大豆分离蛋白／淀粉复合涂膜对白蘑菇贮藏品质的影响

该研究利用大豆分离蛋白／淀粉复合膜液对白蘑菇进行涂膜保鲜,测定不同保藏时期白蘑菇的呼吸强度、失重率、多酚氧化酶（PPO）活性、开伞率等指标。试验结果表明,大豆分离蛋白／淀粉复合膜液对白蘑菇的涂膜能够明显地提高白蘑菇的贮藏品质。     

一氧化氮对双孢蘑菇采后生理及贮藏品质的影响

以硝普钠（SNP）为一氧化氮供体,研究了不同浓度NO在常温（25±1℃）和低温（4±1℃）条件下对双孢蘑菇‘F56’贮藏过程中相关品质（失重率、开伞率、可溶性固形物、维生素C（Vc）、游离氨基酸含量）以及过氧化氢酶（CAT）、过氧化物酶（POD）和多酚氧化酶（PPO）活性的影响。结果表明,0.09 mmol/L SNP释放的NO显著抑制了双孢蘑菇采后失重率和游离氨基酸含量的上升,减缓了可溶性固形物含量的增加、延缓Vc的降解,抑制了开伞率的增大;使CAT、POD的活性显著增强,同时降低PPO活性。因此,0.09mmol/L SNP处理显著提高了常温和低温下双胞蘑菇‘F56’ 贮藏期间的CAT、POD活性,抑制了PPO活性的升高,延缓了菇体品质的下降。     

低温气调贮藏下CO_2含量对双孢蘑菇品质的影响

探讨双孢蘑菇采后贮藏适宜的CO_2体积分数,减少双孢蘑菇贮藏过程中腐败变质的发生,为双孢蘑菇采后贮藏保鲜提供理论依据。在5℃低温和95%相对湿度的低温冷库中,经过不同CO_2体积分数的贮藏,研究其对双孢蘑菇失质量率、硬度、白度、可溶性固形物、呼吸速率和酶活性等指标的影响。结果表明,在贮藏过程中,随着CO_2体积分数的升高,延缓了失质量率的上升和硬度的下降,能显著(p0.05)抑制双孢蘑菇的呼吸速率,使可溶性固形物和酶活性变化缓慢。CO_2体积分数为20%时,能有效抑制双孢蘑菇呼吸速率、多酚氧化酶(PPO)和过氧化物酶(POD)活性的上升,并且在减缓双孢蘑菇硬度、白度、可溶性固形物下降方面效果最好,能极显著(p0.01)地延缓硬度和可溶性固形物的下降。     

气调包装对蘑菇采后品质特性的影响

采用0.04mm PE膜对蘑菇进行气调包装,以空气包装作对照,对贮藏期间在5℃条件下,袋内O2、CO2浓度的动态变化及其对蘑菇呼吸速率、成熟度(开伞率)、表面颜色、失重率、硬度、pH值、维生素C等品质特性的影响进行研究.结果表明,气调包装能有效地降低蘑菇呼吸速率,延缓成熟,抑制开伞.     

油茶粕保鲜膜贮藏保鲜砂梨的应用研究

包膜处理砂梨,对比分析了油茶粕保鲜膜的贮藏保鲜效果。结果表明,随着贮藏时间的延长,砂梨中有机酸含量、还原糖含量及可溶性固形物逐渐下降,失重率提高,多酚氧化酶(PPO)和过氧化物酶(POD)酶活下降,但用包膜处理的梨这些指标下降速度和失重率增加远低于未用包膜处理的砂梨。油茶粕提取物添加的保鲜膜能明显减缓有机酸含量、还原糖含量及可溶性固形物的下降和失重率的增加速度,也能明显降低PPO和POD酶活。油茶粕提取物添加的保鲜膜对砂梨的贮藏保鲜起到促进作用。     

蘑菇采后保鲜技术研究进展

蘑菇属呼吸跃变型,贮藏过程中存在的问题主要有营养成分含量快速下降、失水、褐变、开伞、腐烂等。通过分析近年来国内外对蘑菇保鲜的研究状况,以便为进一步研究蘑菇提供理论参考。     

