Effects of chitosan coating combined with essential oils on quality and antioxidant enzyme activities of grass carp (Ctenopharyngodon idellus) fillets stored at 4 °C

Effects of chitosan coating combined with essential oils from clove, cinnamon and lemon grass on quality and antioxidant enzyme activities of grass carp fillets stored at 4 ± 0.5 °C were evaluated. The quality parameters (including pH, total volatile basic nitrogen (TVB‐N), K value, thiobarbituric acid (TBA) value, shear force and total viable count (TVC)) and antioxidant enzyme activities were analysed periodically. The results indicated that composite chitosan coatings presented better preservation effects than chitosan coating alone. In addition, chitosan–clove essential oil coating had the best quality enhancement effects among treatments by inhibiting deterioration of physicochemical quality and microbial growth and maintaining antioxidant enzyme activities of fillets during refrigerated storage. The negative correlation was observed between the changes in TBA values and antioxidant enzyme activities in fillets. Based on these findings, chitosan–essential oil coatings effectively mitigated oxidative stress and extended shelf life of refrigerated grass carp fillets.     

Effect of Chitosan Gallate Coating on the Quality Maintenance of Refrigerated (4 °C) Silver Pomfret (<Emphasis Type="Italic">Pampus argentus</Emphasis>)

The effect of chitosan (CS)-gallic acid (GA) conjugate (chitosan gallate, CS-g-GA) coating on the quality of silvery pomfret (Pampus argenteus) during refrigerated storage at 4 °C for 15 days was investigated. The total mesophilic and psychrotrophic microbes in control and coated fish samples were counted periodically; physicochemical analyses to determine pH, total volatile basic nitrogen (TVB-N), peroxide value (POV), thiobarbituric acid-reactive substances (TBARS), K-value, and water-holding capacity (WHC) were carried out; and sensory attributes were evaluated. The results indicated that both CS + GA and CS-g-GA coatings effectively preserved the silvery pomfret quality during refrigerated storage. However, CS-g-GA had higher antimicrobial activity and a better ability to inhibit the formation of volatile bases (TVB-N) and lipid oxidation products (POV and TBARS) as well as the degradation of ATP and its breakdown products (K value) than CS + GA during the storage period. Furthermore, the CS-g-GA coating also helped to maintain a higher WHC and had better sensory properties for a longer period of time compared to the other treated samples, thus extending the shelf life and delaying the deterioration of fresh silvery pomfret by 3–6 days during refrigerated storage. These results suggest that a CS-g-GA coating could be employed as an active packaging material in the fish preservation industry.     

含肉桂精油的壳聚糖涂层对冷藏草鱼片的保鲜作用

通过在草鱼片上添加含肉桂精油(CIN)的壳聚糖(chitosan,Ch)涂层,研究含肉桂精油的壳聚糖涂层对草鱼片(4±1)℃ 冷藏16 d期间品质的影响.涂层分别采用质量浓度20 g/L Ch和Ch+CIN[质量浓度20 g/L Ch+1.5％(体积分数)CIN]配方溶液,对未添加涂层和添加不同配方涂层鱼片样品的微生物...     

Gelatin-Chitosan Composite Films and Edible Coatings to Enhance the Quality of Food Products: Layer-by-Layer vs. Blended Formulations

Two different approaches, blending and layer-by-layer electrostatic deposition (LbL), were utilized to combine two biopolymers, gelatin and chitosan, in edible films or coatings. The performance of the blended and LbL composite films and single-component gelatin and chitosan films was compared in terms of mechanical, optical, and spectroscopic properties. In parallel, edible coatings based on these formulations were applied on a food model: fresh-cut melon. Physiological, textural, and microbiological parameters of the coated fruit were studied in comparison with non coated control. Surprisingly, in spite of the higher thickness, the composite films and especially the LbL formulation demonstrated enhanced water vapor permeability as compared to single-component films. The LbL film had higher strength and better elasticity than the blended one. All edible coatings containing chitosan effectively inhibited microbial growth on fresh-cut melons. The LbL formulation demonstrated the most effective inhibition of the total microbial growth especially after 5–7 days of storage, while the blended formulation demonstrated high antifungal activity after 11 days of storage. The LbL formulation demonstrated superior performance in preservation of fruit texture and also slightly reduced fruit weight loss, while the blended formulation did not improve these parameters. Both composite coatings do not obstruct fruit gas exchange and do not cause accumulation of off-flavor volatiles.     

