Effects of chitosan coating and storage position on quality and shelf life of eggs

Effects of chitosan coating and storage positions (small-end down, small-end up or horizontal) on internal quality and shelf life of eggs were evaluated during 5 weeks of storage at 25 °C. Compared with noncoated eggs, all chitosan-coated eggs, irrespective of storage positions, had significantly lesser weight loss, higher Haugh units and higher yolk index throughout the storage. Chitosan coating, irrespective of storage positions, extended the egg shelf life by at least 3 weeks at 25 °C compared with noncoated eggs. Noncoated and chitosan-coated eggs placed small-end down tentatively showed better quality than eggs placed small-end up after 3 and 4 weeks of storage. After 5 weeks of storage, storage positions did not significantly affect quality of noncoated and chitosan-coated eggs. There were no notable differences in total amino acid content of the albumen and fatty acid composition of the yolk between noncoated and chitosan-coated eggs after 5 weeks of storage.     

Development of edible bioactive coating based on modified chitosan for increasing the shelf life of strawberries

For increasing the shelf life of strawberries during storage, bioactive coatings were applied using modified polysaccharides of chitosan. First, antimicrobial tests were performed with selected essential oils to evaluate their antimicrobial capacities against moulds and total flora isolated from strawberries. Red thyme (RT) and oregano extract (OR) were found as strong bioactive agents against moulds and total flora isolated from strawberries, whereas limonene (LIM) and peppermint (PM) had lower antimicrobial properties. These essential oils were also used as bioactive compounds which were sprayed onto strawberries and evaluated for their potential to increase shelf life during storage at 4 °C. RT, PM and LIM were found to be more efficient preservative agents for strawberries during 14 days of storage. Finally, chitosan was functionalized by acylation with palmitoyl chloride to increase its hydrophobicity, to ensure a controlled release and improve its stability and adhesion to the fruit product. LIM and PM were incorporated into the modified chitosan to create bioactive edible coatings and these were tested for their ability to extend the shelf life of fresh strawberries during storage. Formulations based on modified chitosan containing LIM and Tween®80 were shown to perform better than other formulations.     

Effects of chitosan coating on quality and shelf life of silver carp during frozen storage

The effects of chitosan coating on quality and shelf life of silver carp during frozen storage were investigated. Fish samples were treated with aqueous solution of 2% chitosan, and then stored at −3 °C for 30 days. The control and the treated fish samples were analyzed periodically for microbiological (total viable count), chemical (pH, TBA, TVB-N, K-value), and sensory characteristics. The results indicated that the effect of chitosan coating on fish samples was to retain their good quality characteristics and extend the shelf life during frozen storage, which was supported by the results of microbiological, chemical, and sensory evaluation analyses.     

Development and evaluation of chitosan and its derivative for the shelf life extension of beef meat under refrigeration storage

The current study was aimed to study the shelf life of beef meat at refrigeration storage using novel chitosan derivative (Ch‐D). Chitosan was modified with antimicrobial monomethyl fumaric acid (MFA). The chemical structure of the resulting material was characterized by FT‐IR and HR‐XRD. The results confirmed the successful synthesis of conjugate sample. For the shelf life study, following lots were used: control (distilled water), chitosan 0.5%, Ch‐D 0.5%. The samples were kept at 4 °C for 16 days and analyzed at 4‐day intervals. Ch‐D treatment significantly reduced the total viable counts, enterobacteriaceae, lactic acid bacteria, psychrotrophic bacteria, and yeasts–moulds when compared with the chitosan and control during refrigeration storage. The peroxide value (PV) for Ch‐D was 0.19 ± 0.04 meq O₂ kg^?1 fat and chitosan was 0.21 ± 0.07 meq O₂ kg^?1 fat and showed no significant difference (P < 0.05) at the end of the storage. Thiobarbituric acid reactive substance (TBARs) value for Ch‐D was 0.48 ± 0.02 mg MDA kg^?1 and chitosan was 0.57 ± 0.09 mg MDA kg^?1, while the carbonyl contents for Ch‐D was 3.16 ± 0.23 nm  mg^?1 protein and chitosan was 3.11 ± 0.16 nm  mg^?1 protein at 16 days of storage. Values for Ch‐D and chitosan treatments were significantly lower (P < 0.05) for all the quality attributes as compared with the control throughout storage. At the end of storage, Ch‐D treatment showed a significant increase (P < 0.05) in lightness (L^* = 41.54 ± 0.09) and yellowness (b* = 2.23 ± 0.04). The redness for control was high (a* = 6.12 ± 0.09) as compared with the treated samples. Based primarily on microbial counts, Ch‐D treatment extended the shelf life of beef meat by about 8 days, maintaining acceptable quality attributes.     

