Shelf Life Of Fresh Strawberries Research Articles

High-strength, water-resistant polyvinyl alcohol films reinforced with regenerated cellulose fibers for food packaging

Polyvinyl alcohol (PVA) film, a promising biodegradable packaging film material, shows low water resistance and mechanical properties, which hinder its application in the packaging field, particularly in humid or aqueous environments. Herein, PVA/regenerated cellulose fibers (RC) blend films (PVA/RC films) were fabricated by a simple controllable regeneration of cellulose fibers in an aqueous solution of PVA. The potentiation formed by the uniformly distributed RC in PVA/RC films and the competitive advantage of hydrogen bond (N···H-O) formation between urea and PVA afforded superior water resistance and mechanical characteristics to PVA/RC films. In particular, PVA/RC films displayed good tensile strength and elongation at break under dry and humid conditions (75.97 and 35.37 MPa; 281.17% and 624.83%, respectively). The shelf life of fresh strawberries packed in these blend films was extended by an additional 4 days. The present study revealed a simple and economical approach to manufacture PVA-based packaging film materials for use in humid and aqueous environments.

Improving fresh strawberry shelf life and quality by using the fresh‐keeping paper embedded with oregano essential oil and tea polyphenols

SummaryThe short shelf life of fresh strawberries limits its marketing potential, despite its valuable economic and nutritional benefits. An environmentally friendly fresh‐keeping paper was prepared with oregano essential oil (OEO) and tea polyphenols (TP) and used in the storage of strawberries. Results showed that, during the late storage period, the TP and OEO fresh‐keeping paper treatments reduced malondialdehyde (MDA) content by 29.04% and 34.47%, respectively, compared with the control samples. The treatments also reduced decay incidence, weight loss, epidermal microorganisms and total anthocyanins content (TAC). Furthermore, the treatments reduce polyphenol oxidase (PPO) activity, delay the colour development and maintain better sensory attributes. Notably, OEO fresh‐keeping paper treatment not only increased the titratable acidity (TA) and total soluble solids (TSS) content but also improved the scavenging ability of reactive oxygen species by maintaining high levels of superoxide dismutase (SOD) and catalase (CAT) activity. These results demonstrated that fresh‐keeping paper treatment has the potential to extend the post‐harvest life of strawberries and improve their quality.

Eutectic solvent-based bioactive films functionalized with microbial astaxanthin extends shelf life of fresh strawberries

Food waste and consumers safety are critical concerns that necessitate the development of improved packaging systems, such as those involving the use of edible films and coatings, which may act as primary packaging, helping the external (secondary) packaging in its protecting role. However, current options of films/coatings have limitations, such as inefficient plasticizer agents and the need for high levels of active ingredients. To address these challenges, we have created a new packaging material formulated with bio-based sodium alginate (SA) and choline-based deep eutectic solvents (DES), which are eco-friendly and capable of packaging food substrates to enhance their safety and longevity. Using a SA-DES materials we incorporated naturally derived microbial products (astaxanthin - AXT) with antioxidant and antimicrobial properties and evaluated the mechanisms behind the formation of coatings. Our results demonstrate that strawberries coated with alginate-choline chloride:glycerol (SA-[Ch]Cl:Gly) had a longer shelf life, inhibited natural microbial proliferation, and lost less weight than uncoated controls at room temperature. This study demonstrated that DES are a promising and sustainable solution for cost-effective, and biodegradable environmentally friendly packaging systems.

Effect of combining UV-C irradiation and vacuum sealing on the shelf life of fresh strawberries and tomatoes.

