食品保鲜剂协同丁香提取液预处理黄花菜的保鲜效果

为探索食品保鲜剂协同丁香提取液预处理黄花菜的保鲜效果,分别以丁香提取液和食品保鲜剂协同丁香提取液浸泡黄花菜1min,PVC塑料袋包装于室温下贮藏,贮藏期间测定黄花菜的开花率、腐烂率、失重率和褐变率。结果表明,单纯的丁香提取液对黄花菜的保鲜效果不显著,食品保鲜剂协同丁香提取液预处理黄花菜的保鲜效果显著,保鲜期达到6天,避免了阴雨天气不能及时日光干燥造成的损失。     

腐乳生产中香辛料的作用

通过分析细菌型腐乳中常用的9种香辛料：白芷、高良姜、肉桂、甘草、陈皮、丁香、砂仁、樟脑和龙脑等的主要成分,阐述了香辛料使用过程的浸出机理,对提取香辛料有效成分提出了新的建议,并说明了香辛料保管中应注意的问题。     

4-HR对鲜切莲藕褐变以及贮藏品质的影响

以白花莲藕为试材,研究了4-己基间苯二酚(4-HR)对鲜切莲藕产品低温贮藏期间褐变和贮藏品质的影响。结果表明,0.01% 4-HR以及0.01% 4-HR和0.5% VC的混合液处理对鲜切莲藕贮藏期间的褐变有抑制作用,保持了较低的褐变和腐烂指数,同时产品保持较高的硬度和可溶性固形物。0.01% 4-HR和0.5% VC的混合液的防褐变效果最为显著,并且可有效地抑制呼吸和乙醇的积累,控制微生物数量增加,减少腐烂发生。     

脱水黄花菜加工过程中褐变抑制条件的研究

在脱水黄花菜加工过程中非酶促褐变和因过氧化物酶 (POD)引起的酶促褐变严重影响脱水产品的质量。为了探索合理抑制POD活力的方法 ,以鲜黄花菜为材料 ,研究其不同部位及加工过程中POD的活性及变化情况 ,发现POD活力在黄花菜的不同部位上不一样 ,外花瓣和花梗的POD强 ,内花瓣的POD弱。通过热 (沸 )水灭酶、蒸气灭酶与非蒸气 (干燥空气 ,远红外线 ,微波 )灭酶等方法比较 ,热 (沸 )水与非蒸气不能有效地杀灭黄花菜中的POD ,湿热空气 (蒸气 )比干热空气灭酶效果好 ,蒸气灭酶的工艺参数为灭酶温度 98℃ ,灭酶时间 70～ 80s。为了探索合理抑制非酶促褐变的方法 ,用柠檬酸溶液和酸性氯化锌溶液浸泡材料进行正交实验 ,得到了将原料在质量分数 0 5 %的柠檬酸溶液中浸泡 45min的抑制非酶促褐变方法。     

高压静电场（HVEF）联合冰温处理对莲藕贮藏品质变化的影响

以新鲜莲藕为试材,研究了高压静电场联合冰温技术对莲藕贮藏期间褐变和贮藏品质的影响。结果表明,高压静电场处理联合冰温贮藏对莲藕贮藏期间的褐变有抑制作用,贮藏28 d后褐变度仅为7(A410×10),腐烂指数为15%,均明显低于对照。同时产品保持较高的硬度和可溶性固形物含量,贮藏28 d后硬度约保持为3 kgf/cm2,可溶性固形物约为4%。并且贮藏28 d后,呼吸强度为50 mg/kg.h,乙醇含量为18 nmol/g,细菌总数为5 CFU/g,均明显低于对照,说明该处理可以有效地抑制呼吸强度和乙醇的积累,控制微生物数量的增加,减少腐烂发生。     

栅栏技术对毛竹笋采后品质劣变的调控作用

本文研究了栅栏技术对毛竹笋采后品质劣变的作用。对毛竹笋贮藏期间纤维素、木质素含量、苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)活性、可食率、褐变指数以及腐烂率等生理指标进行检测。结果表明,采用栅栏因子处理能够明显抑制毛笋PAL、PPO酶活性、纤维素、木质素的合成,降低硬度;抑制可食率降低、腐烂率的增加及褐变指数升高,从而有效延长采后毛竹笋的贮藏期,从5 d延长到30 d。      

