纳米SiO_2壳聚糖复合膜保鲜草莓的研究

优化壳聚糖纳米SiO2复合膜透CO2性,并将其应用于草莓保鲜实验。结果表明,壳聚糖复合膜最佳配方为：壳聚糖含量2 g,纳米TiO2含量0.07 g,冰乙酸含量1.4 mL,且透CO2量达到最低为0.0909 g/d;优化膜处理的草莓常温下贮藏6 d后,腐烂指数比空白组降低了5.1%;低温4℃下贮藏11 d后,腐烂指数比空白组降低了23.9%。这证明,优化膜处理可有效延长草莓室温、低温下的贮藏保鲜时间。     

纳米TiO2对壳聚糖复合膜性能的研究及保鲜应用

壳聚糖复合膜中添加不同量的纳米TiO2,检测壳聚糖复合膜的透O2性、透CO2性、透水性、透光性及机械性能,并将优化膜应用于嫩姜保鲜。结果表明:当纳米TiO2添加量为0.03g时,壳聚糖纳米TiO2复合膜比单纯壳聚糖膜透O2系数提高了32.2%、透CO2系数降低了15.4%、透水率降低了66.4%;壳聚糖膜的透光率随着纳米TiO2添加量的增加而降低,但在纳米TiO2添加量为0.03g时,此壳聚糖复合膜的透光率在紫外光区10～400nm波长下达到最大。优化膜的机械性能比空白膜的有所提高,抗拉强度提高了13.99%,断裂伸长率提高了50%。将优化膜应用于嫩姜保鲜,其失水率比不做任何处理的嫩姜降低了38%,VC提高了23%,有效地延长了嫩姜的保鲜时间。     

壳聚糖/纳米SiOx复合保鲜膜性能衰减的研究

为了研究壳聚糖/纳米SiOx(CTSS)复合保鲜剂性能的衰减,采用流延法制备研究壳聚糖/纳米SiOx复合膜,并分别放置于4、14、24、34、44℃恒温环境中24 h,测定其pH值、氧气透过系数(OP)、二氧化碳透过系数(CP)和水蒸气透过系数(WVP)以及对青霉、酵母菌的抑菌性;同时,在4℃条件下,用CTSS和CTS分别涂膜处理草莓,并测定草莓腐烂率。结果表明:低温4℃贮藏10 d后,CTSS膜处理的草莓比CTS膜组腐烂指数降低了21.4%;纳米SiOx/壳聚糖复合膜随着放置温度的提高,pH值上升;复合膜OP、CP和WVP增大,44℃比4℃的OP、CP和WVP分别增加了13.02、27.54、25.56 mg/cm2·d;对酵母、青霉的抗菌性能减弱;壳聚糖/纳米SiOx复合膜对气体分子的通透阻力减小,从而导致壳聚糖/纳米SiOx复合保鲜剂性能降低。     

壳聚糖/纳米SiO_x复合膜对艳红桃的保鲜研究

以艳红桃为试材,在室温26～29℃,相对湿度65%～75%条件下,采用均匀试验U10(102×52)与L9(34)正交试验设计联用,研究壳聚糖/纳米SiOx复合对艳红桃品质变化的影响。结果表明:300mL保鲜剂中,壳聚糖5.0g、单甘酯0.11g、改性纳米SiOx0.07g、甘油6.0g、艳红桃浸泡30s,壳聚糖/纳米SiOx处理与空白和壳聚糖处理相比,艳红桃贮藏20d后,失水率分别降低了43.96%和27.41%,还原糖含量分别提高了44.00%和18.26%,VC含量分别提高了66.87%和4.80%,总酸含量分别提高了52.77%和39.76%;腐烂指数分别降低了30.56%、24.24%。表明壳聚糖/纳米SiOx复合膜提高了艳红桃品质,延长了贮藏保鲜期。     

