列车冷链快餐中莴苣菜肴烹饪方式、贮藏品质研究

"冷链快餐"是列车上主要的供食类型,但人们对于蔬菜菜肴的冷配送研究并不多。将莴笋作为研究对象,将莴苣经过油炒、微波和热烫三种烹饪方式包装后,贮藏于1℃和4℃条件下,放置7 d。观测其硝酸盐、亚硝酸盐、维生素C和菌落总数等指标的变化,研究不同烹饪方式和贮藏温度对莴苣菜肴贮藏时的品质影响。结果表明:1℃下能明显增加硝酸盐含量,但能明显减少亚硝酸盐含量,同时能减少菌落总数,维生素C受温度影响较小。各个指标均随着贮藏时间发生显著变化(p0.05)。三种烹饪方式中,热烫能减缓硝酸盐和亚硝酸盐的增加,减弱维生素C的减少,感官评价分数也高于微波和油炒。试验表明:最好选用热烫的烹饪方式贮藏在1℃下并缩短贮藏时间,尽早食用。     

钙和热处理对青椒贮藏品质的影响

研究氯化钙和热处理对青椒贮藏(8℃)过程中失重率、可溶性固形物含量、呼吸强度、可滴定酸含量、VC含量、叶绿素含量等品质指标的影响,结果表明:最佳处理条件是:3%氯化钙与45℃热处理相结合,处理25min。该方法有效降低了青椒的呼吸强度,提高了青椒叶绿素的稳定性,延缓了果实中VC含量的下降,但在一定程度上增加了青椒的失重。     

不同清洗方式对青椒保鲜效果的影响

以青椒为对象,采用自来水、臭氧水、次氯酸钠、二氧化氯和超声波对青椒进行清洗,研究不同清洗方式对青椒保鲜效果的影响。贮藏期间,每2 d测定失重率、可滴定酸含量、可溶性固形物含量、抗坏血酸含量、叶绿素含量和菌落总数等指标。结果表明,臭氧水、次氯酸钠、二氧化氯和超声波清洗能使青椒在贮藏过程中保持较好的感官品质,减缓营养物质可溶性固形物、叶绿素、抗坏血酸含量的下降,抑制可滴定酸含量和细菌菌落总数的增加。5种清洗方式中,使用臭氧水清洗对青椒的保鲜效果最佳,贮藏至10 d仍有商品价值和食用价值,可用于青椒保鲜。     

切分及烹调对叶类蔬菜品质的影响

以芥菜、菜心、生菜等为主要原材料,研究切分方式与烹调方式对叶类蔬菜中维生素C、叶绿素和亚硝酸盐含量的影响,以明确加工条件对叶类蔬菜品质的影响。结果表明,切分后烫漂,叶类蔬菜中维生素C较新鲜蔬菜下降超过40%,亚硝酸盐含量下降超过45%,叶绿素下降不明显,且随细胞液的流失有明显上升趋势;油炒、烫漂和汽蒸三种烹饪方式对叶类蔬菜中叶绿素、维生素C、亚硝酸盐影响的研究表明,汽蒸加工可以保留叶类蔬菜中60~67%的维生素C,可降低40~70%的亚硝酸盐含量,而对叶绿素含量影响不大,是一种较理想的营养烹饪方式。本论文的研究成果具备良好的理论与实践意义,对减少叶类蔬菜烹饪加工过程中营养成分的损失、有害物质的产生、提高叶类蔬菜烹饪品质起到良好的方法借鉴。     

微真空贮藏条件对鲜切西兰花保鲜效果的影响

为探讨微真空贮藏条件对鲜切西兰花保鲜效果的影响,本研究以西兰花为试材,将西兰花用有效氯质量浓度为100 mg/L次氯酸钠溶液消毒处理后,用清水漂洗干净,切分成直径约3-4 cm的小花球,随机装入规格为30 cm×20 cm×8 cm的塑料小筐,放入真空压力为66.65-79.98 KPa、贮藏温度为4±1 ℃的微真空贮藏设施进行贮藏实验,以相同温度下的常压冷藏库贮藏为对照实验,探讨不同贮藏条件对鲜切西兰花感官品质、呼吸强度、失重率、可滴定酸、Vc及叶绿素含量的影响。结果表明：与相同温度下的常压贮藏相比,微真空贮藏可明显提高鲜切西兰花的感官品质,显著降低鲜切西兰花贮藏期间的呼吸强度和失重率,减缓可滴定酸、Vc及叶绿素含量的下降（P〈0.05）。表明微真空贮藏条件能明显提高鲜切西兰花的采后保鲜效果。     

