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J Ethn Foods 3 (2016) 150e158

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Journal of Ethnic Foods

journal homepage: http://journalofethnicfoods.net

Original article Quality and functional characteristics of made with organically cultivated young Chinese (olgari-baechu)

* Su Jin Jung a, Min Jung Kim b, Soo Wan Chae a, c, a Clinical Trial Center for Functional Foods, Chonbuk National University Hospital, Jeonju, South b Korea Food Research Institute, Songnam, c Department of Pharmacology, Chonbuk National University, Medical School, Jeonju, South Korea article info abstract

Article history: Background: Recently, studies on nutritional and functional differences in agricultural products culti- Received 16 March 2016 vated by organic and conventional farming have been frequently reported. However, there are few Received in revised form studies on the physiochemical and sensory characteristics of kimchi made of organically cultivated young 3 April 2016 (olgari-baechu) according to agricultural differences. Accepted 27 April 2016 Methods: Different types of kimchi were produced using three different types of young Chinese cabbage: Available online 7 June 2016 young Chinese cabbage cultivated using the nature-friendly compost (YC-FNC) as a way of organic farming; young Chinese cabbage cultivated using commercially available organic compost (YC-GC); and Keywords: compost the general young Chinese cabbage cultivated using chemical fertilizers (YC-Control) as a way of con- kimchi ventional farming. Physiochemical, sensory, and functional characteristics of these types of kimchi were olgari-baechu compared and analyzed according to the passage of ripening. organic Results: In general nutritional ingredients according to agricultural differences, the YC-Control showed physiochemical high contents in moisture, crude , and crude fat. YC-FNC and YC-GC showed high contents in total dietary fibers, , and phytochemicals significantly (p < 0.01). In inorganic matter YC-FNC and YC- GC had high contents of P, Ca, Mg, and Fe and YC-Control had high contents of N, K, Cu, Mn, and Zn significantly (p < 0.01). YC-Control had a higher rate in approaching the optimum ripening period, pH 4.96, than YC-FNC and YC-GC. Then, it was verified that the ripening of YC-FNC and YC-GC is gradually processed. The total polyphenols and flavonoids contents in YC-FNC and YC-GC were twice as large as YC- Control. Also, it was verified that the contents of the total polyphenol and flavonoid are significantly increased during storage in the kimchi made of all young Chinese regardless of agricultural differences (p < 0.01). Lactic acid bacteria in the kimchi and in all were significantly increased according to the ripening period (p < 0.01). Kimchi made from organic young Chinese cabbage showed higher sensory characteristics and longer storage (p < 0.01) than that of the generally cultivated young Chinese cabbage. Conclusion: The storage periods of the organic young Chinese cabbage kimchi were extended compared to the general young Chinese cabbage kimchi processed by the conventional farming. Kimchi made of organic young Chinese cabbage is a possible functional food because it increases the sensory charac- teristics and tastes. In addition, it enables the intake of highly functional bioactive substances. © 2016, Published by Elsevier B.V. on behalf of Korea Food Research Institute. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

