• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.1
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• pp.1-6
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• 1994

Some physicochemical properties of sugary rices were comparatively analyzed with the original cultivars, using Hwachung su-1, su-2, and Nampung su lines bred in Seoul Nat'l Univ., and EM 5 bred in Kyushu Univ. Sugary rice grains were smaller in width and thickness, and the relative dry weight of 1000 grains of sugary rices ranged from 49% to 72%, compared to normal ones. No distinct starch granules were found in endosperm of sugary rices exposured by SEM, with structural variations between Hwachung su-1 and su-2 lines. Sugary rices showed the significant increases in sucrose, glucose and fructose content, especially much higher in sucrose content showing 5.84-8.79%, in comparison with the normal ones, 1.11∼2.65%. However, sucrose and total sugar content varied within sugary lines carrying the same sugary gene, and were significantly lower in Hwachung su-2. Sugary rices, except Hwachung su-1, showed the same or lower ADV and harder gel characteristics, compared to normal ones. Protein and lipid content were much higher in sugary rices, due to the increased relative proportion of aleurone layer in brown rice caused by thicker aleurone layer than in normal rices and the reduction of endosperm part. However, there were no remarkable changes in amino acid and fatty acid compositions.

• Korean Journal of Breeding Science
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• v.42 no.2
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• pp.151-156
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• 2010

The mutants of sugary-2 (su-2), floury (flo), shrunken-1 (shr-1), and dull-1 (du-1) were crossed to waxy (wx) to produce $F_2$ seeds. Chi-square analysis on the segregating ratio of the $F_2$ seeds revealed that flo, su-2, and shr-1 were independently transmitted with wx, while wx was epistatic over du-1. The floury and sugary-2 were crossed to Hwasunchalbyeo, a waxy variety, and then the $F_4$ of floury-waxy and sugary-2-waxy seeds were developed, respectively. As the parents phenotypes of sugary-2 and floury, the grains of these two lines showed lower hardness and grain weight than normal grain of Hwacheongbyeo. For alkali digestive value (AVD), the sugary-2-waxy showed lower ADV than Hwacheongbyeo. For the gel consistency of grain flours, the floury was medium like Hwacheongbyeo, while those of the sugary-2, floury-waxy, and sugary-2-waxy were soft like Hwasunchalbyeo. The amylose contents in the grains of the sugary-2 and floury were decreased to ~15% whereas that of Hwacheongbyeo was 19.1%. All the lines showing waxy endosperm (Hwasunchalbyeo, floury-waxy, and sugary-2-waxy) showed less than 4% amylose contents. Interestingly, the free sugar content in the brown rice was increased to 9.27% in the sugary-2-waxy, showing transgressive segregation phenomenon where the free sugar contents in its parents, sugary-2 and Hwasunchalbyeo, were 5.98% and 3.98% respectively. Also, the floury-waxy showed transgressive segregation phenomenon, containing 6.15% of free sugar content in the grains.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.5
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• pp.384-389
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• 2002

No-tillage (NT) practice for corn production has advantages of reduction of soil erosion and energy conservation. Research on effects of NT for sweet corn or super sweet corn is very limited. Hybrids of sugary (su) and shrunken-2 (sh2) were tested under NT and conventional tillage (CT) practices to investigate plant characters, ear characters, fresh yield, and grain yield. Sugary hybrids were Golden Cross Bantam 70 (GCB70), Sprint, Geumdanok, and Danok3. Shrunken-2 hybrids were BSS9472, Cambella90, GSS9299, Jubilee, KS-Y-65, and Chodangok1. Emergence rates under NT were lower than those under CT for su, while there was no difference between tillage systems for sh2. There were no differences between CT and NT for days to tasseling and silking, plant height, and ear height for both su and sh2. Ear characters such as ear length, number of kernel rows, number of kernels per row, and t100-kernel weight under NT were not significantly different from those under CT. There were no differences between two tillage practice for fresh and grain yield, rather they showed trend of increases under NT practices. Results from this trial indicate that NT practice for both su and sh2 cultivation may be possible to recommend to farmers.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.107-107
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• 2017

