北京地区主要菠菜品种贮藏性的比较分析

为研究北京地区不同菠菜品种的贮藏性差异,选取具有代表性的5个品种:抗病王、农大菠杂1号、菠杂10号、先锋、日本大叶,测定其相关指标:感官评价、失重率、电导率、维生素C含量、叶绿素含量、过氧化物酶(POD)活性、多酚氧化酶(PPO)活性。记5分为商品性界限值,第11 d时,只有农大菠杂10号感官评价不低于5分,日本大叶第7 d的感官评分为5,失去商品性,日本大叶的失重率最大,为23.14%,农大菠杂1号的失重率最小,为10.78%,维生素C的含量减少最多的是日本大叶,为75.26%,减少最少的是农大菠杂1号,为52.74%。综合评价各项指标,5个不同品种菠菜耐贮藏性好坏的顺序依次为:农大菠杂1号菠杂10号日本大叶抗病王先锋。     

真空预冷压力对菠菜采后贮藏保鲜品质的影响

为探究真空预冷压力对菠菜采后贮藏品质的影响,将菠菜分别置于600、800和1000 Pa真空预冷压力下冷却至4℃,然后于（4±1）℃贮藏15 d。以常压冷藏样品为对照,通过分析菠菜贮藏期间的感官品质、色差、失重率、维生素C、叶绿素和酶活变化,研究真空预冷压力对菠菜采后贮藏品质的影响。结果表明,真空预冷处理可有效延缓菠菜贮藏过程中感官品质的劣变,降低失重率和V_C、叶绿素等成分损失,抑制色泽变化,抑制过氧化氢酶（Catalase,CAT）活力下降和过氧化物酶（Peroxidase,POD）活性升高。综合来看,1000 Pa预冷压力处理组菠菜的贮藏品质最优。     

真空预冷终温和补水率对菠菜采后贮藏品质影响

为研究真空预冷条件对叶菜采后保鲜效果的影响,选择菠菜为试材,考察在贮藏温度4℃,预冷终温为0℃和4℃,补水率分别为0%, 1%和2%(w/w)不同真空预冷条件下,菠菜的失重率、营养品质(叶绿素、维生素C、可溶性固形物含量)及感官品质(色泽、形态、质地)在贮藏期的变化规律。结果表明,经真空预冷终温4℃处理的保鲜效果优于对照组,能更有效降低菠菜失重率,保持其感官品质。真空预冷处理以预冷终温4℃,补水率2%条件下贮藏保鲜效果最优。     

不同气调包装对薄荷贮藏品质的影响及薄荷保鲜呼吸速率模型的建立

为了提高薄荷采后贮藏时间和预测薄荷采后的呼吸速率,通过失重率、相对电导率、色差、感官评分、维生素C含量、总叶绿素含量和菌落总数指标的测定,从包装材料为聚乙烯包装(PE)、邻苯基苯酚复合聚乙烯包装(OPP1.8/PE3.5、OPP1.8/PE4.5、OPP2.3/PE4.5)、高密度聚乙烯包装(HDPE),O₂浓度为3%～7%,CO₂浓度为5%～15%中筛选薄荷的气调包装条件,并以O₂、CO₂和包装材料为因素开展响应面优化试验,优化薄荷采后保鲜的最优气体比例及包装材料,在此基础上研究薄荷挥发性化合物和表面真菌多样性。使用密闭空间系统法测量薄荷在最优包装材料内O₂和CO₂的比例。在此基础上,再采用渗透系统法得到模型方程,并对其进行数值模拟。运用Matlab软件对处于平衡点时的呼吸速率进行计算,利用二次多项式模型对结果进行回归分析。利用高通量测序对最优、最差和对照处理组的薄荷进行测序和分析,比较其优势菌群的占比变化。结果表明：最优气调比例及包装材料为3.5%O<...     

包装膜透气性对韭黄MAP冷藏保鲜效果的影响

为探讨包装膜透气性对低温（1±0.5℃）下韭黄短期自发气调（MAP）贮藏效果的影响,本文测试了5种梯度氧气（O₂）和二氧化碳（CO₂）透过率的聚乙烯薄膜包装袋包装后韭黄在贮藏过程中感官指标、腐烂指数、包装袋内气体成分、相对电导率、组织含水率、丙二醛、可溶性糖和抗坏血酸的变化情况。结果表明,O₂和CO₂气体透过率分别为（4623±834） cm3/m2·24 h·0.1 MPa和（18033±3356） cm3/m2·24 h·0.1 MPa的聚乙烯包装袋MAP处理后,贮藏至28~42 d时包装袋内O₂和CO₂含量维持在11.67%~13.67%和2.43%~3.45%相对平稳状态,使用此包装袋能延缓贮藏过程中韭黄腐烂指数、相对电导率和丙二醛含量的上升,减缓感官指标、组织含水率、可溶性糖和抗坏血酸含量的下降,该包装膜可作为适宜的MAP处理材料结合冷藏技术延长韭黄采后保鲜期。     