1. Introduction agrichemicals and improvements in cultivation techniques, this causes environmental pollution and leads to increases in anxieties Although agricultural productivity in recent years has been about the safety of agricultural products. Recently, consumers want greatly increased by increases in using chemical fertilizers and environmental protection and healthy foods; following social trends in pursuing health has led to sudden increases in the pro- duction and consumption of environmentally friendly agricultural * Corresponding author. Clinical Trial Center for Functional Foods, Chonbuk products [1]. The reason that consumers are interested in organic National University Hospital, 20 Geonjiro, Deokjin-gu, Jeonju-si, 561-712, South Korea. agricultural products is mainly due to environmental protection, E-mail address: [email protected] (S.W. Chae). improvements in livestock welfare, increases in tastes, and http://dx.doi.org/10.1016/j.jef.2016.05.003 2352-6181/© 2016, Published by Elsevier B.V. on behalf of Korea Food Research Institute. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/). S.J. Jung et al / Quality and functional characteristics of kimchi 151 advantages in health. However, controversial issues still exist on 2. Materials and methods whether agricultural products cultivated by organic farming include higher contents in healthy bioactive substances than con- 2.1. Materials and cultivation ventional farming [2e4] or not [5e7]. Also, studies on nutritional and functional differences in both organically and conventionally Cabbages (Chinese cabbage, B. pekinensis RUPR; olgari-baechu) cultivated agricultural products have been constantly reported for experiment were directly planted in a plastic greenhouse [8e17]. The nutritional ingredients and bioactive substances in (5 m 60 m) belonging to Agricultural Soyowon, Co., Ltd. located agricultural products can be varied according to geographic envi- in Jeongwon-Li, Imsil-eup, Imsil-gun, Jeonbuk. It was cultivated ronments, varieties and times of cultivation, soils, and fertilization for 2 months, from April 5 to June 4. The cabbages were divided strategies [18]. It was reported that the amount of accumulated into two groups; fertilization and control groups. The fertilization nitrate inside a plant increases as the amount of nitrogen fertil- group used two fertilizers for cultivating olgari-baechu organi- ization is increased [19]. Also, there were reports that the nitrate is cally; eco-developed fertilizer (livestock excreta reduced to nitrite in the intestines, which reacts with existing fertilizer, YC-FNC; CTCF2 Yoyo Korea Inc., Jeongeup, Korea) and amines in the body and produces nitrosamine, a carcinogen [20,21]. commercial organic compost (YC-GC; functional stevia fertilizer, However, this has still not been determined in clinical studies. Good livestock excreta high-grade fertilizer, Korean stevia; Jeongeup). meals for people have to present good tastes and different bioactive The control group (YC-Control) represents the general olgari- substances (phytochemicals) in addition to nutritional ingredients baechu cultivated using a chemical fertilizer (No. 14, Dongbu Farm such as vitamins and inorganic matter. The reason that the phyto- Hannong, Seoul, Korea) in which three different fertilizers were chemicals have been highlighted in recent years is due to its various prescribed. The fertilizer prescription followed the standard bioactive functions such as antioxidant, anticancer, anti- proposed by the National Academy of Agricultural Science (Good inflammatory, and detoxification. Baechu (Chinese cabbage; Bras- Agricultural Practices program; National Academy of Agricultural sica campestris L. ssp. pekinensis) is one of the most consumed Science 2010 [36]). The eco-developed fertilizer (YC-FNC) treated vegetables in Korea and is used as a major ingredient of kimchi [22]. group was processed by mixing the eco-developed fertilizer Baechu is classified as spring-baechu, summer-baechu, or autumn- (560 kg/10a) with the mixed organic fertilizer (150 kg/10a, Green baechu according to its cultivation season. Also, it is divided into soil N-P-K 4-1-30; Biogreentech Inc., Kyoungki, Korea). The three different types, kyolku, semi-kyolku, and non-kyolku, in which organic compost treated group (YC-GC) was processed by 560 kg/ the kyolku shows a closely packed baechu head. Kimjang kimchi is 10a, and the control group with the chemical fertilizer (YC-Con- usually made of the kyolku baechu, and the spring and summer trol) was processed by the basal fertilizer (urea, 12 kg/10a; kimchis are made of the semi-kyolku spring cabbage (bomdaong phosphatic fertilizer, 18 kg/10a; and potassium chloride, 12 kg/ baechu) and olgari-baechu [23], respectively. The characteristics of 10a) þ additional fertilizer (urea, 42 kg/10a; potassium chloride, the ingredient of cabbages represent high nutritional values due to 18 kg/10a). These fertilizers were applied to the cultivation for 2 its high contents of vitamin C, inorganic matter (Ca, K, Fe, P, etc.), months (Fig. 1). and dietary fibers. Also, it includes a large amount of functional phytochemicals such as benzyl isothiocyanate, indoles, thiocya- 2.2. Nutritional composition analysis nates, and sitosterols [24,25]. Lactobacilli in kimchi produce organic acids and fermentation products using sugars in baechu through a 2.2.1. Proximate analysis fermentation process. Also, the kimchi inhibits the proliferation of The samples were fabricated by cutting the olgari-baechu with a harmful by producing antibiotics, such as bacteriocin, and size of 3 cm 3cm(Fig. 1) after removing foreign materials. The increase functional compounds through generating unique flavors cuts were then packed in a plastic bag and lyophilized (IlShin and piquancy [26]. In particular, it has been reported that various Biobase, Korea) and pulverized (Hanil, Incheon, Korea). A proximate phytochemicals, such as vitamins, chlorophylls, flavonoids, and analysis was implemented by the AOAC method [37]. The moisture polyphenols, included in both the staple ingredient, baechu, and the content was determined using an air-oven heating method at subingredients, such as red pepper powder, , and , and 105C; the content of crude proteins was determined using the different compounds generated by during the Micro Kjeldahl method; the content of crude fats was determined ripening process of the kimchi [23] represent different effects such using an ether extraction method; the content of crude ashes was as anticancer and reverse mutation [27,28], antioxidant [29], anti- determined using a dry ashing method; and the content of crude atherogenic [30], antidiabetic [31], antiaging [32], and fibrinolytics dietary fibers was determined using the Prosky method [37]. [33]. Studies on improving the storage, quality difference [34], and functionality of kimchis have been conducted in different ways. It is 2.2.2. Determination of mineral compositions known that different health functionalities are presented according The contents of the main (P, K, Ca, and Mg) and trace (Fe, Zn, and to ingredients used in kimchis. Although some reports on both the Mn) minerals were determined in the freeze-dried sprouts sam- differences in nutritional and functional ingredients [35] and the ples. Briefly, 1 g was refluxed in a digestion system (Velp DK 42P) quality characteristics of olgari-baechu kimchis have been pre- for 2 hours with 6 mL of 65% HNO3 under different temperatures sented, there are few comparative studies on the quality and sen- (30 minutes at 50C; 30 minutes at 80C; 30 minutes at 150C; and sory characteristics of the olgari-baechu kimchi according to 30 minutes at 165 C) and for 3 hours with 4 mL of 70% HClO4 (30 agricultural practices. As the production and consumption of safe minutes at 165C; 60 minutes at 180C; 60 minutes at 190C; and foods has emerged as an important issue under the idea of health 30 minutes at 200C). After cooling, 10 mL of ultrapure water was and environmental protection, it is important and is required to added to each sample, which was left to stand for 60 minutes at analyze and determine the differences in the quality and sensory 120C. Final volumes were adjusted to 50 mL with ultrapure water. characteristics of environmentally friendly agricultural products. K, Ca, Mg, Fe, Zn, and Se were determined in the digested solutions Thus, in this study the physiochemical and sensory characteris- by flame-atomic absorption spectrometry (Analyst 200; Perkin tics of the kimchis made of organically and conventionally cultivated Elmer Waltham, MA, USA), while P content was determined ac- olgari-baechu were investigated, while the kimchis were stored for cording to the 4500-P B. The vitamin C composition was analyzed over 24 days in order to determine the effects of cultivation methods using the ascorbic acid standard method [38] in a UV/VIS spectro- on the quality and sensory characteristics of these kimchis. photometer at 670 nm. 152 J Ethn Foods 2016; 3: 150e158

Fig. 1. Three different types of young Chinese cabbage and Olgari-baechu kimchi cultivated using different of fertilizers.

