Characterization of yellow and development of instant flours by hydrothermal process / Caracterización de arroz manchado y elaboración de harinas instantaneas por proceso hidrotérmico

RESUMO

Commercial brown and yellow milled rice submitted to inappropriate storage conditions were characterized and utilized to develop instant flours that were used in the preparation of atoles. The grains were classified as long-thin; the average size was 2.13 x 6.79 mm. The milling yields obtained in laboratory with paddy rice were 70 per cent brown rice and 60 per cent milled rice. Brown rice and yellow milled rice had similar amylose contents, 22.5 and 25.6 per cent respectively. Gel consistency was solf with low gelatinization temperature (63-68ºC) for both samples. Field fungi, such as Helminnthosporium oryzae, and storage fungi, such as Aspergillus spp, were present in paddy, yellow milled and commercial rice. The fungus Helminthosporium oryzae, Aspergillus spp, and Penicillum spp were not present in instant flours. Instant flours were prepared by soaking the grain in water, and then steaming, dryng and milling it. The highest values for water absortion index were obtained from yellow milled instant rice flour. the color of yellow milled instant rice flour varied from white ("L") to pale yellow (lesser values of "b"). The lower viscosity of the instant flours indicates the breakdown of polymers and reveals that unintact starch granules were not present in instant flours. Protein and ash contents of brown and milled rice were unaffected by hydrothernal process, and the lipid content showed only little changes. Sensory analyses carried out on the atoles prepared with instant flours considered them acceptable, specially for products made from milled yellow rice