不同复合保鲜剂处理对青椒采后贮藏品质的影响

以青椒为试材,选取1-甲基环丙烯(1-methylcyclopropene,1-MCP)、SO_2保鲜剂、乙烯吸收剂3种保鲜剂,通过两两组合的形式(1-MCP+SO2保鲜剂、1-MCP+乙烯吸收剂和SO_2保鲜剂+乙烯吸收剂)对青椒进行处理,测定贮藏期间青椒的品质和生理相关指标。结果表明,1-MCP+SO_2保鲜剂处理组保鲜效果较好,贮藏20 d后,青椒果实还原糖含量、VC含量、可滴定酸含量和叶绿素含量分别高于对照组15.17%、20.36%、16.32%、5.68%,且对照组青椒果实的失重率、腐烂率和乙烯呼吸速率分别是1-MCP+SO_2保鲜剂处理组的2.7、2.9、1.8倍,可见3种保鲜剂组合对青椒还原糖含量、VC含量、可滴定酸含量和叶绿素含量的下降均有抑制作用,并且可降低青椒果实的失重率、腐烂率和乙烯生成速率。     

不同护绿方式、烹饪方式对莴苣菜肴的品质影响

选用较常见的莴苣作为试验材料,采用CaCl_2浸泡、Na HCO_3漂烫、沸水漂烫3种护绿方式对莴苣护绿后,再分别采用微波、油炒、热烫3种烹饪方式进行烹饪,观测其Vc、亚硝酸盐、叶绿素、菌落总数等指标以及进行感官评价。结果表明:不同的护绿方式对Vc、叶绿素及感官评价有显著影响,其中Na HCO_3漂烫和CaCl_2浸泡表现出明显的优势;不同烹饪方式对Vc、亚硝酸盐有极显著影响,均是热烫较好;而菌落总数和大肠菌群在经过处理后均检测出极少数量,在标准范围内;筛选出比较好的工艺组合是CaCl_2浸泡结合热烫。     

壳寡糖涂被纸包装对西兰花采后保鲜的影响

以西兰花(Brassica oleacea)为试材,采后以1%、2%、3%的壳寡糖涂被纸包装处理,置于4℃,85%～95%RH环境中贮藏。以不包装及普通纸包装处理为对照,研究壳寡糖涂被纸包装对西兰花贮藏品质、采后生理的影响。结果表明,不同浓度的壳寡糖涂被纸包装均能减缓西兰花采后失重;延缓果实可滴定酸、还原性抗坏血酸、叶绿素含量的下降;抑制游离脯氨酸含量的上升;有效保持采后西兰花的感官与营养品质,延长货架期。以2%壳寡糖涂被纸包装处理的各项指标优于其他处理,为西兰花采后保鲜最经济、效果最佳的处理方式。     

微真空贮藏对西兰花采后品质的影响

为探讨微真空贮藏条件对果蔬的保鲜效果,以西兰花为试验材料,研究了贮藏温度为(3±0.5)℃、真空压力为66.7 kPa～80.0 kPa的微真空贮藏条件下西兰花采后品质的变化。结果表明:与相同温度下的常压贮藏相比,微真空贮藏能显著(P<0.05)降低西兰花花球的失重率和可滴定酸含量的下降,延缓西兰花花球中VC、可溶性蛋白质的降解及游离氨基酸的生成量,抑制叶绿素分解及花球色差的变化。表明微真空贮藏条件能显著(P<0.05)提高西兰花的采后保鲜品质。     