抗菌肽壳聚糖复合膜对水果黄瓜的保鲜作用

为了延长水果黄瓜的货架期,本研究选用两种浓度的抗菌肽(1.00%、1.25%)分别与1.00%的壳聚糖复配成可食性复合膜,室温下对水果黄瓜进行喷淋涂膜处理后,在其表面覆盖一层PE保鲜膜,置于温度25℃、湿度40%～60%的环境下贮藏,每隔2 d测定其感官指标和理化指标(失重率、腐烂率、硬度、维生素C、可滴定酸和叶绿素含量)。结果表明,经21d贮藏后,1.00%的抗菌肽与壳聚糖复合膜处理组的失水率仅4.97%,腐烂率16.67%,硬度由9.53降至6.43,比空白组高42.50%,维生素C含量14.01 mg/100g,仅比贮藏前下降1.40%,果皮叶绿素含量0.63 mg/g,保鲜效果最佳。由此可得,抗菌肽与壳聚糖复合膜处理,能明显延缓黄瓜的腐败、失绿,减少维生素C和可滴定酸的损失,较好地保持黄瓜的硬度。     

TiO_2-大豆蛋白复合膜保鲜草莓的研究

采用正交试验设计优化Ti O2-大豆蛋白复合涂膜制备的工艺条件,测定其抗菌性能。用Ti O2-大豆蛋白复合涂膜低温贮藏草莓,测定贮藏过程中各组草莓的失重率、总菌落数、可溶性单糖及颜色等指标的变化情况。结果表明,最优工艺条件:Ti O2添加量2.00 g/150 m L,大豆分离蛋白和甘油质量浓度分别是4.50 g/150 m L和3.75g/150 m L。Ti O2-大豆蛋白复合膜对大肠杆菌和金黄色葡萄球菌均有很好的杀灭效果。经过涂膜处理的草莓在-4℃下贮藏8 d,失重率比空白组降低17.3%,总菌落数减少97.0%,颜色及可溶性单糖含量的变化比空白组稳定,说明Ti O2-大豆蛋白复合膜可有效延长草莓在低温下的贮藏时间。     

纳米二氧化钛改性 LDPE 薄膜包装对草莓品质的影响

为了探索纳米二氧化钛改性LDPE薄膜对采后草莓的保鲜效果,研究了普通LDPE薄膜和纳米二氧化钛改性LDPE薄膜两种不同包装对4 ℃下草莓贮藏品质的影响。研究发现,与对照组相比,纳米二氧化钛改性LDPE薄膜可抑制草莓贮藏过程中腐烂指数和失重率的上升,延缓可滴定酸含量和硬度的下降,减少乙烯释放量,保持果实贮藏后期较高的抗坏血酸和总酚含量以及较高的抗氧化能力。至贮藏第14 d,纳米二氧化钛改性LDPE薄膜包装中草莓的腐烂指数和乙烯释放量分别比对照组低60.72%和40.32%,可滴定酸含量和硬度分别比对照组高9.02%和24.31%,抗坏血酸和总酚含量分别比对照组高29.22%和10.73%。研究结果表明,纳米二氧化钛改性LDPE薄膜有利于保持草莓的贮藏品质,其作为草莓保鲜包装具有潜在的应用前景。     

纳米二氧化钛改性LDPE薄膜包装对草莓品质的影响

为了探索纳米二氧化钛改性LDPE薄膜对采后草莓的保鲜效果,研究了普通LDPE薄膜和纳米二氧化钛改性LDPE薄膜两种不同包装对4 ℃下草莓贮藏品质的影响。研究发现,与对照组相比,纳米二氧化钛改性LDPE薄膜可抑制草莓贮藏过程中腐烂指数和失重率的上升,延缓可滴定酸含量和硬度的下降,减少乙烯释放量,保持果实贮藏后期较高的抗坏血酸和总酚含量以及较高的抗氧化能力。至贮藏第14 d,纳米二氧化钛改性LDPE薄膜包装中草莓的腐烂指数和乙烯释放量分别比对照组低60.72%和40.32%,可滴定酸含量和硬度分别比对照组高9.02%和24.31%,抗坏血酸和总酚含量分别比对照组高29.22%和10.73%。研究结果表明,纳米二氧化钛改性LDPE薄膜有利于保持草莓的贮藏品质,其作为草莓保鲜包装具有潜在的应用前景。     

