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.     

Effect of rapeseed protein–gelatin film containing grapefruit seed extract on ‘Maehyang’ strawberry quality

To develop a packaging film for ‘Maehyang’ strawberries, an edible film containing antimicrobial grapefruit seed extract (GSE) was manufactured. Addition of GSE to the rapeseed protein–gelatin (RG) film inhibited the growth of pathogenic bacteria such as Escherichia coli O157:H7 and Listeria monocytogenes. Packaging of ‘Maehyang’ strawberries with the RG film containing 1.0% GSE decreased the populations of total aerobic bacteria and of yeast and moulds in the strawberries by 1.03 and 1.34 log CFU g^?1, respectively, after 14 days of storage, compared to that of the control. Sensory evaluation of the GSE‐RG film‐packaged strawberries produced better sensory scores than did the control. These results suggest that RG film containing GSE can be used to package strawberries and to extend shelf life.     

Effect of chitosan coating combined with postharvest calcium treatment on strawberry (Fragaria × ananassa) quality during refrigerated storage

Strawberries (Fragaria × ananassa Duch.) were coated with either 1% or 1.5% chitosan (CS) or chitosan combined with calcium gluconate (CaGlu). Following treatment, strawberries were stored at 10 °C and 70 ± 5% RH for one week. The effectiveness of the treatments in extending fruit shelf-life was evaluated by determining fungal decay, respiration rate, quality attributes and overall visual appearance. No sign of fungal decay was observed during the storage period for fruit coated with 1.5% CS (with or without the addition of CaGlu) or 1% CS + 0.5% CaGlu. By contrast, 12.5% of the strawberries coated with 1% CS lacking calcium salt were infected after five days of storage. The chitosan coating reduced respiration activity, thus delaying ripening and the progress of fruit decay due to senescence. Chitosan coatings delayed changes in weight loss, firmness and external colour compared to untreated samples. Strawberries coated with 1.5% chitosan exhibited less weight loss and reduced darkening than did those treated with 1% chitosan, independently of the presence or absence of CaGlu. However, addition of calcium to the 1% chitosan solution increased the firmness of the fruit. Coated samples had greater visual acceptability than had untreated fruits. The addition of calcium gluconate to the chitosan coating formulation increased the nutritional value by incrementing the calcium content of the fruit.     

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.     

PHYSICAL AND PHYSICOCHEMICAL CHARACTERISTICS OF THREE U.S. STRAWBERRY CULTIVARS GROWN IN THE PACIFIC NORTHWEST

Totem, Shuksan, and Puget Reliance are the three predominant strawberry cultivars in the U.S. Northwest. Fruit shape and size, volume, density, porosity, specific gravity, moisture content, water activity, color, firmness, pH value, titratable acid, and mineral content were determined. The three cultivars had significantly different physical and physicochemical properties (P < 0.05). Shuksan had the largest volume, and lowest density and specific gravity. The soluble solids and texture of Puget Reliance were the highest among the three cultivars. Totem had the highest ratio of soluble solids to total acids (SS/TA). Despite these differences, all three strawberry cultivars had attractive color, a high SS/TA ratio, and thus, good commercial qualities. These strawberry cultivars were also excellent sources of manganese, ranging from about 19% to 21% DRI (Dietary Reference Intake) manganese in 100 g fresh strawberries.     

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.     

不同处理对赛买提杏贮藏保鲜效果的影响

以保鲜袋包装杏果实为对照,分别采用保鲜袋+1.5%壳聚糖抗菌纸铺垫;保鲜袋+200mg/m3浓度的臭氧气体;保鲜袋+1.5%壳聚糖抗菌纸铺垫+200mg/m3浓度的臭氧气体三种不同处理方法进行贮藏保鲜,考察不同处理对杏果贮藏品种的影响。试验表明,3个处理组的保鲜效果在各个方面均高于对照组,并且能够有效的减缓杏果腐败率的上升,保持杏果可溶性固形物(SSC)、VC和可滴定酸(TA)的含量,抑制杏果PPO活性,延长贮藏期限。其中保鲜袋+1.5%壳聚糖抗菌纸铺垫+200mg/m3浓度的臭氧气体处理方法对杏果的贮藏保鲜效果最为显著。     

Variations in antioxidant properties of strawberries grown in Brazilian savannah and harvested in different seasons

