Synthesis of chitosan-caffeic acid derivatives and evaluation of their antioxidant activities

In this study, the antioxidant activities of different molecular weights (M_w) and grafting ratios of chitosan–caffeic acid derivatives were investigated. The grafting process was achieved using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC) as covalent connector under different conditions such as molecular-weight of chitosan, molar ratio of chitosan and caffeic acid, reaction temperature, pH, and reaction time. The half-inhibition concentrations (IC₅₀) of products were calculated by reduction of the 1,1-diphenyl picryl hydrazyl in the radical-scavenging assay and reduction of the Fe³⁺/ferricyanide complex to the ferrous form in reducing power assay. The EDAC showed maximum activity at 3-h, pH 5.0 and room temperature conditions, except high-molecular-weight chitosan in pH 2.0. The products were water-soluble in all pH and showed lower viscosity than native chitosan. The highest grafting ratio of caffeic acid was observed at 15% in low-molecular-weight chitosan. After 5% grafting of caffeic acid into chitosan, the grafting efficiency was increased by decreasing molecular-weight of chitosan at the same conditions. Caffeic acid has main role in the antioxidant activity of products. The maximum IC₅₀ of radical-scavenging activity (0.064 mg/ml) was observed at the highest caffeic acid containing derivative. Water-soluble chitosan and caffeic acid derivatives were obtained by this study without activity loss.     

生姜酵素发酵过程中生物活性成分含量及其抗氧化活性的变化

以生姜作为发酵原料,通过加入酵母菌、副干酪乳酸菌、醋酸杆菌(沪酿1.01)进行复合菌发酵制得生姜酵素,定期取样以测定生姜发酵过程中6-姜酚、姜辣素含量的变化,以表征生姜发酵过程生物活性的变化,测定发酵过程中抗氧化活性物质总酚及黄酮的含量,通过测定DPPH自由基清除率,来表征生姜发酵过程中抗氧化活性的变化。结果表明:生姜酵素发酵的15 d过程中,发酵的pH在不断下降,最终降至3.51;6-姜酚含量在第2 d达到最高,为130.02 μg/mL;姜辣素总含量在第4 d达到最高(2.46%),整体从最初含量2.24%小幅度上升至2.40%,表明生姜发酵后生物活性成分含量保持较好;抗氧化性指标黄酮的含量在第2 d最高,以芦丁当量计为0.131 mg/g,之后含量稍有降低;DPPH自由基清除率在发酵前6 d内处于上升趋势,第6 d达到最高94.33%;总酚含量的变化趋势与DPPH自由基清除率基本相同,发酵终期其含量以没食子酸当量计,较初期升高了0.02 mg GAE/g,两者的测定数据说明,生姜酵素在发酵过程中的抗氧化性保持较好。     

Fluctuations in the phenolic content and antioxidant capacity of dark fruit juices in refrigerated storage

The changes in total phenol content and antioxidant capacity were monitored in six industrial dark fruit juices during 29-day refrigerated storage. The initial total phenol values ranged from 1302.1 mg/L GAE (strawberry) to 1919.8 mg/L GAE (black currant) with a mean of 1573.3 mg/L GAE. All juices exhibited fluctuations in TP values with a marked increase after 48 hours in refrigerated storage, and a greater overall TP content in 5/6 studied juices after 29 days. Antioxidant capacity was evaluated using the DPPH radical scavenging assay and cyclic voltammetry (CV) and expressed as Trolox equivalent antioxidant capacity (TEAC). Black currant juice exhibited the highest TEAC values according to both CV (2.42 mM Trolox) and the DPPH assay (5.68 mM Trolox), while cranberry juice antioxidants exhibited the greatest storage stability and the smallest antioxidant capacity decrease on day 29, 20% (CV) and 15% (DPPH assay). At the end of 29-day storage 5/6 juices exhibited a significant loss in antiradical activity and all 6 juices exhibited a significant loss in TEAC derived from CV measurements. Significant linear correlation was observed between the results of CV measurements and the DPPH antiradical activity (r² = 0.62).     