冷却牛肉货架期及微生物多样性分析

目的 对冷却牛肉中的初始微生物进行鉴定,了解细菌菌落结构,为储藏冷却牛肉提供理论数据。方法 通过传统纯培养的方法和16S rDNA克隆分析法相结合,研究冷却牛肉中微生物菌落总数及结构。结果 冷却牛肉中的初始细菌总数为2.6×104 CFU/g,筛选出8株优势菌株,根据其形态、颜色等特征鉴定为：S01和S02都为假单孢菌属,S03为希瓦氏菌属,S04、S06为不动杆菌属,S05为窄食单胞菌属,S07 为嗜冷杆菌,S08 为葡萄球菌属。结论：冷却牛肉中优势菌为假单胞菌和希瓦氏菌属,在4 ℃条件下,货架期为5天。     

Plasticizer types and coating methods affect quality and shelf life of eggs coated with chitosan

ABSTRACT:  Effects of different plasticizer types (glycerol, propylene glycol, and sorbitol) and coating methods (brushing, dipping, and spraying) on the internal quality and shelf life of chitosan-coated eggs were evaluated during 5 wk of storage at 25 °C. The Haugh unit and yolk index values suggested that chitosan coating, irrespective of the plasticizer types, extended the shelf life of eggs by almost 3 wk at 25 °C compared with noncoated eggs. After 5 wk of storage, plasticizer types did not significantly affect the quality (weight loss, Haugh unit, and yolk index) of chitosan-coated eggs. However, there was an observable trend indicating that use of sorbitol rather than propylene glycol and glycerol as a plasticizer was better in reducing weight loss (whole egg) of chitosan-coated eggs during a 5-wk storage. After a 5-wk storage, there were no significant differences in weight loss and weight of albumen and yolk among chitosan-coated eggs, regardless of the coating methods. However, both brushing and dipping methods yielded chitosan-coated eggs with better yolk (higher yolk index values) and albumen (lower pH) qualities than did the spraying method. During 3 to 5 wk of storage, the Haugh unit values of chitosan-coated eggs by the brushing method were higher than or comparable to those by dipping or spraying. Therefore, coating of eggs with chitosan using sorbitol as a plasticizer and by the brushing method may offer a protective barrier in preserving the internal quality and thus extending shelf life of eggs.     

Gelatine–starch films: Physicochemical properties and their application in extending the post‐harvest shelf life of avocado (Persea americana)

