Instrumental and Sensory Characteristics of Commercial Korean Rice Noodles

In this study, the rheological properties of several commercial rice noodle strands were investigated. In the bending test, failure stress decreased as the cooking temperature increased from 80 to 90 °C, and the cooking time increased from 3 to 4 min for higher rice content noodles (>60%). The stress–relaxation test and sensory tests were carried out with bundles of noodles to investigate correlations with the bending test. The modulus of elasticity was higher at 80 than 90 °C. However, no correlation was found between cooking temperature and the rheological properties of lower rice content noodles. In the stress relaxation test, the deviation was larger due to the empty space in the bundle. In the correlation analysis, sensory stickiness was correlated with a modulus of elasticity in the bending test. Comparing the bending and stress–relaxation tests, each instrumental variable showed differences in the rheological properties of rice noodles in strands and bundles. However, the bending test measured with noodle strands seemed to be most suitable as a method of measuring the rheological properties of rice noodles.

Hd1 Allele Types and Their Associations with Major Agronomic Traits in Korean Rice Cultivars

Optimizing flowering time in crop plants is critical for maximizing yield and quality under target environments. While there is a wide range of heading date variation in Korean rice cultivars, the underlying gene mechanisms are unclear. Here, we sequenced the protein coding regions of Hd1, the major rice heading date gene, from 293 Korean rice cultivars and investigated the associations between Hd1 allele types and major agronomic traits under four different environments. There were four functional Hd1 and five nonfunctional hd1 alleles distributed among the 293 Korean rice cultivars. The effects of the Hd1 allele types were highly significant for days to heading in all four environments, explaining 51.4–65.8% of the phenotypic variation. On average, cultivars carrying nonfunctional hd1 headed 13.7 days earlier than those carrying functional Hd1. While the Hd1 allele types exhibited highly significant effects on culm length and protein content under all four environments, the differences between cultivars carrying Hd1 and hd1 were minimal. The effects of the Hd1 allele types on amylose content were significant in only one of the four environments. Our results provide useful information for fine-tuning rice heading dates by utilizing different Hd1 alleles in rice breeding programs.

Inactivation of Indigenous Microorganisms and Salmonella in Korean Rice Cakes by In-Package Cold Plasma Treatment

The antimicrobial effects of in-package cold plasma (CP) treatment on Korean rice cakes (KRC) were evaluated. The CP treatment (25 kV) inactivated indigenous mesophilic aerobic bacteria by 0.8–1.0 log CFU/g, irrespective of the position of KRC in the package. The addition of a shaking step during CP treatment increased the reduction in microbes by ~1 log CFU/g. The microbial inactivation efficiency increased significantly when the treatment time increased from 1 to 3 min. Microbial inactivation activity was highest for packages containing eight rice cakes. The optimized CP treatment achieved a 2.0 ± 0.1 log CFU/g reduction in indigenous bacteria. In addition, the optimum CP treatment inactivated indigenous yeast and molds and Salmonella in KRC by 1.7 ± 0.1 log CFU/g and 3.9 ± 0.3 log CFU/g, respectively. No significant changes in color and firmness were observed, and the surface temperature of KRC did not exceed 22 °C after CP treatment. Moreover, CP treatment damaged the cellular membrane of Salmonella, mainly by inducing lipid peroxidation. This study demonstrates the potential use of in-package CP treatment for the non-thermal microbial inactivation of KRC.

Influence of sowing methods on biometric indicators of domestic and international rice varieties

This article presents the results of a study on the introduction of South Korean rice varieties, the influence of transplanting methods on the biometric indicators of local and foreign varieties, as well as the selection of varieties adapted for transplanting method using mechanization.