保鲜剂对鄂莲3号采后品质的变化

嘉兴市莲藕种植面积大,鄂莲3号在7月成熟,高温加剧莲藕褐变,且易失水腐烂。筛选符合国家标准的保鲜剂用于抑制莲藕的褐变,延长莲藕的贮藏期,维持莲藕食用品质与商品性。选择不同浓度二氧化氯、柠檬酸、VC、Ca Cl_2 4种保鲜试剂,洗净莲藕浸泡保鲜剂后,冷藏20 d后测定指标;通过测定色差、总糖、总酸及多酚氧化酶活性等指标,100 mg/L ClO_2、1%柠檬酸和0.7%V_C处理对莲藕褐变与PPO酶活抑制效果较明显;0.6%CaCl_2处理组对莲藕硬度保持有较好作用;所选的4种保鲜剂可较好地控制莲藕在贮藏期内可溶性糖含量下降的幅度,柠檬酸处理后莲藕总酸经初步测定未上升,且腐烂率较低,试验取得较好地保鲜效果。     

栅栏技术对毛竹笋采后品质劣变的调控作用

本文研究了栅栏技术对毛竹笋采后品质劣变的作用。对毛竹笋贮藏期间纤维素、木质素含量、苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)活性、可食率、褐变指数以及腐烂率等生理指标进行检测。结果表明,采用栅栏因子处理能够明显抑制毛笋PAL、PPO酶活性、纤维素、木质素的合成,降低硬度;抑制可食率降低、腐烂率的增加及褐变指数升高,从而有效延长采后毛竹笋的贮藏期,从5 d延长到30 d。     

成熟度结合1-MCP处理与不同低温贮藏对塞外红苹果的保鲜效果

以"塞外红"苹果为试材,将刚采摘的果实根据果皮颜色(淡红色、深红色)分为低和高2种成熟度,再将2种成熟度果实均采用0μL/L(CK)和1.0μL/L浓度的1-MCP处理后,放在0℃和2℃低温条件下贮藏。贮藏45、90、135 d时测定果实硬度、可溶性固形物含量(SSC)、可滴定酸(TA)、Vc、乙醇、乙醛、呼吸强度和乙烯释放量,同时调查果实腐烂/裂果和果皮、果心褐变情况。结果表明:与CK相比,1-MCP处理能较好保持贮藏135 d期间果实硬度、SSC、TA、Vc等内在品质,能明显(P≤0.05)降低果实腐烂率/裂果率和果心褐变率,完全抑制果皮褐变率,同时抑制乙醇和乙醛等有害物质的积累,延缓呼吸强度和乙烯释放量的增加,延缓果实衰老。结果还表明,成熟度低(淡红色)和0℃低温贮藏虽能较好地保持果实硬度,降低果实腐烂和果心褐变,但却出现了果皮褐变。初步判断2种成熟度塞外红果实贮藏后期的果皮褐变可能由0℃长期低温导致,而成熟度高(深红色)的果实和2℃条件下贮藏果实出现较高的果心褐变率和腐烂率由果实衰老造成。     

香辛料调味品褐变机理的分析研究

研究了香辛料调味品在贮藏期间褐变度（DB）及有关成分的变化,分析确定了引起褐变的原因及引起酶促褐变的主要底物,并探讨了香辛料调味品中多酚氧化酶（PPO）的部分酶学特性。实验结果表明,香辛料调味品在贮藏过程中PPO活性和褐变度的变化呈显著负相关性（r=-0.9535）,即褐变主要是由酚类发生的酶促氧化所致,香辛料调味品PPO的最适反应pH为6.8,PPO与不同底物结合力的大小依次为焦性没食子酸>酪氨酸>儿茶酚>苯酚>愈创木酚;化学抑制剂CA（柠檬酸）、Na2SO3、Vc、Zn（Ac）2、EDTA-2Na、L-cys和植酸对PPO活性均有不同的抑制作用,尤以Na2SO3、L-cys、CA的抑制作用明显。      