新型纳米涂膜用于赣南脐橙保鲜的研究

利用纳米TiO2和纳米SiOx分别对壳聚糖进行改性,探讨了改性前后抗菌性能的变化。在室温条件下进行了赣南脐橙的保鲜实验,测定了赣南脐橙贮藏期间腐烂率、Vc、可溶性固形物和可滴定酸等变化情况。实验结果表明:2种复合膜对桔青霉、黑曲霉等霉菌均具有显著的抑菌效果;赣南脐橙在室温贮藏90 d后,与空白组相比,腐烂率分别降低15.5%和13.7%,Vc含量分别提高10.6%和8.8%,可溶性固形物分别提高7.7%和3.9%,可滴定酸分别提高12.5%和7.5%,达到了较好的保鲜效果。     

壳聚糖/纳米TiO_2复合涂膜对芒果保鲜效果的影响

研究用壳聚糖单一涂膜及壳聚糖/纳米TiO_2复合涂膜对芒果保鲜效果的影响,并对不同纳米TiO_2添加量的复合膜进行微观形态观察。结果表明,当壳聚糖/纳米TiO_2复合膜中壳聚糖质量分数为1%,纳米TiO_2质量分数为0.03%时,涂膜处理可以保持芒果果实硬度、V_C及可滴定酸含量,延缓果胶的降解速度,保持细胞膜的功能活性。在贮藏第20 d时,芒果转黄指数为58.16%,失重率为6.72%,说明壳聚糖/纳米TiO_2复合涂膜对芒果在13℃贮藏条件下起到了较好的保鲜作用。     

Antifungal Coatings on Fresh Strawberries (Fragaria × ananassa) to Control Mold Growth During Cold Storage

ABSTRACT: Chitosan (2%) -based or hydroxypropyl methylcellulose (HPMC) (1%) -based coatings were applied on fresh strawberries to evaluate their antifungal efficacies against Cladosporium sp. and Rhizopus sp. Potassium sorbate (PS) was also incorporated into coating formulas to evaluate any additional inhibitory effects on mold inhibition. Strawberries were inoculated with Cladosporium sp. or Rhizopus sp. at a level of approximately 10³ log colony-forming units (CFU) /g, coated with 2% chitosan, 2% chitosan containing 0.3% PS, or 1% HPMC containing 0.3% PS, and stored at about 5°C and about 50% RH up to 23 d for enumeration of mold, yeast, total aerobes, and coli forms. To assess antifungal activity of the coating materials in vitro, coating solutions were embedded into agar plates and the diameters of radial mold growth were measured after inoculation. In addition, weight loss of coated strawberries and water vapor permeability of the coatings were measured. No significant combined inhibitory effects between chitosan and PS on fungal growth on fresh strawberries were detected. However, significant combined inhibition activity was observed in in vitro testing when PS was formulated into chitosan. Antifungal activity of chitosan against Cladosporium sp. and Rhizopus sp. was not affected by the autoclaving process of coating solutions. Coating treatment also reduced total aerobic count, coliforms, and weight loss of strawberries during storage. Hence, chitosan can be used as a natural antimicrobial coating on fresh strawberries to control the growth of fungi, thus extending shelf-life of the fruits.     

纳米SiO_x对壳聚糖膜CO_2透气性的影响

制备了不同纳米SiOx添加量的纳米SiOx/壳聚糖复合膜,研究纳米SiOx对复合膜CO2透气性能的影响,并且以"米良1号"猕猴桃为试材,在室温20～22℃,相对湿度63%～70%条件下,研究纳米SiOx添加量对猕猴桃呼吸作用以及对还原糖和总酸含量的影响。结果表明:纳米SiOx添加量为0.03 g/100 mL时,膜的CO2透过系数比对照降低了67.30%,猕猴桃呼吸高峰出现在第13天,比对照延迟了7天,并可有效地保持还原糖和总酸含量,说明该处理对猕猴桃的成熟衰老有明显的抑制作用。     