2.3. Preparation and fermentation of kimchi 2.4. pH and acidity

The subingredients used to produce kimchi, such as red pepper, Each kimchi sample (100 g) was crushed (MR 4050 CA) for 3 garlic, ginger, leek, and glutinous rice flour, were purchased from a minutes and was diluted five times using 10 g of distilled water. large discount store on the day prior to preparation. The compo- Then, the pH of the kimchi samples was measured (PP-15; Sartorius sition ratios of the ingredients used in the kimchis are presented in Co., Elk Grove Village, IL, USA) and the titratable acidity was deter- Table 1. The first process of producing the kimchis was selecting mined by titrating with 0.1N NaOH to an end point of pH 8.3 [37]. fresh olgari-baechu with similar size and shape and then washing þ the whole body (stem leaf). Then, the washed olgari-baechu was 2.5. Reducing sugar contents preserved with a 7% sun-dried salt solution (80e90% of NaCl, Sinan sun-dried salt; Sinan-gun, Korea) for 1 hour. The next process is The reducing sugar content in kimchi was measured by Yang washing the preserved olgari-baechu three times and dewatering it et al's [39] colorimetry using dinitrosalicylic acid. Dinitrosalicylic for 30 minutes before applying the kimchi producing process. Garlic acid reagent was added to the dilute solution of kimchi, the mixture and ginger were prepared by cleaning and crushing (MR 4050 CA; was stirred thoroughly, left 5 minutes for reaction, and cooled Braun, Madrid, Spain). In the production process of the olgari- down. For the solution with developed color, we measured absor- baechu kimchis, the composition ratios of the ingredients were bance at 546 nm (UV-1,650PC; Shimadzu Co., Kyoto, Japan) and determined as follows: the preserved olgari-baechu, 100 g, was converted the result into glucose concentration for presentation. mixed with 3.7 g of garlic, 1.5 g of ginger, 5.1 g of green onion, 4.8 g of red pepper powder, 6.2 g of liquid salted anchovy (Daesang Co., Ltd.), and 80 g of starch (glutinous rice:water ¼ 1:9) [34]. The 2.6. Microbiological analysis kimchis were stored at 5C for 24 days. The experiments were implemented using the stored kimchi samples with a specific The total number of bacteria was measured using 10 g of the storage of 0 days (the day of storage), 7 days, and 24 days. kimchi sample; 90 mL of 0.1% sterilized peptone water was added to the sample and the mixture was homogenized using a bag mixer (400 Model W STOMACHER; Korea Scientific Co., Daejeon, Korea) Table 1 Ingredients in olgari-baechu kimchi. and the supernatant diluted with 0.1% peptone. The viable bacteria were counted using MRS and phenylethanol agars (Difco; Becton, Ingredients Weight (g) Dickinson and Company, Franklin Lakes, NJ, USA) with 2% sucrose Young Chinese cabbage 100 (PES [39]). Each sample was serially diluted with 0.85% (w/v) Garlic 3.7 physiological saline. The total number of bacteria was Ginger 1.5 Red pepper powder 4.8 determined by spread-plating onto the MRS agar and incubating at Green onion 5.1 371 C for 48 hours, and the Leuconostoc genus population was Anchovy juice 6.2 counted by spread-plating onto the PES agar after incubation at Thick salt d 20C for 48 hours [13]. In counting the number of lactobacilli, the Glutinous rice 8.0 number of colonies was counted (colony-forming units/mL) by S.J. Jung et al / Quality and functional characteristics of kimchi 153 incubating the sample at 37 ± 1C for 48 hours after solidifying it 3. Results using MRS agar (Lactobacilli MRS agar; Becton, Dickinson and Company) with a 0.05% BCP indicator and overlapping PCA agars in 3.1. Proximate and nutrients contents order to avoid diffusion colonies. The results of the analyses of general nutritional contents in the 2.7. Total polyphenol and flavonoid contents organic olgari-baechu (YC-FNC, YC-GC) and the control group, general olgari-baechu (YC-Control: chemical fertilizer), are pre- 2.7.1. Sample preprocessing sented in Table 2. The YC-Control represents high contents of A microwave sample extraction device (Mars; CEM, Matthews, moisture, crude fat, and crude protein and YC-FNC and YC-GC had NC, USA) was used to prepare the sample by mixing 10 g of each high contents of total dietary fibers and vitamin C. In the case of sample with 50 mL of 70% methanol was added to the sample. The inorganic matters, P, Ca, Mg, and Fe, YC-FNC and YC-GC showed extraction was implemented at 90C for 1 hour and 100 mL of each higher contents than YC-Control. YC-Control had significant extraction was applied to the experiment. (p < 0.01) N, K, Cu, Mn, and Zn contents compared to YC-FNC and YC-GC. 2.7.2. Total polyphenol assay The total polyphenol contents of the sample were measured using 3.2. Correlation between the physiochemical characteristics of the e the Folin Denis method [40]. That is, the sample solution, 0.1 mL, was test cultivation soil and the cabbage after harvesting mixed with 6 mL of distilled water and 0.5 mL of the FolineDenis reagent and the mixture was laid at room temperature for 3 minutes. The results of the analyses of the correlation between the Then, a saturated Na2CO3 solution of 1.5 mL was added to the mixture. physiochemical characteristics of the test cultivation soil and the The sample was then laid at room temperature for 1 hour and the cabbage after harvesting are presented in Table 3. The correlation absorbance was measured at 765 nm (UV 1,601; Shimadzu) with gallic between the pH value in the test cultivation soil and the moisture e acid (Sigma Aldrich Co., St Louis, MO, USA) as a standard solution. (p < 0.049) and crude protein (p < 0.031) showed a negative figure but the correlation between the vitamin C content (p < 0.032) and fl 2.7.3. Total avonoid assay the total polyphenol content (p < 0.025) represented a positive The analysis of the total flavonoid contents was performed on figure. Also, the correlation between the P2O5 content of phos- 10 g of the kimchi sample by adding 20 mL of 90% ethanol. Then, it phoric acid in the soil and the K (p < 0.009) and crude fiber was centrifuged at 3,000 rpm for 10 minutes and the supernatant (p < 0.017) contents of the cabbage showed a positive figure. The collected. Three more extractions were implemented three times correlation between the K content in the soil and the moisture and by adding 8 mL of 80% ethanol to the residue. The total mixture was protein contents of the cabbage showed a positive figure but the made up to 50 mL by missing the previous extracts with 80% of correlation between the vitamin C content (p < 0.026) and the total ethanol and was kept at room temperature for 40 minutes. Then, polyphenol (p < 0.031) content showed a negative figure. the absorbance was measured at 415 nm with quercetin (Sigma- eAldrich Co.) used as reference [41]. 3.3. pH and acidity 2.8. Sensory characteristics Changes in the acidity and pH according to storage periods in the kimchi made of olgari-baechu cultivated by varying fertilizer The produced kimchis were stored at 5C in a refrigerator and prescriptions are presented in Table 4. The pH in all types of olgari- evaluations of the kimchis were performed at 0 days (the day of baechu kimchi was 5.51 on the day of preparing the kimchi. The pH storage), 7 days, and 24 days after storage. In the sensory evaluation, values after 7 days and 24 days of storage were 5.0 and 4.5, the kimchi sample was prepared with about 15 g in a dish for each test respectively. There was a tendency of the pH value to decrease group. A deep breath of the odor was taken for 4e5 seconds for significantly according to the length of time of storage (p < 0.001). appreciating it and the taste and texture were evaluated by chewing The acidity on Day 0 was about 0.29e0.30% and the values after 7 the sample without swallowing it. To avoid the effects of residual days and 24 days of storage were 0.32e0.36 and 0.36e0.40%, tastes on other kimchi samples, some boiled rice and water were respectively. The acidity increased significantly according to provided to the evaluator. The sensory evaluation was performed by ripening period (p < 0.001). appearance. The odor evaluation consisted of four items: acidic odor, moldy odor, fresh cabbage odor, and fresh acidic odor. The taste evaluation consisted of acidic taste, moldy taste, and fresh acidic odor 3.4. Reducing sugar and fresh sourness taste. The texture evaluation consisted of fracture ability and chewiness. Then, the general taste was also evaluated. The Changes in reducing sugars of the olgari-baechu kimchi during fi levels for each evaluation were presented by a 5-point rating scale (5, storage are presented in Fig 2. There were no signi cant differences very good; 4, good; 3, acceptable; 2, poor; and 1, very poor). in reducing sugar contents between YC-Control and YC-FNC and YC-GC kimchi groups. Also, the reducing sugar contents were < 2.9. Statistical analysis generally decreased after 24 days of storage (p 0.002) compared to the early stage of the storage. Data obtained from the study are presented as mean ± standard deviation and the differences between samples and growth con- 3.5. Microbiological aspects ditions were tested by one-way analysis of variance followed by post hoc Duncan's multiple range comparison tests, using SPSS Changes in the total number of and other bacteria version 18.0 software (SPSS Inc., Chicago, IL, USA) for Windows. in the olgari-baechu kimchi according to storage periods are pre- Statistical significance was defined as p < 0.05. The correlation sented in Table 5. The total number of Lactobacillus sp. in both YC- between the physiochemical characteristics of the test cultivation FNC and YC-GC kimchi and YC-Control kimchi started to increase soil and the olgari-baechu after harvesting was verified using after 7 days and was further increased after 24 days significantly Pearson's correlation coefficient. compared to that of Day 0 (p < 0.001). 154 J Ethn Foods 2016; 3: 150e158

