The nutraceutical quality of tomato fruit during domestic storage is affected by chitosan coating

Fruits and vegetables are highly perishable foods which usually undergo a gradual loss of nutraceuticals during storage. Chitosan‐based edible coatings are extensively studied thanks to antimicrobial activity and great potential to extend the shelf life. However, little information is presently available on the nutraceutical quality of chitosan‐coated products. The present study is addressed to evaluate accompanied by a delayed degradation of some phenolic compounds during storage. These results indicate that chitosan coating is effective in maintaining the quality parameters, the coated fruit showed less weight loss (?16%) and more firmer (+40%) than control fruit, chitosan‐coated tomato emitted significantly lower ethylene (?41%) than control, and slowing down the nutraceutical loss occurring in postharvest, mainly of the lycopene, main carotenoid, found in tomato fruits. These results indicate that chitosan coating is effective in slowing down the nutraceutical loss occurring in postharvest, thus representing a promising tool to preserve bio‐protective phytochemicals during fruit conservation.

Practical applications

During storage and domestic conservation, the nutraceutical quality of fruits and vegetables usually decreases and can undergo deterioration due to physiological disorders and mechanical damages. In the last decade, use of edible coatings has attracted interest as a promising technology to prolong the shelf life of particularly perishable foods. These coatings act as protective barriers decreasing transpiration rate and gas transfer across the product surface, thus promoting the maintenance of nutritional quality.     

Chitosan and postharvest decay of fresh fruit: Meta-analysis of disease control and antimicrobial and eliciting activities

Consumers are increasingly aware of the importance of regular consumption of fresh fruit in their diet. Since fresh fruit are highly sensitive to postharvest decay, several investigations focused on the study natural compounds alternative to synthetic fungicides, to extend their shelf life. A long list of studies reported the effectiveness of the natural biopolymer chitosan in control of postharvest diseases of fresh fruit. However, these findings remain controversial, with many mixed claims in the literature. In this work, we used random-effects meta-analysis to investigate the effects of 1% chitosan on (a) postharvest decay incidence; (b) mycelium growth of fungal pathogens Botrytis cinerea, Penicillium spp., Colletotrichum spp. and Alternaria spp.; and (c) phenylalanine ammonia-lyase, chitinase and β-1,3-glucanase activities. Chitosan significantly reduced postharvest disease incidence (mean difference [MD], −30.22; p < 0.00001) and in vitro mycelium growth (MD, −54.32; p  < 0.00001). For host defense responses, there were significantly increased activities of β-1,3-glucanase (MD, 115.06; p = 0.003) and chitinase (MD, 75.95; p < 0.0002). This systematic review contributes to confirm the multiple mechanisms of mechanisms of action of chitosan, which has unique properties in the natural compound panorama. Chitosan thus represents a model plant protection biopolymer for sustainable control of postharvest decay of fresh fruit.     

Effects of chitosan coating on postharvest life and quality of longan fruit

The effects of chitosan coating in extending postharvest life of longan fruits and maintaining their quality were investigated. The fruits were treated with aqueous solutions of 0.5, 1.0 and 2.0% chitosan, respectively, and then stored at 2°C and 90% relative humidity. Changes in respiration rate, polyphenol oxidase (PPO) activity, colour, eating quality, and weight loss were measured. The effect of chitosan coating on disease incidence was also evaluated. The application of chitosan coating reduced respiration rate and weight loss, delayed the increase in PPO activity and the changes in colour, and eating quality, and partially inhibited decay of fruit during storage. Furthermore, increasing the concentration of chitosan coating enhanced the beneficial effects of chitosan on postharvest life and quality of the fruit.     

Shelf life extension of minimally processed water caltrop (Trapa acornis Nakano) fruits coated with chitosan

Freshwater caltrop (Trapa acornis Nakano) fruits are very perishable and susceptible to browning, and thus have a short shelf life. In this study, minimally processed water caltrop (MPWC) fruits were treated with 0.0% (control), 0.5%, 1.0% and 2.0% of chitosan aqueous solutions, respectively, and stored at 4 ± 1 °C, 80–85% relative humidity for 15 day. Effects of the chitosan coating on MPWC fruit shelf life and qualitative attributes were evaluated by investigating fresh weight loss, browning index, phytochemicals and browning‐related enzymes activities. Results showed that 1.0% and 2.0% chitosan coating significantly extended shelf life of MPWC fruit by reducing browning occurrence and fresh weight loss, preserving ascorbic acid, soluble solid and titratable acidity as well as total phenol content, also inhibiting the increase in phenylalanine ammonia lyase, polyphenol oxidase and peroxidase activities compared to the control during storage. However, 0.5% chitosan coating seemed to be ineffective in prolonging shelf life and conserving quality of MPWC fruit except for keeping more total phenols during storage in comparison with the control.     