1-MCP结合二氧化氯处理对青椒货架期品质的影响

为研究青椒货架期品质保鲜新技术,延长货架期,于室温(25±1)℃贮藏条件下,分别用1-MCP(1 mg/L)、1-MCP(1 mg/L)和ClO₂(30 mg/L)联用对青椒进行熏蒸处理,定期测定相关的指标,包括腐烂率、转红率、硬度、失重率、V_C含量、叶绿素含量、还原糖含量等。结果发现:1-MCP单独处理以及1-MCP结合ClO₂处理在青椒贮藏保鲜过程中均起到良好的效果,但1-MCP结合ClO₂处理比1-MCP单独处理更能有效保持青椒贮藏过程中的品质,抑制青椒的腐烂、失重和转红,延缓叶绿素的降解速率。货架期结束时,对照组中腐烂率是1-MCP+ClO₂处理组(3.33%)的5倍;V_C含量、还原糖和叶绿素含量分别高于对照27.40%、44.31%、20%。在整个贮藏期间,1-MCP结合ClO₂处理的果实硬度仅下降了6.70%。结果表明,1-MCP结合ClO₂处理可以有效延缓青椒的采后生理变化,保持青椒的品质。     

呼吸调控下的细胞膜完整性对仔姜贮藏失水的影响

通过比较包装与否对高水分仔姜贮藏失水的影响,探究裸露仔姜即使在高湿冷库贮藏依然失水严重的原因及包装控制呼吸从而抑制失水的机制。设置未包装相对湿度(relative humidity, RH)60%组、未包装RH95%组、包装[30μm双向拉伸聚丙烯薄膜(biaxially oriented polypropylene, BOPP)] RH60%组12℃下贮藏仔姜12 d,每2 d测定其感官、气体成分、呼吸强度、硬脆度、失重率、相对电导率、丙二醛含量、活性氧及相关酶活性等指标。结果表明,12 d后未包装RH60%组、未包装RH95%组、包装(30μm BOPP)RH60%组的失重率分别为47.8%、21.0%、2.5%,即包装处理能显著减少失重率的上升,并保持较高硬脆度且有良好的感官得分。同时包装能营造低O₂高CO₂环境,降低呼吸速率,从而抑制了·O₂^-及H₂O₂等活性氧的上升,且其低呼吸速率也增强了抗氧化酶(过氧化氢酶、过氧化物酶、超氧化物歧化酶)的活性,...     

风干鲫鱼制品在加工过程中的品质研究

作者以菠菜为原材料,研究延迟预冷对菠菜冷链流通过程中营养和品质的影响。将新鲜菠菜分别放置0、1、5、9 h后,压差预冷至4 ℃,有膜和无膜包装分别在4 ℃下运输、销售,家庭冷藏保鲜各2 d,测定营养和品质的变化。结果表明：菠菜4 ℃冷链流通6 d后,延迟预冷0 h有膜包装营养和品质最佳,感官评价为7.2,失重率为4.25%,维生素C、叶绿素、可溶性蛋白质量分数分别为4.66 mg/hg、0.73 mg/g和0.35 mg/g。因此,菠菜采后应在1 h内进行田间预冷,同时结合防雾膜包装进行4 ℃菠菜冷链流通可较好地保持菠菜采后新鲜度和贮藏品质。     

真空预冷结合不同贮藏压力对韭菜品质的影响

真空预冷技术应用于韭菜的预处理,研究了不同贮藏压力(绝压2、6、10 kPa和常压)对韭菜感官评价、呼吸强度、叶绿素含量、失重率的影响。结果表明:贮藏压力越低,韭菜呼吸强度越弱,货架期越长,韭菜在常压条件下的呼吸强度是2 kPa条件下的4.89倍;随着贮藏压力的升高,韭菜的失重率和呼吸强度逐渐升高,而韭菜的感官评价和叶绿素含量逐渐降低;贮藏在2kPa的韭菜品质保持最好,夏季贮藏14 d后的感官评价、呼吸强度、叶绿素含量和失重率分别为8.2、23.6 mg CO_2/kg·h、28 mg/100 g Fw、1.2%。     