曲酸-海藻酸钠复合膜的制备及其对百合鳞茎片褐变的抑制作用

为了开发百合鳞茎片的活性包装材料,本研究利用3因素3水平L₉(3⁴)正交试验评价合适的海藻酸钠、甘油及曲酸浓度来制备复合液膜,并研究其对百合鳞茎片在4 ℃贮藏15 d的褐变抑制作用。结果表明,复合膜最佳配方中海藻酸钠、甘油及曲酸浓度分别为8 g/L、0.3%和1.0 g/L;同时曲酸-海藻酸钠涂膜能够抑制百合鳞茎片褐变和微生物生长,抑制百合鳞茎片多酚氧化酶(PPO)、过氧化物酶(POD)和苯丙氨酸解氨酶(PAL)的活性,且与对照组相比三种酶活性分别减少31%、21%和29%;涂膜处理能够抑制酚类和醌类增加,与对照组相比,酚类和醌类含量分别减少16%、15%。曲酸-海藻酸钠涂膜同样能够阻止百合鳞茎片硬度降低和丙二醛(MDA)含量增加。综上,曲酸-海藻酸钠涂膜能很好地抑制百合鳞茎片褐变以及保持百合鳞茎片品质。     

Effect of antimicrobial spice and herb extract combinations on Listeria monocytogenes, Staphylococcus aureus, and spoilage microflora growth on cooked ready-to-eat vacuum-packaged shrimp

Two spice and herb extract combinations from galangal (Alpinia galanga), rosemary (Rosmarinus officinalis), and lemon iron bark (Eucalyptus staigerana) were evaluated for their ability to inhibit the growth of inoculated Listeria monocytogenes and Staphylococcus aureus and naturally present spoilage microflora on cooked ready-to-eat shrimp stored for 16 days at 4 or 8 °C. A combination of galangal, rosemary, and lemon iron bark significantly reduced (P < 0.05) levels of aerobic bacteria and lactic acid bacteria at 4 °C on day 12 by 1.6 and 1.59 log CFU/g, respectively. By day 16, levels of these bacteria were equivalent to those of controls. The shrimp treated with this spice and herb extract combination had significantly lower (P < 0.05) lipid oxidation from day 4 to day 16. Similarly, a combination of galangal and rosemary extract significantly reduced (P < 0.05) levels of aerobic bacteria and lactic acid bacteria at 8 °C on day 8 by 2.82 and 2.61 log CFU/g, respectively. By days 12 and 16, levels of these bacteria were equivalent to those of controls. The shrimp treated with this spice and herb combination had significantly lower (P < 0.05) lipid oxidation on days 4 and 16. None of the spice and herb extract combinations had an effect on levels of L. monocytogenes or S. aureus or changed the color or pH of the shrimp during storage. The results of this study indicate that combinations of galangal, rosemary, and lemon iron bark extracts can be used to control the growth of spoilage microflora on ready-to-eat shrimp.     

百合鳞片褐变过程中膜脂过氧化研究

以宜兴卷丹百合作为实验材料,研究百合鳞片采后低温贮藏过程中膜脂过氧化与褐变的关系。结果表明：在低温贮藏过程中,百合鳞片不同部位的褐变度、细胞膜透性、超氧阴离子自由基（O2－·）产生速率、H2O2和丙二醛含量均随着贮藏时间的延长呈上升趋势,且中层鳞片的上升速率始终低于外层和内层鳞片;内源过氧化物酶（peroxidase,POD）、超氧化物歧化酶（superoxide dismutase,SOD）、过氧化氢酶（catalase,CAT）及脂氧合酶（lipoxygenase,LOX）活力呈先上升后下降趋势。中层鳞片中SOD和CAT活力始终高于外层和内层,而内源POD和LOX活力始终低于外层和内层鳞片;百合鳞片细胞活力在贮藏过程中逐渐降低,但中层鳞片的细胞活力始终高于外层和内层。百合鳞片褐变与膜脂过氧化密切相关,且不同部位百合鳞片在贮藏过程中褐变速率存在一定差异,表现为内层＞外层＞中层。本研究结果可为百合鳞片褐变机理的研究提供一定的实验依据。     

兰州百合采后贮藏保鲜研究进展

目的兰州百合营养丰富,采后易褐变,造成经济损失严重。通过对兰州百合采后贮藏保鲜研究进行综述,以期为兰州百合品质提升和减损增效提供一定的参考。方法在查阅国内外相关文献的基础上,紧密结合产业发展,综合分析兰州百合的传统保鲜、物理保鲜和化学保鲜方法。结果窖藏、沙藏、预冷、低温、气调、臭氧、紫外照射、二氧化氯、1-甲基环丙烯(1-MCP)和涂膜保鲜均可有效地保持兰州百合的贮藏品质,生物保鲜研究仍有待进一步加强。结论兰州百合贮藏过程中的褐变机制亟需明确,贮藏保鲜技术仍需挖掘,不同保鲜技术的复合应用前景广阔。     

