Alginate coatings containing grapefruit essential oil or grapefruit seed extract for grapes preservation

Biodegradable coatings based on 1% and 2% sodium alginate (NaAlg) with and without grapefruit seed extract (GSE) or grapefruit essential oil (GEO) were applied to table grapes to preserve their quality. Changes in weight loss, firmness and antioxidant activity were assessed over 15 days of cold storage. The effectiveness of developed coatings to control postharvest decay of inoculated grape berries stored for 5 days at 20 °C was also investigated. Biodegradable coatings based on pure NaAlg and those containing GSE were efficient in reducing weight loss and maintaining firmness during storage. Coatings incorporating either GEO or GSE were able to preserve the antioxidant activity of treated grapes and to reduce decay incidence in inoculated fruits. Coatings formulated with 2% NaAlg‐1% GSE showed the greatest preservation of antioxidant activity and the highest antifungal effect, with an effective control of water and firmness losses. These coatings can be recommended for maintaining table grapes quality.     

Effect of Nanochitosan-Based Coating With and Without Copper Loaded on Physicochemical and Bioactive Components of Fresh Strawberry Fruit (Fragaria x ananassa Duchesne) During Storage

Edible coatings based on nanochitosan (50–110 nm) with and without copper loaded were evaluated on physicochemical and bioactive components of strawberry. Fresh fruits were coated with copper-free and copper-loaded nanochitosans and stored at 4?±?1 °C with 70 % relative humidity for 20 days. Both nanochitosan coatings provided an effective control in reducing weight loss and firmness as well as delayed changes in the respiration rate during 3 weeks. The antioxidant activity declined throughout the storage period of strawberries, although the decrease in antioxidant activity showed a slower rate in the strawberries coated with copper-free nanochitosan followed by copper-loaded nanochitosan compared with the control. Anthocyanin concentrations increased in fruits coated with copper free as well as copper-loaded nonochitosan at the first 12 days of storage followed by reduction in slow rates. However, no increase of anthocyanin was recorded for uncoated samples. Intensive reduction was recorded in ascorbic acid content of strawberries coated with copper-loaded nanochitosan, while the minimum loss of the ascorbic acid content was related to the copper-free nanochitosan. Also, both nanochitosans showed a significant suppression on the polyphenol oxidase and peroxidase activity, whereas a high rate of increase was recorded in control strawberry. The nanochitosan coatings with or without copper loaded significantly suppressed the visual loss and fungal decay of the strawberries during the storage compared with the control. The sensory evaluation of coated strawberries revealed that no effect on the consumer acceptability was detected as well as that copper-free nanochitosan showed better results in the point of preserving the overall flavor and appearance compared with the copper-loaded one.     

Influence of 1-Methylcyclopropene (1-MCP) on Postharvest Storage Quality in Green Bell Pepper Fruit

The goal of this research was to evaluate the efficiency of 1-methylcyclopropene (1-MCP) on maintaining the quality parameters and antioxidant activity of bell pepper cv. Selika (an original red cultivar) and cv. H1530 (??ever-green?? line) after 18?days storage at 7°C and 3?days at 20°C. Fruits were harvested at green color, from a commercial shade net house in the desert region in Israel. In both cultivars, 600?nL?L^?1 1-MCP reduced weight loss and maintained firmness more than control or 900?nL?L^?1 1-MCP. Overall, 1-MCP treatment had a pronounced effect on delaying ripening processes as shown by inhibiting color changes, decreasing decay, and maintaining quality of non-climacteric green pepper fruit. 1-MCP treatment reduced the lipophilic antioxidant activity of this fruit, but the hydrophilic antioxidant activity remained similar to that observed at harvest.     