Table 2 Proximate composition, mineral and vitamin contents of olgari-baechu kimchi.

Samples Nutrients (g/100 g)

Moisture Protein Ash Fiber Vitamin C

* YC-Control 17.3 ± 0.5b 2.33 ± 0.1c 17.9 ± 0.4b 14.8 ± 0.4a 31.3 ± 0.4a 19.3 ± 0.9a y YC-FNC 8.08 ± 0.1a 1.70 ± 0.1b 11.8 ± 0.1a 15.0 ± 0.3a 36.7 ± 1.7b 350.2 ± 1.7b z YC-GC 7.50 ± 0.5a 1.45 ± 0.1a 12.1 ± 0.1a 16.7 ± 0.5b 40.5 ± 1.3c 377.7 ± 13.1c p 0.001 0.001 0.001 0.023 0.004 0.001

Samples Minerals (mg/100 g)

NP K CaMgCuFeMnZn

* YC-Control 23.3 ± 0.1c 4.7 ± 0.3a 44.3 ± 0.01b 1.5 ± 0.57a 1.7 ± 0.01a 2.8 ± 0.1b 8.2 ± 0.1a 64.3 ± 0.2c 33.9 ± 0.6b YC-FNCy 19.2 ± 0.2b 6.1 ± 0.1b 30.2 ± 0.01a 2.1 ± 0.01b 1.9 ± 0.01b 2.4 ± 0.02a 23.5 ± 0.7c 25.3 ± 0.02b 27.7 ± 0.6a z YC-GC 15.0 ± 0.2a 7.2 ± 0.5c 36.5 ± 0.06a 2.1 ± 0.02b 1.9 ± 0.01b 2.4 ± 0.01a 15.9 ± 2.3b 15.8 ± 0.01a 27.9 ± 0.3a p 0.001 0.003 0.001 0.001 0.03 0.001 0.004 0.001 0.001

YC-Control, young Chinese cabbage commonly cultivated using chemical fertilizers; YC-FNC, young Chinese cabbage commonly cultivated using nature friendly composts; YC- GC, young Chinese cabbage commonly cultivated using general composts. * Young-Chinese cabbage commonly cultivated using chemical fertilizers. y Young-Chinese cabbage commonly cultivated using nature friendly composts. z Young-Chinese cabbage commonly cultivated using general composts. a-c Mean in the bars are significantly different at p <0.05 by Duncan's multiple range test.