贮藏温度和包装方法对两种叶菜采后品质的影响

对两种典型叶类蔬菜进行适宜贮藏条件及包装方式的研究。以菠菜和芹菜为试验材料,比较两种冷藏条件(4℃和9℃)、两种包装方式(薄膜包装和气调包装)对贮藏过程中理化(失重率、叶绿素含量、VC含量和亚硝酸盐含量等)和感官等品质指标及货架期的影响。结果表明,在一定范围内,菠菜和芹菜在低温和气调下贮藏的感官品质(外观和颜色)、内部品质(鲜重、叶绿素含量、VC含量和亚硝酸盐含量)均效果较好。4℃结合气调包装相对薄膜包装可以有效抑制叶绿素的分解、感官品质的下降和亚硝酸盐含量的增加,减少营养成分的损失,延长菠菜和芹菜的货架寿命4～10d左右,但薄膜包装能有效抑制失重率增加。     

Influence of Cooking Methods on Antioxidant Activity of Vegetables

ABSTRACT:  The influence of home cooking methods (boiling, microwaving, pressure-cooking, griddling, frying, and baking) on the antioxidant activity of vegetables has been evaluated in 20 vegetables, using different antioxidant activity assays (lipoperoxyl and hydroxyl radicals scavenging and TEAC). Artichoke was the only vegetable that kept its very high scavenging-lipoperoxyl radical capacity in all the cooking methods. The highest losses of LOO· scavenging capacity were observed in cauliflower after boiling and microwaving, pea after boiling, and zucchini after boiling and frying. Beetroot, green bean, and garlic kept their antioxidant activity after most cooking treatments. Swiss chard and pepper lost OH· scavenging capacity in all the processes. Celery increased its antioxidant capacity in all the cooking methods, except boiling when it lost 14%. Analysis of the ABTS radical scavenging capacity of the different vegetables showed that the highest losses occurred in garlic with all the methods, except microwaving. Among the vegetables that increased their TEAC values were green bean, celery, and carrot after all cooking methods (except green bean after boiling). These 3 types of vegetables showed a low ABTS radical scavenging capacity. ccording to the method of analysis chosen, griddling, microwave cooking, and baking alternately produce the lowest losses, while pressure-cooking and boiling lead to the greatest losses; frying occupies an intermediate position. In short, water is not the cook's best friend when it comes to preparing vegetables.     

Effects of some technological processes on glucosinolate contents in cruciferous vegetables

Effects of blanching, boiling and freezing of selected cruciferous vegetables (Brussels sprouts, white and green cauliflower, broccoli, and curly cale) on their glucosinolate (GLS) contents were determined. It was found that blanching and cooking of the vegetables led to considerable (P < 0.05) losses of total GLS, from 2.7 to 30.0% and from 35.3 to 72.4%, respectively. No systematic changes in total GLS were found in the vegetables that were blanched and frozen for 48 h. In addition, the highest concentration of cancer-protective compounds, such as aliphatic and indole GLS, were found in Brussels sprouts (sinigrin and glucobrassicin) and in broccoli (glucoraphanin).     

Antioxidant capacities and total phenolic contents of 56 vegetables

The antioxidant capacities and total phenolic contents of lipophilic and hydrophilic extracts of 56 commonly consumed vegetables were studied. The resulted showed that antioxidant capacities and total phenolic contents in the lipophilic fraction were higher than those in hydrophilic fraction. The different vegetables had diverse antioxidant capacities. The highest antioxidant capacities and phenolic contents were found in Chinese toon bud, loosestrife, perilla leaf, cowpea, caraway, lotus root, sweet potato leaf, soy bean (green), pepper leaf, ginseng leaf, chives, and broccoli, while the values were very low in marrow squash and eggplant (purple). Furthermore, several phenolic compounds were detected, and chlorogenic acid, gallic acid and galangin were widely found in these vegetables. The results provide support for dietary guidelines as well as epidemiological research.     

β-Carotene and Ascorbic Acid Retention in Fresh and Processed Vegetables

Broccoli, carrots, and green beans (grown in 2 consecutive years) were randomly divided into 3 treatments: fresh-refrigerated (F-R), frozen (FZ) or canned (C) (carrots only). FZ or C vegetables were processed within 24 h and stored for up to 1 yr. F-R vegetables were held at 4 °C for 3 wk (broccoli and green beans) or 6 mo (carrots). Trans b-carotene (Tb-C) and total ascorbic acid (AA) were determined at specified times, before and after microwave cooking. Vitamin content differed between years due to environmental conditions. Blanching resulted in AA loss, but retention remained stable after freezing broccoli and green beans. F-R green beans lost >90% AA after 16 d storage. Linear decreases in AAwere found in most F-R or FZ vegetables. Tb-C decreased slightly during freezer storage. Reductions in Tb-C occurred in canned carrots. Microwave cooking had minimal effects on AA or Tb-C.     