BACKGROUND: Several storage techniques have been developed to extend the post‐harvest shelf life of horticultural products. One method involves the use of edible or biodegradable coatings. Such coatings are made of biological materials that are used to coat fresh products, providing a semi‐permeable barrier to water vapour and gases, e.g. O₂ and CO₂. The influence of starch concentration, glycerol content and pH on the carbon dioxide permeability (CO₂P) and mechanical properties of gelatine–starch edible films were evaluated. RESULTS: Results showed that increments in the starch concentration and pH resulted in higher CO₂P values. Film puncture strength increased when the starch concentration decreased and the maximum resistance value (32.6 N) was obtained at pH 6. Deformation was mainly affected by glycerol and starch content. Some films were chosen in order to evaluate their effect, as coatings, in the post‐harvest shelf life of avocados (Persea americana Mill c.v. Hass). Fruits were immersed in the coating solutions, air dried and stored at two temperatures. Changes in colour, weight loss and pulp firmness were determined in fruits stored at 6 °C. In addition, respiration rate was measured in avocados kept at 20 °C. CONCLUSION: The application of gelatine–starch coatings delayed the ripening process of avocados, as indicated by a better pulp firmness and retention of skin colour, and lower weight loss of coated fruits in comparison with control avocados. The coatings also resulted in a delayed respiratory climacteric pattern, by 3 days, for coated fruits. Copyright © 2007 Society of Chemical Industry     

Recent advances in gelatine and chitosan complex material for practical food preservation application

Both gelatine and chitosan are safe, odourless, edible, biodegradable, biocompatible, cost-efficient and commercially available biopolymers, which promotes the possibility of forming complex. Many factors, including origin, molecular weight, deacetylation degree, pH, salts, concentration, temperature, active materials, modifiers, etc., could impose effect on the process of producing gelatine-chitosan complex. The formed gelatine-chitosan complex has excellent physicochemical properties such as antibacterial property and antioxidant property, and could effectively preserve practical food (such as meat, vegetables and fruits). This article comprehensively reviews recent advances in factors affecting the complex forming process and practical food preservation application of gelatine-chitosan complex. It aims to provide an overview of the value of gelatine-chitosan complex as an effective preservation alternative in food technology.     

Packaging-specific influence of chitosan on color stability and lipid oxidation in refrigerated ground beef

We examined the influence of chitosan on lipid oxidation and color stability of ground beef stored in different modified atmosphere packaging (MAP) systems. Ground beef patties with chitosan (1%) or without chitosan (control) were packaged either in high-oxygen MAP (HIOX; 80% O₂ + 20% CO₂), carbon monoxide MAP (CO; 0.4% CO + 19.6% CO₂ + 80% N₂), vacuum (VP), or aerobic packaging (PVC) and stored at 1 °C. Chitosan increased (P < 0.05) redness of patties stored in PVC and CO, whereas it had no effect (P > 0.05) in HIOX. Chitosan patties demonstrated lower (P < 0.05) lipid oxidation than controls in all packaging. Control patties in PVC and HIOX exhibited greater (P < 0.05) lipid oxidation than those in VP and CO, whereas chitosan patties in different packaging systems were not different (P > 0.05) from each other. Our findings suggested that antioxidant effects of chitosan on ground beef are packaging-specific.     

Combined effect of chitosan and modified atmosphere packaging for shelf life extension of chicken breast fillets

The combined effect of dipping in a chitosan solution (1 g/100 ml) and packaging under modified atmosphere (MAP, 70% CO₂, 30% N₂) on shelf life extension of refrigerated chicken fillets was investigated. Microbiological (Total Viable Counts, Pseudomonas spp., Lactic Acid Bacteria and Enterobacteriaceae), physicochemical (headspace gas composition, pH, color and Thiobarbituric Acid test) and sensory (odor and taste) parameters were monitored for up to 14 days. TVC were 3.9–4.9 log cfu/g lower on day 6 of storage in treated vs. untreated air-packaged samples with the strongest effect being shown by the combination of chitosan plus MAP. A similar reduction in LAB, Pseudomonads and Enterobacteriaceae was recorded during storage. pH values varied between 5.73 (day 8, for acetic acid treated samples) and 6.28 (day 6, for air-packaged samples). Malondialdehyde (MDA) values ranged between 0.19 and 0.80 mg/kg indicating negligible oxidation of lipids. The color parameter L* decreased with time in the air-packaged samples but remained unaffected in all other treatments. Parameters a* and b* were not significantly affected by the chitosan or the MAP treatments. Based on the microbiological and sensory data, shelf life of air-packaged, chitosan-treated, MAP-treated and chitosan/MAP treated samples was 5, 11, 12 and 14 days, respectively.     