Effect of hot air on Deglet Noor palm quality parameters and on Ectomyelois ceratoniae

Insect infestation caused by Ectomyelois ceratoniae or carob moth is one of the main postharvest problems that lead to a decrease of marketable quality of dates. The control of carob moth is a mandatory process for exported fruits, and the main chemical method used to prevent pest diseases of palm date is methyl bromide. However, its use is being restricted due to direct, harmful effects to the environment, and indirect effects on humans. Hot air treatments (HATs) could be physical alternatives to methyl bromide and other chemicals. Three HATs (55 °C for 30 min, 60 °C for 15 min, 60 °C for 20 min) were studied on Deglet Noor date fruits when stored for 45 d at 2 °C followed by a retail period of 4 d at 23 °C. The results showed that the use of HATs led to 100% E. ceratoniae larvae mortality in naturally-infested date. These HATs did not cause any damage on fruit quality and reduced mesophilic bacterial counts (<1 log CFU g⁻¹). These HATs, especially the combination of highest temperature and longer time of application (60 °C for 20 min), decreased the antioxidant activity (25% in DPPH and 14% in FRAP assay). Storage time also had a significant impact, reducing color (h°), antioxidant activity, and total phenolic content of date fruits (39%). When this storage was accompanied by a retail period at 23 °C, the firmness and sensorial parameters of date fruits was significantly reduced. Nevertheless, all date fruits from HATs and control treatments maintained their marketability quality for 45 d at 2 °C followed by a retail period of 4 d at 23 °C. Results show that HATs are a physical, non-chemical, treatment for E. ceratoniae larvae mortality that maintained date fruits' postharvest quality.     

Suppression of internal browning and maintenance of antioxidants in beeswax plus salicylic acid coated pear fruit during different storage conditions

Postharvest application of edible waxes blended with antioxidants is an effective strategy to regulate postharvest quality and antioxidant losses in fruits. Effect of beeswax coatings (BW 1.0% and 2.0%) alone or enriched with salicylic acid (SA) on antioxidant properties of pear fruit was studied during 67 days of cold storage and 20 days of supermarket storage conditions respectively. Results showed that under both the storage conditions fruits coated with BW + SA maintained higher total phenolic content (TPC), antioxidant activity and ascorbic acid content (AsA) as compared to the control. Furthermore, combined coatings significantly reduced polyphenol oxidase (PPO) activities and inhibited internal browning (IB) in pears throughout cold and supermarket storage. Overall, the BW 2.0% + SA 2.0 mM exhibited the most competitive effect in terms of preserving the antioxidant properties and preventing internal browning in pears during storage.     

Utilisation Potential of Feijoa Fruit Wastes as Ingredients for Functional Foods

Feijoa fruits have high antioxidant activity as they contain significant concentrations of polyphenols (PPs), carotenoids and vitamins. This study evaluates the colour, pH, total soluble solids (TSS), pectin fibre content, total extractable PP content (TEPC) and total antioxidant activity of the extracts generated from the fruit wastes (primarily skin and some flesh) remaining after feijoa flesh consumption. Extractions were conducted at room temperature and 50 °C using accelerated solvent extraction technology and different extraction media [water, acidified water (containing citric acid, pH?3.5), and 30, 50 and 80 % (v/v) aqueous ethanol solutions]. Results show that the composition and properties of the extracts depend on the extraction media and, to a lesser extent, on the extraction temperature. The 80 % ethanolic extract was bright green in colour. The water and acidified water extracts showed more browning than the ethanolic extracts, suggesting possible detrimental sensory impacts for food applications. The TSS decreased in the order of 80, 50 and 30 % ethanolic and water extracts. The 50 % ethanolic extract had the highest TEPC and antioxidant activity at both extraction temperatures, which was supported by high performance liquid chromatography analyses. The extracts produced with solutions containing less ethanol, especially water extracts, had higher pectin contents. The UA content of the extract produced using water alone was the highest (5.56 % as GalA) at 20 °C, whilst that produced using 30 % ethanol solution was the highest (3.90 % as GalA) at 50 °C. Higher extraction temperature (50 °C) resulted in lower pectin contents. These results demonstrate the potential of feijoa waste extracts, especially 50 and 80 % ethanolic extracts, as ingredients for functional food applications.     