山药果蔬在乳酸菌发酵过程中组分及生物活性变化

通过对山药果蔬乳酸菌发酵液理化指标、微生物指标、酶活性、抗氧化性及抑菌活性的测定,研究其发酵过程中组分和生物活性的变化。结果显示:pH值和总酸含量在2~4 d变化最快,8 d后趋于稳定;总糖含量先下降、后上升、最后又下降,12 d后达到最低并趋于稳定;亚硝酸盐含量第4天最高,10 d后降至最低;前6 d是微生物主要增殖期,随着时间延长,乳酸菌逐渐成为优势菌种,并抑制其他杂菌生长;超氧化物歧化酶(superoxide dismutase,SOD)、淀粉酶、蛋白酶和脂肪酶随着时间延长,活性逐渐增强,SOD活性最高,脂肪酶活性最低;DPPH自由基、羟自由基、超氧阴离子自由基清除率和总抗氧化活性随着时间延长逐渐增强,10 d后最高且趋于稳定;对大肠杆菌和金黄色葡萄球菌的抑制率随时间延长逐渐增强,12 d后最高。本研究为果蔬乳酸菌发酵的工艺和功能研究提供了一定的理论依据。     

竹叶酵素发酵过程中代谢产物及抗氧化活性的变化

对竹叶酵素发酵过程中不同发酵时间的乙醇、总酸、乳酸、醋酸、总酚的含量和pH值进行了跟踪检测,考察各代谢产物与各抗氧化指标(DPPH自由基清除能力、ABTS自由基清除能力和还原力)相关性,并利用主成分分析建立竹叶酵素发酵过程中综合指标变化评价方法。结果表明,竹叶酵素发酵过程中,乙醇含量从第10 d后的0.55%增加至180 d的2.73%,达到最高;总酸含量经发酵100 d上升至4.78 mg/mL后逐渐下降,发酵过程中pH值从4.37降至3.54后趋于稳定;乳酸和醋酸含量在前60 d快速上升,之后开始趋于平缓;总酚含量持续上升积累至0.63mg/m L,与对DPPH、ABTS自由基的清除率和还原力均分别呈极显著的正相关(p0.01)。结论:竹叶酵素抗氧化性较好,尤其对ABTS自由基的清除能力较强,总酚含量可作为评价竹叶酵素抗氧化性的指标。综合评价指标(CEI)在第230 d时最高,可作为判定前发酵参考终点和补料发酵时间点的依据。     

Comparative study on antioxidant properties of carrot juice stabilised by high‐intensity pulsed electric fields or heat treatments

BACKGROUND: The effect of high‐intensity pulsed electric field (HIPEF) processing (35 kV cm^?1 for 1500 µs using 6‐µs bipolar pulses at 200 Hz) on the antioxidant features (vitamin C, β‐carotene, total phenolic compounds and antioxidant capacity) of carrot juice as well as on peroxidase activity was investigated and compared to the observed in heat pasteurised juices (90 °C for 60 s or 30 s) having the fresh juice as a reference. RESULTS: HIPEF and heat‐treated carrot juices had higher β‐carotene and lower vitamin C contents than the untreated juices immediately after processing. The antioxidant capacity of the juices was significantly modified neither by HIPEF nor by thermal treatments. POD activity decreased drastically (≥93.3%) after processing irrespective of the treatment applied. Vitamin C and β‐carotene content decreased throughout the storage following an exponential trend (R² = 0.801–0.984) with degradation rates between 1.7 × 10^?2 and 3.5 × 10^?2 day^?1. Vitamin C and β‐carotene contents were better maintained in HIPEF‐treated than in heat‐pasteurised juices throughout the storage. Total phenolic content and the antioxidant capacity of the HIPEF‐treated juice did not substantially differ from that of the thermally treated juice for 56 days. CONCLUSION: HIPEF processing may help to achieve fresh‐like carrot juices with increased amounts of health‐related phytochemicals. Copyright © 2009 Society of Chemical Industry     

Effect of refrigerated storage on vitamin C and antioxidant activity of orange juice processed by high-pressure or pulsed electric fields with regard to low pasteurization

