estimation of amylose content of starches after precipitation of amylopectin by concanavalin-A. Starch-Starke, Weinheim, v. 42, n. 8, p. 302-305, 1990.

ZHANG, G. Y.; HAMAKER, B. R. Slowly Digestible starch: concept, mechanism, and proposed extended glycemic index. Critical Reviews in Food Science and

Nutrition, London, v. 49, n. 10, p. 852-867, 2009.

ZHOU, Z. et al. Composition and functional properties of rice. International Journal

4 PROPRIEDADES FUNCIONAIS DE AMIDO DE ARROZ SUBMETIDO À