Modified Atmosphere and Modified Humidity Packaging of Fresh Mushrooms

Sorbitol and sodium chloride were used to modify the in-package relative humidity (IPRH) of fresh mushrooms (water irrigated and CaCl₂ irrigated) stored in a modified atmosphere package (MAP) at 12°C. No differences were observed for maturity index and microbial population between mushrooms stored in modified atmosphere package (MAP) with or without moisture absorbers. Lower IPRH was observed in packages containing water irrigated (normally grown) mushrooms with sodium chloride, but resulted in over-drying of mushrooms and did not improve color. Normally grown mushrooms with 10 and 15g sorbitol had the best color. IPRH of 87–90%, within 9 days storage was considered optimum. No improvements in quality were found with moisture absorbers with normally grown mushrooms. However, a small amount of sorbitol helped to avoid condensation with CaCl₂ irrigated mushrooms.     

Influences of preharvest spraying Cryptococcus laurentii combined with postharvest chitosan coating on postharvest diseases and quality of table grapes in storage

The effects of preharvest spray with Cryptococcus laurentii combined with chitosan coating after harvest on decay and quality of table grapes during storage periods were evaluated in the present study. Preharvest spray with C. laurentii (PreA) significantly decreased decay index (DI), and postharvest chitosan coating (PCC) enhanced the effectiveness of the pre-harvest spray when fruits were stored at 0 °C. PreA combination with PCC increased the activities of polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) of fruit in storage. PreA + PCC treatment was effective in reducing weight loss of fruits by 85% at 17 d storage and 38% at 42 d storage as compared to PreA alone at the same stage. In addition, PreA enhanced the ratio of soluble solids content (SSC) to titratable acid (TA) by 12% at harvest time, 7% at 17 d storage and 25% at 42 d storage, mainly by increasing SSC and decreasing TA in fruit stored at 0 °C. These results suggested that integration of preharvest spray with C. laurentii and postharvest chitosan coating treatment may be a promising management strategy for decay control and quality maintenance of table grapes.     

Development of shelf-life kinetic model for modified atmosphere packaging of fresh sliced mushrooms

Mushrooms are highly perishable and their shelf-life depends on processing, package properties and environmental conditions during storage and distribution. The aims of this work were to evaluate the effect of temperature and number of film perforations on quality and develop shelf-life kinetic model for a modified atmosphere packaging (MAP) for sliced button mushrooms. Sliced mushrooms were packed in a tray, covered with cellophane film, and stored for 7 days at four levels of temperature (0, 5, 10, and 15 °C) and three levels of perforations at each temperature ranging the number of perforations from 1 (58 perforations per m²) to 6 (349 perforations per m²). Headspace gas composition and quality parameters (weight loss, pH, firmness and colour) were measured throughout the storage period. Increasing the storage temperature required an increase of the number of perforations in order to obtain the optimum MAP conditions. Temperature had a significant effect (p < 0.05) on quality of sliced mushrooms. Firmness was identified as a critical quality parameter; therefore, a kinetic model was developed to describe the influence of temperature on firmness and predict shelf-life of sliced mushrooms. Fresh sliced mushrooms had a shelf-life of 1, 2, 4, and 7.5 days at 15, 10, 5, and 0 °C, respectively, under optimum MAP conditions.     

Evaluation of MAP engineering design parameters on quality of fresh-sliced mushrooms

Modified atmosphere packaging (MAP) relies on the interplay between product-respiration and package-film-permeability with the aim of maintaining initial quality and extending shelf-life of fresh produce. This work evaluates the effect of MAP engineering design parameters (amount of product, number of perforations and weight of CO₂ scavenger) on quality of sliced mushrooms. Sliced button mushrooms were packed in a tray, covered with cellophane film, and stored at 10 °C for 3 days. Headspace gas composition and chemical and physical quality parameters (weight loss, pH, firmness and colour) were measured throughout the storage period. All design parameters produced a significant effect (p < 0.05) on quality. Addition of CO₂ scavenger in the package increased the deterioration of mushrooms. MAP optimisation design requires consideration of mushroom weight and number of film perforations. The optimal conditions found were 110 g of sliced mushrooms and 2 perforations (0.33 mm diameter) which led to an equilibrium gas composition of 3.6% O₂ and 11.5% CO₂, after 3 days of storage at 10 °C.     