冬枣采后生理与气调贮藏关键技术研究

该文研究气调贮藏对冬枣采后生理及贮藏品质的影响,延长冬枣贮藏期。以陕西阎良冬枣为试验材料,采用气流法测定呼吸强度,研究冬枣的呼吸类型。在贮藏温度(0±0.5)℃、相对湿度90%～93%的条件下,分别采用0%CO₂+10%O₂+90%N₂、1%CO₂+10%O₂+89%N₂、2%CO₂+7%O₂+91%N₂、0%CO₂+21%O₂+79%N₂四种气体配比贮藏冬枣,每10 d用配制的气体换气1次。贮藏期间分别测定冬枣抗坏血酸、可滴定酸、还原糖含量和过氧化物酶、多酚氧化酶和苯丙氨酸解氨酶的活性,贮藏到120 d计算商品果率、失重率和硬果率,并进行感官鉴评,研究不同气体配比对冬枣采后生理及贮藏品质的影响。研究结果表明冬枣为呼吸跃变型果实,贮期抗坏血酸、可滴定酸含量均表现为不同程度的下降趋势,还原糖含量、过氧化物酶、多酚氧化酶和苯丙氨酸...     

鲜切菠菜和香菜专用自发气调包袋的研制

为满足鲜切菠菜和香菜包装的需求,本文采用不同透气率和不同面积的气调窗与包装袋相结合进行试验,分别研制出鲜切菠菜和香菜最适宜的气调包装(MAP)袋。结果表明:鲜切菠菜和香菜都适宜选用O₂和CO₂透过速率分别为4×105和1.6×106 cm3/m2·d·atm的气调窗,所需要气调窗的面积均为5~7.5 cm2/kg;综合计算气调窗和薄膜的透气量可知,适于鲜切菠菜和香菜包装袋的O₂和CO₂的透过量应分别为3.17×103~3.74×103和1.42×104~1.65×104 cm3/kg·d·atm,袋内气体稳定后,鲜切菠菜的O₂和CO₂分别为7.34%~8.30%和5.31%~5.49%,鲜切香菜的O₂和CO₂分别为3.96%~7.16%和4.89%~6.52%,在4 ℃条件下此类型的包装袋均可延长货架期6 d以上。研制的自发气调包装袋可使鲜切菠菜和香菜处于适宜的气体状态,很好地避免包装袋内由于无氧呼吸产生的异味问题,且保留原有的鲜切产品气味,延长其货架期,为鲜切企业提供有力的技术支持。     

包装膜特性对菠菜品质的影响

探究不同特性PE膜包装对菠菜贮藏期间生理特征,营养价值以及感官品质的影响。采用4种不同特性的PE膜对菠菜进行包装,4±1℃条件下贮藏12 d,每隔3 d测定菠菜的袋内顶空气体组分、呼吸速率、失重率、腐烂率、颜色变化、叶绿素含量及VC含量的变化。采用主成分分析法对所测定指标进行综合分析。结果表明,PE3相对于其余3种不同膜特性的PE膜,可以明显降低失重率、腐烂率,较好的维持叶绿素含量和VC含量,可以很好地维持菠菜的品质。     

不同包装方式对香酥虾球品质的影响

为研究不同包装方式对香酥虾球（crispy shrimp balls）贮藏过程中品质的影响,以聚乙烯尼龙（PE/PA）作为包装材料,采用普通热封包装、气调包装（100% N₂、70% N₂+30% CO₂、50% N₂+50% CO₂、30% N₂+70% CO₂、100% CO₂）和真空包装7种包装方式,测定不同贮藏时间下香酥虾球的感官评分、脂质、蛋白质和微生物指标的变化,确定香酥虾球的最佳包装方式,同时,采用电子鼻/舌和气相色谱-质谱联用技术（GC-MS）对最佳包装方式下香酥虾球贮藏过程中的风味品质变化进行研究。结果表明,在贮藏过程中,30% N₂+70% CO₂气调包装组和100% CO₂气调包装组的过氧化值、羰基价、丙二醛含量、蛋白质羰基含量和菌落总数均低于其他组,感官评分和蛋白质巯基含量则均高于其他组（P<0.05）。随着CO₂浓度增加,香酥虾球的品质劣变速率降低,但100% CO₂气调包装组在贮藏30 d后存在塌瘪现象。因此,最佳包装方式为30% N₂+70% CO₂的气调包装。在最佳包装方式下（30% N₂+70% CO₂气调包装）,香酥虾球贮藏过程中的风味成分变化明显,贮藏30 d后香酥虾球中的醇类、醛类、含氮硫类及含氧类的挥发性种类及含量总量显著（P<0.05）增加。新鲜和贮藏30 d香酥虾球的挥发性风味物质分别有39种和57种,新鲜香酥虾球中甲酸乙烯酯、环丁醇、3,4-癸二烯和3,3-二苯基-5-甲基吡唑含量较高,贮藏30 d后香酥虾球中甲酸乙烯酯、2-异氰基-环己醇（反式）、3-环己基丙醇、（E,E）-2,4-十二烷醛、柠檬醛、2-异氰基-2,4,4-三甲基戊烷和2,3-环氧丁烷含量较高。本研究表明30% N₂+70% CO₂的气调包装可以有效减缓香酥虾球的品质劣变。     