山苍子精油壳聚糖复合涂膜保鲜金柑

为了延长金柑的贮藏期,以金柑为原料,研究室温条件下山苍子精油壳聚糖复合涂膜对金柑果实失重率、可溶性固形物、可滴定酸、VC、总糖、感官等指标的影响。结果表明:山苍子精油壳聚糖复合涂膜抑制了金柑的失重,处理组可溶性固形物、可滴定酸、VC、总糖、感官均优于对照组。其中失重率、可溶性固形物、VC均有显著性差异,第30天时处理组、对照组的失重率分别为5.92%,8.35%,可溶性固形物分别为10.31%,8.67%,VC分别为15.77,8.32mg/100g。山苍子精油壳聚糖复合涂膜降低了营养物质的消耗,有效地延缓了金柑的衰老。     

基于假单胞菌生长模型预测冷却牛肉的货架期

假单胞菌（Pseudomonas spp.）的生长繁殖是影响冷却牛肉货架期的重要因素。为确定假单胞菌为冷却牛肉的特定腐败菌并建立其货架期预测模型,将屠宰后的冷却牛肉4 ℃贮藏,测定了假单胞菌数量与菌落总数、挥发性氨基氮（TVBN）值、颜色明度值（L*）及感官评定分值等品质指标,并确定了冷却牛肉的假单胞菌腐败限控量。将冷却牛肉分别置于0 ℃、5 ℃、10 ℃、15 ℃、20 ℃和25 ℃条件下进行假单胞菌计数,建立Gompertz方程的初级生长模型和二级模型,并进行了模型的验证,建立了货架期预测模型。研究表明,Gompertz预测模型能有效预测4～25 ℃条件下假单胞菌在冷却牛肉中的生长情况,在0 ℃、5 ℃和10 ℃温度条件下,对牛肉货架期进行验证,与实际货架期相比偏差＜1 d,表明货架期预测模型适用。     

A novel emulsion coating and its effects on internal quality and shelf life of eggs during room temperature storage

Effects of mineral oil (MO), chitosan solution (CH) and their emulsions (MO:CH = 75:25, 50:50, and 25:75 ratios) as coating materials in preserving internal quality of eggs were evaluated during a 5‐weeks storage at 25 °C. Consumers (n = 109) evaluated surface properties and purchase intent of freshly coated eggs. As storage time increased, Haugh unit and yolk index values decreased whereas weight loss increased. Noncoated eggs rapidly changed from AA to B and C grades after 1 and 3 weeks, respectively. However, all emulsion‐coated eggs maintained their A‐grade quality for 4 weeks. Compared with noncoated eggs, all emulsion coatings reduced weight loss of eggs by at least seven times (0.88–1.03% vs. 7.14%). Only MO:CH = 25:75 emulsion‐coated eggs were not sensorially glossier than noncoated eggs. All emulsion‐coated eggs had >80% positive purchase intent and were negative for Salmonella. This study demonstrated that MO:CH emulsion coatings preserved internal quality and prolonged shelf life of eggs.     

Effects of chitosan-based coating and modified atmosphere packaging (MAP) on browning and shelf life of fresh-cut lotus root (Nelumbo nucifera Gaerth)