壳聚糖对于肉类食品防腐和保鲜的应用研究进展

壳聚糖是1种来源于蟹、虾等甲壳类动物贝壳的天然高分子聚合物.对于多种食源性丝状真菌、酵母、细菌等具有广谱抗性,并且具有很好的抗脂质过氧化作用.以壳聚糖为材料制成的包装膜,具有透气屏障的作用,可以延缓被包裹物与外界的气体交换以及包裹物自身营养成分的流失.这些特性使壳聚糖作为潜在的食品防腐剂或食品包裹材料具有很高的市场应用潜力和应用价值.本文主要对近年来壳聚糖作为食品防腐剂在延长生鲜肉、鱼、火腿制品保存期方面的研究和应用情况进行了综述.     

Chitosan Acetate as an Active Coating Material and Its Effects on the Storing of Prunus avium L.

ABSTRACT: In this article, chitosan acetate (CA) was prepared by the method of solid–liquid reaction. CA was a stable faint yellow powder with water solubility. CA kept the same backbone in the chemical structure as the raw material of chitosan, and it also had the similar antibacterial properties with chitosan. CA could form a coating film on the outside surface of the sweet cherries, could effectively retard the loss of the water, titratable acidity, and ascorbic acid of sweet cherries, and could induce a significant increase in the peroxidase and catalase activities in the fruit. The CA coating could also increase the ratio of the total soluble solids and titratable acidity in the fruit. The application of CA effectively maintained quality attributes and extended postharvest life of the sweet cherries. The results revealed that the CA salts had potential application in active edible coating materials in the storage of fresh fruit.     

The effect of chitosan coating incorporated with ethanolic extract of propolis on the quality of refrigerated chicken fillet

Chitosan is considered as a functional packaging component for maintaining the quality and increasing the shelf life of perishable foods include meat, poultry, fish, dairy products, and all cooked leftovers. The present study was conducted to evaluate edible coating of chitosan (2%) containing ethanolic extract of propolis (1% and 2%) on microbiological (mesophilic aerobic, psychrotrophic, lactic acid bacteria, coliforms, and Staphylococcus aureus counts), chemical (TBARS, TVN and Peroxide values) and sensory (odor, color, texture, taste, and overall acceptance) properties of chicken fillet. Microbial analysis showed that coating had a significant reducing effect on growth of bacteria during 12 days at 4 °C. Besides, the increase of TBARS, Total volatile nitrogen, and peroxide value of samples coated by chitosan and ethanolic extract of propolis was less than control group. According to our results, chitosan and propolis can be used to enhance the shelf life of fillet and maintain its quality.

Practical applications

Propolis is used for infections caused by bacteria, viruses, fungus, and by single‐celled organisms called protozoans. Propolis is also used as an antioxidant and anti‐inflammatory agent. Ethanol extract of propolis improve the properties of chitosan edible coating in chicken fillet preservation. The chitosan coating incorporated with ethanolic extract of propolis can improve the microbial, chemical, and sensory quality of food and enhance the shelf life of them by synergistic effects.     

Effect of chitosan on incidence of brown rot,quality and physiological attributes of postharvest peach fruit

The effect of chitosan (5.0 and 10.0 mg ml ⁻¹) on the incidence of brown rot (caused by Monilinia fructicola), quality attributes and senescence physiology of peaches was investigated. It was found that both concentrations of chitosan reduced the incidence of brown rot significantly and delayed the development of disease compared with the control, but were less effective than the fungicide prochloraz. Chitosan‐treated peaches were firmer and had higher titratable acidity and vitamin C content than prochloraz‐treated or control peaches. Compared to control (water‐treated) peaches, chitosan‐treated peaches showed lower respiration rate, less ethylene and malondialdehyde (MDA) production, higher superoxide dismutase (SOD) activity and better membrane integrity. Hence it can be concluded that chitosan has the potential to control brown rot, preserve valuable attributes and prolong the shelf life of postharvest peaches, presumably because of its antifungal property and inhibition of the ripening and senescence process of postharvest peaches. © 2000 Society of Chemical Industry     

Effect of chitosan coating in preventing deterioration and preserving the quality of fresh‐cut papaya ‘Maradol’