BACKGROUND: Strawberries are nutritive fruits and a source of antioxidants. We evaluated antioxidant properties of ‘Camino Real’ strawberries grown in the Brazilian savannah, harvested in different seasons. Analytical and meteorological data were analyzed by partial least squares regression. RESULTS: Fruits from May showed the lowest contents of total phenolics (1789.78 mg kg^?1 fresh weight (FW)), catechin (21.37 mg kg^?1 FW), quercetins (4.89 mg kg^?1 FW) and total ellagic acid (208.68 mg kg^?1 FW) and the lowest antioxidant activity by 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) (11.39 mg Butylated hydroxytoluene (BHT) eq. g^?1 FW) and ferric reducing antioxidant power (FRAP) (22.01 mg ferrous sulfate eq. g^?1 FW) assays. Strawberries harvested in July presented the lowest concentrations of total (190.61 mg kg^?1 FW) and individual anthocyanins (73.88 mg kg^?1 FW and 5.96 mg kg^?1 FW for pelargonidin‐3‐glucoside and cyanidin‐3‐glucoside, respectively), but the highest contents of vitamin C (685.47 mg kg^?1 FW), DPPH (18.87 mg BHT eq. g^?1 FW) and FRAP (39.30 mg ferrous sulfate eq. g^?1 FW). The highest contents of free ellagic acid (26.11 mg kg^?1 FW), pelargonidin‐3‐glucoside (291.82 mg kg^?1 FW) and cyanidin‐3‐glucoside (11.84 mg kg^?1 FW) were found in strawberries from September. Rain in the previous 30 days to harvest influenced negatively many phenolics and antioxidant activity of strawberries harvested in May. In July, longer photoperiod and lower temperature at 30 days previous to harvest probably led to higher antioxidant activity and vitamin C. Increased photoperiod and temperature at the final stage of maturation seem to raise pigments and free ellagic acid in strawberries. CONCLUSION: It was possible to observe significant relationships among meteorological and antioxidant variables for strawberries grown in the Brazilian savannah. Copyright © 2011 Society of Chemical Industry     

Effectiveness of Zataria multiflora Boiss essential oil and grape seed extract impregnated chitosan film on ready-to-eat mortadella-type sausages during refrigerated storage

BACKGROUND: The effectiveness of chitosan films containing Zataria multiflora Boiss essential oil (ZEO) (5 and 10 g kg^?1) and grape seed extract (GSE) (10 g kg^?1) on lipid oxidation and microbial (lactic acid bacteria, aerobic mesophiles and inoculated Listeria monocytogenes) characteristics of mortadella sausage at 4 °C for 21 days was evaluated. The release of total phenolics (TPs) into sausage was also assessed. RESULTS: All films exhibited antibacterial activity against L. monocytogenes on agar culture media. Chitosan films containing ZEO were the most effective on the growth of bacteria. The growth of L. monocytogenes was significantly inhibited by ZEO‐GSE containing films especially during storage of the sausages for 6 days. Aerobic mesophiles and lactic acid bacteria were the most sensitive and resistant groups to films by 0.1–1.1 and 0.1–0.7 log cycles reduction, respectively. Sausages wrapped by 10 g kg^?1 GSE + 10 g kg^?1 ZEO films had the lowest degrees of lipid oxidation, which was 23% lower than the control. The TPs of ZEO films decreased to zero after 6 days, whereas TPs of GSE films followed a slight decrease during the storage. CONCLUSION: Antimicrobial/antioxidant chitosan film could be developed by incorporating GSE and ZEO for extending the shelf life of mortadella sausage. Copyright © 2011 Society of Chemical Industry     

Effect of a combined treatment of rice bran protein film packaging with aqueous chlorine dioxide washing and ultraviolet-C irradiation on the postharvest quality of ‘Goha’ strawberries

To investigate the effects of postharvest treatments on strawberry (Fragaria × ananassa Duch.) quality, a combination of non-thermal treatments was investigated as a potential hurdle technique. Specifically, ‘Goha’ strawberry samples were treated with 50 ppm aqueous chlorine dioxide (ClO₂) and 5 kJ/m² ultraviolet-C (UV-C) irradiation and packed with rice bran protein (RBP) film containing 1% grapefruit seed extract (GSE). The initial population of total aerobic bacteria in the strawberries was 3.15 log CFU/g, while that of samples treated with ClO₂/UV-C and packed with RBP film containing GSE was 1.64 log CFU/g. In terms of yeast and mold populations, the control had 2.98 log CFU/g, while the samples treated with the combined non-thermal processing and packed with the RBP film had 1.09 log CFU/g. In addition, after 11 days of storage, combined non-thermal treatment with RBP film packaging reduced the initial populations of total aerobic bacteria and of yeast and molds in the strawberries by 2.63 and 2.84 log CFU/g, respectively. Titratable acidity (TA) in the strawberries decreased during storage, but there was no significant difference among treatments. Postharvest treatments employed in this study produced a negligible change in the color of the strawberries, and sensory evaluation results indicated that the combined postharvest treatments provided better sensory scores compared with the control group. Therefore, these results suggest that a postharvest treatment consisting of 50 ppm ClO₂/5 kJ/m² UV-C with RBP film packaging containing GSE may be useful for maintaining the quality of ‘Goha’ strawberries.     