A better knowledge of the effect of refrigerated storage on the nutritional and antioxidant characteristics of foods processed by emerging technologies with regard to thermal traditional technology is necessary. Thus, freshly squeezed orange juice was processed by high-pressure (HP) (400 MPa/40 °C/1 min), pulsed electric fields (PEF) (35 kV/cm/750 μs) and low pasteurization (LPT) (70 °C/30 s). The stability of vitamin C and antioxidant activity was studied just after treatment and during 40 days of refrigerated storage at 4 °C. The determination of total vitamin C (ascorbic acid plus dehydroascorbic acid) was achieved by HPLC whereas the antioxidant activity was assessed by the measurement of the DPPH• radical scavenging. Just after treatment, all treated orange juices showed a decrease lower than 8% in vitamin C content compared with the untreated one. At the end of refrigerated storage, HP and LPT juices showed similar vitamin C losses (14 and 18%, respectively) in relation to untreated juice, although HP juices maintained better the vitamin C content during more days than LPT juices. Regarding antioxidant activity, after 40 days at 4 °C, differences among treated juices were no significant in terms of antiradical efficiency (AE=1/EC₅₀T_EC50). HP and PEF may be technologies as effective as LPT to retain antioxidant characteristics of orange juice during refrigerated storage.     

Production,Characterization and Application of a Xylanase from Streptomyces sp. AOA40 in Fruit Juice and Bakery Industries

Streptomyces sp. AOA40, which produces halotolerant and thermotolerant xylanase, was isolated from Mersin soil. Various carbon sources were tested for xylanase production with selected fermentation medium. The best carbon source was selected as corn stover. The effect of corn stover concentration and particle size, composition of fermentation medium, fermentation condition such as initial pH and agitation rate on xylanase production was determined. After production, xylanase was partially purified with ion-exchange chromatography and gel filtration chromatography for characterization of xylanase and application in fruit juice and dough improvement. The optimum pH for the activity of xylanase occurred at pH 6.0 in phosphate buffer, while the optimum temperature was 60°C. The relative xylanase activity in the pH ranges of 4–9 remained between 59.93 and 54.43% of the activity at pH 6.0 (100.00%). The xylanase activity showed a half-life of 172 min at 70°C, which was reduced to 75 min at 80°C. The enzyme was highly inhibited by 10–100 mM of Hg⁺², EDTA, Mg⁺², SDS and 100 mM Cu⁺². Clarity of fruit juices increased after enzymatic treatment of apple (17.85%), grape (17.19%) and orange juice (18.36%) with partially purified xylanase and also reducing sugar concentrations of these fruit juices were improved by 17.21, 16.79 and 19.57%, respectively. Also, dough volume was raised 17.06% with using partially purified Streptomyces sp. AOA40 xylanase in bread making.     

Characteristics of fermentation and bioavailability of isoflavones in Korean soybean paste (doenjang) with application of Bacillus sp. KH-15

We attempted to increase the fibrinolytic activity and aglycone contents of isoflavone in doenjang prepared with Bacillus sp. KH‐15. An initial rapid increase of viable cells was observed in the first 30 days followed by a gradual decrease to 1.78 × 10⁸ CFU g^?1 wet weight. The amino type nitrogen sharply was increased after 15 days, and showed the highest level (788.7 mg%) after 90 days. The total nitrogen was increased from 2.21% to 2.52% of final content after 90 days. Soluble carbohydrate was increased to 32.9 mg g^?1 for 60 days, and after 60 days, the content was slowly decreased to 29.5 mg g^?1. A rapid increase in fibrinolytic and caseinolytic activities were observed in the first 30 and 45 days of fermentation followed by a gradual decrease to 2.54 and 144.5 U g^?1, respectively. β‐Glucosidase activity also showed a similar change pattern of the caseinolytic and fibrinoytic activities. Daidzein and genistein were increased to the maximum level of 764.5 and 561.4 mg kg^?1 at day 30, respectively. At day 90, the contents of daidzein and genistein were 661.5 and 524.9 mg kg^?1, respectively. The rats were fed a diet supplemented with either doenjang powder prepared with Bacillus sp. KH‐15 (D‐1 group) or commercial doenjang powder (D‐2 group) for 40 days. The level of serum total isoflavones in the D‐1 group was significantly higher than that in the D‐2 group.     