壳聚糖-三七叶黄酮复合保鲜剂对冷鲜黄牛肉的保鲜效果

目的：研究壳聚糖-三七叶黄酮复合保鲜剂对冷鲜黄牛肉的保鲜效果。方法：通过抗氧化及抑菌实验确定复合保鲜剂的最佳配比,并通过贮藏实验分析该复合保鲜剂对冷鲜（（4±2）℃）黄牛肉的保鲜效果。结果：壳聚糖与三七叶黄酮粗提液体积比为1∶1的复合保鲜剂的抗氧化性和抑菌性均较好。贮藏第10天时,使用该复合保鲜剂涂膜肉样的pH值、总挥发性盐基氮含量和菌落总数仍在可食用范围内,同时感官评分也在可接受范围内。结论：壳聚糖-三七叶黄酮复合保鲜剂对冷鲜黄牛肉具有较好的保鲜效果,有效延长其保鲜时间。     

白藜芦醇和壳聚糖复合生物保鲜剂对冷藏鱿鱼品质的影响

为了降低鱿鱼中甲醛含量和改善鱿鱼的贮藏品质,研究了白藜芦醇和壳聚糖对鱿鱼品质和货架期的影响。实验分为对照组、白藜芦醇组(0.2%)、壳聚糖组(1.0%)、白藜芦醇(0.2%+壳聚糖1.0%)组。鱿鱼在(0±0.5) ℃贮藏20 d。以挥发性盐基氮(TVB-N)、硫代巴比妥酸值(TBA)、硬度、弹性、甲醛含量的变化、菌落总数(TVC)和感官评分作为评价指标,研究其对鱿鱼的保鲜效果。结果表明:相对对照组,白藜芦醇+壳聚糖显著(p<0.05)降低菌落总数、TVB-N、TBA值和甲醛含量,使硬度和弹性下降程度变缓,显著提高感官评分。白藜芦醇+壳聚糖能够改善鱿鱼的品质,抑制微生物的增殖,并减缓脂肪氧化,延长鱿鱼的货架期,可以用于鱿鱼的保鲜。     

采前喷施壳聚糖复合膜对猕猴桃软腐病的防控及其保鲜作用

以‘贵长’猕猴桃为试材,通过病原菌分离、致病性测定和DNA测序鉴定了修文县猕猴桃软腐病病原菌,并选用壳聚糖、钙盐和糊精分别与茶多酚、甘氨酸、柠檬酸、抗菌肽混合制备和筛选了复合膜剂,研究了采前幼果期和壮果末期果面喷施壳聚糖复合膜对猕猴桃软腐病的防控及其保鲜作用。结果表明,修文县猕猴桃软腐病病原菌为葡萄座腔菌（Botryosphaeria dothidea）和拟茎点霉菌（Phomopsis sp.）;采前喷施不同壳聚糖复合膜对其软腐病的防效均达60%以上（添加茶多酚防效86.54%、甘氨酸防效61.54%、柠檬酸防效71.15%、抗菌肽防效69.23%）,显著降低丙二醛（MDA）积累,提高果实的超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）活性,诱导增强果实的抗病性。同时,该复合膜能有效地增加果实单果质量和体积,显著提高果实VC、可溶性固形物、可溶性总糖、可滴定酸、叶绿素和蛋白质的含量,促进猕猴桃产量的增加和品质的改善。此外,施用该复合膜还能有效提高和维持果实硬度、降低果实呼吸强度以及果实质量损失率和营养物质的损失,明显抑制果实可溶性固形物和可溶性总糖含量的上升速率和延缓组织的衰老软化,从而提高了猕猴桃耐贮性。研究结果为猕猴桃优质栽培、病害有机防控和果实绿色保鲜提供了科学依据和新途径。     