Table 3 Correlation coefficients between physical properties of soil after harvesting that affects the composition of olgari-baechu.

Soil

þ 2þ 2þ pH Total N P2O5 K Ca Mg y pH (soil) 1 0.866 (0.333) 0.919 (0.257) 1.000 (0.006) 0.494 (0.671) 0.958 (0.186) Young Chinese cabbage N 0.867 (0.332) 0.502 (0.665) 0.993 (0.075) 0.872 (0.326) 0.861 (0.339) 0.974 (0.146) y P 0.913 (0.267) 0.588 (0.600) 1.000 (0.009) 0.917 (0.261) 0.805 (0.404) 0.992 (0.081) K 0.335 (0.783) 0.761 (0.499) 0.063 (0.960) 0.326 (0.789) 0.654 (0.546) 0.050 (0.968) * Ca 0.963 (0.174) 0.698 (0.508) 0.992 (0.083) 0.965 (0.168) 0.711 (0.497) 1.000 (0.011) Mg 0.778 (0.433) 0.359 (0.766) 0.962 (0.175) 0.784 (0.427) 0.931 (0.238) 0.926 (0.247) Cu 0.305 (0.802) 0.771 (0.440) 0.963 (0.175) 0.184 (0.882) 0.969 (0.160) 0.197 (0.874) * * Moisture 0.997 (0.049) 0.825 (0.382) 0.947 (0.208) 0.998 (0.043) 0.559 (0.622) 0.977 (0.137) * Lipid 0.970 (0.156) 0.718 (0.490) 0.987 (0.101) 0.972 (0.150) 0.691 (0.515) 0.999 (0.029) * * Protein 0.999 (0.031) 0.889 (0.303) 0.899 (0.288) 0.998 (0.037) 0.452 (0.702) 0.943 (0.216) Ash 0.587 (0.601) 0.104 (0.934) 0.858 (0.343) 0.595 (0.595) 0.994 (0.071) 0.795 (0.415) * Fiber 0.909 (0.274) 0.579 (0.607) 1.000 (0.017) 0.913 (0.268) 0.811 (0.397) 0.990 (0.088) * * Vitamin C 0.999 (0.032) 0.840 (0.365) 0.938 (0.226) 0.999 (0.026) 0.537 (0.639) 0.971 (0.154) * * Total polyphenol 0.999 (0.025) 0.885 (0.308) 0.903 (0.282) 0.999 (0.031) 0.459 (0.696) 0.946 (0.211) Total flavonoid 0.627 (0.568) 0.154 (0.902) 0.883 (0.311) 0.635 (0.562) 0.987 (0.103) 0.825 (0.383)

Significance as determined by Pearson's correlation coefficient. * p < 0.05. y p < 0.01.

Table 4 Changes in pH and acidity (% citric acid) of the Olgari Baechu kimchi with fermen- tation time.

Sample Fermentation time (d) p

0724

* pH YC-Control 5.51 ± 0.3c 4.96 ± 0.04b 4.30 ± 0.03a 0.001 y YC-FNC 5.31 ± 0.03c 5.07 ± 0.02b 4.48 ± 0.04a 0.001 z YC-GC 5.58 ± 0.03c 5.09 ± 0.01b 4.67 ± 0.02a 0.001 * Acidity YC-Control 0.31 ± 0.03a 0.36 ± 0.01b 0.62 ± 0.02c 0.001 y YC-FNC 0.29 ± 0.03a 0.34 ± 0.01b 0.37 ± 0.01c 0.001 z YC-GC 0.28 ± 0.02a 0.35 ± 0.01b 0.38 ± 0.02c 0.001

YC-Control, young Chinese cabbage commonly cultivated using chemical fertilizers; YC-FNC, young Chinese cabbage commonly cultivated using nature friendly com- posts; YC-GC, young Chinese cabbage commonly cultivated using general composts. * Young-Chinese cabbage commonly cultivated using chemical fertilizers. y Young-Chinese cabbage commonly cultivated using nature friendly composts. Fig. 2. Changes in reducing sugar contents of baechu kimchi during its fermentation at z Young-Chinese cabbage commonly cultivated using general composts. 5C for 24 days. YC-Control, young Chinese cabbage commonly cultivated using chemical a-c Mean in the bars are significantly different at p <0.05 by Duncan's multiple fertilizers; YC-FNC, young Chinese cabbage commonly cultivated using nature friendly range test. composts; YC-GC, young Chinese cabbage commonly cultivated using general composts. S.J. Jung et al / Quality and functional characteristics of kimchi 155

Table 5 Table 7 Counts of total microbial and total of olgari-baechu kimchi with Sensory score of olgari-baechu kimchi during fermentation at 5C. fermentation time (colony-forming units/g).* Attributes Samples Fermentation time (d) p Sample Fermentation time (d) p 0724