葛根加工过程中酶促褐变及其护色效果研究

为有效控制新鲜葛根加工过程中发生的酶促褐变,研究了新鲜葛根中多酚氧化酶(PPO)的部分酶学性质,包括PPO的最适pH值、最适温度、热稳定性等,以及不同化学抑制剂对PPO的抑制效果。结果表明,葛根PPO的最适pH值为4.4,最适温度为55℃;在90～100℃下热处理1～3min,可使该酶基本失活,质量分数1.5%的氯化钠,0.75%的柠檬酸和0.3%的氯化钙配成的复合护色液,对葛根PPO活性具有较强的抑制作用。加工过程中,采用复合护色液对切分成型后的葛根半成品进行护色处理,可使其维持原有组织的洁白色泽。     

莴笋多酚氧化酶的酶学特性研究

采用分光光度法测定莴笋多酚氧化酶(PPO)活性,考察底物特异性、pH值、温度、热稳定性、底物浓度、金属离子及抑制剂对PPO酶活特性的影响,研究莴笋PPO酶学特性。结果表明,莴笋PPO的最适底物为邻苯二酚,最适pH值5.0,最适温度25℃;90℃热处理60 s莴笋PPO酶活基本完全丧失;莴笋PPO最适底物浓度为0.10 mol/L,PPO酶促褐变反应动力学符合米氏方程,相应的动力学参数Km=0.667 mol/L,Vmax=826.4 OD/min;Mg2+、Ca2+、Mn2+、Zn2+对PPO酶活有一定的的抑制作用,Cu2+和Fe3+对PPO酶活有一定的促进作用;五种抑制剂对抑制莴笋PPO酶活力均具有一定的作用,且抑制作用随抑制剂浓度的增大而加强,试验范围内抑制作用由强到弱依次为:抗坏血酸L-半胱氨酸Na HSO3柠檬酸EDTA,抗坏血酸对莴笋PPO酶活的抑制效果最佳。     

大豆分离蛋白涂膜处理对库车小白杏冷藏保鲜效果

采用大豆分离蛋白对库车小白杏进行涂膜处理,通过测定贮藏期小白杏腐烂率及相关品质指标的变化,评价小白杏的保鲜效果。结果表明,大豆分离蛋白涂膜处理能降低小白杏的腐烂率,保持小白杏的硬度,抑制呼吸强度,延缓可溶性固形物(TSS)、可滴定酸(TA)和VC的降解,保持其感官品质,达到延长贮藏期的目的。综合考虑,添加质量分数6%大豆分离蛋白涂膜处理的保鲜效果最佳。     

1-MCP处理对黄秋葵果实采后品质的影响

为探讨1-MCP处理黄秋葵对其保鲜效果影响的最佳浓度,以黄秋葵为试验原料,分别用有效成分为0,0.4,0.8,1.2μL/L的1-MCP粉剂溶液对黄秋葵熏蒸24 h,于4℃下冷藏,测定其失质量率、叶绿素和木质素含量、PPO和CAT酶活力。结果表明,低浓度1-MCP处理能有效保持黄秋葵在贮藏过程中的品质,可以适当延长货架期。其中,0.4μL/L 1-MCP处理黄秋葵保鲜效果最好,为商业生产中黄秋葵贮藏保鲜提供了一定的理论依据。     

Effects of UV-C treatment on inactivation of Escherichia coli O157:H7, microbial loads, and quality of button mushrooms

This study investigated the effects of ultraviolet-C (UV-C) light applied to both sides of mushrooms on microbial loads and product quality during storage for 21 d at 4 °C. Microflora populations, color, antioxidant activity, total phenolics, and ascorbic acid were measured at 1, 7, 14 and 21 d of storage. Additionally, the inactivation of Escherichia coli O157:H7 by UV-C was determined. Results showed that UV-C doses of 0.45-3.15 kJ m⁻² resulted in 0.67-1.13 log CFU g⁻¹ reduction of E. coli O157:H7 inoculated on mushroom cap surfaces. UV-C radiation also reduced total aerobic plate counts by 0.63-0.89 log CFU g⁻¹ on the surface of mushrooms. Although mushrooms treated with UV-C had more severe browning with increasing dosage after initial treatment, the control mushrooms also browned as indicted by lower L* and higher a* values after 21 d of storage at 4 °C. In addition, the UV-C treatments apparently inhibited lesion development on the mushroom surface. During the first 7 d, irradiated mushrooms had lower antioxidant activity, total phenolics, and ascorbic acid content compared to non-radiated samples. However, irradiated mushrooms reached similar amounts of these nutrients as the control after 14 d of storage at 4 °C. In summary, UV-C radiation could potentially be used for sanitizing fresh button mushrooms and extending shelf-life.     