Measurement of non-enzymic browning of dehydrated carrot

Non-enzymic browning of sulphited dehydrated carrot is measured by extracting brown materials with 2% acetic acid containing 1% formaldehyde, followed by precipitation of interfering pigments absorbing at 420 nm with 10% lead acetate and ethyl alcohol. The presence of sulphur dioxide is shown to reduce the absorption at 420 nm of a glucose—glycine browning solution and an extract of dehydrated carrot, the effect depending on time of incubation and exposure to light. The use of formaldehyde in the extraction solvent overcomes the effect of sulphur dioxide at concentrations up to 19 200 parts/million. The presence of carotenoids is shown to increase the absorption of browning extracts at 420 nm leading to high results. The interference from pigment materials is overcome by precipitation with lead acetate and ethyl alcohol. The use of both formaldehyde and lead acetate has no additional effect on browning determinations. Comparative tests of the proposed lead-alcohol precipitation method with an alcohol precipitation method, using both a glucose-glycine browning mixture and an extract of dehydrated carrot, shows only the lead-alcohol precipitation method to overcome errors due to carotenoid pigments either originally present in the extract or added as β-carotene, while the additional use of formaldehyde during extraction is necessary to overcome errors due to sulphur dioxide. Browning of dehydrated sulphited carrot stored for up to 20 days at 50 °C decreased with time of storage when measured by the alcohol precipitation method and in dehydrated non-sulphited carrot, browning showed only a slight increase with storage time. When measured by the lead-alcohol precipitation method, browning showed only a slight increase in stored dehydrated sulphited carrot, but a marked increase in stored dehydrated non-sulphited carrot, in agreement with visual observations.     

Effects of heat treatment on the quality of fresh-cut Chinese water chestnut

A heat treatment to inhibit browning and maintain the quality of fresh‐cut Chinese water chestnut was developed. Slices of Chinese water chestnut, cv. Guilin, were immersed in boiling water for 30 s, placed into film‐wrapped trays and then stored at 4 °C for up to 12 days. Changes in browning, eating quality and disease incidence were measured. The effect of heat treatment on the content of total phenolics and activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) was also evaluated. The heat treatment effectively prevented browning associated with PAL, PPO and POD activities and total phenolic content and delayed the decrease in eating quality, which is associated with reduced total soluble solids, titratable acidity and ascorbic acid, compared with fresh‐cut Chinese water chestnut. Inhibition of browning by heat treatment without microbial growth was achieved for 12 days of storage at 4 °C. These results showed that heat treatment effectively maintained the quality of fresh‐cut Chinese water chestnut.     

Prevention of enzymatic browning of apple cylinders using different solutions

Inhibition of enzymatic browning and decay on cut surfaces of Golden Delicious apple using ascorbic acid, cysteine, sodium chloride, calcium chloride, citric acid and sodium ascorbate alone or in combinations was investigated at 4 and 10 °C for a storage period of 0, 7 and 14 days, in an attempt to find the most effective treatment. Apple segments immersed in ascorbic acid and citric acid alone showed visual traces of browning after 7 days storage at 4 °C. After 14 days storage, only ascorbic acid and ascorbic acid plus sodium chloride had moderate browning, while all other treatments were severely affected. However, at 10 °C, only ascorbic acid was effective in reducing the level of browning, although its effect was minimal after 14 days storage. Browning was more severe at 10 °C than 4 °C in all solutions. The browning measurement (a* value) became increasingly positive from 7‐ to 14‐day storage. Microbial decay was absent in all treatments within 7 days at 4 and 10 °C. However, three test solutions showed microbial decay after 14 days storage at 10 °C in addition to the control solution, which showed decay at both 4 and 10 °C storage temperatures.     

Antioxidant responses in minimally processed celery during refrigerated storage

This work studies the effect of storage temperature (0, 4 and 10 °C) and time on the antioxidant capacity of cut celery packaged in polystyrene trays sealed with PVC film. Samples were taken at 0, 7, 14, 21 and 28 days of storage to determine total phenols, chlorogenic acid and ascorbic acid. The browning potential and antioxidant capacity of the product were also evaluated. The antioxidant power presented similar behaviour for the three temperatures tested, decreasing after the first 7 days and then increasing up to day 14. Such increase coincided with an elevation of the ascorbic acid content, which was stronger for higher temperatures. As a general conclusion, minimally processed celery retained its initial antioxidant capacity for a period of 21 days at 0 °C, showing the lowest levels of browning potential at this temperature.