Use of an edible coating containing galbanum gum and cumin essential oil for quality preservation in sweet cherries

Nowadays, the use of natural compounds is considered as an effective strategy for maintaining the quality and heath promoting capacity of fresh products. Changes in quality parameters, main phenolics and antioxidants of sweet cherries in response to coating with a novel bioactive edible coating were studied. Fruit were treated with different concentrations of galbanum gum (GG), cumin essential oil (CEO) and CaCl₂ (CA) and stored at 2 ± 1°C with 90–95% RH for 30 days plus 1 day at ambient condition, and were subjected to quality analysis. All phenolic constituents and antioxidants of fruit juice were substantially decreased during storage in control fruit and a bioactive coating containing 1 or 2% GG + 100 or 200 µL L⁻¹ CEO + 1% CA maintained main fruit phytochemicals including phenolics, phenolic acids, flavonols, anti-stress and antioxidant enzymes activities. The coating significantly (P ≤ 0.01) enhanced fruit total antioxidant activity, flavonoids and ferulic acid contents. The results showed that it is possible to enhance the sweet cherry fruit health-promoting phytochemicals and shelf life by the use of a natural edible coating containing GG and CEO.     

Effect of solid content and composition of hydroxypropyl methylcellulose–lipid edible coatings on physicochemical,sensory and nutritional quality of ‘Valencia’ oranges

‘Valencia’ oranges were coated with edible coatings based on hydroxypropyl methylcellulose (HPMC), beeswax (BW) and shellac. Coatings were prepared at two BW/shellac ratios (1:3 and 3:1) and two solid content (SC) (4% and 8%). A commercial wax at a 10% SC, as a control of coated fruits, and an uncoated control were also tested. Oranges were stored up to 16 weeks at 5 °C, followed by 1 week at 20 °C. Although sensory quality was not negatively affected by coating application, care should be taken to the SC and shellac content of the formulations, since an increase in these parameters translated in a significant increase in the level of ethanol. Results indicate that HPMC–BW–shellac coating with 4% SC and a BW/shellac ratio 1:3 would provide the best compromise to extend shelf life of ‘Valencia’ oranges by reducing weight loss, providing gloss and maintaining the nutritional quality of the fruits.     

Effects of short‐term N2 treatment on quality and antioxidant ability of loquat fruit during cold storage

BACKGROUND: Loquat fruit is susceptible to microbial decay and quality deterioration during postharvest distribution. In this study, in a search for effective alternatives to methods currently used for quality maintenance, the effects of short‐term pre‐storage N₂ treatment on the quality and antioxidant ability of loquat fruit were investigated. RESULTS: Loquat fruits were exposed to 100% N₂ for 6 h at 20 °C and then stored at 5 °C for 35 days. Short‐term N₂ treatment significantly delayed the increase in fruit decay rate and decreases in total soluble solid and titratable acidity contents, thereby maintaining better eating quality and extending the storage life of fruits. It also markedly delayed increases in membrane permeability, malondialdehyde content and superoxide anion production rate. In addition, N₂‐treated fruits exhibited significantly higher superoxide dismutase and catalase activities and lower lipoxygenase activity than control fruits. CONCLUSION: Short‐term pre‐storage N₂ treatment effectively reduced fruit decay and maintained quality in loquat fruits during cold storage. The reduction in fruit decay and quality deterioration by the treatment was correlated with enhanced antioxidant ability and reduced lipid peroxidation. Copyright © 2009 Society of Chemical Industry     

Effect of Osmotic Dehydration and Pectin Edible Coatings on Quality and Shelf Life of Fresh-Cut Melon

The aim of this work was to investigate the influence of osmotic dehydration and pectin edible coating on quality parameters of fresh-cut melon. Fruits were osmodehydrated in 40°Bx sucrose solution containing 0.5% calcium lactate or dipped in 0.5% calcium lactate solutions. Then, samples were coated with 1% pectin. Melon pieces dipped in sanitizing solution (nontreated sample) were used as control. Weight loss, respiration rate, firmness, color parameters (lightness, chroma, and whiteness index), sensory acceptance, microbial growth, and structural changes of fruits were evaluated during storage at 5 °C for 14 days. The shelf life of the control sample was limited to 9 days due to microbial growth and sensory rejection, while treated samples showed a shelf life of 14 days. Higher preservation of firmness in coated samples was attributed to the action of calcium salt on melon structure, causing a strengthening of the cell wall. Calcium lactate also inhibited microbial growth along storage, improving microbiological stability of fresh-cut melon. The use of calcium lactate dips and pectin edible coatings hindered weight loss and maintained fruit color characteristics during the storage time. However, these pretreatments probably masked melon taste, reducing the sensory acceptance scores at the end of shelf life study. The combination of osmotic dehydration and pectin coatings was a good preservation alternative for fresh-cut melon, since it improved fruit sensory acceptance, promoting the reduction of product respiration rate, as well as the maintenance of quality parameters during 14 days.     