0724 * External appearance A 3.40 ± 0.75 3.65 ± 0.74 3.30 ± 0.57 0.269 * y Lactic acid YC-Control 6.81 ± 0.26a 6.90 ± 0.03a 7.92 ± 0.08b 0.001 B 3.05 ± 0.76 2.95 ± 0.69 3.40 ± 0.75 0.135 y z bacteria YC-FNC 6.33 ± 0.11a 6.53 ± 0.03b 7.98 ± 0.03b 0.001 C 3.10 ± 0.55 2.85 ± 0.67 3.20 ± 0.89 0.296 z YC-GC 6.98 ± 0.01a 7.69 ± 0.05b 8.26 ± 0.06b 0.001 Odor A 2.10 ± 1.21a 3.65 ± 0.75b 3.25 ± 0.55b 0.001 * Total bacteria YC-Control 7.21 ± 0.02a 7.53 ± 0.07b 7.75 ± 0.07c 0.001 Acidic odor B 2.35 ± 1.14a 2.95 ± 0.69b 3.45 ± 0.83b 0.001 y YC-FNC 6.51 ± 0.03a 7.79 ± 0.15b 7.89 ± 0.07b 0.001 C 2.20 ± 1.00a 2.85 ± 0.67b 3.20 ± 0.89b 0.002 z YC-GC 7.40 ± 0.03a 7.94 ± 0.15b 7.83 ± 0.03b 0.001 Moldy odor A 1.85 ± 1.22a 2.85 ± 1.04b 3.25 ± 0.87b 0.004 B 1.65 ± 0.75a 2.10 ± 0.97a 2.80 ± 1.24b 0.003 YC-Control, young Chinese cabbage commonly cultivated using chemical fertilizers; C 1.80 ± 0.83a 2.35 ± 0.93a 2.90 ± 0.89b 0.001 YC-FNC, young Chinese cabbage commonly cultivated using nature friendly com- Fresh cabbage odor A 3.05 ± 1.05b 2.00 ± 1.02a 2.32 ± 0.97a 0.008 posts; YC-GC, young Chinese cabbage commonly cultivated using general composts. b b a * B 3.10 ± 0.87 2.81 ± 1.17 2.54 ± 0.98 0.005 Young-Chinese cabbage commonly cultivated using chemical fertilizers. b b a y C 3.25 ± 1.01 2.80 ± 1.13 2.50 ± 0.95 0.006 Young-Chinese cabbage commonly cultivated using nature friendly composts. a b b z Fresh acidic odor A 2.25 ± 1.20 3.00 ± 0.80 3.10 ± 0.91 0.016 Young-Chinese cabbage commonly cultivated using general composts. B 2.60 ± 1.23 2.70 ± 0.77 2.55 ± 0.89 0.332 a-c Mean in the bars are significantly different at p <0.05 by Duncan's multiple C 2.42 ± 1.01 2.81 ± 0.96 2.50 ± 1.00 0.079 range test. Taste A 2.00 ± 1.03a 2.80 ± 1.10b 2.90 ± 1.02b 0.017 B 2.20 ± 1.15 2.45 ± 0.99 2.80 ± 1.01 0.204 Table 6 Acidic taste C 2.30 ± 1.26 2.25 ± 1.07 2.90 ± 0.78 0.106 Changes in the total polyphenol and flavonoid contents of the olgari-baechu kimchi Moldy taste A 1.95 ± 1.01a 2.90 ± 0.91b 3.55 ± 0.69c 0.001 with fermentation time.* B 1.65 ± 0.93a 2.25 ± 0.97a 2.95 ± 1.01b 0.001 a a b Sample Fermentation time (d) p C 1.85 ± 1.14 2.20 ± 1.13 2.90 ± 1.08 0.048 Fresh cabbage taste A 3.25 ± 1.20b 3.10 ± 1.07a 2.35 ± 0.75a 0.002 0724 B 3.55 ± 1.15b 3.15 ± 0.99b 2.50 ± 1.00a 0.001 * b b a Total polyphenol YC-Control 57.9 ± 2.50a 78.8 ± 4.05b 81.0 ± 2.74b 0.038 C 3.40 ± 1.04 3.20 ± 1.02 2.40 ± 1.02 0.001 y a b c (mg/ GAE/100g YC-FNC 83.2 ± 1.37a 88.8 ± 1.41b 102.5 ± 0.89c 0.001 Fresh sourness taste A 2.05 ± 1.09 2.80 ± 1.05 3.90 ± 0.85 0.014 z a a b extract) YC-GC 63.2 ± 2.11a 85.0 ± 0.13b 98.2 ± 0.13c 0.001 B 2.15 ± 1.30 2.50 ± 0.94 3.10 ± 0.64 0.015 * a a b Total flavonoid YC-Control 4.1 ± 0.17a 8.5 ± 1.21b 11.7 ± 0.59c 0.001 C 2.06 ± 1.05 2.35 ± 1.13 3.12 ± 0.88 0.001 y (mg/ QE/g YC-FNC 6.5 ± 1.85a 9.5 ± 1.69b 12.6 ± 1.16b 0.001 Texture fracturability A 2.80 ± 1.01 2.45 ± 1.19 2.95 ± 0.83 0.300 z extract) YC-GC 5.2 ± 0.28a 8.7 ± 0.65b 11.9 ± 1.24c 0.001 B 2.95 ± 0.69 2.65 ± 0.96 2.85 ± 1.02 0.132 C 3.00 ± 0.92 2.85 ± 1.16 3.01 ± 0.85 0.129 YC-Control, young Chinese cabbage commonly cultivated using chemical fertilizers; Chewiness A 3.70 ± 1.03 3.21 ± 0.98 3.10 ± 1.21 0.184 YC-FNC, young Chinese cabbage commonly cultivated using nature friendly com- B 3.75 ± 0.99 3.15 ± 1.01 2.95 ± 0.75 0.086 posts; YC-GC, young Chinese cabbage commonly cultivated using general composts. ± ± ± * C 3.60 0.86 3.16 1.02 3.02 0.99 0.082 Young-Chinese cabbage commonly cultivated using chemical fertilizers. ± ± ± y Total acceptance A 2.56 0.94 2.95 0.69 3.05 0.89 0.151 Young-Chinese cabbage commonly cultivated using nature friendly