• Food Science and Preservation
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• v.20 no.1
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• pp.88-96
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• 2013

This study was investigated to compare the major chemical components of kohlrabi (Brassica oleracea var. gongylodes) flesh and kohlrabi peel. Among the proximate compositions, the crude fat of kohlrabi peel contained lower than that of kohlrabi flesh, while the contents of carbohydrate and the crude protein were higher in the kohlrabi peel. Total free sugar content of the flesh kohlrabi was higher than that of the peeled kohlrabi, and the major free sugars of the flesh kohlrabi and peeled kohlrabi were identified as fructose and glucose. The value of glutamic acid was greater in amino acids of kohlrabi flesh and kohlrabi peel, and the contents of total amino acids and essential amino acids were higher in kohlrabi peel compared with kohlrabi flesh. Kohlrabi flesh also contained a higher level of unsaturated fatty acids than kohlrabi peel. The contents of organic acid were higher in kohlrabi peel, and the level of oxalic acid was the highest in both kohlrabi. The vitamin C contents of flesh kohlrabi and peeled kohlrabi were 231.36 mg/100 g and 402.75 mg/100 g, respectively. The mineral content of the peeled kohlrabi was higher than that of the flesh kohlrabi, and the mineral contents of the flesh and peeled kohlrabi were greater in the order of K>Ca>Mg>Na. As a result, the contents of total amino acid, essential amino acid, organic acid, vitamin C and mineral were higher in the peeled kohlrabi, and the free sugar and unsaturated fatty acid contents of the flesh kohlrabiwere higher.

• Horticultural Science & Technology
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• v.28 no.3
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• pp.469-475
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• 2010

The major deterring factor of radish consumption is bitter and pungent tastes caused by glucosinolates. Recently kohlrabi was introduced in Korea and mainly cultivated in Jeju Island during winter. Since the texture and taste of kohlrabi are similar to radish, the kohlrabi is expected to substitute radish. This study was done to compare compositional quality between kohlrabi and radish. The kohlrabi contained less reducing sugars, cellulose and pectin than the radish. The kohlrabi had harder texture than the radish. The total amino acid content in the kohlrabi was 2.7-fold higher than that in the radish. Especially hydrophilic amino acids including aspartate, glutamate and arginine, were about 3-fold higher in the kohlrabi, suggesting that the kohlrabi was more palatable than the radish. The total contents of glucosinolates in the radish in inner and outer section were higher than those in the kohlrabi by 12.4- and 28.5-fold, respectively. In a sensory test, the kohlrabi was evaluated less bitter and pungent than the radish. The kohlrabi contained more glucoraphanin, an anticancer compound, than the radish. Furthermore, the sweetness of the kohlrabi was evaluated higher than that of the radish, though kohlrabi contained less reducing sugars, probably due to high contents of hydrophilic amino acids. In conclusion, the kohlrabi was evaluated as more favorable in taste and contained more functional compounds than the radish, and thus it can be a good replacement vegetable for radish.

• The Korean Journal of Community Living Science
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• v.26 no.2
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• pp.405-414
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• 2015

This study examines the effects of purple Kohlrabi fresh and peel ethanol extracts on the antioxidative activity and antiproliferation of human cancer cells (Hep G2 human liver, HCT-116 human colon, and A549 human lung cancer cells.) The total flavonoid and anthocyanin content of purple Kohlrabi ethanol extracts were much greater in the peel than in the flesh. The DPPH radical scavenging activity and antioxidative index of purple Kohlrabi peel extracts were similar to those of the BHA and the BHT. Antiproliferation effects of purple Kohlrabi peel extracts on human cancer cells (Hep G2, HCT-116, and A549) strengthened in a dose-dependent manner. In particular, the antiproliferation activity of purple Kohlrabi peel extracts exceeded 40% in colon cancer cells. These results indicate that the purple Kohlrabi peel may contain bioactive compounds such as flavonoids as well as anthocyanin and that these compounds may facilitate cancer prevention.