Sweet corns are enjoyed worldwide as processed products and fresh ears. Types of sweet corn are based on the gene(s) involved. The oldest sweet corn type has a gene called "sugary (su)". Sugary-based sweet corn was typically named "sweet corn". With its relatively short shelf life and the discovery of a complementary gene, "sugary enhanced (se)", the sweet corn (su only) was rapidly replaced with another type of sweet corns, sugary enhanced sweet corn, which has recessive homozygous su/su, se/se genotype. With the incorporation of se/se genotype into existing su/su genotype, sugary enhanced sweet corn has better shelf life and increased sweetness while maintaining its creamy texture due to high level of water soluble polysaccharide, phytoglycogen. Super sweet corn as the name implies has higher level of sweetness and better shelf life than sugary enhanced sweet corn due to "shrunken2 (sh2)" gene although there's no creamy texture of su-based sweet corns. Distinction between sh2/sh2 and su/su genotypes in seeds is phenotypically possible. The Involvement of se/se genotype under su/su genotype, however, is visually impossible. The genotype sh2/sh2 is also phenotypically epistatic to su/su genotype when both genotypes are present in an individual, meaning the seed shape for double recessive sh2/sh2 su/su genotype is much the same as sh2/sh2 +/+ genotype. Hence, identifying the double and triple recessive homozygous genotypes from su, se and sh2 genes involves a testcross to single recessive genotype, chemical analysis or DNA-based marker development. For these reasons, sweetcorn breeders were hastened to put them together into one cultivar. This, however, appears to be no longer the case. Sweet corn companies began to sell their sweet corn hybrids with different combinations of abovementioned three genes under a few different trademarks or genetic codes, i.g. Sweet $Breed^{TM}$, Sweet $Gene^{TM}$, Synergistic corn, Augmented Supersweet corn. A total of 49 commercial sweet corn F1 hybrids with B73 as a check were genotyped using DNA-based markers. The genotype of field corn inbred B73 was +/+ +/+ +/+ for su, se and sh2 as expected. All twelve sugary enhanced sweet corn hybrids had the genotype of su/su se/se +/+. Of sixteen synergistic hybrids, thirteen cultivars had su/su se/se sh2/+ genotype while the genotype of two hybrids and the remaining one hybrid was su/su se/+ sh2/+, and su/su +/+ sh2/+, respectively. The synergistic hybrids all were recessive homozygous for su gene and heterozygous for sh2 gene. Among the fifteen augmented supersweet hybrids, only one hybrid was triple recessive homozygous (su/su se/se sh2/sh2). All the other hybrids had su/su se/+ sh2/sh2 for one hybrid, su/su +/+ sh2/sh2 for three hybrids, su/+ se/se sh2/sh2 for three hybrids, su/+ se/+ sh2/sh2 for four hybrids, and su/+ +/+ sh2/sh2 for three hybrids, respectively. What was believed to be a classic super sweet corn hybrids also had various genotypic combination. There were only two hybrids that turned out to be single recessive sh2 homozygous (+/+ +/+ sh2/sh2) while all the other five hybrids could be classified as one of augmented supersweet genotypes. Implication of the results for extension service and sweet corn breeding will be discussed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.1
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• pp.55-58
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• 2000

Germination of sweet and super sweet corn is lower than normal corn due to the higher sugar and lower starch contents of kernels. Sweet corn seeds are easily deteriorated in the field under the unfavorable condition, therefore it is important to identify the optimal harvesting time for seed production. This trial was conducted to investigate the responses of germination percentage of shrunken-2(sh2), brittle(bt), sugary(su), and sugary enhancer(se) hybrids in relation to harvesting dates. Eight hybrids of four different gene sweet corns were harvested at 15, 20, 25, 30, 35, 40, 45, and 50 days after silking(DAS). Germination test was performed using paper towel method. Mean germination percentages across eight hybrids showed the highest value at 45 DAS. There were significant differences among genes and within gene for germination. Shrunken-2 hybrid Mecca was higher than su hybrids for germination, indicating that sh2 would not be poorer than su Late harvesting beyond the optimal harvesting date might not be desirable because of more lodging and ear rots. Theoretical optimal harvesting date estimated from the regression equation was 40.9 DAS, however, practical date for harvesting would be a few days later than the estimated date if seedling vigor might be considered. Kernel dry weight per ear showed similar response to germination. Regression equation showed the highest kernel dry weight at 40.7 DAS. Significant correlations between kernel dry weight and germination were observed, impling that kernel dry matter accumulation would be an important factor for germination.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.4
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• pp.305-310
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• 2002