Development and Evaluation of a Film and Edible Coating Obtained from the <Emphasis Type="Italic">Cajanus cajan</Emphasis> Seed Applied to Fresh Strawberry Fruit

The aim of this work was to develop and evaluate the effect of an edible coating produced with protein isolate and gum from the Cajanus cajan seed to be applied to strawberries (Fragaria spp.). The films were formulated using 1 and 2% gum, and 5 and 10% protein isolate, as well as glycerol (2%) as a plasticizer. The formulated films were evaluated in terms of water vapor permeability (WVP), opacity, color, scanning electron microscopy, and texture. Once the ideal formulation with sufficiently low WVP and opacity was selected, it was applied to the strawberries, which were evaluated in terms of mass loss, color, firmness, acidity, pH, soluble solids, anthocyanin content, vitamin C content, and acceptability degree by an untrained consumer panel. Results showed that film made from 5% of protein isolate and 1% of gum had the lowest WVP of all treatments. Applied to strawberries, the coating resulted in a reduction of the total soluble solid content, the consumption of citric acid, and the mass loss of coated with respect to uncoated strawberries after 10 days of storage at 5 °C, without causing sensorial changes.     

Prefreezing application of whey protein‐based edible coating to maintain quality attributes of strawberries

Prefreezing application of whey protein concentrate (WPC)‐based edible coating to maintain quality attributes of strawberries was studied. Beeswax (BW) was added to the solutions (0%, 20% and 40% with respect to the solids contained in the mixture WPC/glycerol). Coated and control fruits were frozen, stored at ?20 °C and thawed. After thawing, weight loss, firmness, microstructure and colour parameters were measured. Coating with 20% BW reduced strawberries weight loss after thawing (55%). Strawberries firmness was maintained equally in all groups analysed although a slight improvement at the cell microstructure alterations caused by the freezing process was observed in coated fruits. Strawberries brightness was similar in all groups. Colour parameter a* showed a tendency to decrease with the increasing BW concentration, and only b* of coated fruits was lower than controls. The application of whey protein coating could be an attractive treatment to maintain quality attributes of strawberries undergoing the freezing process.     

Effect of plant extracts on lipid oxidation during frozen storage of minced fish muscle

The aim of the study is to determine the effect of pomegranate seed extract (PSE) and grape seed extract (GSE) addition to chub mackerel minced muscle on lipid oxidation during frozen storage. Each extract was added to minced fish muscle at 2% concentration and then stored at ?18 °C for 3 months. The effect of plant dietary fibres to control lipid oxidation was compared with untreated samples (control). Formation of lipid hydroperoxides and thiobarbituric acid‐reactive substances (TBARS) was significantly inhibited by PSE and GSE addition when compared with control. Both extracts significantly retarded lipid oxidation according to the results of TBARS. A significant reduction of L* (lightness), a* (redness) and b* (yellowness) values was detected during frozen storage. GSE added samples had the highest redness and the lowest lightness and yellowness. However, samples with PSE showed the lowest redness and highest yellowness and h° (hue angle) values. The results from this study suggest GSE is a very effective inhibitor of primary and secondary oxidation products in minced fish muscle and have a potential as a natural antioxidant to control lipid oxidation during frozen storage of fatty fish.     

Effects of Antimicrobial Edible Coating of Thymol Nanoemulsion/Quinoa Protein/Chitosan on the Safety,Sensorial Properties,and Quality of Refrigerated Strawberries (<Emphasis Type="Italic">Fragaria × ananassa</Emphasis>) Under Commercial Storage Environment

The effectiveness of the edible coating with thymol nanoemulsion on the safety, sensorial properties, and quality of refrigerated strawberries was investigated under commercial storage conditions. Spontaneous emulsification was used to obtain the thymol nanoemulsion that was included on quinoa protein/chitosan coatings. During the entire storage time, strawberries coated with thymol-antimicrobial packaging had a lower fungal and yeast load compared with the controls (uncoated and coated with quinoa protein/chitosan). The flavour and aroma of the coated strawberries was initially affected, although this sensory appreciation was improved from the fifth day of storage and showed similar scores than the controls, and presenting better aroma score at day 12 of storage. Furthermore, the shelf life of the thymol nanoemulsion-coated strawberries increased in 4 days, unlike that in the both controls. Further, the application of these biocoatings on strawberries significantly decreased the weight loss relative to that in the control, during 16 days of storage at 5 °C and 90% relative humidity, and did not alter the quality parameters (pH, titrable acidity, and percentage of soluble solids). These results suggest that the application of thymol/nanomulsion-loaded edible films is an effective strategy to increase the shelf life of highly perishable products such as strawberries.     

