Influence of combined hot air and UV-C treatment on the antioxidant system of minimally processed broccoli (Brassica oleracea L. var. Italica)

Broccoli develops a fast senescence that deteriorates the nutritional quality of the product. In this work, a combined treatment with hot air and UV-C were applied to minimally processed broccoli florets to investigate their effects on the antioxidant system during storage at 20 °C. Application of UV-C and heat enhanced by approximately 13% the levels of total antioxidants immediately after treatment. These levels were lower than initials in both control and treated samples. Nevertheless, higher values (ranged from 12 to 50%) were also detected in treated samples during storage. In general, higher values of antioxidants were correlated with elevated levels of phenols (from 10 to 17%) and ascorbic acid (from 11 to 17%) in treated florets. The increment in the content of phenolics in treated broccolis was correlated to an increased phenylalanine ammonia lyase (PAL) activity. The combined treatment also affects the activity of enzymes involved in removal of reactive oxygen species. An increase of about 50% in superoxide dismutase activity was detected after treatment. During the first days of storage this higher activity was about 40%. Enzymes that remove H₂O₂ like catalase and ascorbate peroxidase showed an enhanced activity toward the end of storage. The combined treatment diminished the peroxidase (POX) activity approximately 60% after the treatment and near 50% after two days of storage, suggesting a minor role of this enzyme in detoxification of H₂O₂. In conclusion, combined treatment may contribute to enhance the protection against oxidative molecules not only by increasing levels of phenolics and ascorbic acid but also by enhancing the activity of enzymes involved in removing reactive oxygen species.     

Maintaining quality and bioactive compounds of broccoli by combined treatment with 1‐methylcyclopropene and 6‐benzylaminopurine

BACKGOUND: Broccoli deteriorates very quickly after harvest at ambient temperature due to the loss of green colour and the consequent yellowing of florets. To search for an effective method to control quality deterioration, the effect of 1‐methylcyclopropene (1‐MCP) combined with 6‐benzylaminopurine (6‐BA) treatment on visual quality, antioxidant enzymes and bioactive compounds in broccoli florets were investigated. RESULTS: A combined treatment of 2.5 µL L^?1 1‐MCP and 200 mg L^?1 6‐BA significantly reduced the increase of lightness (L*) value, and retained a high level for the hue value (H) and chlorophyll content. Superoxide dismutase, ascobate peroxidase and catalase activities increased while the activity of peroxidase decreased during storage in treated samples in comparison with the controls. The combined treatment enhanced the biosynthesis of glucosinolate and the formation of the anticarcinogen sulforaphane, which improved the health benefit of broccoli. CONCLUSION: These results indicate that a combined treatment of 1‐MCP and 6‐BA could be a good candidate for maintaining the visual quality and enhancing the nutritional value in broccoli during storage at 15 °C. © 2012 Society of Chemical Industry     

中草药提取液对采后西兰花主要致腐菌的抑制作用研究

为探讨中草药提取液对采后西兰花致腐菌芸苔生链格孢菌和核盘菌的抑制效果,采用生长速率法、滤纸片法对不同中草药提取液的抑菌效果进行对比,然后利用西兰花活体验证试验做进一步验证,筛选出抑菌效果较好的中草药种类,并进一步通过体积浓度梯度稀释法,对其最小抑菌浓度(MIC)和最小杀菌浓度(MBC)进行了探讨。结果表明:不同天然植物提取液对采后西兰花主要致腐微生物链格孢菌和核盘菌均有不同程度的抑制作用,其中山豆根、肉豆蔻提取液的抑菌效果较强。山豆根、肉豆蔻提取液对链格孢菌的MIC均为占培养液体积(V/V)的10%、MBC分别为占培养液体积(V/V)的20%和40%;山豆根、肉豆蔻提取液对核盘菌的MIC分别为占培养液体积(V/V)的20%和10%,MBC分别为占培养液体积(V/V)的40%和20%。     