Functional Properties of Antimicrobial Lysozyme-Chitosan Composite Films

ABSTRACT: Lysozyme-chitosan composite films were developed for enhancing the antimicrobial properties of chitosan films. A 10% lysozyme solution was incorporated into 2% chitosan film-forming solution (FFS) at a ratio of 0%, 20%, 60%, and 100% (w lysozyme/w chitosan). Films were prepared by solvent evaporation. Lysozyme release from the film matrix, the antimicrobial activity of films against Escherichia coli and Streptococcus faecalis , and basic film properties were investigated. The lysozyme release proportionally increased with increasing initial concentration of lysozyme in the film matrix, and the amount of released lysozyme was in natural log relationship with time. The films with 60% lysozyme incorporation enhanced the inhibition efficacy of chitosan films against both S. faecalis and E. coli , where 3.8 log cycles reduction in S. faecalis and 2.7 log cycles reduction in E. coli were achieved. Water vapor permeability of the chitosan films was not affected by lysozyme incorporation, whereas the tensile strength and percent elongation values decreased with increased lysozyme concentration. Scanning electron microscopy images revealed that lysozyme was homogeneously distributed throughout the film matrix. This study demonstrated that enhanced antimicrobial activity of lysozyme-chitosan composite films can be achieved by incorporating lysozyme into chitosan, thus broadening their applications in ensuring food quality and safety.     

纳米包装材料对生菜保鲜品质的影响

制备一种含纳米银、纳米TiO2和高岭土的食品用纳米包装材料,研究该材料在生菜贮藏过程中的保鲜效果。对纳米膜进行结构表征及物理特性检测。并检测贮藏过程中生菜质量损失率、叶绿素、VC、多酚氧化酶活性、丙二醛含量等指标变化。研究结果表明：纳米粒子均匀分布在包装材料中,与普通包装材料相比,纵向拉伸强度增加31.69%,透湿量和透氧量降低28.07%和2.10%;4℃、贮藏14d,纳米包装处理的生菜质量损失率、丙二醛含量、多酚氧化酶比活力分别为1.35%、23.01nmol/g、5.43U/g,显著低于普通包装2.75%、26.35nmol/g(P＜0.05)、7.63U/g(P＜0.01),VC和叶绿素含量显著高于对照组。纳米包装材料较好地保持生菜在贮藏过程中感官品质和营养成分,延长贮藏时间。     

Antimicrobial activity and physical properties of chitosan–tapioca starch based edible films and coatings

Antimicrobial activity of edible coating solutions based on chitosan and blends of chitosan–tapioca starch with or without potassium sorbate (KS) addition was studied. The agar well diffusion assay showed an antagonist effect on the efficiency of chitosan against Lactobacillus spp. when KS and/or tapioca starch were present. A salmon slice coating assay showed that the chitosan solution was the best coating since aerobic mesophilic and psychrophilic cell counts were reduced, pH and weight loss remained acceptable throughout refrigerated storage, extending global quality to 6-days. Chitosan–tapioca starch based films reduced Zygosaccharomyces bailii external spoilage in a semisolid product but were not effective against Lactobacillus spp. The results suggest that antibacterial action depended on the application technique, due to the fact that chitosan is more available in a coating solution than in a film matrix. Interactions between chitosan–starch and/or KS could affect film physical properties and the antimicrobial activity of chitosan. The addition of chitosan reduced water vapor permeability and solubility of starch films.     

Cellulose Nanocrystal Reinforced Chitosan Coatings for Improving the Storability of Postharvest Pears Under Both Ambient and Cold Storages

Cellulose nanocrystal (CNC, 0%, 5%, and 10% w/w, in chitosan, dry basis) reinforced 2% chitosan aqueous coatings were evaluated for delaying the ripening and quality deterioration of postharvest green D'Anjou (Pyrus communis L.) and Bartlett (Pyrus communis L.) pears during 3 wk of ambient storage (20 ± 2 °C and 30 ± 2% RH) or 5 mo of cold storage (–1.1 °C and 90% RH), respectively. Ethylene and CO₂ production, color, firmness, and internal fruit quality were monitored during both storage conditions. Moisture and gas barrier, antibacterial activity, and surface morphology of the derived films were also evaluated to investigate the mechanisms of delayed fruit ripening and quality deterioration. In the ambient storage study, the 5% CNC reinforced chitosan coating significantly (P < 0.05) delayed green chlorophyll degradation of pear peels, prevented internal browning, reduced senescence scalding, and improved retained fruit firmness. During cold storage, the 5% CNC reinforced chitosan coating showed a competitive effect on delaying fruit postharvest quality deterioration compared to a commercial product (Semperfresh?, Pace International, Wapato, Wash., U.S.A.). The 5% CNC coating strongly adhered to the pear surface, provided a superior gas barrier and a more homogenous matrix in comparison with the other coatings tested. Hence, it was effective in delaying ripening and improving the storability of postharvest pears during both ambient and cold storage.     