Changes in anthocyanins in arils of chitosan-coated pomegranate (Punica granatum L. cv. Rabbab-e-Neyriz) fruit during cold storage

Edible coatings as chitosan treatments (0%, 1% and 2%) were applied to ‘Rabbab-e-Neyriz’ pomegranate (Punica granatum L.). The effect of chitosan coating on individual anthocyanins and colour parameters of the juice during storage at 2 °C or 5 °C was examined. Six predominant anthocyanins were identified in the juice, with up to 935 mg/L total anthocyanins at the time of harvest. Cyanidin 3,5-diglucoside (402 mg/L) was the major pigment. The total anthocyanin content and chroma decreased with storage time in all applied treatments, although lightness and hue angle increased. These changes were reduced with chitosan treatments and at lower storage temperature (2 °C as compared to 5 °C). Based on the obtained results, the diglucoside anthocyanins were more stable than the monoglucosides. Chitosan coating followed by cold storage delayed anthocyanin degradation and prevented colour deterioration in the pomegranate arils.     

Effect of alginate/nano-Ag coating on microbial and physicochemical characteristics of shiitake mushroom (Lentinus edodes) during cold storage

The effect of a novel alginate/nano-Ag coating material on the preservation quality of shiitake mushroom (Lentinus edodes) during 4 ± 1 °C storage was investigated. The results showed that the alginate/nano-Ag coating had quite a beneficial effect on the physicochemical and sensory quality, compared to the control treatment. After a 16-day storage, mushroom weight loss, softening, and browning of the alginate/nano-Ag coating were significantly inhibited. The lower microbial counts, including mesophilic, psychrophilic, pseudomonad, and yeasts and moulds, in treated mushrooms during storage should be attributed to the alginate/nano-Ag coating. Meanwhile, the contents of the reducing sugar, total sugar, total soluble solids and electrolyte leakage rate were increased to 3.9 mg/g, 11.2 mg/g, 5.1% and 16.5% for the alginate/nano-Ag coating and 3.7 mg/g, 8.3 mg/g, 6.3% and 31.7% for the control treatment. Therefore, the alginate/nano-Ag coating could be applied for preservation of the shiitake mushroom to expand its shelf life and improve its preservation quality.     

Modeling of potassium sorbate diffusion through chitosan films

The mechanism of potassium sorbate (K-sorbate) release from chitosan films was studied as a function of immersion time in aqueous solution. Fick's law was applied to calculate the diffusion coefficient and the power law defining the type of diffusion mechanism. The novelty in this study is the compound diffusion mechanisms comparison through chitosan film (CF) and chitosan emulsion film. Initially, the lipid was selected to obtain the emulsion films. The evaluation was based on the water vapor permeability (WVP). The lower WVP (32.45% less than chitosan film) was found using 0.5 g/100 g of palmitic acid for 2.0 g/100 g of chitosan. Then, active chitosan films (ACF) were obtained incorporating K-sorbate on CF at 0.1 and 0.5 g/100 g of K-sorbate. Also, active palmitic acid-chitosan films (APEF) were obtained, incorporating 0.1 g/100 g of K-sorbate. The mechanisms of K-sorbate diffusion through ACF and APEF were mainly non-Fickian. However, the K-sorbate diffusion coefficient did not reduced in lipid presence.     

Fate of post-processing inoculated Listeria monocytogenes on vacuum-packaged pepperoni stored at 4, 12 or 25 °C

