Maurício de Oliveira

TIMM, NEWITON DA SILVA ; LANG, GUSTAVO H. ; FERREIRA, CRISTIANO D. ; POHNDORF, Ricardo S. ; Oliveira, Maurício
Abstract
The main objective of this study was to optimize the infrared radiation (IR) drying of parboiled rice on the temperatures of 70, 100, and 130°C and grain bed depth of 5, 10, and 15 mm. The effects of the temperature and grain bed depth on drying kinetics, head rice yield (HRY), milling and color parameters, and cooking properties were evaluated using response surface methodology. The drying temperature and bed depth presented a significant effect on HRY, whiteness, transparency, milling degree, L* , C* , relative crystallinity, cooking time, leached amylose, solubilized protein, and hardness. The longer exposure times to IR resulted in grains with an increase in the intensity of endosperm fissures and lower HRY. There is a tendency that the best condition to dry parboiled rice with IR is at higher temperatures and lower grain bed depth.

Practical applications

The present study optimized infrared radiation drying of parboiled rice as a function of the drying temperature and grain bed depth. The results provide scientific support on making decision during industrial rice processes. Severe infrared radiation drying conditions can reduce the HRY, increase cooking time, and intensify undesired sensory attributes.

VILLANOVA, FRANCIENE ALMEIDA ; EL HALAL, SHANISE LISIE MELLO ; VANIER, Nathan Levien ; POLIDORO, EDIMARA ; WANG, YA'JANE ; de Oliveira, Maurício
Background and objectives

Six different long‐slender rice genotypes were studied, being three pure lines (Puita Inta CL, Guri CL, and Irga 424 RI) and three hybrid lines (Titan CL, Lexus CL, and Inov CL). Samples were submitted to parboiling process under different steaming pressures (0.25, 0.50, and 0.75 kgf/cm2).

Findings

Results were dependent on genotype instead of line cluster. Intermediate steaming pressures may be useful for five cultivars; Titan CL was the only exception. Titan CL exhibited the lowest amylose content and the highest amylopectin average chain length, gelatinization temperature, and relative crystallinity. At the intermediate parboiling level of 0.50 kgf/cm2, Titan CL exhibited 8.32% of broken grains while the others exhibited values between 2.10% and 4.72%.

Conclusions

Titan CL had a more stable crystalline structure that hindered water intake into starch granules. For this reason, Titan CL may be parboiled at severe steaming pressure of 0.75 kgf/cm2 in order to achieve the same extent of gelatinization and physicochemical and cooking quality than the other studied cultivars.

Significance and novelty

The main rice cultivars grown in South America were studied. Results may help rice industries that work with long‐slender high‐to‐intermediate‐amylose rice to select proper parboiling parameters for each cultivar.

DA COSTA, CLÁUDIA MILITZ ; DOS SANTOS, RAILSON SCHREINERT ; MARINI, NACIELE ; DA MAIA, LUCIANO CARLOS ; VANIER, Nathan Levien ; ELIAS, Moacir Cardoso ; de Oliveira, Maurício ; COSTA DE OLIVEIRA, ANTONIO
The quality concept for cooked rice (Oryza sativa L.) varies according to customers culture and habits, varying from stickier, in Asia, to looser grains, more appreciated in South America. This parameter, no matter the taste, is an important factor in the evaluation of what constitutes a good rice grain. Higher grain stickiness is associated not only with lower amylose content, but also with amylopectin chain length and the net of proteins reinforced by intra and intermolecular disulfide bonds around the rice starch granule. Therefore, the present study compared four rice genotypes and the effectiveness of seed zinc coating treatments: T0 (without zinc sulfate) and TZnSO4 (with 8.81 g of ZnSO4.7H2O. kg−1 of seeds). Here we show that both treatments affect transcript accumulation of important sulfur-metabolism-enzymes. However, the higher levels of transcripts from these genes did not result in higher cysteine or serine levels. The adhesiveness of cooked mature rice grains is greatly impacted by genotype, but no evidence that transcript up-regulation could be associated to stickiness.

VILLANOVA, FRANCIENE ALMEIDA ; EL HALAL, SHANISE LISIE MELLO ; VANIER, Nathan Levien ; POLIDORO, EDIMARA ; WANG, YA'JANE ; de Oliveira, Maurício
Background and objectives

Six different long‐slender rice genotypes were studied, being three pure lines (Puita Inta CL, Guri CL, and Irga 424 RI) and three hybrid lines (Titan CL, Lexus CL, and Inov CL). Samples were submitted to parboiling process under different steaming pressures (0.25, 0.50, and 0.75 kgf/cm2).

Findings

Results were dependent on genotype instead of line cluster. Intermediate steaming pressures may be useful for five cultivars; Titan CL was the only exception. Titan CL exhibited the lowest amylose content and the highest amylopectin average chain length, gelatinization temperature, and relative crystallinity. At the intermediate parboiling level of 0.50 kgf/cm2, Titan CL exhibited 8.32% of broken grains while the others exhibited values between 2.10% and 4.72%.

Conclusions

Titan CL had a more stable crystalline structure that hindered water intake into starch granules. For this reason, Titan CL may be parboiled at severe steaming pressure of 0.75 kgf/cm2 in order to achieve the same extent of gelatinization and physicochemical and cooking quality than the other studied cultivars.

Significance and novelty

The main rice cultivars grown in South America were studied. Results may help rice industries that work with long‐slender high‐to‐intermediate‐amylose rice to select proper parboiling parameters for each cultivar.