微环境气调对冰温贮藏下蓝莓果实品质及挥发性成分的影响

为了明确不同气体微环境对冰温贮藏蓝莓品质和挥发性成分的影响,以‘莱克西’蓝莓为试材,研究不同的气体微环境在冰温贮藏（?0.5±0.3 ℃）0~80 d期间果实品质和挥发性成分的变化。结果表明,在贮藏期间,3种不同的气调环节中,O₂变化范围分别为15.4%~18.2%、13.1%~15.9%和6.1%~13.4%,CO₂变化范围分别为2.2%~4.5%、4.5%~8.8%和8.8%~14.8%。与对照相比,微环境气体调控延缓了蓝莓果实的营养物质（V_C、花色苷和可滴定酸）和硬度的下降,保持了较低的腐烂率和较高的果霜覆盖指数,还能够抑制醛类物质生成,促进萜类物质的生成。其中,O₂含量维持在6.1%~13.4%,CO₂含量维持在8.8%~14.8%的气体微环境对蓝莓贮藏的效果最佳,有利于蓝莓果实的长期贮藏。     

不同自发气调包装膜对鲜食大豆保鲜效果的比较

为筛选适于鲜食大豆采后贮藏保鲜的自发气调保鲜包装材料,研究微孔膜和不同厚度聚乙烯（polyethylene,PE）膜包装对鲜食大豆在冷藏（0.0±0.2） ℃期间采后生理及品质变化规律。结果表明：与微孔膜相比,PE膜包装对鲜食大豆具有更好的自发气调保鲜效果,O2体积分数平衡值为16%～17.5%,CO2体积分数平衡值为4.3%～5.8%时,能够更有效地抑制呼吸作用,延缓腐烂进程,降低质量损失率,抑制叶绿素的降解,保持鲜食大豆的水分和色泽。采用0.03 mm和0.05 mm PE膜包装的鲜食大豆无腐烂保鲜期达50 d,鲜食大豆腐烂率比微孔膜包装降低11%。综合来看,0.03 mm PE膜包装鲜食大豆的保鲜效果最好,适合于鲜食大豆贮藏流通过程中的保鲜。     

包装材料对高氧气调包装冷鲜肉品质变化的影响

气调包装能有效延长冷却肉的货架期,但是不同阻隔性的包装材料对冷却肉的保质期影响差异显著,因此选用3种不同阻隔性的包装材料,对冷鲜肉进行高氧气调包装(35% CO2、65% O2),测定冷鲜肉在贮藏期的菌落总数、大肠菌群、色泽、挥发性盐基态氮、汁液流失率和pH值等指标,观察不同阻隔性的材料对冷却肉货架期品质的影响。结果表明：高氧包装条件下,高阻隔材料包装的冷却肉在贮存10d菌落总数已经超标,pH值在贮存期内处于二级鲜肉的范围内;中阻隔包装材料包装的冷却肉菌落总数对数值在保质期内未超过6(lg(CFU/g)),但是肉色保持的较好,感官评价相对较好,但是汁液流失较大;低阻隔包装材料低阻隔性的包装材料菌落变化最大,13d时菌落总数对数值达到6.46(lg(CFU/g)),肉的色泽相对较差,气味和总体可接受性也较差,因此,中阻隔性包装材料效果较好。     

Sensory Characteristics of Fresh-Cut Spinach Preserved by Combined Factors Methodology

Fresh‐cut spinach was treated with citric acid and ascorbic acid solutions and packaged in monooriented polypropylene (OPP) bags or low density polyethylene (LDPE) bags. Sensory attributes, chlorophyll retention, and weight loss were evaluated throughout refrigerated storage. Mathematical models were developed to analyze and predict the effect of the citric acid and ascorbic acid concentrations and storage time on off‐odor development, general appearance, wilting, browning, and color. Sensory attributes of fresh‐cut spinach decreased with storage time. Type of film affected off‐odor development, but did not influence visual sensory attributes. Chemical treatment and type of packaging film did not affect chlorophyll retention. Both types of packaging film controlled weight loss.     