If present, Listeria monocytogenes may not be eliminated during processing of pepperoni or may be introduced during peeling, slicing, or packaging. We evaluated the fate of the pathogen on sliced inoculated pepperoni during vacuum-packaged storage, and potential differences in survival among three types of inocula, including nonacid-adapted, acid-adapted and pepperoni extract-habituated cultures. Commercial pepperoni (two replicates, three samples per treatment) was sliced and inoculated (3 to 4 log CFU/cm²), before vacuum-packaging and storage for up to 180 days at 4, 12 or 25 °C. Samples were periodically analyzed for pathogen counts (PALCAM agar) and total bacterial counts (tryptic soy agar with 0.6% yeast extract). The pH of the product was relatively stable (4.50–4.81) throughout storage. Overall, levels of the pathogen (all inocula) and total counts decreased continuously during storage at all temperatures. The pathogen died slower at 4 °C than at 12 and 25 °C, while at 12 and 25 °C the death rates were similar. Death rates depended on type of inoculum and generally decreased in the order: acid-adapted, extract-habituated and nonacid-adapted inoculum. At day 60, pathogen levels were below the detection limit and remained undetectable throughout the rest of the 180-day storage period, regardless of inoculum type and storage temperature. Therefore, storage of sliced vacuum-packaged pepperoni, especially at ambient temperature, prior to consumption may reduce the potential risk of listeriosis.     

Ultraviolet irradiation: The generator of Vitamin D2 in edible mushrooms

Fresh Shiitake mushrooms (Lentinula edodes), Oyster mushrooms (Pleurotus ostreatus), Button mushrooms (Agaricus bisporus), and Abalone mushrooms (Pleurotus cystidus) were irradiated with Ultraviolet-A (UV-A; wavelength 315–400 nm), Ultraviolet-B (UV-B; wavelength 290–315 nm), and Ultraviolet-C (UV-C; wavelength 190–290 nm). Irradiation of each side of the mushrooms for 1 h, was found to be the optimum period of irradiation in this conversion. The conversions of ergosterol to vitamin D₂ under UV-A, UV-B, and UV-C were shown to be significantly different (p < 0.01). The highest vitamin D₂ content (184 ± 5.71 μg/g DM) was observed in Oyster mushrooms irradiated with UV-B at 35 °C and around 80% moisture. On the other hand, under the same conditions of irradiation, the lowest vitamin D₂ content (22.9 ± 2.68 μg/g DM) was observed in Button mushrooms.     

Anti-listeria activity of poly(lactic acid)/sawdust particle biocomposite film impregnated with pediocin PA-1/AcH and its use in raw sliced pork

A novel poly(lactic acid) (PLA)/sawdust particle (SP) biocomposite film with anti-listeria activity was developed by incorporation of pediocin PA-1/AcH (Ped) using diffusion coating method. Sawdust particle played an important role in embedding pediocin into the hydrophobic PLA film. The anti-listeria activity of the PLA/SP biocomposite film incorporated with Ped (PLA/SP + Ped) was detected, while no activity against the tested pathogen was observed for the control PLA films (without SP and/or Ped). Dry-heat treatment of film before coating with Ped resulted in the highest Ped adsorption (11.63 ± 3.07 μg protein/cm²) and the highest anti-listeria activity. A model study of PLA/SP + Ped as a food-contact antimicrobial packaging on raw sliced pork suggests a potential inhibition of Listeria monocytogenes (99% of total listerial population) on raw sliced pork during the chilled storage. This study supports the feasibility of using PLA/SP + Ped film to reduce the initial load of L. monocytogenes on the surface of raw pork.     

Round scad protein-based film: Storage stability and its effectiveness for shelf-life extension of dried fish powder

Storage stability of different round scad (Decapterus maruadsi) protein-based films including (1) control film without palm oil and chitosan, (2) film with 25% palm oil (glycerol substitution) and (3) film with 25% palm oil and 40% chitosan (protein substitution) was investigated. During storage (54% relative humidity, 28-30 °C), tensile strength (TS) of the films without and with 25% palm oil or 25% palm oil in combination with 40% chitosan increased continuously, while elongation at break (EAB) decreased markedly when storage time increased up to 8 weeks (p < 0.05). No changes in water barrier properties were observed throughout the storage time up to 4 weeks (p > 0.05). Film solubility slightly increased but protein solubility decreased continuously during storage (p < 0.05). All films became darker and more yellowish as storage time increased. When round scad muscle protein-based films were used to cover dried fish powder, the samples covered with the film containing 25% palm oil and 40% chitosan showed lower thiobarbituric acid reactive substances (TBARS) and yellowness than other samples during the extended storage up to 21 days (p < 0.05). No differences in moisture content of all samples covered with different films were noticeable (p > 0.05), except those covered with HDPE, which had the lowest moisture content. Thus, round scad protein-based film incorporated with palm oil and chitosan could be a promising packaging material to prevent lipid oxidation in oil enriched foods.     