Evaluation of the antioxidant potential of grape seed and bearberry extracts in raw and cooked pork

The effect of grape seed extract (GSE) and bearberry (BB), on lipid oxidation (TBARS, mg malondialdehyde (MDA)/kg muscle), colour (CIE ‘a’ redness value), pH, microbial status (log₁₀CFU colony forming units/g pork) and sensorial properties of cooked pork patties was investigated. GSE (0–1000 μg/g muscle) and BB (0–1000 μg/g muscle) were added to raw pork (M. longissimus dorsi) patties which were stored in modified atmosphere packs (MAP) (75% O₂:25% CO₂) for up to 12 days at 4 °C. Cooked pork patties were stored in MAP (70% N₂:30% CO₂) for up to 4 days at 4 °C. Mesophilic plate counts and pork pH were unaffected by GSE and BB. GSE and BB addition decreased (P < 0.05) lipid oxidation (TBARS) in raw pork patties on days 9 and 12 of storage, relative to controls. Antioxidant activity of GSE and BB was observed in cooked pork patties demonstrating the thermal stability of GSE and BB. The ‘a’ redness values of raw and cooked pork patties marginally increased with increasing GSE concentration. The sensory properties of cooked pork patties were unaffected by GSE and BB addition. Results obtained demonstrate the potential for using health promoting nutraceuticals in meat and meat products.     

Physico-mechanical properties of chitosan films with carvacrol and grape seed extract

The physico-mechanical properties of 3 films composed by carvacrol, grape seed extract (GSE) and chitosan in different proportions were studied. The films, prepared by solvent casting technique with the following compositions of the casting solutions in carvacrol, GSE and chitosan: film-1: 9.6 ppm–684 ppm–1.25% w/v, film-2: 60 ppm–400 ppm–1.2% w/v and film-3: 90 ppm–160 ppm–1.24% w/v and were compared to a control (1.25% w/v chitosan) film. Mechanical, structural, barrier and colour properties of the films were evaluated. Film-3 presented the lowest water vapour and carbon dioxide permeabilities (WVP and CO₂P) and tensile strength (TS) values and the highest oxygen permeability (O₂P), whereas film-1 presented the highest water content and the lowest crystallinity, CO₂P, TS and luminosity. These results suggest that in the range studied, carvacrol and GSE affect the film structure and its mechanical properties due to hydrophilic (GSE) and hydrophobic (carvacrol) compounds. This work will help the development of edible films, based on physico-mechanical properties, contributing to food preservation and shelf-life extension.     

Effect of cold atmospheric plasma and pulsed electromagnetic fields on strawberry quality and shelf-life

The effect of cold atmospheric plasma (CAP) and pulsed electromagnetic fields (PEMF) on the metabolic process, microbiological, enzymatic and quality parameters of fresh strawberries, after processing and during storage at 1 and 6 °C, was studied. CAP was more effective on microorganisms, reducing the total viable count by ~0.9 logCFU/g. Phenolic compounds and antioxidant activity were increased after CAP processing by ~20.9 and 16.5%, respectively. PEMF strawberries were firmless by ~16% compared to control. Both treatments did not significantly affect the weight loss, color, anthocyanins content and pH-value. B-glucosidase activity was higher for PEMF strawberries by at least 35 and 20%, compared to control and CAP respectively, explaining PEMF enhancing aromatic-profile. Ascorbic acid was decreased during storage, nevertheless, nonthermal treated samples showed higher values by at least 10%, compared to control samples. The shelf-life at 1 °C for control, CAP and PEMF strawberries was estimated as 13, 17 and 15 days, respectively.     

纳米SiO2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0.07g,冰乙酸含量1.4mL,且透CO2量达到最低为0.0909g/d;优化膜处理的草莓常温下贮藏6d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...     

Effects of Short-term Exposure to Low O2 and High CO2 Atmospheres on Quality Attributes of Strawberries

Strawberries (Fragaria ananassa Duch., cv. ‘Selva') were stored 10 days in 1.0%, 0.5%, or 0.25% 0₂ or air + 20% CO₂; or 6 days in air + 50% or 80% CO₂ at 0 or 5°C without detrimental effects on quality. Decay and softening were reduced by treatments. An untrained taste panel, under ordinary eating conditions, did not consistently differentiate ‘Pajaro’ strawberries kept in 0.25% 0₂ from those stored in air. A trained taste panel, under controlled conditions, perceived slight off-flavor in ‘G3’ strawberries kept in 0.25% or 0% 0₂. This correlated with ethanol, ethyl acetate, and acetaldehyde in juice. The 50% or 80% CO₂ treatments caused injury after 8 to 10 days, while 20% CO₂ treatments did not. All high CO₂ treatments caused increase in pH of juice.     

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。