Effect of gas barrier characteristics of films on aflatoxin production by Aspergillus flavus in peanuts packaged under modified atmosphere packaging (MAP) conditions

The effects of the gas barrier characteristics of three films (ASI, ASII and ASIII) and storage temperature on the growth of, and aflatoxin production by, Aspergillus flavus in peanuts packaged in air and under a modified gas atmosphere of CO₂:N₂ (65:35) were investigated. Mold growth was barely visible in air packaged peanuts using high-medium barrier films (ASI and ASII) and stored at 20°C with more extensive growth occurring in air packaged peanuts stored at 25 and 30°C. Extensive mycelial growth and sporulation occurred in all air packaged peanuts in a low barrier film (ASIII), especially at 30°C. Gas packaging inhibited mold growth in peanuts packaged in a high gas barrier film at 20°C. However, mold growth occurred in gas packaged peanuts packaged in film ASII at higher storage temperatures while extensive mycelial growth was observed in all peanuts packaged in film ASIII irrespective of storage temperature. Levels of aflatoxin greater than the regulatory limit of 20 ng/g were detected in all air packaged peanuts with the highest level of aflatoxin (76 ng/g) being detected in peanuts packaged in a high gas barrier film ASI. Aflatoxin production was inhibited in gas packaged peanuts using a high barrier film. However, higher levels of aflatoxin were detected in all gas packaged peanuts in medium-low gas barrier films (ASII and ASIII), particularly at higher storage temperatures. This study has shown that MAP using a CO₂:N₂ (65:35) gas mixture was effective in controlling aflatoxin production by A. flavus in peanuts to levels less than the regulatory limit of 20 ng/g. However, the antimycotic effect of low O₂-high CO₂ atmospheres is dependent on the gas barrier characteristics of the packaging films, especially at higher storage temperatures.     

QUALITY CHANGES IN FRESH‐CUT SPINACH (SPINACIA OLERACEA) UNDER MODIFIED ATMOSPHERES WITH PERFORATIONS

ABSTRACT

Fresh‐cut spinach leaves were stored for 4 days at 15C and 75% relative humidity under modified atmosphere packaging to assess the impact of differential in‐pack gas atmospheres generated through different packaging films and variable in‐pack weight on the quality of stored produce. After 4 days of storage, retention of chlorophyll, β‐carotene and ascorbic acid was better in low‐density polyethylene (LDPE) packages than in polypropylene (PP) packages. LDPE film‐packaged samples had higher phenolic content than PP film‐packaged samples. Low in‐pack O₂ (1–2 kPa) along with the buildup of CO₂ (8–10 kPa) seems to have enhanced the retention of antioxidant components, i.e., β‐carotene and ascorbic acid, in LDPE packages. This helped in chlorophyll retention and also prevented formation of oxidation compounds of phenols that otherwise caused browning of cut surfaces. Thus, O₂ and CO₂ permeability of packaging film or in‐pack weight of produce might be such that equilibrated O₂ partial pressures remain near to 1–2 kPa so as to affect a beneficial increase in the phenolic content along with concomitant retention of chlorophyll.

PRACTICAL APPLICATIONS

Fresh‐cut spinach leaves have received an enormous demand due to their utility in various traditional Indian preparations. Shelf life and quality of fresh‐cut produce may be greatly reduced due to high rates of respiration. Traditional packaging and handling techniques reduce the shelf life and sensory quality of fresh‐cut spinach. Temperature control and atmospheric modifications help to maintain produce quality by reducing respiration rate and enhance shelf life by minimizing the adverse effects of cutting. This research focused on evaluation of respiratory behavior of fresh‐cut spinach leaves at a temperature commonly encountered during transportation and retail distribution, i.e., 15C, and the effect of different polymeric films and in‐pack weights on produce quality. The results of the study suggest that packaging of fresh‐cut spinach in polymeric film packages could maintain the sensory quality and reduce degradation of various physicochemical constituents. Utilization of the results for proper design of modified atmosphere packages for this highly perishable produce can prove to be extremely beneficial for safe storage and transportation to urban retail markets.