Effect of Time, Temperature, and Slicing on Respiration Rate of Mushrooms

ABSTRACT:  Respiration rate measurement considering the effects of cutting, temperature, and storage time are important for the shelf life study and modified atmosphere-packaging design of fresh-cut produce. This study investigates in the respiration rate of fresh whole and sliced mushrooms at 0, 4, 8, 12, 16, and 20 °C under ambient atmosphere and different storage times. The O₂ consumption rate increased with temperature and ranged from 22.13 to 102.41 mL/(kg.h) and 28.87 to 143.22 mL/(kg.h) for whole and sliced mushrooms, respectively, in the temperature range tested. Similar trend was observed for CO₂ production rate. Slicing of mushrooms increased the respiration rate by 30% at 0 °C and 40% at 20 °C indicating that the mushrooms are not as sensitive to the stress caused by cutting as other fresh produce. Storage time affected both respiration rate of whole and sliced mushrooms and this effect was prominent at higher temperatures. The respiration rates increased initially for some time, then decreased and reached steady state value at 12, 16, and 20 °C. A 2nd-order polynomial equation was used to fit the respiration rate data as a function of time at each temperature tested.     

Fresh Mushroom Quality as Affected by Modified Atmosphere Packaging

The effect of O₂ concentration, at 2–6% CO₂ on shelf-life of fresh mushrooms in modified atmosphere packages (MAP) was studied. For conventional mushrooms optimum in-package O₂ was 6% to reduce cap development. Mushrooms irrigated with 0.3% calcium chloride during cropping had a higher rate of maturation and optimum O₂ was 2% during storage. At this low O₂ concentration, however, storage may be potentially hazardous and is not recommended. Surface moisture of mushrooms significantly increased during storage and may have obscured any beneficial effect of MAP on mushroom color. Precise control of relative humidity in the package is recommended.     

Changes in microbial and postharvest quality of shiitake mushroom (Lentinus edodes) treated with chitosan-glucose complex coating under cold storage

The effect of chitosan, glucose and chitosan-glucose complex (CGC) on the microbial and postharvest quality of shiitake (Lentinus edodes) mushroom stored at 4 ± 1 °C for 16 days was investigated. Mushroom weight loss, respiration rate, firmness, ascorbic acid, total soluble solids, microbial and sensory quality were measured. The results indicate that treatment with CGC coating maintained tissue firmness, inhibited increase of respiration rate, reduced microorganism counts, e.g., pseudomonads, yeasts and moulds, compared to uncoated control mushroom. The efficiency was better than that of chitosan or glucose coating treatment. In addition, CGC coating also delayed changes in the ascorbic acid and soluble solids concentration. Sensory evaluation proved the efficacy of CGC coating by maintaining the overall quality of shiitake mushroom during the storage period. Our study suggests that CGC coating might be a promising candidate for maintaining shiitake mushroom quality and extending its postharvest life.     

Effect of chitosan-based solutions applied as edible coatings and water glazing on frozen salmon preservation – A pilot-scale study

The aim of this research was to compare the effect of chitosan solutions on frozen salmon preservation with that of water glazing. For this purpose, three chitosan solutions (0.25%, 0.50% and 0.75% w/v) and water were applied in different amounts (6%, 8% and 11% of coated fillet weight) directly on the surface of frozen salmon. In order to accelerate the deterioration processes, salmon was stored during 14 weeks at −5 °C. Microbial and chemical indices were used to assess deterioration during storage and the coating stability was evaluated through weight loss measurements. The results obtained showed that chitosan coatings can be a good barrier to protect frozen fish from deterioration. Microbial growth, assessed by total viable counts (TVC), and total volatile basic nitrogen (TVB-N) were maintained below the maximum limits recommended which are 5 × 105 CFU/g and 35 mg nitrogen/100 g fish, respectively. The use of 0.50% and 0.75% chitosan solutions generally demonstrated to be more efficient in preventing salmon weight loss.     