山豆根、肉豆蔻及其复合提取液对西兰花保鲜效果的影响

分别配制料液比为1:10(m/V)的山豆根、肉豆蔻及其复合提取液,对西兰花浸泡处理15 min,以蒸馏水为对照,自然风晾干,然后在温度为(3±1)℃条件下贮藏,研究3种不同提取液处理对西兰花生理生化变化的影响。结果表明:与对照相比,3种保鲜处理均可在不同程度上延缓西兰花感官品质的下降,抑制西兰花呼吸强度和质量损失率,减缓可溶性蛋白质、可滴定酸、Vc及叶绿素含量的降解,改善细胞膜渗透率,减少丙二醛的积累。其中料液比为1:10的山豆根提取液保鲜效果最佳,各项指标均显著优于对照(P<0.05)。     

不同质量浓度臭氧化水对鲜切西兰花贮藏品质的影响

采用不同质量浓度臭氧化水处理鲜切西兰花。结果表明:质量浓度2.0mg/L的臭氧化水处理组保鲜效果最优,在贮藏12d时与对照组相比,质量损失率降低24.37%,VC含量提高40.7%,多酚氧化酶酶活降低23.5%,过氧化物酶酶活降低25.6%;在4℃的条件下,质量浓度2.0mg/L的臭氧化水处理组鲜切西兰花贮藏期可达到15d。     

预冷、冷藏运输和销售方法对青花菜品质的影响

研究压差预冷和冷库预冷,聚苯乙烯泡沫箱加冰0℃冷藏运输1d,4℃和20℃加收缩膜和不加收缩膜包装及20℃加湿销售2d青花菜品质的变化。结果表明:压差预冷青花菜的预冷速度快于冷库预冷;聚苯乙烯泡沫箱加冰冷藏运输1d后,4℃销售的青花菜品质好于在20℃下销售青花菜的品质,加收缩膜包装青花菜的品质好于无收缩膜包装青花菜的品质,其失重率和营养损失少。青花菜压差预冷、聚苯乙烯泡沫箱加冰0℃冷藏运输和4℃用收缩膜包装销售2d的冷链物流方法最好,其冷链物流后的青花菜感官评价、失重率、叶绿素含量、VC含量、可溶性蛋白含量、可溶性糖含量分别为4.3、2.23%、42.56mg/100g、167.27mg/100g、535mg/100g和1.03%。     

低温等离子体处理提高鲜切西兰花贮藏品质

本文以鲜切西兰花(Brassica oleracea)为试材,采用低温等离子体(Cold Plasma,CP)处理,分析CP处理对鲜切西兰花保鲜效果的影响。结果表明,与对照相比,CP能有效杀灭西兰花表面的细菌;贮藏5 d,CP处理的鲜切西兰花的硬度、粘力和咀嚼性分别为44.45 kg/cm2、12.51和139.88 mJ,而对照组分别为34.84 kg/cm2、7.71和83.63 mJ,表明CP处理能够明显抑制西兰花的质构变化;鲜切西兰花贮藏过程中的乙烯释放速率呈现先上升后下降的趋势,CP处理明显抑制了其乙烯释放速率;电子鼻的主成分分析和线性判别分析发现,随着贮藏时间的延长,对照组和CP处理的鲜切西兰花的气体成分差异显著;聚类分析结果表明,CP处理的鲜切西兰花15d贮藏品质相当于未处理的鲜切西兰花贮藏11d。因此,CP处理能够明显延长鲜切西兰花的贮藏寿命,维持其较好品质。     