A Cooling System with Water Recycle for Blanched Vegetables

A water conserving cooling system with water recycle for blanched vegetables was designed to complement a previously developed water recycling blancher. The two stage cooler consisted of an evaporative cooling section with forced air and water sprays and a flume cooler with water, which was both refrigerated and recycled. A pilot scale blanching and cooling system was constructed, and broccoli spears were processed. The cooling system was effective at lowering the product temperature rapidly while maintaining the quality of the product at a high level as determined by ascorbic acid concentration, percentage of total solids, percentage of retained chlorophyll, and microbial counts.     

茉莉酸甲酯处理对模拟运输振动圆椒贮藏品质的影响

圆椒营养丰富但质地脆嫩,在运输过程中容易受到振动引起的机械损伤。本实验探究了20 μmol/L的茉莉酸甲酯(methyl jasmonate,MeJA)对模拟运输振动后的圆椒在常温条件(20±1) ℃下贮藏的保鲜效果,对圆椒在贮藏期间的感官评分、硬度、呼吸强度、失重率以及圆椒可溶性固形物(SS)、维生素C(V_C)和叶绿素的含量进行了测定。结果表明:振动损伤会加速圆椒贮藏期间品质的下降;20 μmol/L的MeJA能较好的维持振动后圆椒的感官品质,抑制圆椒硬度的下降及失重率的上升,保持较低的呼吸强度,延缓圆椒SS、V_C及叶绿素含量的下降,有效保持了振动后圆椒的外观品质和营养价值,减少圆椒的逆境胁迫损伤,延长其货架期。     

Reprocessing effect on the quality of domestically cooked (boiled/stir-fried) frozen vegetables

This was a study of the effect on quality parameters of reprocessing (blanching at 97 °C for increasing times+freezing) prior to domestic cooking (boiling or stir-frying) of frozen green peas (cv. Mastim) and beans (cvs. Paloma and Moncayo). The results were compared with those of frozen control samples directly boiled or stir-fried. Kramer shear was the most suitable mechanical test for evaluating the effect of reprocessing on mechanical behaviour in both boiled and stir-fried frozen vegetables. Reprocessing significantly affected the mechanical behaviour of both green bean varieties with both cooking methods. Reprocessed products were softer than those supplied by the industry, and softening was significantly greater the longer the blanching time. The colour was more uniform and homogeneous in boiled than in stir-fried reprocessed vegetables; colour parameters showed that reprocessing affected the colour of stir-fried samples more significantly than that of boiled samples. In all the studied vegetables, less chlorophyll and more ascorbic acid were retained when samples were stir-fried than when they were boiled, although chlorophyll and ascorbic acid decreased with increasing reprocessing time in both cooking methods. In the two frozen green bean varieties in particular, SEM microphotographs confirmed the results of mechanical tests, indicating that with both cooking methods, the mechanical parameters were lower in the reprocessed samples than in the controls. The shortest reprocessing procedure (blanching at 97 °C for 2, 3 min+freezing), as a compromise among quality parameters, could shorten the time required for domestic stir-frying of frozen green peas and boiling or stir-frying of frozen green beans.     

VITAMIN C AND β-CAROTENE IN FRESH AND FROZEN GREEN BEANS AND BROCCOLI IN A SIMULATED SYSTEM

The reduced ascorbic acid and β-carotene contents of “retail market-fresh” (RMF) and “fresh-frozen” (FF) green beans and broccoli in a simulated handling system were determined. Changes in ascorbic acid content in the two vegetables during a retail market period and frozen storage followed different patterns. In green beans, ascorbic acid content decreased during refrigerated storage for up to 7 days, but in broccoli there was a significant increase. Blanching resulted in a loss of approximately 40% of the ascorbic acid in broccoli. Ascorbic acid content of FF green beans stored at-20C for 16 weeks was approximately twice that in RMF green beans, but in FF broccoli stored under the same conditions it was only about half that of RMF broccoli. β-carotene content of green beans and broccoli did not change during either the retail market simulation of frozen storage and did not differ from that of fresh.