BACKGROUND: Chitosan can form antimicrobial, semi‐permeable barriers that limit gas exchange and reduces water loss in fruits. Consumer interest in fresh‐cut papaya fruit is leading to increasing demand because of its sensorial and antioxidant properties. However, papaya is a highly perishable product that is prone to loss of weight, loss of firmness and microbial attack. The aim of this study was to evaluate the effect of chitosan coatings on the overall quality of fresh‐cut papaya. Chitosan coatings of low (LMWC), medium (MMWC) and high (HMWC) molecular weights, at concentrations of 0.01 and 0.02 g mL^?1, were applied to fresh‐cut papaya cubes. The treated cubes were stored at 5 °C and changes in quality were evaluated. RESULTS: MMWC maintained the highest color values (L* and b*) and firmness. Chitosan coatings suppressed mesophilic plate count, and the growth of molds and yeast, compared to controls. The MMWC coatings at 0.02 g mL^?1 resulted in the highest antimicrobial activity and decreased the activity of the enzymes polygalacturonase and pectin methylesterase, followed by low and high MW chitosan coatings at 0.02 g mL^?1. CONCLUSION: The application of the MMWC treatment at 0.02 g mL^?1 could be used to reduce deteriorative processes, maintain quality and increase the shelf life of fresh‐cut papaya stored at 5 °C. Copyright © 2008 Society of Chemical Industry     

壳聚糖涂膜对南湖菱果实贮藏生理及品质的影响

以新鲜南湖菱果实为试材,研究壳聚糖涂膜对南湖菱果实贮藏期间品质和生理的影响。用1.0g/100mL和2.0g/100mL壳聚糖溶液对果实涂膜后,4℃±1℃、相对湿度(90±2)%条件下贮藏15d,测定果实贮藏期间质量损失率、VC、总酚、可溶性总糖、蔗糖、还原糖和可溶性固形物含量变化与多酚氧化酶(PPO)、抗坏血酸过氧化物酶(APX)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)比活力以及丙二醛(MDA)含量的变化。结果表明:1.0g/100mL和2.0g/100mL壳聚糖涂膜显著减少果实表面失水,减缓VC、总酚、可溶性总糖、蔗糖、还原糖和可溶性固形物含量下降,维持果实营养品质;同时抑制褐变酶PPO比活力,减缓抗氧化酶APX和SOD比活力上升,减少膜脂过氧化产物MDA积累。因此,1.0g/100mL和2.0g/100mL壳聚糖涂膜能够有效地保存果实营养物质,延缓果实衰老,可以作为安全廉价的保鲜方法应用于南湖菱果实贮藏保鲜。     

涂膜保鲜剂中添加茶多酚对黄花梨贮藏品质的影响

探讨壳聚糖与天然抑菌抗氧化物质茶多酚对黄花梨进行涂膜保鲜的可行性。用茶多酚和壳聚糖混合液处理黄花梨,结合PE保鲜袋包装贮藏,测定贮藏过程中果实呼吸强度、多酚氧化酶(polyphenol oxidase,PPO)活性、VC含量、果实硬度及腐烂率等各项指标的变化。结果表明,壳聚糖联合茶多酚对黄花梨的保鲜效果优于单一保鲜剂,涂膜剂中添加茶多酚可明显抑制多酚氧化酶活性、延缓果实呼吸高峰出现的时间、降低黄花梨的烂果率,VC的保存率高于对照组。涂膜保鲜剂中添加茶多酚量为0.3%时保鲜效果最佳。壳聚糖中添加茶多酚能够明显延长黄花梨的保鲜期。     

壳聚糖对果蔬的抗菌保鲜效果及其应用研究进展

由于采后旺盛的生理代谢, 新鲜水果和蔬菜会出现品质劣变, 采取有效的抗菌保鲜策略是果蔬采后贮藏过程亟待解决的问题。天然大分子壳聚糖作为果蔬的活性包装材料具有来源广泛、安全和可生物降解等优点。本文综述了近年来壳聚糖基涂层/膜用于果蔬保鲜包装的抗菌保鲜效果及其对果蔬品质的影响, 首先介绍了壳聚糖的来源及应用特点以及制备壳聚糖薄膜材料的常用方法, 然后综述了壳聚糖及其与其他生物活性材料复合使用在果蔬保鲜中的应用, 并总结了使用壳聚糖基涂层/膜保鲜对果蔬外观品质、营养品质、挥发性香气物质等方面的影响; 最后, 对壳聚糖在果蔬抑菌保鲜机制方面的研究进行归纳介绍, 以期为其未来发展和应用提供新的思路。     

Assessment of coating tomato fruit with shrimp shell chitosan and N,O-carboxymethyl chitosan on postharvest preservation