• Journal of Animal Science and Technology
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• v.55 no.1
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• pp.19-23
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• 2013

The current study was carried out to determine the effects of Kohlrabi (Brassica oleracea var. gongylodes) on proliferation and differentiation of pig preadipocytes and $_3T_3-L_1$ cells. Pig preadipocytes were isolated from the backfat of the new-born pigs. Twenty-four hours after seeding, the cells were washed with DMEM/F-12 (designated day 0). To measure the cell proliferation, the cells were treated with 25 ng/ml and 100 ng/ml ethanol extracts of Kohlrabi (peel and flesh) for two days (day 0 ~ 2). To measure differentiation, the cells were treated with Kohlrabi for two days (day 0 ~ 2) and cell differentiation was measured on day 6. Twenty-five ng/ml and 100 ng/ml of Kohlrabi peel decreased proliferation of pig preadipocytes by 4.59% and 17.7%, respectively, compared with the control and Kohlrabi flesh by 11.4% and 19.2%, respectively. However, Kohlrabi did not inhibit cell differentiation. To measure the effects of Kohlrabi on proliferation and differentiation of $_3T_3-L_1$ cells, the cells were treated with Kohlrabi for two days in culture, like pig preadipocytes. Kohlrabi (both peel and flesh) did not show any effects on cell proliferation and differentiation. In summary, the results of the current study showed that Kohlrabi decreased proliferation of pig preadipocytes, but no inhibitory effects on differentiation of the cells. Kohlrabi had no effects on proliferation and differentiation of $_3T_3-L_1$ cells.

• The Korean Journal of Food And Nutrition
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• v.30 no.5
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• pp.935-942
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• 2017

In the present study, kohlrabi-kimchi was prepared for assessment of changes in sensory qualities and measurement of changes in quality characteristics according to the storage period for the purpose of using kohlrabi as an ingredient of Kimchi. Examination of the physicochemical properties of kohlrabi-kimchi according to the storage period showed that the acidity increased steadily throughout the storage period, while soluble-solids content, pH and hardness decreased as the storage period elapsed. Meanwhile, the L value increased and then it decreased as the storage period elapsed, but, the a value increased and the b value gradually decreased after day 14 of storage. Reducing sugars increased up to day 10 of storage, and then they decreased slowly after day 15 of storage. Measurement of changes in lactic acid bacteria in kohlrabi-kimchi according to the storage period showed bacterial growth showing typical tendencies of Kimchi with a rapid increase on day 5 of storage and a decrease thereafter. Assessment of sensory qualities of kohlrabi-kimchi according to the storage period showed that the highest scores for appearance and sourness, odor, texture, and overall scores were obtained on day 15 of storage. Based on the above results, it was determined that the optimal maturity period of kohlrabi-kimchi is day 15 of storage.

• Food Science and Preservation
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• v.21 no.5
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• pp.601-608
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• 2014

To determine the optimal shelf life for maintaining the high quality of kohlrabi, the changes in the physiological and secondary metabolites of kohlrabi stems during storage were investigated. The results showed that the kohlrabi maintained its marketable quality for two weeks at room temperature and for two months in cold storage ($4^{\circ}C$). Interestingly, the total phenol and flavonoid contents sharply declined along with the quality deterioration after two-week storage at room temperature. Moreover, insignificant changes in these compounds were observed for two months during the cold storage. The secondary metabolites of the kohlrabi were also influenced by its storage condition. The total phenol and total flavonoid contents of the kohlrabi significantly increased with the storage periods at low temperature, and significantly decreased with the storage periods at room temperature. In terms of the packaging, no significant difference in the total phenol content of the kohlrabi was found between the packaged and non-packaged types of storage. However, the flavonoid content of the packaged kohlrabi was higher than that of the non-packaged kohlrabi at the end of their storage. The content of glucosinolates, an anti-cancer ingredient was maintained during the storage, so the vegetables remained good sources of these compounds when stored in cold storage even for a long period. This study showed a close correlation between the secondary metabolites and the change in the quality of kohlrabi during storage. The results also suggested that secondary metabolites such as phenolics can be considered quality indicators of the shelf life of kohlrabi.