Differences in susceptibility of Agaricus bisporus strains to bacterial blotch and in natural cap colour related to compost composition

The influence of cultivation substrate (compost) quality as an environmental factor was determined on three traits of interest in the selection of Agaricus bisporus strains. Induced variations in compost nitrogen and copper content were used to modify compost quality. Compost effect and strain × compost interaction were found to be significant for bacterial blotch susceptibility, natural cap colour and yield. Two classes of strain not affected by compost quality were identified in a group of commercial and wild strains: white mushrooms susceptible to bacterial blotch and brown resistant mushrooms. The relation between compost composition quality and mushroom quality traits are specific for each group of strain. Nitrogen and copper content of composts were of interest as indicators of compost quality but other factors have to be evaluated for better compost characterization.     

Influence of modified atmosphere packaging on sensory quality of shiitake mushrooms

Shiitake mushrooms (Lentinus edodes) were packaged under air in two macroperforated packages (A—9.0 × 10³ perforations/m², 0.1 mm² surface and B—17 perforations/m², 0.1 mm² surface) and under two gas mixtures (15% and 25% O₂) in polyethylene packages, and stored at 5 °C for 18 d. The sensory quality of the mushrooms was evaluated using a trained assessors panel.

Mushrooms packaged in macroperforated packages A showed the smallest deterioration rate. However, weight loss after 6 d of storage reached 15%, which is unacceptable. Besides, shelf life of shiitake mushrooms in active modified atmosphere was limited by off-odour development. Mushrooms in these packages developed off-odour after 12 d of storage due to the fact that O₂ concentrations fall bellow 5%.

On the other hand, the shelf life of mushrooms packaged in macroperforated packages B was limited by their sensory deterioration, particularly by changes in the colour and uniformity of their gills. In this film, mushrooms could be stored for approximately 10 d with a weight loss lower than 2%.

Results from the present work suggest that during the first 6 d of storage all the evaluated packaging conditions were useful for reducing mushroom deterioration rate.     

Effect of alginate coating on physicochemical and sensory qualities of button mushrooms (Agaricus bisporus) under a high oxygen modified atmosphere

Button mushrooms (Agaricus bisporus) were dipped for 2 min in different concentrations (1%, 2% and 3%) of alginate, then placed in jars and ventilated continuously with 100% O₂ for up to 16 d at 4 °C. Mushroom respiration rate, weight loss, texture, color, percent open caps, chemical properties and activities of polyphenol oxidase (PPO), and peroxidase (POD) were measured. The results indicate that treatment with alginate coating (2%) + 100% O₂ maintained a high level of firmness, and delayed browning and cap opening. In addition, alginate coating (2%) + 100% O₂ also delayed changes in the soluble solids concentration, total sugars and ascorbic acid, and inhibited the activity of PPO and POD throughout storage. Our study suggests that the use of alginate coating under a high oxygen modified atmosphere has the potential to maintain button mushroom quality and extend its postharvest life to 16 d.     

Quality retention of oyster mushrooms (Pleurotus florida) by a combination of chemical treatments and modified atmosphere packaging

Three preservation techniques, chemical treatment, modified atmosphere packaging (MAP) and low temperature storage were used to improve physico-chemical attributes of oyster mushrooms. Mushrooms were treated with a solution of sorbitol (0.05%, w/v), citric acid (3%, w/v) and CaCl₂ (1%, w/v). Chemically treated mushrooms were packed under two different gas compositions. Physico-chemical, textural and sensory properties of the samples were assessed during storage at 4 °C for 25 d. Chemical treatment of mushrooms followed by modified atmosphere packaging using 10% O₂ and 5% CO₂ provided better retention of quality characteristics and received higher sensory ratings compared to other samples, resulting in a storage life of 25 d. Material with this treatment underwent minimal changes in weight, pH and TSS. Radical scavenging activity and total polyphenol contents were retained at 85 and 91% levels, respectively. Control samples without chemical treatment and with chemical treatment, kept under similar packaging conditions, underwent spoilage after 5 and 15 d, respectively.     