composts. ± a ± b ± c z B 2.60 0.68 3.40 0.85 3.58 0.55 0.003 Young-Chinese cabbage commonly cultivated using general composts. C 2.70 ± 1.02a 3.55 ± 0.69b 3.56 ± 0.43c 0.038 a-c Mean in the bars are significantly different at p <0.05 by Duncan's multiple range test. Data are presented as mean ± standard deviation (n ¼ 20). A, young Chinese cabbage commonly cultivated using chemical fertilizers; B, young Chinese cabbage commonly cultivated using nature friendly composts; C, young 3.6. Total polyphenol and flavonoid Chinese cabbage commonly cultivated using general composts. * Young-Chinese cabbage commonly cultivated using chemical fertilizers. y fl Young-Chinese cabbage commonly cultivated using nature friendly composts. The total polyphenol and avonoid contents in the olgari-baechu z Young-Chinese cabbage commonly cultivated using general composts. kimchis during storage are presented in Table 6. The total polyphenol a-c Mean in the bars are significantly different at p <0.05 by Duncan's multiple < content in YC-Control kimchi (p 0.038) was decreased from 57.9 mg range test. on Day 0 to 81.0 mg on Day 24. Over the same time, the total flavo- noid content (p < 0.001) increased from 4.1 mg to 11.7 mg. In the case GC kimchis showed improvement in overall appearance during of YC-FNC and YC-GC kimchi, the total polyphenol and flavonoid storage periods compared to YC-Control kimchi (p < 0.05). contents were significantly increased (p < 0.001) according to in- creases in storage periods and the bioactive substance contents 4. Discussion increased more according to fermentation. In this study, the nature-friendly compost-based olgari-baechu (YC-FNC) kimchi, the two types of organic compost-based olgari- 3.7. Sensory characteristics baechu (YC-GC) kimchi, and the conventional farming (chemical fertilizers)-based general olgari-baechu (YC-Control) kimchi were The results of the sensory evaluation, such as external appear- produced by varying agricultural applications and these different ance, odor, taste, fractural taste (texture), and total appearance, kimchis were stored at 5C. Then, the quality, sensory, and func- during its storage periods in the olgari-baechu kimchis produced by tional characteristics of the kimchis were analyzed according to varying agricultural applications are presented in Table 7. The storage periods; 0 days, 7 days, and 24 days. YC-Control showed olgari-baechu kimchi generally represented decreases in fresh cab- high contents of moisture, crude protein, and crude fat and YC-FNC bage odor and fresh cabbage taste according to passage of storage and YC-GC had high contents of dietary fiber, vitamin C, and total compared to the days just after producing it and acidic odor, moldy bioactive substances. Seong et al [35] showed similar results that odor, moldy taste, and fresh sourness taste were significantly organic cabbage represent lower moisture contents than general increased (p < 0.01). YC-Control kimchi showed increases in moldy cabbage and show 1.5 times higher total dietary fiber content than odor (p < 0.004) and moldy taste (p < 0.001), and fresh sourness general cabbage (2.0% of organic cabbage vs. 1.1% of general cab- taste (p < 0.014) after 7 days from the storage compared to YC-FNC bage). Also, organic cabbage have 2.5 times higher vitamin C con- and YC-GC kimchis but represented decreases in fresh cabbage odor tent than general cabbage (47.4 mg of organic cabbage vs.19.2 mg of (p < 0.008) and fresh acidic odor (p < 0.002). Also, YC-FNC and YC- general cabbage). In this study, it was verified that YC-FNC and YC- 156 J Ethn Foods 2016; 3: 150e158