• Mycobiology
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• v.42 no.4
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• pp.409-411
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• 2014

In March 2014, a kohlrabi stem rot sample was collected from the cold storage room of Daegwallyong Horticultural Cooperative, Korea. White and fuzzy mycelial growth was observed on the stem, symptomatic of stem rot disease. The pathogen was isolated from the infected stem and cultured on potato dextrose agar for further fungal morphological observation and to confirm its pathogenicity, according to Koch's postulates. Morphological data, pathogenicity test results, and rDNA sequences of internal transcribed spacer regions (ITS 1 and 4) showed that the postharvest stem rot of kohlrabi was caused by Sclerotinia sclerotiorum. This is the first report of postharvest stem rot of kohlrabi in Korea.

• Food Science and Preservation
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• v.21 no.6
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• pp.824-830
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• 2014

In this study, the quality characteristics of cookies with added purple kohlrabi (Brassica oleracea var. gongylodes) powder were investigated and analyzed through chemical and sensory evaluation. Samples were prepared with different levels (0, 1, 3, and 5%) of freeze-dried kohlrabi powder. The addition of Kolarbi powder decreased the moisture and fat contents, but the ash content was significantly increased (p<0.05). The pH and density of the cookie dough decreased significantly with the increasing levels of kohlrabi powder added (p<0.05). The spread ratio of the cookies generally decreased as more kohlrabi powder was added, but the decrease was not statistically significant. The hardness of the cookies increased significantly, however, with the increasing levels of kohlrabi powder added (p<0.05). The Hunter's color L, a, and b values significantly decreased with increasing kohlrabi powder compared to those of the control (p<0.05). In the sensory evaluation, the cookies to which 3 and 5% kohlrabi powder were added showed remarkably higher values for color, taste and appearance. These results suggest that purple kohlrabi powder is a good ingredient for improving the sensory and quality characteristics of cookies.

• Preventive Nutrition and Food Science
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• v.19 no.4
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• pp.281-290
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• 2014

The aim of the present study was to evaluate the anti-diabetic, anti-inflammatory, antioxidant potential, and total phenolic content (TPC) of green and red kohlrabi cultivars. Anti-diabetic and anti-inflammatory activities were evaluated via protein tyrosine phosphatase (PTP1B) and rat lens aldose reductase inhibitory assays and cell-based lipopolysaccharide (LPS)-induced nitric oxide (NO) inhibitory assays in RAW 264.7 murine macrophages. In addition, scavenging assays using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical, and peroxynitrite ($ONOO^-$) were used to evaluate antioxidant potential and TPC was selected to assess phytochemical characteristics. Between the two kohlrabi cultivars, red kohlrabi (RK) had two times more TPC than green kohlrabi (GK) and showed significant antioxidant effects in DPPH, ABTS, and $ONOO^-$ scavenging assays. Likewise, methanol (MeOH) extracts of RK and GK inhibited LPS-induced NO production in a dose dependent manner that was further clarified by suppression of iNOS and COX-2 protein production. The MeOH extracts of RK and GK exhibited potent inhibitory activities against PTP1B with the corresponding $IC_{50}$ values of $207{\pm}3.48$ and $287{\pm}3.22{\mu}g/mL$, respectively. Interestingly, the RK MeOH extract exhibited significantly stronger anti-inflammatory, anti-diabetic, and antioxidant effects than that of GK MeOH extract. As a result, our study establishes that RK extract with a higher TPC might be useful as a potent anti-diabetic, antioxidant, and anti-inflammatory agent.

• Preventive Nutrition and Food Science
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• v.16 no.2
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• pp.189-193
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• 2011

Kohlrabi (Brassica oleracea var. gongylodes L.) slices were dehydrated with maltodextrin (MD) at concentrations of 20, 30, and 40% (w/w), and the dried samples were compared with the freeze-dried and hot-air dried samples regarding various physicochemical qualities. The MD-treated samples had better results than those of freeze-dried or hot-air dried samples in terms of rehydration ratio and color. The total phenolic content of the MD-treated sample was similar to that of the freeze-dried and higher than that of hot-air dried sample. The ascorbic acid content of the MD-treated samples was also higher than that of the hot-air dried one. These results suggest that kohlrabi can be dehydrated with MD instead of hot air.