菌酶协同下的低温压榨菜籽粕抗氧化肽制备工艺研究

以枯草芽孢杆菌、酿酒酵母、黒曲霉、米曲霉为供试菌株,碱性蛋白酶为供试酶,菜籽粕为发酵原料,采用液态发酵法制备具有抗氧化活性的菜籽多肽。以铁氰化钾还原法测定的菜籽多肽抗氧化活性吸光值为评价指标,进行料液比、pH、发酵温度、发酵时间、菌种组合、菌酶比单因素实验,再对料液比、pH、发酵温度和发酵时间4个因素做响应面实验,得到最佳发酵工艺参数:菌种组合为枯草芽孢杆菌、黑曲霉、米曲霉为(V/V/V=1:1:1),菌酶比为1:1(V/V),接种量为10%(V/V),转速150 r/min,料液比为1:20(g/mL),pH为8,发酵温度为36℃,发酵时间为36 h,此时菜籽多肽抗氧化能力最强,吸光值为1.26。此外,本文对最优工艺下制备的菜籽多肽的抗氧化活性也进行了测试,在设定的最大浓度0.7648 mg/mL处,多肽对超氧阴离子和DPPH自由基的清除率分别达到67.4%和76.78%,抗脂质过氧化活性达到61.5%,研究表明实验所制备的菜籽多肽具有较好的抗氧化活性。     

西兰花酵素在发酵过程中生化指标变化及其抗氧化活性研究

以西兰花作为发酵原料,通过加入酵母菌、乳酸菌、醋酸杆菌复合发酵,研究西兰花酵素发酵过程中生化指标以及抗氧化性变化。其中,以p H值、菌落总数、总糖、乙醇、乳酸和乙酸作为生化指标考察西兰花酵素发酵过程中的变化;通过测定总酚、DPPH自由基清除率、超氧化物歧化酶(SOD)、氧自由基吸收能力(ORAC)作为抗氧化性变化指标。研究表明:在发酵过程中,p H值不断降低,由最初的4.49±0.02降低到3.51±0.03;菌落总数在第3 d最高,为9.03(±0.45)×10~7 CFU/m L;总糖被微生物利用消耗,由213.20±0.12 mg/m L降低到79.24±0.07 mg/m L;最终乙醇、乳酸和乙酸含量分别为28.23±0.06 mg/m L、7.89±0.05 mg/m L和11.66±0.05mg/m L;而抗氧化性指标总酚、DPPH自由基清除率、SOD和ORAC在前7 d处于上升趋势,7 d后趋于稳定。其中,DPPH自由基清除率、ORAC与总酚有正相关性(p0.01)。相对于实验室自制桑葚酵素,DPPH自由基清除率较高,抗氧化性较好。     

Short-wave ultraviolet-C light effect on pitaya (Stenocereus griseus) juice inoculated with Zygosaccharomyces bailii

Fresh pitaya (Stenocereus griseus) juice was inoculated with Zygosaccharomyces bailii to be processed using a continuous ultraviolet-C light (UV-C) (57 μW/cm²) system. Inoculated and uninoculated juices were processed at selected flow rates (16.49, 23.78, and 30.33 mL/s) and treatment times (5, 10, 15, 20, 25, and 30 min). Untreated, inoculated, and uninoculated pitaya juices were stored at 4 °C during 25 days. Microbiological (yeasts plus molds and total counts) and physicochemical (pH, total soluble solids, color, phenolic compounds, betalains, and antioxidant activity) characteristics were evaluated in fresh and processed juices. The net change in color increased as treatment time increased, reaching a maximum value of 3.9. A substantial reduction of phenolic compounds (11.6%), betalains (14.6%), and antioxidant activity (37.0%) were observed in juice treated at 30.33 mL/s during 30 min. A reduction of 1.8 log cycles of Z. bailii was observed at the highest UV-C light treatment.     

Antioxidative activity of chitosans with varying molecular weights

Antioxidant activity of chitosans of different molecular weights (30, 90 and 120 kDa chitosan) in salmon (Salmo salar) was investigated. The progress of oxidation was monitored by employing the 2-thiobarbituric acid-reactive substances (TBARS) and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assays. In general, all chitosans exhibited antioxidative activities in salmon. The addition of chitosans to salmon reduced lipid oxidation for seven days of storage. The TBARS values of salmon containing chitosan were significantly lower than those of the control (p < 0.01). At 0.2% (w/v) and 0.5% (w/v) concentrations, the TBARS with chitosan addition was decreased by 75% and 45%, respectively, over 15 days. At 1% concentration, the TBARS value with native chitosan addition was decreased by 32% after 15 days of storage. 90 kDa chitosan showed an increased DPPH free radical-scavenging activity with increasing concentration in the range of 0.2–1% (w/v). The free radical-scavenging activity of the 0.2 mM DPPH solution was saturated by 30 kDa chitosan at a concentration of ?0.7% (w/v), resulting in a strong antioxidant activity of approximately 85%. This was comparable to the DPPH free radical-scavenging activity of BHT.     