GC had about 18 times higher vitamin C contents than YC-Control. fermentation process are varied according to ingredients of sub- Vitamin C is usually biosynthesized to react as plants are exposed to materials, storage temperature, storage salinity, etc. [4,34]. The environmental stress. It is known that such vitamin C has various reducing sugar in the Salicornia herbacea powder added young functionalities such as antioxidant and anticancer activity [42e44]. radish water kimchi showed the maximum value after 13 days from YC-Control had higher contents of N, K, Cu, Mn, and Zn than YC-FNC its fermentation and then the value is decreased [49]. In this study and YC-GC but YC-FNC and YC-GC had higher contents of P, Ca, Mg, the reducing sugar content in the olgari-baechu kimchi approaches and Fe. There was a large difference in the inorganic nutritional its optimum ripening time after 7 days from the fermentation and contents of the kyolku baechu [35] according to agricultural differ- is significantly decreased after 24 days from the fermentation. This ences in which organic cabbages had higher contents of Ca, P, Fe, shows that the reducing sugar contents vary according to materials Mg, S, and Zn than general cabbages (cultivated using organically used in kimchis. synthesized agrichemicals and chemical fertilizers) except for K It was verified that changes in the total number of bacteria in YC- compared to this study. The difference in inorganic nutritional FNC and YC-GC kimchis approached the maximum value after 7 days contents in this study is not only because of the subject of non- of fermentation and the value was maintained after 24 days from the kyolku baechu, but due to the production method that the general fermentation. YR-Control showed increases in the total number of olgari-baechu is cultivated by prescribing chemical fertilizers only bacteria in the initial stage (Day 0) of the fermentation and showed while the cultivation is implemented without using agrichemicals. decreases in the level after 24 days of fermentation. This shows that In general, factors influenced by the nutritional and functional tendencies in changing the total number of bacteria are different contents in agricultural products can be varied according to culti- according to agricultural applications. The number of microbes is vation environments and fertilization conditions [17]. In the results rapidly increased according to processes of the fermentation in of the investigation of the relationship between the test cultivation kimchis. Then, as the number of lactobacilli approaches its maximum soil and the general ingredients in olgari-baechu after harvesting it, level, it represents the unique tastes of piquancy and aroma in kim- there was a positive relationship between the pH value in the soil chis. As the kimchi approaches its optimum ripening time, the and the moisture and protein contents. Also, the relationship be- number of Leuconostoc mesenteroides approaches its maximum value tween the pH value in the soil and the vitamin C and total poly- and the number of , which causes acidifica- phenol contents in cabbages showed a positive figure. This shows tion, is increased as the time of decreasing the number of microor- that the vitamin C and total polyphenol contents were relatively ganisms, L. mesenteroides [45]. YC-FNC and YC-GC kimchis had very low according to increases in the K content. It is considered that high contents of bioactive substances compared to YR-Control differences are caused by organic matters of P, K, and N, which are kimchi: the total polyphenol and flavonoid contents were about externally provided from the prescription of chemical fertilizers in 1.3e2 times higher than YR-Control from the initial stage (Day 0) of conventional farming. Also, this is due to the fact that the growing its fermentation and were slightly increased during fermentation. In conditions in plants are rapidly changed and there are few chances the fermentation process of kimchis, lactobacilli generate organic of biosynthesizing bioactive substances because of decreasing acids and fermentation products through the sugar included in exposure frequencies to environmental stresses caused by patho- cabbages and that increases tastes and healthy functionalities. In genic attacks such as damage from disease and harmful insects. addition, fermentation creates antibiotics such as bacteriocin for In general, decreases in pH during the fermentation process of inhibiting harmful bacteria, which represents unique flavors in kimchis are because of different organic acids generated by the kimchis. Factors in increasing bioactive substances of kimchis are interaction between various enzymes included in raw materials different according to materials, fermentation conditions, pH, oxy- and microorganisms contributing to the fermentation. In particular, gen contents, temperature, and preservative agents [45]. the acidity and pH in kimchis represent fresh acidic taste (fresh Kong et al [46] reported that the young radish cultivated by sourness odor) and that becomes an important factor of governing sulfur treatments shows 2.5 times higher sulfur similar substance, the quality of kimchis [45]. The pH value in the olgari-baechu kimchi which is a type of phytochemical, contents than that of cultivating it was 5.34 in the early stage and was maintained at 4.40 after 4e67 in general types of soil, which represents high effects of inhibiting days of storage [34]. In this study the pH value in the olgari-baechu the growth of AGS cancer cells [11,46]. In addition, organic to- kimchi was about 4.30e4.67 after 24 days. In the case of the young matoes showed two times higher flavonoid contents than general radish kimchi produced by sulfur treatments, it showed the pH tomatoes [50]. Similarly, in this study the organic olgari-baechu value (4.3e4.4) as an optimum ripening period after 4e5 weeks of kimchi represented higher bioactive substances than the general fermentation [46]. In the case of the organic young radish kimchi olgari-baechu kimchi. In particular, the contents of the nutritional fermented at 5C, the pH value was 5.41 after 24 days of fermen- and bioactive substances in agricultural products are influenced by tation and the general young radish kimchi showed a decrease in uses of fertilizers [51], soil microorganisms [52], attacks of harmful the pH value as 4.36. It was considered that the general young insects [53], harvest time [54], and other different factors [12,55]. radish kimchi represents faster ripening than that of the organic Although the large differences in the bioactive substance contents young radish kimchi [47]. In this study the general olgari-baechu is believed to be the effects of applying chemical fertilizers and kimchi showed a sudden decrease in the pH value to 4.96 after 7 attacks of harmful insects on the generation of the substance while days from the storage. It shows a similar tendency of the fast the process and fermentation condition in the kimchi are not ripening in the general olgari-baechu kimchi compared to that of the different, more specific reasons need to be investigated even organic olgari-baechu kimchi. Increases in the total acidity of kimchis though there are agricultural differences. are caused by lactic and nitric acids generated during its fermen- The YC-FNC and YC-GC kimchis had high scores for preference tation process and bacilli contributing to the fermentation are such as general tastes and odors. In general, the best taste in cab- varied according to fermentation temperatures. As lactobacilli in- bage kimchis is presented by the total acid contents of 0.6e0.8% and creases according to the fermentation process, the reducing sugar is the sourness taste and acidic odor are dramatically increased after 2 decreased. In particular, the reducing sugar is used as nutritional weeks from the ripening [56]. In the case of the general olgari- resources in microorganisms and plays an important role in baechu kimchi in this study, the preference of the best taste was growing the microorganisms. As the reducing sugar in kimchis presented after 14 days from the ripening and the preference in the reaches 50%, the kimchis approach its optimum ripening time [48]. organic olgari-baechu kimchi showed a high level after 24 days from It is known that the growing conditions of microorganisms in a fermentation. It is considered that the organic olgari-baechu kimchi S.J. Jung et al / Quality and functional characteristics of kimchi 157 has small and high amounts of moisture and fibers, respectively, the content of phenolic acids and flavonoids in foods. Mol Nutr Food Res e which leads to slowing of fermentation. In addition, the optimum 2009;53(Suppl. 2):S151 83. [16] Lima GPP, da Rocha SA, Takaki M, Ramos PRR and Ono EO. 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