肉桂醛抗菌复合保鲜剂涂膜对采后荔枝的保鲜效果

对贮藏期荔枝的主要致腐菌进行科赫氏验证、形态学分析和ITS序列鉴定,优化肉桂醛抗菌复合保鲜剂的配方,探究其在荔枝保鲜中的应用效果。结果显示:引起荔枝腐烂的主要致腐菌为黑根霉(Rhizopus nigricans),肉桂醛复合保鲜剂可明显抑制荔枝的霉变。复合保鲜剂的组分(壳聚糖、玉米醇溶蛋白、甘油)均可显著减缓荔枝果实的可溶性固形物质量分数的下降和质量损失率的上升,延长荔枝的贮藏期;根据综合平衡法从正交试验组合中优选出复合保鲜剂最佳配方,即壳聚糖质量浓度1.2 g/100 mL、玉米醇溶蛋白质量浓度1.6 g/100 mL、甘油质量浓度0.7 g/100 mL、肉桂醛质量浓度750 mg/L。优选配方处理荔枝常温贮藏8 d时,果皮腐烂指数0.16,商品果率92.3%,贮后果皮色泽鲜亮,感官品质好,保鲜效果佳。     

邻苯基苯酚结合果蜡涂膜处理对采后贡柑贮藏品质的影响

为延长贡柑贮藏期,探究邻苯基苯酚结合果蜡涂膜处理对采后贡柑果实的保鲜效果,本研究以采后德庆贡柑果实为实验材料,研究了0.2%浓度邻苯基苯酚结合果蜡涂膜处理对采后贡柑在常温贮藏期间果实品质的影响,观察和测定了贮藏期间果实的腐烂率、硬度、可滴定酸（TA）、可溶性固形物（TSS）、维生素C（V_C）、细胞膜的通透性、丙二醛（MDA）以及超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的活性。结果表明,对照果在第6 d就开始腐烂,而0.2%邻苯基苯酚涂膜处理果实在第12 d才开始腐烂,并在贮藏后期处理组腐烂率明显低于对照组,显著延长了采后贡柑的常温贮藏时间（P<0.05）。与对照相比,经0.2%邻苯基苯酚结合果蜡涂膜处理能有效维持贡柑果实较高的TA、TSS和V_C的含量;同时,0.2%邻苯基苯酚结合果蜡涂膜处理明显减缓了果实的软化,降低了采后贡柑果实的失水率,保持了较高的硬度。此外,经0.2%邻苯基苯酚结合果蜡涂膜处理可有效维持果实组织中SOD和CAT活性在贮藏后期保持较高水平,并减少丙二醛（MDA）的积累,进而延缓果实组织细胞膜透性增加,有效抑制采后贡柑果实品质的劣变。因此,0.2%邻苯基苯酚结合果蜡涂膜处理可作为有效的保鲜方式用于贡柑果实的采后保鲜。     

Chitosan: antimicrobial activity and potential applications for preserving minimally processed strawberries

In this research the possible use of chitosan coating on fresh-cut strawberries was investigated. Manually sliced strawberries were treated with a solution of 1% chitosan, packaged in modified atmosphere with high (80%) and low (5%) percentage of oxygen and then stored at 4, 8, 12 and 15 °C. Changes in microbiological quality were measured and the shelf life of the samples, as stability time, was kinetically modelled in order to check the effects of storage temperature on the most relevant microbial indices for product quality.A chitosan coating inhibited the growth of microorganisms and affected significantly and positively the stability time of the products, above all when the samples were packaged in modified atmosphere (with low and high percentage of oxygen). Besides, the presence of high percentage of oxygen, combined with chitosan coating, seemed to affect positively the colour.The data revealed that applying a chitosan coating prolonged effectively the quality and extended the shelf life of fresh-cut strawberries.     