Effects of various clarification treatments on phenolic compounds and color of apple juice

The purpose of this study was to investigate the changes that occur during conventional clarification using gelatin, bentonite, silica sol, and water-soluble chitosan on the phenolic compounds, antioxidant activity, and color of apple juice. The apple material used in this study was of two varieties: Sampion and Idared. The changes in the polyphenols composition (procyanidins, hydroxycinnamic derivatives, and dihydrochalcones) were monitored through the clarification process. Sampion apple control juices contained more total polyphenols than do Idared apple juices. In Sampion variety apple juice, the dominant polyphenols are the flavan-3-ols (86% of total polyphenols), followed by hydroxycinnamic acids (9.7%), dihydrochalcones (3.0%), and flavonols (1.3%). In Idared apple juice the hydroxycinnamic acids (especially chlorogenic acid) are dominant (about 48% of total polyphenols), followed by flavan-3-ols (40%). However, the concentration of polymeric procyanidins in Sampion apple juices was 62.8 and 46.3% less when the Profloc (chitosan) and gelatin treatments were used, respectively. Aktivbentonit and Puranit (bentonite) supplementary added in juices clarification have some protective effect on polymeric procyanidins only with Profloc treatment. That kind of effect was not observed in Idared apple juices with almost eight times smaller polymeric procyanidins concentration than in Sampion apple juices. The antioxidant activity, measured by the DPPH (1,1-diphenyl-2-picrylhydrazyl radical) method, ranged from 0.20 mg TEAC/mL in Idared apple juice to 0.30 mg TEAC/mL in Sampion apple juice, measured by the ABTS method, from 0.17 to 0.48 mg TEAC/mL, respectively. Clarification of apple juices with chosen clarifying agents has statistically no significant (p>0.05) influence on antioxidant capacity. This study suggests that chitosan can be used as a conventional clarifying aid of apple juices and that treatment has no impact on their biochemical parameters.     

Shelf life extension of ground meat stored at 4 °C using chitosan and an oxygen absorber

The combined effect of chitosan (1%) and an oxygen absorber on shelf life extension of fresh ground meat stored at 4 °C was investigated. Parameters monitored over a 10‐day storage period were Total Viable Count (TVC), Pseudomonas spp., Brochothrix thermosphacta, lactic acid bacteria, Enterobacteriaceae, pH, thiobarbituric acid (TBA), colour, odour and taste. Microbial populations were reduced by 0.4–2.0 log CFU g^?1 for a given sampling day using either chitosan or the oxygen absorber, with the more pronounced effect being achieved by the combination of two. Thiobarbituric acid values for all samples increased during storage with the exception of samples treated with both chitosan and the oxygen absorber in which Thiobarbituric acid values decreased. Changes in pH values with time/different treatments were statistically insignificant. Colour parameters were affected by most treatments. On the basis of microbiological and sensory evaluation, a shelf life extension of 5–6 days was obtained for samples treated with the chitosan and the oxygen absorber combination.     

不同发酵方式制备树莓-石榴复合果汁酵素的抗氧化活性研究

以树莓、石榴复合果汁为原料,采用自然发酵、单一添加嗜热链球菌（Streptococcus thermophilus）、单一添加干酪乳杆菌（Lactobacillus casei）及同时添加嗜热链球菌和干酪乳杆菌发酵四种方式制备酵素,并对其发酵过程中的pH值、总酚、总黄酮及抗氧化能力（·OH、O2-·及DPPH自由基清除率）变化进行研究,以评价不同制备方式对树莓-石榴复合果汁酵素抗氧化活性的影响。结果表明,混菌发酵方式优于单菌发酵和自然发酵方式,能增加树莓-石榴复合果汁酵素中总酚含量、总黄酮含量,并提高其抗氧化能力。混菌发酵72 h时,总酚含量（0.57 mg/mL）、·OH清除率（67%）及O2-·清除率（54%）最高;发酵60 h时,总黄酮含量（0.41 mg/g）及DPPH自由基清除率（94%）最高;pH值变化最小,利于发酵进行。     