Changes in the antioxidant capacity and phenolic compounds of <Emphasis Type="Italic">maesil</Emphasis> extract during one-year fermentation

This study aimed to identify the effects of soaking time and fermentation temperature and period on the total phenolics, total flavonoids, and antioxidant activity of maesil extract. Green maesil fruits were fermented with brown sugar at 15 or 25°C for one year. After soaking maesil for 90 days, the fruits were removed and the remaining liquid was further ripened for 275 days, whereas other samples continued to ferment with maesil until 365 days. Total phenolics, total flavonoids, and antioxidant activities of the extracts fermented with maesil for one year were higher compared with those wherein the fruits were removed at day 90. The total phenolic and total flavonoid contents were relatively higher at 15°C, whereas the ABTS and ferric-reducing antioxidant power (FRAP) activities were significantly higher at 25°C. The total phenolic and total flavonoid contents highly correlated with the antioxidant activities. These results show that fermentation temperature plays a critical role in enhancing the phenolic compounds and antioxidant activity of maesil extract.     

Shelf-life extension of peaches through sodium alginate and methyl cellulose edible coatings

The objective of this study was to determine the effect of sodium alginate and methyl cellulose coatings on the respiration rate, firmness, acidity, pH, total soluble solids and desiccation rate of peaches. Coated and uncoated control fruits were stored at 15 °C and 40% RH. Respiration rate, moisture loss, and changes in firmness, total titrable acidity, pH and total soluble solids of coated and control samples were determined at 3‐day intervals. The respiration rate, moisture loss and changes in quality parameters were much lower in coated peaches as compared with the control. While the maximum acceptable shelf‐life at 15 °C for control samples was 15 days, the coated samples maintained their acceptability up to 21 and 24 days, respectively, with sodium alginate and methyl cellulose coating. The reduced respiration and transpiration rates as a result of coatings were considered responsible for maintaining the quality and increasing the shelf‐life of peaches.     

Double Layer Coatings: A New Technique for Maintaining Physico-Chemical Characteristics and Antioxidant Properties of Dragon Fruit During Storage

A double layer coating was evaluated for maintenance of quality of dragon fruit during storage at 10?±?2 °C and 80?±?5 % RH for 28 days. Significant differences (p?<?0.05) were observed between control and the treated fruit. However, a double layer coating with 600 nm droplet size?+?1.0 % conventional chitosan showed promising results in all the tested parameters, while the fruit treated with 1,000 nm droplet size?+?1.0 % conventional chitosan showed some negative effects on fruit surface. Increase in weight loss was 12.0 % in fruit treated with 600 nm droplet size and 1.0 % conventional chitosan as compared to the control. Antioxidants and gaseous analysis also proved the efficacy of double layer coatings with 600 nm droplet size?+?1.0 % conventional chitosan. Thus it can be concluded from the present investigation that double layer coating could be used for maintaining quality in dragon fruit for up to 28 days without any off-flavours.     

Effect of shrimp chitosan coatings as affected by chitosan extraction processes on postharvest quality of strawberry

Edible coatings as affected by chitosan extraction processes were used to preserve the quality of strawberries (Fragaria × ananssa) during their storage at ambient temperature (20–25 °C). Thus, three different chitosans were prepared from shrimp shell and were designated as the following: C1 by classical method, C2 without the decoloration step, and C3 without the decoloration step and the deproteinization step. In order to study the effectiveness of coatings, changes in physicochemical parameters and mold spoilage were studied. Chitosan coatings had no significant effects on titrable acidity, pH and soluble solids content (SSC) of strawberries throughout the storage, while the SSC content of control fruits increased with the storage time. In contrast, chitosan coatings delayed changes in weight loss and the appearance of fungal infection. Coated samples had greater visual acceptability than had the untreated fruits. By visual analysis, it was possible to verify that the best quality was maintained until the day 12, for the strawberries coated with C3 (1 %).     