The performance of 7 sugary (su) and 12 shrunken-2 (sh2) sweet com hybrids which are commercially grown in the United States was tested in Korea. The 100-seed weight of su hybrids (16.5-23.6 g) was much heavier compared to that of sh2 hybrids (10.9-17.5 g). The germination rate of su and sh2 hybrids at $25^{\circ}C$ ranged 93.3-100% and 86.7-98.9%, the emergence rate of su and sh2 hybrids in cold test ranged 78.9-97.8% and 62.2-97.8%, and field emergence rate of su and sh2 hybrids ranged 74.4-100.0% and 79.9-98.2%, respectively. In su hybrids, there was a significantly positive correlation between germination rate at $25^{\circ}C$ and emergence rate in cold test or early growth. In contrast, in sh2 hybrids seed weight was positively correlated with early plant growth, while not with the germination rate at $25^{\circ}C$ or emergence rate in cold test and field. Most sh2 hybrids produced larger and more marketable ears compared to su hybrids although there were significant differences among the hybrids in the same genotype. At harvest (24 days after pollination) soluble solids content of su hybrids (24.3-27.1 Brix %) was much higher than that of sh2 hybrids (13.8-18.0 Brix %), while total sugars of sh2 hybrids (21.4-28.6% on the dry weight basis) was much higher compared to su hybrids (2.4-15.9%). Considering germination and emergence rates, marketable ear production, and total sugar content, 'GCB 70' and 'Sweet Satin' in su hybrids and 'Ice Queen', 'Aspen', 'Sweet Magic', 'Bandit', 'Xtrasweet 82', 'Aspen', and 'Cambella 90' in sh2 hybrids performed better than other hybrids.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.7
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• pp.632-638
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• 2006

Characteristics of sweet (sugary, su) and super sweet (shrunken-2, sh2) corn seeds shelled by different threshing methods at different moisture content status were studied. Hybrid seeds of a su (Early Sunglow ${\times}$ Golden Cross Bantam 70, GCB 70) and a sh2 (Xtrasweet 82 ${\times}$Fortune) were dried to moisture content of 12, 15, 18, and 21%. Hand shelling did not give any mechanical damages to seeds, while an electrical corn thresher gave some visible mechanical damages. The emergence rate of hand shelled seeds was higher than that of machine shelled seeds by $6{\sim}14%$ for a su and by $9{\sim}18%$ for a sh2 hybrid depending on seed moisture contents in cold test. The optimum seed moisture content to reduce mechanical threshing damages and to improve seed quality was 15% for su and 12% for sh2 hybrid seeds. At the optimum seed moisture contents, germination rate at $25^{\circ}C$, emergence rate in the cold test and ${\alpha}-amylase$ activity were highest, while the percentage of damaged seeds and leakage of total sugars and electrolytes in soaking water were minimized.

• Preventive Nutrition and Food Science
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• v.8 no.2
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• pp.179-184
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• 2003

The use of high amylose maize varieties significantly affected the alkaline-cooking process and characteristics of alkaline-processed food products, such as masa and tortilla chips. High amylose maize varieties had softer endosperm textures with move tightly attached pericarps than normal maize. Masa prepared from high amylose mutant maize was less cohesive than that of normal maize due to insufficient dispersion of amylopectin and excessive retrogradation of starches. Tortilla chips prepared from amylose-extender dull (ae du), amylomaize V, and Ⅶ had slightly increased oil absorption, while tortilla chips from dull (du) and amylose-extender sugary-2 (ae su-2) had oil contents similar to that of control chips. Increased oil absorption of the tortilla chips was due to their increased surface area. Tortilla chips produced from high amylose mutant maize had darker color than control chips, presumably due to the pigmented pericarp tissues, higher levels of reducing sugars, and phenolic compounds present in the kernel.

• Nutrition Research and Practice
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• v.16 no.sup1
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• pp.21-36
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• 2022

BACKGROUND/OBJECTIVES: The long-term health impacts of dietary sugar have begun to be reported. The committee on the 2020 Dietary Reference Intakes for Koreans for sugar intended to update the scientific evidence on the association of added sugar intake with health outcomes, including mortality. This study evaluated the evidence on the association of dietary sugar with the all-cause and cardiovascular disease mortality from cohort studies. SUBJECTS/METHODS: The PubMed and ScienceDirect databases were searched until July 2021. The search terms were based on multiple combinations of keywords, such as added sugar, beverage, and mortality, included in the title or abstract. Two authors independently assessed the eligibility criteria of study selection and extracted the information from each selected article for this systematic review. RESULTS: The literature search identified 276 articles. Seventeen cohort studies met the inclusion criteria and were included in this systematic review. This study extracted information on the cohort and participants, dietary assessment methods, exposure and its comparison groups, health outcomes, and risk measures. Five articles reported added sugar intake, and 15 articles reported the food sources of the added sugar in the association with mortality. Increased mortality was observed in higher added sugar intake and a lower intake of less than 5% of energy, while higher discrepancies between gender, age groups, and countries were noted. In addition, nutritious sugary foods and beverages did not increase mortality. CONCLUSIONS: A 'U' or 'J' shaped relationship between the added sugar intake and mortality was estimated. The observed discrepancy indicated the need for more evidence to establish the dose-response relationship for Koreans.