高水分玉米低温真空干燥新技术研究及应用

将真空干燥技术引入到粮食干燥领域,研究高水分玉米低温真空干燥生产工艺和设备,300 t/d生产试验表明,低温真空干燥能使高水分玉米达到安全储藏水分以下,出机玉米硬度高、品质较好,与传统的热风干燥方式相比,低温真空干燥能解决玉米干燥后裂纹率高的问题,节约能耗20%左右,玉米真空干燥有较好的发展前景.     

Effects of pulsed light treatments on quality and antioxidant properties of fresh-cut mushrooms (Agaricus bisporus)

This study investigated the impact of pulsed light treatments on microbial quality, enzymatic browning, texture and antioxidant properties of fresh-cut mushrooms. The reduction of the native microflora of sliced mushrooms ranged from 0.6 to 2.2 log after 15 days of refrigerated storage by flashing at 4.8, 12 and 28 J cm⁻². Pulsed light treatments allowed extension of the microbiological shelf life of fresh-cut mushrooms by 2–3 days in comparison to untreated samples, while providing a high quality product. The use of high pulsed light fluencies (12 and 28 J cm⁻²) dramatically affected the texture of sliced mushrooms due to thermal damage induced by the treatments. Enzymatic browning was also promoted by an increase in polyphenol oxidase activity when the highest dose of pulsed light was applied. At 28 J cm⁻², phenolic compounds, vitamin C and antioxidant capacity were significantly reduced. Our results suggest that the application of pulsed light at doses of 4.8 J cm⁻² could extend the shelf life of fresh-cut mushrooms without dramatically affecting texture and antioxidant properties.     

稻谷低温储藏保鲜技术研究

在冬季干冷气候条件下,利用机械通风对储粮降温后用聚氯乙烯塑料泡沫板(或防虫磷药糠装袋)进行压盖试验,对稻谷在不同储藏方式下的储藏品质、菌落数、微生物区系等项目的变化进行对比分析,结果表明应用低温储粮技术储存稻谷等粮食能够起到保鲜作用,从而延缓粮食陈化,具有一定的可行性、实用性和良好的市场前景,进一步达到绿色储粮技术要求。     

Effects of ultrasound and high pressure argon on physico-chemical properties of white mushrooms (Agaricus bisporus) during postharvest storage

Effects of high pressure argon (H), ultrasound (U) and their combination treatments (UH) on physico-chemical characteristics of white mushrooms were studied during 9 d of postharvest storage at 4 °C. H treated samples exhibited the smallest weight loss and respiration rate compared to all other samples. Mass losses after 9 d of storage were 3.01%, 5.09%, 5.39% and 9.59% for H, UH, U and untreated mushrooms, respectively. Furthermore, U treated samples showed lower polyphenol oxidase activity (PPO, E.C. 1.14.18.1) during storage while UH treated samples showed a slight increase in antioxidant capacity during storage and also experienced reduced mass loss and respiration rate. In addition, treated samples were effective in retaining mushrooms colour changes compared to control. Physico-chemical properties of differently treated mushrooms (UH, H and U) stored at 4 °C were significantly different (p < 0.05) from control.     

气调处理对“早生新水”梨果实贮藏品质的影响

为研究气调环境对冷藏和货架期间早生新水’梨果实贮藏品质的影响,筛选其适宜的气调贮藏技术参数,对其冷藏和货架期间果实失重率、腐烂率、糖、酸、叶绿素含量及果皮色差进行测定。结果表明：低温冷藏60d,货架期3d,对照果实果皮和果心出现褐变,固有风味降低。处理Ⅴ的梨果实冷藏和货架期间果皮、果肉和果心严重发黑、果肉呈水渍状,果皮有汁液溢出。适宜比例的O 2、和CO 2气体配比组合可抑制冷藏和货架期间果实糖损耗和果实褐变。综合得出：1% CO2、8% O2 和92%N2 的气体配比（处理Ⅲ）可显著降低冷藏期间果实带皮硬度的下降速率,抑制果实葡萄糖、果糖和山梨醇的降解、以及果实果皮叶绿素尤其是叶绿素b的降解或氧化,延缓果实褐变,较好的保持果实固有风味;较好地保持货架期间胚乳的完整、色泽和果实固有风味,抑制果肉褐变。1% CO2、8% O2 和92%N2的气体配比结合温度为1±0.5 ℃、相对湿度为80%-85%的冷藏参数,可使果实的冷藏期延长至60d,货架期3d。