| Potherb mustard (Brassica junce Coss. Var. multiceps Tsen et Lee), with Chinese name Red-in-Snow, is a cultivar of mustard(Brassica juncea Coss.). Potherb mustard also called leaf mustard, is widely cultured in the south of Changjiang River. Different cultivars have different adaptability. Pickled potherb mustard is very common in the district of Zhejiang, China, mainly because it can be preserved in long time in industry and house. However, most of pickled potherb mustard in the conventional food processing as products had low added value, and had no appropriately preserved time and methods. Moreover, the nutrition in potherb mustard, which was preserved in different time phases, was not clear. In the present research, the chemical characteristics and nutrients of the potherb mustard from Cixi, Ningbo during pickling was investigated. Mustard including withering and fresh materials was pickled by three different methods(dry-cured, wet-salted, lactobacillus inoculated-pickling). Chemical parameters such as nitrite and nitrate were analyzed, and phenolic acids and antioxidant activities were also evaluated.There are three main facts in this research:1 The effects of withering and pickling methods on the phytochemical properties of pickled mustard:1) In three pickling methods, using both withering and fresh material, salt content in pickled materials suddenly rose to about 40％in the first week of pickling (p＜0.01), compared to that of raw materials, then increased slowly. Dry-cured with fresh materials had the highest salt content in the eighth week, reached 52.35％. Inoculated-pickling using withering material had the lowest salt content of 42.8％. Generally speaking, the orders of the salt content were as follows: fresh pickling＞withering pickling; dry-cured＞wet salted＞inoculated-pickling.2) In the initial period of pickling, with the natural and the inoculated fermentation, the titratable acidity showed an increased tendency, and gave a maximum value in 2-3rd week, then decreased, probably causing by the higher concentration of salt; in 7-8th week, the titratable acidity rose slightly again. Inoculated-pickling with both fresh and withering material had the maximum titratable acidity value, respectively reached 2.0％and 2.83％. Compared with raw material, all values of the titratable acidity showed a significant (p＜0.01) increase. The average titratable acidity: inoculated-pickling(1.74％)＞wet-salting(1.50％)＞dry-curing (1.48％). However, three persevered methods had no significant differences (p＞0.01). Although the titratable acidity values of fresh pickling all reached maximum in the 3rd week, the value with inoculated-pickling was the higher than those of the other two treatments. Likewise, the values obtained with withering-pickling treatment were the same as those with fresh pickling. The most obvious differences between withering and fresh pickling were that the peak values of titratable acidity using withering materials occurred one week later than that of fresh pickling.3) In different preserve processes, the proteins all showed a slowly decreased trend. For example, dry-cured, wet-salted and inoculated-pickling of fresh materials reduced from 28.56 to 24.44, to 24.15, to 21.64g/100g of DW, respectively. Compared with raw material, dye-cured was not significantly different, wet-salted(p＜0.05) and inoculated-pickling(p＜0.01)were all significantly different. The three treatments of withering-pickled decreased from 41.17 to 35.06, to 24.57, to 25.62 g/100g of DW respectively, which were significant differences compared with raw materials: dye-cured (p＜0.05), wet-salted and inoculated-pickling (p＜0.01). The protein contents with the inoculated-pickling decreased more quickly than the other two pickles.4) In the processing of preserve, the free amino acid of potherb mustard increased with time, and had the highest values in the 6-7th week (p＜0.01), then decreased. There were no significant differences between different pickled methods.5) The nitrate contents in fresh pickling descended with time, whereas withering-pickled slightly rose, and then descended. In the 2nd week, the nitrate content of different pickled fresh materials decreased by 35％,31％和36.2％respectively(p＜0.01). The nitrate contents with withering-pickled treatment in 3 weeks increased slowly (p＞0.05), however, in the 4th week, the nitrate decreased significantly (p＜0.05).6) The nitrite contents in pickling showed a changing trend, and the highest values were found in the 5th week, then decreased The highest values of the nitrite in fresh materials using dry-cured, wet-salted and inoculated-pickling were 814.47,931.15,499.93mg/KgDW respectively, and the nitrite content in withering were 691.99,695.44,572.41 mg/KgDW respectively, which all were significantly different compared with raw materials(p＜0.01). The nitrite contents in both fresh and withering materials using dry-cured was higher than the other two treated methods (p＜0.05).7) The nitrate and nitrite contents in fresh materials using wet-salted and inoculated-pickling were significant negative correlation in 5 weeks (p＜0.05), whereas the nitrate and nitrite in the withered materials all showed significant negative correlation(p＜0.01).2 Changes of Phenols content in different preserved potherb mustards:1) The total phenols rose firstly, and then decreased. The total phenols contents with inoculated-pickling were higher than that in other two treatments, the values in fresh materials and withering ones increased from 7.74 to 10.95, 3.96 to 9.91 mg/gDW respectively (p＜0.01).2) Gallic acid, protocatechnic acid, p-benzoic acid and vinillic acid in the pickling increased (p＜0.01). Caffeic acid, p-cinnamic acid, ferulic acid and sinapic acid firstly increased, then decreased, which were significantly different compared with raw materials (p＜0.01). In all phenolic acids of pickling potherb mustard, the sinapic acid content was the highest(323.33ug/gDW), and the gallic acid was the lowest(20.93ug/gDW).3) Total phenolic acid, the sum of eight phenolic acids, were increased firstly in pickling, and then decreased. The total phenolic acid values using the same pickled methods with different raw materials showed no difference(p＞0.05); the valus using fresh materials but different pickled methods were similar(p＞0.05); the value using withering materials with different pickled methods were significantly different(p＜0.05).3 The results obtained by the antioxidant capability in vitro of pickling potherb mustards indicated that:1) The antioxidant capabilities were evaluated by FRAP, ABTS and DPPH, which all showed the same trend: an increase firstly and then descending. These data were all significantly different compared with raw materials(p＜0.05).2) The antioxidant capability correlated with total phenols significantly (p＜0.01), and three antioxidant systems all showed significantly dependent with another (p＜0.01).
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