Comparison of the polyphenolic composition and antioxidant activity of European commercial fruit juices

Thirty six commercial European fruit juices were tested to ascertain their antioxidant capacity and polyphenolic composition. Six of the products were labelled 100% pomegranate juice, the others included 20 brands of diluted pomegranate juice or pomegranate blended with other fruit juices and 10 different non-pomegranate fruit juices. The antioxidant capacity of all the juices was determined while anthocyanin, ellagitannin and ellagic acid profiles of the 26 pomegranate juices and pomegranate juice blends were obtained using HPLC-PDA-MS(2). Additional analysis was conducted on seven of the juices using HPLC with an on-line antioxidant detection system. Three of the "pure" pomegranate juices had the highest ellagitannin content and the highest antioxidant capacity. Only one of these three juices was rich in anthocyanins. The other "pure juices" had differences in their HPLC "pomegranate" fingerprint and also had a lower antioxidant capacity, in some cases lower than that of some of the blended juices. Vitamin C rather than phenolic compounds was the major contributor to the antioxidant capacity for some of the juices. Statistical analysis of both the antioxidant assay and the HPLC on-line antioxidant data demonstrated that the ellagitannins were the major antioxidants in the pomegranate juices. The complexity of the polyphenolic profile of pomegranates necessitates the use of HPLC-PDA-MS(2) for a thorough evaluation of juice composition and authenticity.     

Synthesis,characterization and functional properties of galactosylated derivatives of chitosan through amide formation

Low molecular weight chitosan (LMWC) and chitooligosaccharide (COS) derivatives were obtained by the introduction of lactobionic acid (LA) through amide formation, obtaining different complexes COS-LA and LMWC-LA (1–5), with a degree of substitution (DS) between 3 and 16%. The synthesis of these derivatives was monitored by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), High-Performance Liquid Chromatography-Size Exclusion Chromatography (HPLC-SEC) and proton Nuclear Magnetic Resonance (¹H NMR) analyses. Different functional properties, solubility, water binding capacity (WBC) and fat binding capacity (FBC), as well as the antioxidant activity (DPPH radical scavenging activity) of these derivatives were evaluated. Solubility, WBC and FBC increased in all of the chitosan derivatives respect to those of the native LMWC or COS. The most substituted derivative (LMWC-LA1, DS 15%) presented the highest value of solubility (14.4 mg/mL) while the highest levels of WBC and FBC were obtained for the derivative with a DS of 3% (LMWC-LA5; 4730% and 7100%, respectively). COS and COS-LA presented the best DPPH scavenging abilities, as shown by their low values of EC₅₀ (1.29 and 3.45 mg/mL, respectively). An inverse relationship between the DS of chitosan derivatives and antioxidant activity was observed. LMWC-LA5 (3% DS) was the derivative with the highest DPPH activity, being higher than LMWC in all the concentrations assayed (10.2–14.3% and 6.9–13.7%, respectively). Due to their enhanced functional properties, these chitosan derivatives could be considered as very promising for their future use as additives in the food industry (i.e. to bind fat and cholesterol or avoid hardening of foods).     

Changes in the phenolic compounds and antioxidant activities of mustard leaf (<Emphasis Type="Italic">Brassica juncea</Emphasis>) kimchi extracts during different fermentation periods

This study was conducted to investigate the changes in the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities of 80% methanol and water extracts from mustard leaf kimchi during different fermentation periods. The methanol extract exhibited higher TPC and TFC than the water extract. Both extracts from kimchi fermented for two months showed the highest antioxidant effects against the scavenging activities of 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radicals and 2,2-azino-bis diammonium salt (ABTS) radicals. Moreover, the methanol extract from kimchi fermented for two months showed the highest nitrite scavenging activity. The highest metal (Fe²⁺) chelating effect of the methanol extract and water extract was observed after three months and one month, respectively. Caffeic acid showed the highest increase with fermentation. These findings suggest that the antioxidant activities of kimchi depend on the fermentation period. Accordingly, this study provides basic data for improving the antioxidant activity of mustard leaf kimchi through the establishment of their fermentation period.