Comparison of free amino acid,carbohydrates concentrations in Korean edible and medicinal mushrooms

Ten popular species of both edible and medicinal Korean mushrooms were analysed for their free amino acids and disaccharides. The average total free amino acid concentration was 120.79 mg g⁻¹ in edible mushrooms and 61.47 mg g⁻¹ in medicinal mushrooms, respectively. The average total of free amino acids for all mushrooms, edible mushrooms and medicinal mushrooms was 91.13 mg g⁻¹. Agaricus blazei (227.00 mg g⁻¹) showed the highest concentration of total free amino acids; on the other hand, Inonotus obliquus (2.00 mg g⁻¹) showed the lowest concentration among the 10 species of mushrooms. The average total carbohydrates concentration was 46.67 mg g⁻¹ in the 10 species of mushrooms, where the edible mushrooms contained 66.68 mg g⁻¹ and the medicinal mushrooms contained 26.65 mg g⁻¹. The carbohydrates constituents of the 10 mushroom species were mainly mannose (36.23%), glucose (34.70%), and xylose (16.83%).     

Non-volatile taste components of Agaricus blazei, Agrocybe cylindracea and Boletus edulis

Three species of dried mushrooms are commercially available in Taiwan, namely Agaricus blazei (Brazilian mushroom), Agrocybe cylindracea (black popular mushroom) and Boletus edulis (king bolete), and their non-volatile taste components were studied. All mushrooms were high in contents of carbohydrate, crude fiber and protein but low in contents of crude ash and fat. Arabitol, myo-inositol, mannitol and trehalose were detected in these three mushrooms, whereas glucose was not found in B. edulis. Contents of total soluble sugars and polyols ranged from 150.33 to 225.08 mg/g. Total free amino acid contents were low in these three mushrooms and ranged from 8.97 to 14.91 mg/g. The contents of MSG-like components ranged from 1.24 to 4.40 mg/g were in the descending order of the A. blazei, A. cylindracea and B. edulis. Total 5′-nucleotides contents of A. blazei and A. cylindracea were higher than that of B. edulis whereas flavor 5′-nucleotides content of A. blazei was higher than those of A. cylindracea and B. edulis. Equivalent umami concentrations values in three mushrooms ranged from 10.46 to 135.90 g per 100 g. Overall, these three mushrooms possessed highly umami taste.     

Physiological responses and quality attributes of table grape fruit to chitosan preharvest spray and postharvest coating during storage

The effects of preharvest chitosan spray (PCS) or/and postharvest chitosan coating (PCC) treatments on the quality and physiological response of table grape fruit stored at 20 or 0 °C was evaluated, respectively. PCS/PCC treatment showed the best control effect on decay. PCC or PCS/PCC treatment significantly decreased the weight loss of fruit stored at 20 °C. Additionally, all chitosan treatments inhibited the increase in rate of soluble solid content to titratable acid in fruit, stored at 20 °C, while enhancing the rate at 0 °C and affecting the content of total phenolic compounds in the fruit. Furthermore, the activities of superoxide dismutase decreased in all chitosan treatments and PCS or/and PCC treatments also changed the activities of polyphenol oxidase, peroxidase and phenylalanine ammonia-lyase. The results indicated the beneficial effect of chitosan by preharvest spray and/or postharvest coating on fruit quality and resistance to fruit decay.     

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.     

Development of a prototype of a colourimetric temperature indicator for monitoring food quality

Temperature greatly affects the food quality and safety. Temperature control is an important condition during distribution and storage. An intelligent and biodegradable temperature indicator packaging material was developed based on a natural and heat-sensitive pigment (anthocyanin – ATH). Different concentrations of ATH were incorporated into chitosan matrix films (2.00%, w/w) that were applied as a surface coating on card paper, forming the chitosan card paper system (CH-Sys). The novelty of this work is an alternative packaging material that is biodegradable, simple manufacturing and indicates temperature variations in a specific range by irreversible visual colour changes. The CH-Sys changed irreversibly the colour from light violet to light yellow in response to different temperature exposition (40 °C until 70 °C), independently of luminosity (0 or 1000 lx). The results indicated that the CH-Sys has a great potential for use as a temperature indicator prototype in the specific temperature range studied in this work.