The effect of coating tomato fruit (Lycopersicon esculentum) with shrimp shell chitosan, a deacetylated form of chitin, and a chitosan derivative, i.e. N,O-carboxymethyl chitosan (NOCC) on postharvest preservation was studied. The effects of various chitosan and NOCC concentrations on fruit ripening behavior, as well as fruit physical and chemical characteristics were evaluated during storage at room temperature (25–30 °C). Coating the fruit with 2 % (w/v) chitosan or NOCC solutions was found to be more effective in extended its storage life than coating with 0.5 % (w/v) solutions. Covered tomatoes were firmer, higher in titratable acidity, and exhibited less red pigmentation than the control uncoated fruits at the end of storage. These results suggest the suitability of chitosan and its derivative NOCC as an alternative means of preserving fresh fruits.     

Effectiveness of edible coatings combined with mild heat shocks on microbial spoilage and sensory quality of fresh cut broccoli (Brassica oleracea L.)

The use of edible coatings and mild heat shocks is proposed as postharvest treatments to prevent microbial deterioration of refrigerated broccoli. Minimally processed broccoli was coated with either chitosan or carboxymethyl-cellulose (CMC) combined or not with a previous application of a mild heat shock. The evolution of microbial populations (mesophilic, psycrotrophic, Enterobacteriaceae, molds and yeast, and lactic acid bacteria) was studied during 20 d of storage and fitted to Gompertz and logistic models. Results revealed that, at the end of the storage, chitosan coating significantly reduced all microbiological population counts, except lactic acid bacteria; while higher reduction was observed with chitosan coating combined with a heat shock treatment. A significant delay at the beginning of the exponential phase was observed for all the bacterial populations analyzed. On the other hand, CMC coating, with and without a previous thermal treatment, did not exert any antibacterial effect. Excellent agreement was found between experimental microbial counts and predicted values obtained from Gompertz and logistic models. Kinetic modeling was found to be valuable for prediction of microbiological shelf life of broccoli during storage. Results showed that the application of chitosan coating effectively maintained microbiological quality and extended shelf life of minimally processed broccoli. According to these results, the use of the edible chitosan coating alone or in combination with a heat mild shock appear to be a viable alternative for controlling microbiological growth and sensory attributes in minimally processed broccoli. PRACTICAL APPLICATION: The continuous consumer interest in high quality and food safety, combined with environmental concern has induced to the development and study of edible coatings that avoid the use of synthetic materials. The edible coatings, formed from generally recognized as safe materials, have the potential to reduce weight loss, respiration rate, and improve food appearance and integrity. It is one of the most effective methods to maintain food quality. On the other hand, heat treatments have been demonstrated to be effective as a nonchemical means of improving postharvest quality for a variety of horticultural products. The applications of mild heat shocks combined with edible coatings constitute an alternative for the natural preservation of crops for which the use of synthetic chemicals is objectionable.     

Perspectives for chitosan based antimicrobial films in food applications

Recently, increasing attention has been paid to develop and test films with antimicrobial properties in order to improve food safety and shelf life. Active biomolecules such as chitosan and its derivatives have a significant role in food application area in view of recent outbreaks of contaminations associated with food products as well as growing concerns regarding the negative environmental impact of packaging materials currently in use. Chitosan has a great potential for a wide range of applications due to its biodegradability, biocompatibility, antimicrobial activity, non-toxicity and versatile chemical and physical properties. Thus, chitosan based films have proven to be very effective in food preservation. The presence of amino group in C2 position of chitosan provides major functionality towards biotechnological needs, particularly, in food applications. Chitosan based polymeric materials can be formed into fibers, films, gels, sponges, beads or even nanoparticles. Chitosan films have shown potential to be used as a packaging material for the quality preservation of a variety of food. Besides, chitosan has widely been used in antimicrobial films to provide edible protective coating, in dipping and spraying for the food products due to its antimicrobial properties. Chitosan has exhibited high antimicrobial activity against a wide variety of pathogenic and spoilage microorganisms, including fungi, and Gram-positive and Gram-negative bacteria. The present review aims to highlight various preparative methods and antimicrobial activity including the mechanism of the antimicrobial action of chitosan based films. The optimisation of the biocidic properties of these so called biocomposites films and role of biocatalysts in improvement of quality and shelf life of foods has been discussed.     