This research presents the effect of combining UV-C irradiation and vacuum sealing on the shelf life of strawberries and quartered tomatoes and compares it with the effect of the sole use of UV-C irradiation or vacuum sealing. A constant UV-C dose of 360 J/m2 was used for the samples' irradiation, and all the vacuum-sealed samples were stored at a reduced pressure of 40kPa. Organoleptic analysis, microbial population quantification of yeast and mold, Pseudomonas sp., weight loss, and pH measurements were obtained to identify the spoilage occurrence, monitor the samples' quality, and quantify the shelf life. Sensory evaluation was conducted by 12 consumer panelists to evaluate the aroma, taste, color, texture, and the overall acceptance of the samples. The results revealed that the combination of UV-C irradiation and vacuum sealing prolongs the shelf life of perishables more than the sole use of UV-C irradiation or vacuum sealing. The achieved shelf-life increase using this combination was 124.41% and 54.41% for strawberries and quartered tomatoes, respectively, while acceptable sensory characteristics were maintained throughout the storage period. Hence, this food preservation method can be further improved and integrated in the daily life of modern consumers and the operations of fresh produce retailers, as it could effectively reduce the spoilage rates of fresh produce and help achieve the UN SDG 12.3, which aims to reduce food loss and waste by 50% by 2030 at the consumer and retail levels. PRACTICAL APPLICATION: The system can be further developed and introduced to the market as a kitchen appliance for households or as a predistribution step for fresh produce distribution centers. The shelf-life extension capability of this system, which does not involve any use of chemical substances, would make it an attractive solution for households and food retailers.

High-performance carboxymethyl cellulose-based hydrogel film for food packaging and preservation system

Most traditional food packaging and preservation films suffer from limited stretchability and relatively simple functionality, which severely restricts their practical application. In this study, a highly stretchable and versatile sodium carboxymethyl cellulose (CMC)/polyvinyl alcohol (PVA)/poly(ethylene imine) (PEI)/tannic acid (TA) hydrogel film was elaborately designed and demonstrated as an efficient food packaging and preservation system. The dynamic reversible non-covalent within three-dimensional (3D) network structures served as sacrificial bonds to dissipate the loaded energy and endowed the hydrogel film with excellent elongation ~400 %, which is much larger than that of conventional food packaging films (<50 %). Furthermore, the optimized CMC/PVA/PEI/TA3 hydrogel film delivers versatile performances, including self-healing, whole UV-blocking (<400 nm), strong adhesive strength (234.08 KPa), antioxidation virtues, oxygen barrier (32.64 cm3*μm/(m2*d*KPa)) and water vapor barrier (642.92 g/(m2*24 h)). Notably, the shelf life of fresh strawberries, mangoes, and cherries was prolonged by at least one week under ambient conditions when the packaging box was covered by the fabricated CMC/PVA/PEI/TA3 film. Thus, our work not only provides a highly stretchable and versatile hydrogel film but also boosts the in-depth comprehension and rational design of robust food packaging and preservation films.

Deep learning-based postharvest strawberry bruise detection under UV and incandescent light

Bruising is one of the major defects of strawberries. Strawberry bruised areas are often visible as flattened, sunken, and discolored. Postharvest strawberries can be bruised by compression, impact, or vibration forces during harvesting, transportation, and packinghouse operations. These bruises make strawberries more vulnerable to rot or disease, thus shortening their shelf life. Bruises can also cause consumers to abandon purchase decisions. Therefore, inspecting strawberry bruises is an important procedure for commercial strawberry farms to guarantee the high quality of strawberries sent to the market. A novel technique was developed in this study to detect bruises on strawberry images captured by a color camera under incandescent and ultraviolet (UV) light. Mask Region-Based Convolutional Neural Networks (Mask R-CNN), a deep learning method, was utilized for the strawberry bruise detection. Four bruise severities were classified according to the estimated bruise ratio of every single strawberry (Minor Bruise, Light Bruise, Moderate Bruise, and Severe Bruise). The results showed that Mask R-CNN could accurately detect whether a strawberry is bruised or not under both lighting conditions. However, the strawberry bruise severity classification accuracy of the proposed machine vision technique was improved significantly under UV light compared to incandescent light. For whole strawberry bruise detection under UV light, the F1 score for detecting strawberry bruises was 0.99, and the highest F1 score for whole strawberry bruise severity classification was 0.92 for Minor Bruise. This strawberry bruise detection system can assist farmers in detecting bruised strawberries on the processing line or an automated strawberry harvester, improve the quality of strawberries that are sent to the market, and avoid shortening the shelf life of fresh strawberries.