Postharvest Changes in Antioxidant Capacity,Enzymatic Activity,and Microbial Profile of Strawberry Fruits Treated with Enzymatic and Divalent Ions

Strawberry fruits are highly perishable and cannot be stored for more than 1–2 days at ambient condition. Therefore, it was thought desirable to enhance the shelf-life of harvested strawberry using pectin methyl esterase and divalent ions. The freshly harvested fruits of strawberry were treated with different concentrations of pectin methyl esterase (50–300 units) and divalent calcium ions (calcium chloride) for 5–30 min using response surface methodology—Box–Behnken design. The treated and untreated (control) fruits were packed in plastic punnets and stored at two different temperature conditions, viz., 7 °C with 80 % relative humidity (RH) and 25 °C with 60 % RH, for evaluating the shelf-life. Appropriate physico-chemical and microbiological parameters were determined at alternate days during their storage. Overall firmness and color values (L, a, b) decreased, while physiological weight loss (percent) increased during their storage. No food-borne pathogens, viz., Salmonella, Staphylococcus, and coliforms, were observed during storage. Total antioxidant capacity and ferric reducing antioxidant power decreased, while lipoxygenase and polyphenol oxidase activities increased during storage at 7 and 25 °C. The shelf-life of treated strawberry was found to be 10 days at 7 °C as against 6 days for control fruits under similar conditions. The treated strawberry had shelf-life of 2 days compared to 1 day for control maintained at 25 °C.     

Effect of Processing and Storage on The Antioxidant Activity of Frozen and Pasteurized Shadblow Serviceberry (Amelanchier canadensis)

Serviceberry fruits were pasteurised in glass jars at two temperatures, 85 and 100°C, while another batch was packed in polyethylene bags and frozen at a temperature of ?20 ± °C. Processed fruits were stored for 10 months: frozen fruit at ?20 ± 1°C; and pasteurised fruit at room temperature without access to light. Refrigerated storage and pasteurization lowered the DPPH antioxidant activity of serviceberry fruit. In the former, the change was not great, whilst pasteurisation caused an approximately twofold increase in EC50. On the basis of total anthocyanin content and total polyphenolic content measurements, it would appear that the antioxidant properties of serviceberry were affected mainly by anthocyanins. Pasteurising at 100°C allowed slightly better preservation of these compounds during long-term storage.     

Effect of native and acetylated‐crosslinked waxy corn starch‐beeswax coatings on quality attributes of raspberries during storage

Edible coatings (ECs) are a thin layer of a mixture of edible materials, applied in the liquid state and dried over the surface of a food product to maintain its quality during storage. This work was aimed to study the effect of ECs made from wx corn starch (WCS) or acetylated cross‐linked starch (ACLS) added with beeswax on fresh raspberry quality attributes during short‐term cold storage. Freshly harvested fruits were coated, dried, packed in plastic trays and stored up to 8 days at 4°C. During storage quality parameters such as firmness, respiration rate, anthocyanins content, total phenols, color changes, and weight loss were evaluated. A clear effect on control of respiration rate was observed in coated raspberries. Respiration rate of uncoated fruit was 4.5 ± 0.28 mmol/kg/h and decreased to 4.2 ± 0.27 for ACLS and to 4.1 ± 0.08 mmol/kg/h for WCS‐coated raspberries, after 56 h of storage at 15°C. Ethylene production followed a similar trend under these conditions decreasing from 0.043 ± 0.005 to 0.034 ± 0.004 mmol/kg/h for uncoated and ACLS coated fruits, respectively, indicating an effect on ripening control. Additionally, ACLS and WCS coatings permitted the preservation of color without affecting anthocyanins content. However, the presence of anaerobic metabolites and reduction of terpenes production in cold stored coated raspberries indicated hypoxic conditions, which can adversely affect shelf‐life quality attributes of raspberries such as firmness and weight loss.     