茶多酚、壳聚糖、溶菌酶复合保鲜剂对高白鲑鱼片保鲜效果的影响

为研究茶多酚、壳聚糖和溶菌酶复合保鲜剂对高白鲑鱼片的保鲜效果,采用L₉(34)正交实验,将茶多酚、壳聚糖和溶菌酶复合使用,以K值和菌落总数(TVC)为评价参数,对复合保鲜剂配方进行优化。结果表明:最佳复合保鲜剂使用量为茶多酚浓度0.1 g/kg,壳聚糖浓度4.0 g/kg,溶菌酶浓度0.5 g/kg。经最佳复合保鲜剂处理后K值、TBA值和菌落总数均显著低于对照组(p<0.05),在冰藏条件下能将高白鲑的一级鲜度延长至4 d,维持良好鲜度品质,延长保鲜期。研究结果为今后高白鲑的高品质保鲜提供数据支持和参考依据。     

Effect of bilayer coating composed of polyvinyl alcohol,chitosan, and sodium alginate on salted duck eggs

The composite bilayer film based on polyvinyl alcohol, sodium alginate, and chitosan were developed in this study, and the effects of the related coating on internal-quality changes of salted duck eggs (SDEs) during storage were determined. The results showed that the overall properties of the bilayer film were better than those of monolayer films, including storage stability. Coatings could significantly (p < 0.05) reduce quality deterioration of SDEs such as water loss, oil exudation, and gritty. The bilayer coating was more effective in inhibiting the increase of egg yolk pH and total bacterial counts than monolayer coatings. After storage for 60 days, water content of bilayer coated SEDs was 19.7% higher than that of the control SDEs, oil exudation was 38% higher, and gritty texture was 27.9% higher. Moreover, bilayer coating could prolong the shelf life of SDEs to more than 60 days at 25°C and 50% relative humidity according to the results of total bacterial count experiment, while the shelf life of control SDEs was less than 45 days. This study indicated the potential application of bilayer composite coating for preservation of SDEs.     

淀粉-壳聚糖可食性复合薄膜保鲜布林的研究

本文主要研究了不同种类的淀粉与壳聚糖复合所形成的被膜对于布林的保鲜效果。分别用木薯淀粉,土豆淀粉,玉米淀粉与壳聚糖制成不同涂膜液对布林进行涂膜处理,在常温(15～25℃)下储藏。涂膜的布林在贮藏期间,其水分损失,硬度,可溶性固形物,总酸度的变化均小于对照组, 并且可延长保质期3～7d。就不同的淀粉成分而言,对于布林的保鲜作用,土豆淀粉-壳聚糖复合薄膜的保鲜作用最佳,玉米淀粉-壳聚糖复合薄膜的作用优于木薯淀粉-壳聚糖复合薄膜。     

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。     

Effects of chitosan coating containing lysozyme or natamycin on shelf‐life,microbial quality,and sensory properties of Halloumi cheese brined in normal and reduced salt solutions

The effects of chitosan (C) coating with or without lysozyme (L) or natamycin (N) on shelf‐life, microbial quality, and sensory properties of Halloumi cheese held at 3 °C or 25 °C in 5%, 10% or 15% (w/v) NaCl were examined. Coatings increased cheese shelf‐life by ≥ 5 days than the control when brined in 5% and 10% NaCl at 3 °C but did not affect the shelf‐life of cheese in 15% NaCl. Nonetheless, coatings reduced psychrotrophs, anaerobes, lactic acid bacteria, and yeasts and molds by 1.8 to 2.2 log in 15% brined cheese. Reductions of microbial species contaminating Halloumi cheese at 10% and 15% brine were not significantly different with CL and CN coatings throughout storage at 3 °C. Coatings did not adversely affect sensory properties of cheese. Therefore, brine concentration could be reduced to 10% for CL and CN‐coated cheeses.