Chitosan Coating Effect on Storability and Quality of Fresh Strawberries

The effect of chitosan coating (1.0 and 1.5% w/v) in controlling decay of strawberries at 13°C was investigated as compared to a fungicide, iprodione (Rovral®). Chitosan coating significantly reduced decay of berries (P ≤ 0.05) compared to the control. There was no significant difference between chitosan and fungicide treatments up to 21 days storage. Thereafter, Rovral®-treated berries decayed at a higher rate than chitosan-coated berries. Chitosan-coated berries stored at 4°C were firmer, higher in titratable acidity, and synthesized anthocyanin at a slower rate than Rovral®-treated or nontreated berries. Chitosan coating decreased respiration rate of the berries with a greater effect at higher concentration.     

河阴石榴的采后保鲜技术

研究贮藏温度、化学杀菌剂处理和涂膜对河阴石榴果皮褐变、质量损失率、腐烂及籽粒品质等指标的影响。结果表明,在120 d的贮藏期内,4.5℃会引起河阴石榴果实冷害,果皮褐变严重、腐烂率增大。1%壳聚糖涂膜处理降低果实的腐烂率、褐变指数和质量损失率的效果优于1%海藻酸钠和1%羧甲基纤维素钠涂膜。噻菌灵、甲基托布津和多菌灵1 000倍稀释液浸果60 s可以显著降低果实腐烂率,3种化学杀菌剂处理之间无显著差异。以42%噻菌灵悬浮剂1 000倍液浸果,而后以1%壳聚糖溶液涂膜,用0.015 mm聚乙烯保鲜袋单果包装后放入6℃条件下贮藏120 d,河阴石榴的腐烂率为3.46%,质量损失率为2.13%,褐变指数为0.11,可溶性固形物含量为14.5%,籽粒品质评分为92,具有较高的商品价值。     

Composite starch-based coatings applied to strawberries (Fragaria ananassa)

Starch-based coatings were used to the extend storage life of strawberries (Fragaria ananassa) stored at 0 degree C and 84.8% relative humidity. Effects of coating formulation (including starch type, plasticizer, lipid and antimicrobial agent) were analysed with respect to fruit quality. Plasticizer addition was necessary for film and coating integrity to avoid pores and cracks. Plasticizer presence reduced weight losses and maintained surface colour of fruits. Amylomaize coatings showed lower water vapour and gas permeabilities and decreased weight losses for longer periods than corn starch ones. Coatings with sorbitol showed lower permeabilities than glycerol ones. Coatings with antimicrobial agents decreased microbial counts, extending storage life of coated fruits by 10 to 14 days in comparison to the control. The addition of 2 g/l sunflower oil to the formulations decreased the water vapour permeability of starch-based films, maintained the surface colour of coated fruits and controlled effectively fruit weight losses during storage. Lipid addition minimized the effects of starch and plasticizer types. Composite starch-based coatings showed selective gas permeability (CO2 higher than O2) which helps to delay senescence of fruits.     

Effects of chitosan coating on shelf life of cold-stored litchi fruit at ambient temperature

Postharvest pericarp browning of litchi fruit results in an accelerated loss in shelf life and a reduced commercial value. Visual quality was lost in only 6 h at ambient temperature when fruit were removed from storage at 2 °C, due to browning. The experiment was conducted to test the role of chitosan coating in inhibiting skin browning and extending shelf life of cold-stored litchi fruit at ambient temperature. Litchi fruit were treated with 2 g chitosan/100 g solution and then stored for 20 days at 2 °C and 90–95% relative humidity (RH), prior to shelf life evaluation at 25 °C and 80–90% RH. Changes in polyphenol oxidase (PPO) activity, anthocyanin concentration, colour index, eating quality and concentrations of total soluble solids and titratable acidity were measured. The effects of chitosan coating on disease incidence were also evaluated. Application of chitosan coating delayed the decrease in anthocyanin content, the increase in PPO activity and the changes in colour index and eating quality, reduced the decrease in concentrations of total soluble solids and titratable acidity, and partially inhibited decay. The results suggested that treatment with chitosan coating exhibited a potential for shelf life extension at ambient temperature when litchi fruit were removed from cold storage.