The present study investigated the effect of chitosan coating containing antibrowning agents and modified atmosphere packaging (MAP) on the browning and shelf life of fresh-cut lotus root stored at 4 °C for 10 days. The atmosphere in the packages was evaluated for O₂ and CO₂ concentrations. The browning on the surface of lotus root slices was prevented by chitosan-based coating and MAP treatment. L* values of coated + MAP and control samples were 68.8 and 48.9 after 8 days storage, respectively. For a^? and b^? values, samples of coated + MAP treatment had the slowest increasing trends among all the treatments. At the end of storage, the coated + MAP samples exhibited the lowest polyphenol oxidase (PPO) activity and malondialdehyde (MDA) content. Its highest overall visual quality (OVQ) scores (> 7) demonstrated that chitosan-based coating + MAP treatment could provide a better inhibitory effect on the browning and extend the shelf life of fresh-cut lotus root.Industrial relevance: Fresh-cut vegetables have drawn the attention of industry as a novel lightly processed product. Both edible coating and MAP treatment cause changes in atmosphere composition and respiration rate of lotus root slices. This combined treatment could be used to control the browning and improve the storage life of this fresh-cut vegetable. This information could be useful for the development of novel application to edible coating and MAP design for lightly processed lotus root.     

The impact of packaging system and temperature abuse on the shelf life characteristics of ground beef

New ground beef packaging systems have warranted investigation of their spoilage and quality characteristics. Furthermore, analysis of ground beef spoilage in modified atmosphere packaging (MAP) and stored at abusive temperature is lacking. This research aimed to determine the effect of packaging systems and temperature abuse on the sensory and shelf-life characteristics of ground beef. Ground beef patties were packaged using polyvinyl chloride overwrap (OW), HI-OX MAP (80% O₂, 20% CO₂), LO-OX MAP (30% CO₂, 70% N₂), CO-MAP (0.4% CO, 30% CO₂, 69.6% N₂), or vacuum (VAC) prior to color, odor, biochemical, and microbial analyses over display. CO-MAP exhibited more desirable color and consumer acceptability throughout display. Lean discoloration and odor scores were lower for anaerobic packaging than aerobic packaging. Microbial results mirrored sensory preferences for anaerobic packaging. These results indicate anaerobic packaging extends shelf-life properties and desirable sensory attributes throughout display and temperature abuse.     

初始菌落数与真空热缩包装冷鲜牛肉保质期的关系

通过研究真空热缩包装的冷鲜牛肉在包装前的菌落总数与包装后保质期的关系,证明了控制微生物是延长冷鲜牛肉保质期的重要因素,同时为真空热缩的冷鲜牛肉产品的预期保质期提供了参考数据,也为冷鲜牛肉相关生产标准的制定提供了数据支持.     

Effect of ultraviolet irradiation combined with chitosan coating on preservation of jujube under ambient temperature

The effect of ultraviolet irradiation combined with chitosan coating on fresh jujube under ambient temperature was investigated. In the first period, the jujubes were irradiated for 4, 6, 8, 10 min at 253.7 nm ultraviolet, or coated with 1%, 1.5%, 2% and 2.5% of chitosan, respectively. In the second period, the jujubes were firstly irradiated 6 min, and then coated with 1.5% of chitosan. The result showed that combined treatment could reduce decay incidence of jujubes and restrain increase of respiration rate, weight loss, malonaldehyde content and electrolyte leakage of jujubes. Furthermore, the activities of superoxide dismutase, peroxidase, and catalase were maintained at higher level, and the decrease of ascorbic acid and chlorophyll was restricted. The present data indicated that treating post-harvest jujubes with ultraviolet irradiation combined with chitosan coating was an effective method, and might be considered in commercial application for preservation of postharvest fruit.     

不同淀粉与大豆分离蛋白混合涂层对冷却牛肉贮藏品质的影响

研究淀粉（木薯淀粉、红薯淀粉、马铃薯淀粉、玉米淀粉、豌豆淀粉和高直链淀粉）与大豆分离蛋白混合可食性涂层对冷却牛肉贮藏品质的影响。研究在4℃下贮藏5d过程中,各种淀粉与大豆分离蛋白混合涂层对冷却牛肉失重率、颜色、pH、硫代巴比妥酸值和感官评价得分的影响。结果发现豌豆淀粉和玉米淀粉与大豆分离蛋白混合涂层不仅有效降低冷却牛肉中水分损失（分别为9.97%和12.83%,低于聚乙烯膜包装）,而且较好的保持冷却牛肉的感官指标。