鲜切西兰花的PE薄膜保鲜包装技术研究

在商业贮运温度(4℃)和货架储存温度(25℃)及不同湿度(RH40%、60%、80%)条件下,采用厚度为0.006、0.011、0.017mm的普通聚乙烯薄膜(PE)及0.018、0.028、0.039mm的激光打孔PE膜对鲜切西兰花进行保鲜包装。以西兰花的感官品质、失重率和叶绿素含量为评价指标,并利用薄膜的透湿性实验对相关机理进行了探讨。结果表明,激光打孔PE薄膜的透湿率大于普通PE薄膜;对同种薄膜而言,随着厚度的增加,透湿率减少。在25℃环境下贮存4d,激光打孔膜包装的霉变现象比普通PE膜严重,且对同种薄膜而言,厚度越大,包装试样的黄化和霉变程度越轻,保鲜包装效果越好。激光打孔膜包装试样的失重率和失重速率均明显大于普通PE膜;在相同贮存条件下,PE薄膜越厚,试样的失重率越小。故从包装试样的感官品质和水分的保持方面看,普通PE膜优于激光打孔PE膜,且薄膜越厚效果越好。随着贮存时间的延长,试样中的总叶绿素含量均呈下降趋势;从叶绿素的保持方面而言,薄膜越厚,保鲜效果最好,且试样中叶绿素a的损失幅度和速率远远大于叶绿素b。4℃的低温贮存环境利于产品感官品质、水分及总叶绿素含量的保持,利于其PE薄膜的保鲜包装。     

超声波-微波处理条件对西兰花泥总酚含量及其品质的影响

目的 优化西兰花总酚的超声波-微波提取工艺条件, 同时考察加工工艺对产品形貌和流变学等品质特性的影响。方法 以西兰花总酚提取率为指标, 通过单因素和正交实验对超声波功率、超声时间、微波功率、微波时间进行优化, 并对最优条件下提取的西兰花泥的颜色变化、流变学特性及微观结构进行测定。结果 最佳提取条件为: 超声功率120 W、超声时间1 min、微波功率280 W、微波时间60 s。在该提取条件下, 西兰花总酚提取量为0.362 mg/g。经过超声波-微波处理后, 西兰花的总颜色变化ΔE为4.96。在剪切速率0.1~100 s-1的范围内未经处理和最优条件制备的西兰花泥样品均表现出剪切稀释现象。动态流变学分析结果表明, 经过超声波-微波处理的西兰花泥在角频率为0.628~62.8 rad/s时, 储能模量G′和损耗模量G″均随角频率的增加而增加, G′均远大于G″, 表明西兰花泥呈三维网络状结构, 损耗系数tanδ均随角频率的增加且均小于1, 表明西兰花泥样品弹性占主导地位, 具有类似于凝胶的性质。微观结果显示, 超声-微波处理使西兰花结构变得更加连续紧密, 适度处理可以使得西兰花的结构得到一定改良。结论 超声波-微波处理可以有效提高西兰花总酚提取量,改善产品色彩饱和度,同时表现出更滑爽的口感和更好的黏弹性, 以及更均匀紧密的微观结构。本研究致力于为西兰花的高值化加工提供新方法, 在有效提高西兰花中功能性成分含量的同时考察加工工艺对品质的影响, 对于提高西兰花产品品质和资源高值化利用具有重要的参考意义。     

Effect of industrial processing on amino acid content of broccoli

The levels of amino acids in broccoli stems and florets before and after various blanching times (in the case of freezing) and after bottling have been studied to elucidate to what extent nutrient quality is affected by industrial processing. The following amino acids (mg kg^?1 fresh weight) were identified by ion exchange chromatography in raw broccoli florets: glutamine (1338), proline (732), asparagine (578), valine (310), arginine (296), isoleucine (204), threonine (169), leucine (166), phenylalanine (159), aspartic acid (140), lysine (127), alanine (122), tyrosine (105), S‐methylcysteine (96), histidine (89), ornithine (59), glutamic acid (44), γ‐aminobutyric acid (31), glycine (11) and serine (0.2). Raw stems contained the same amino acids but at lower levels (p < 0.05). The levels of all these amino acids fell during both industrial processes studied (bottling and freezing after blanching for 60, 90, 120 and 150 s), particularly in the frozen samples (losses of 50–70% in the florets and 20–50% in the stems). In summary, losses of broccoli amino acids were lower if blanching times were kept short. The optimal blanching time at 94 °C for florets and stems intended for freezing was 90 s, and this did not result in any great loss of nutritional value related to amino acid content. Bottled florets had greater nutritional value than those frozen after being exposed to the longest blanching times (120 and 150 s). © 2001 Society of Chemical Industry