EFFECT OF CHITOSAN COATING ON SHELF LIFE AND QUALITY OF FRESH-CUT MUSHROOM

ABSTRACT

The effect of chitosan coating in fresh‐cut mushroom preservation, including microbiological, enzyme activities, color characteristics and chemical quality attributes, was examined. However, application of chitosan coating to enzyme activity control and quality maintenance of fresh‐cut mushroom was investigated. Fresh‐cut mushrooms were treated with aqueous solution of 0.5, 1 and 2 g chitosan/100 mL, placed in polyethylene bags, and then stored at 4C. Application of chitosan coating delayed discoloration associated with reduced enzyme activities of polyphenoloxidase, peroxidase, catalase, phenylalanine ammonia lyase and laccase, as well as lower total phenolic content. Also, it reduced enzyme activities of cellulase, total amylase and α‐amylase. Microbiological development of the fresh‐cut mushroom treated with chitosan coating was also inhibited compared to the control. The results showed that increasing the concentration of chitosan coating enhanced the beneficial effects of chitosan on extended shelf life and maintained quality of fresh‐cut mushroom.

PRACTICAL APPLICATIONS

In general, the results showed that the application of chitosan coating (with optimum concentration of 2%) of oyster mushroom was observed to greatly inhibit the enzyme activities and lowest microbial count (Y, M and B) during storage at 4C for 15 days. Recommendations for selection of an appropriate chitosan concentration with refrigeration at 4C were given to be a potentially useful tool for extending the shelf life of fresh oyster mushroom. Furthermore, from a technological point of view, it would be conceivable to use chitosan coating in processed mushrooms provided that their safety is assessed and their commercial feasibility is demonstrated. It is concluded that the technique used produced good results; the product showed good quality during processing and storage with respect to microbiological, physical and chemical properties. Also, this technique is important to prevent the decrease in market value and the concomitant economic losses.

     

Combination of heat treatment and chitosan coating to improve postharvest quality of wolfberry (Lycium barbarum)

The synergistic application of hot water dip at 42 °C for 30 min and 1% chitosan coating on differentiation in postharvest quality traits, microstructure as well as microbiological evolution of wolfberry fruits was investigated. Fresh wolfberry fruits were stored at 2 ± 0.5 °C and 90% relative humidity (RH) for 28 days. Results indicated the combination of prestorage heat treatment and chitosan coating maintained higher levels of ascorbic acid, total phenolic contents and antioxidant capacity as well as lower decay, compared with untreated wolfberry fruits. The possible mechanism was that the heat treatment almost sealed open stomata to limit the sites of pathogen penetration into fruits independently, followed by the biofilm formed by chitosan which controlled secondary infections as well as slowed changes in fruit respiration and metabolic activity in wolfberries. The synergistically treated fruit also exhibited a higher acceptability obtained by sensory analysis after cold storage. In this sense, the integrated application of heat treatment and chitosan coating could be regarded as an effective strategy to extend storage life and maintain the postharvest quality of wolfberry fruits.     

壳聚糖结合1- 甲基环丙烯处理对李果实货架期品质的影响

为改善贮藏后李果实品质和开发综合贮藏保鲜技术,研究贮藏前壳聚糖涂膜处理及其结合贮藏后1- 甲基环丙烯(1-MCP)熏蒸处理对货架期“牛心”李果实品质的影响。结果表明：贮藏前采用10、15、20g/L 壳聚糖溶液涂膜处理及其结合贮藏后采用1.0μl/L 1-MCP 熏蒸可以有效保持低温贮藏(2℃、4 周)后货架期(23～25℃)李果实的硬度,延缓果实VC 含量的下降和果皮色泽的转红,抑制果实腐烂的发生。壳聚糖和1-MCP 的结合处理比两者各自的处理效果都好,能进一步显著地改善李果实在货架期的品质表现,为李果实综合贮藏保鲜技术开发提供依据。     

Effect of chitosan/nano-silica coating on the physicochemical characteristics of longan fruit under ambient temperature

A novel chitosan/nano-silica hybrid film was prepared using tetraethoxysilane as precursor by in situ sol–gel process, and characterized by transmission electron microscopy. Its effect on preservation quality of longan fruits (Dimocarpus longan Lour. cv Shijia) was investigated under ambient temperature. The present study revealed that the excellent semi-permeable film of chitosan/nano-silica markedly extended shelf life, reduced browning index, retarded weight loss and inhibited the increase of malondialdehyde amount and polyphenoloxidase activity in fresh longan fruit. In addition, the peroxidase activity of longan fruit coated with hybrid film was lower than that in other treatment fruits. Decreases in the contents of total soluble solids, titratable acidity and ascorbic acid were also significantly inhibited by hybrid films. These data indicated that the chitosan/nano-silica coating might provide an attractive alternative to improve preservation quality of fresh longan fruits during extended storage.     

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.