Practical applications

Results support the possibility of reducing the high salt concentration in brine solution of Halloumi cheese by using a chitosan coating containing lysozyme or natamyc in which provided similar shelf‐life and microbial stability. The coatings did not adversely affect the sensory properties of cheese and can be applied by a simple step during processing which facilitates their use in the food industry.     

天然复合型保鲜剂对北太平洋柔鱼品质及其体内甲醛含量的影响

为了延长北太平洋柔鱼的货架期,保持新鲜度。以茶多酚、壳聚糖以及其复合溶液作为保鲜剂,通过测定鲜度指标(感官评价、菌落总数、pH、TVB-N值和K值),来探讨北太平洋柔鱼在贮藏期内的品质变化情况,同时检测柔鱼体内甲醛含量的变化。结果表明:随冷藏时间增加,各组感官分值均呈现下降趋势,并且复合组分值最高;各组菌落总数、K值均随冷藏时间的延长而逐渐增加,复合组菌落总数、K值最低;茶多酚组、复合组和空白组的pH均呈现先下降后上升的趋势,而壳聚糖组呈现下降的趋势;茶多酚组、空白组和壳聚糖组的TVB-N在贮藏第4 d后值发生明显上升,空白组和复合组的TVB-N值在第7 d时分别为60.99和11.42 mg N/100 g;随着冷藏时间的增加,添加保鲜剂组的甲醛含量均低于空白组且复合组的甲醛含量最低。综合评价,空白组和复合组的K值分别在第5 d和第7 d超标,复合保鲜剂可以延长鱼体的保鲜期。     

Physicochemical,microbiological, and sensory attributes of chitosan-coated grass carp (Ctenopharyngodon idellus) fillets stored at 4°C

This study investigated the effect of chitosan coating (1 and 2%) on the quality of grass carp fillets stored at 4°C for 20 days. During storage, the physicochemical properties (pH, thiobarbituric acid value, total volatile basic nitrogen value, trimethylamine nitrogen value, K-value, water loss, and instrumental texture), microbiology (total viable count and psychrotrophic count), and sensory properties were evaluated. The results showed that chitosan coating could effectively inhibit bacterial growth, improve physicochemical and sensory qualities, and it reduced the deterioration of the quality of grass carp fillets. Compared with fillets without chitosan coating, the shelf life of fillets with 1 and 2% chitosan coating was extended by ~3 and 6–7 days, respectively.     

壳聚糖复合保鲜对草鱼肌肉品质变化的影响

为探讨有效的冷鲜草鱼保鲜技术方案,分别以壳聚糖复合保鲜液（10 mg/mL壳聚糖＋5 mg/mL茶多酚＋2 000 U/mL溶菌酶）和无菌水（对照组）处理草鱼片,通过对比草鱼冷藏过程中鲜度（K值）、ATP关联物含量、汁液流失率、质构特性、挥发性气味等指标的变化情况,分析壳聚糖复合保鲜对草鱼肌肉品质变化的影响。结果表明：冷藏过程中,草鱼肉的K值、次黄嘌呤含量、汁液流失率、黏附性和挥发性物质随时间延长有不同程度增加,但保鲜组样品的增幅明显小于对照组;对照组草鱼的肌苷酸含量和硬度随时间延长逐渐下降,而保鲜组则先上升后下降,且下降变化率明显低于对照组。说明壳聚糖复合保鲜液对草鱼保鲜效果较好,能有效延缓鱼肉的品质劣变进程。     

明胶-壳聚糖-迷迭香提取物复合膜对南美白对虾品质的影响

以鱼皮明胶、壳聚糖为复合膜基质材料,通过添加迷迭香提取物制备明胶-壳聚糖-迷迭香提取物复合膜(G-C-RE),并研究G-C-RE复合膜对冷藏南美白对虾的保鲜效果。结果表明,经G-C-RE复合膜涂膜处理的南美白对虾菌落总数、挥发性盐基氮(TVB-N)、硫代巴比妥酸值(TBARS)均显著低于对照(P<0.05)。相对于明胶-壳聚糖复合膜(G-C),添加迷迭香提取物能够减缓蛋白氧化,显著降低蛋白质羰基含量(P<0.05)。G-C-RE复合膜可改善南美白对虾的黑变程度,维持较高的感官评分,保持虾的良好品质。明胶-壳聚糖-迷迭香提取物复合膜可作为新型保鲜包装材料用于水产品的品质。