Ultrasound-Assisted Chitosan–Surfactant Nanostructure Assemblies: Towards Maintaining Postharvest Quality of Tomatoes

A novel ultrasound-assisted chitosan–surfactant nanostructure assembly was developed to allow better delivery of chitosan particles into intact fruit tissues for extension of postharvest life. Three solutions of 1 % chitosan–surfactant nanostructure assembly with micelle sizes of 400, 600 and 800 nm were prepared and applied as an edible coating on tomatoes. The fruits were stored at 15?±?2 °C and 70–80 % relative humidity for 20 days. The indicators of tomato ripening, which included loss of firmness, decline of titratable acidity, decline of chlorophyll content and increase in soluble solid content, were delayed in the treated fruits in comparison to the control (p?<?0.05). A delay of approximately 5 days in ripening was observed by evaluating the colour evolution from green to red. The treatment significantly (p?<?0.05) enhanced the phenolic content while maintaining a lower level of respiration in comparison to the control, throughout most of the storage duration. However, weight loss was higher in the treated fruits in comparison to the control. No significant difference in the resultant effects was observed by using chitosan–surfactant nanostructure assemblies of different micelle sizes (p?>?0.05).     

CaCl_2对采后不同成熟度冬枣抗氧化及细胞壁代谢的影响

为探讨CaCl_2处理对不同成熟度冬枣(Zizyphus Jujuba Mill.cv.Dongzao)抗氧化能力及细胞壁代谢的影响,试验采用1%和2%CaCl_2浸泡处理白熟期(WM)和半红期(HM)冬枣果实,以水处理为对照,测定20±2℃贮藏过程中果实硬度、过氧化氢(H_2O_2)、丙二醛(MDA)、超氧化物歧化酶(SOD)、过氧化物酶(CAT)、抗坏血酸(As A)、还原型谷胱甘肽(GSH)、多聚半乳糖醛酸酶(PG)以及细胞壁组分(水溶性果胶(WSP)、离子结合果胶(ISP)和共价结合果胶(CSP))变化。结果表明,在贮藏过程中1%和2%CaCl_2处理可显著延缓WM和HM期果实硬度下降,抑制H_2O_2和MDA积累,维持较高水平的SOD和CAT活性以及As A和GSH含量,同时,降低PG活性以及WSP和ISP含量,增加CSP含量,其中1%CaCl_2处理对HM期果实作用效果最显著,通过提高其抗氧化活性和抑制细胞壁降解过程,使其在贮藏期间保持较好的果实品质。     

Increasing Cold Tolerance of Cactus Pear Fruit by High-Temperature Conditioning and Film Wrapping

Pre-storage high-temperature conditioning (HTC, 38 °C, and 95% RH for 24 h) and individual film wrapping (IFW) with a perforated polyolefinic heat-shrinkable film were used as individual treatments or in combination to mitigate chilling injury of first crop cactus pear cv ‘Gialla’. The fruit was stored for 21 days at either 2 or 8 °C (CS) plus 1 week of simulated marketing conditions (SMC) at 20 °C. The reduction in peel disorders and decay in HTC-treated fruit stored at 2 °C was comparable to that detected in control fruit stored at 8 °C. IFW was more efficient than HTC in reducing peel disorders, almost completely inhibited weight loss, and preserved freshness in fruit stored at 8 °C as well as in those stored at 8 °C. The internal quality of the fruit (pH, total soluble solids, titratable acidity, vitamin C, polyphenols, betaxanthins, antioxidant capacity, acetaldehyde, and ethanol) was slightly affected by treatments. Combining HTC with IFW did not improve fruit tolerance to low temperature but reduced decay with respect to individual treatments. IFW with a perforated film in combination with HTC is a good means of overcoming the stringent conditions of cold quarantine treatments, maintaining fruit freshness and reducing decay in cold-stored cactus pears.