Edible multilayer coating using electrostatic layer‐by‐layer deposition of chitosan and pectin enhances shelf life of fresh strawberries

SummaryThis study aimed to develop an edible multilayer coating by electrostatic layer‐by‐layer deposition (LbL) of chitosan‐pectin biopolymers to extend the shelf life of strawberries. A fixed concentration of chitosan (2% w/v) and varying pectin concentrations (0.25–1% w/v) in an LbL sequence were initially applied to coat on the low‐density polyethylene (LDPE) film. The successful assembly of these biopolymers in the LDPE film was confirmed by their zeta potential (chitosan, +43 mV and pectin, −36 to −42 mV) and Fourier transform infrared (FTIR) spectroscopy in the range of 1800–1600 cm‐1 indicating the strong interactions between chitosan and pectin. Chitosan (2% w/v) and pectin (0.25% w/v) had the lowest water vapour permeability (WVP) of 1.86 ± 0.02 × 10−9 in gday‐1 m‐1 Pa‐1 among all other formulations. The application of the coating on strawberries extended the shelf life (9 days) compared to the control (6 days) at room temperature (25 °C) while still retaining the colour, firmness and pH of strawberries. The results obtained illuminate the potential application of safer, ecofriendly and sustainable packaging materials in the food industry.

Effect of edible coatings on the shelf-life of fresh strawberries: A comparative study using TOPSIS-Shannon entropy method

The aim of this study was to evaluate the effect of carboxymethyl cellulose (CMC), low methoxyl pectin (LMP), Persian gum (PG), and tragacanth gum (TG) edible coatings on the physicochemical properties of strawberries during storage period at 4 °C. The results showed a significantly less weight loss and decay for coated strawberries compared to the control. So that, the TG and CMC coated strawberries exhibited the lowest weight loss (3.65%) and decay (32.66%) at day 16 of storage, respectively. Edible coatings reduced the rate of deterioration in ascorbic acid, total phenolics, and anthocyanins in fruit over time. There was no significant difference observed between the coated and untreated strawberries in firmness and color characterization during storage time. Coatings improved the sensorial attributes of the fruit during storage so that, the CMC coated strawberries exhibited the highest score. TOPSIS-Shannon entropy method used to compare different coatings to improve the shelf-life of strawberries. The comparison between different coatings via TOPSIS analysis showed that the CMC was the most appropriate coating to reduce the weight loss, decayed and preserved nutritional ingredients of strawberries during the storage period.

Effect of Gaseous Ozone and Heat Treatment on Quality and Shelf Life of Fresh Strawberries during Cold Storage

ABSTRACT Ozone is a powerful oxidant agent which is used in foods preservation on account of its ability of killing microorganisms. In the present study, the combined effects of ozone gas treatment and heat treatment on the physicochemical and sensory characteristics and shelf-life of strawberries kept under refrigeration were investigated. Strawberries were heat treated, ozonated at concentrations of 0.5, 1.0, and 1.5 ppm for 40 min and ozonated at the above-mentioned conditions in combination with heat treatment. Ozone and heat treatment affected significantly (p < .05) weight loss percentage and titratable acidity. Total soluble solids (TSS) content was affected significantly by heat treatment, ozone treatment at concentrations of 0.5 and 1.0 ppm and by the ozone treatments at all concentrations plus heat treatment. Color parameters L*, a*, b*, and pH were affected significantly by ozonation at concentration of 1.5 ppm plus heat treatment. Firmness, pH, and color parameter L* were affected significantly by ozonation at 1.0 ppm. Heat treatment and ozonation at 1.0 ppm plus heat treatment also affected firmness. In conclusion, strawberries treated with ozone at a concentration of 0.5 ppm and at 0.5 ppm plus heat treatment recorded a higher score in sensory analysis and slightly longer storage time.

Improvement of storage quality of strawberries by pullulan coatings incorporated with cinnamon essential oil nanoemulsion

This study was aimed at evaluating the effect of pullulan coating incorporated with cinnamon essential oil (CEO) nanoemulsion on the shelf life and senescence of fresh strawberries during room storage. Pullulan-CEO nanoemulsion prepared using ultrasound treatment had smaller particle size (162.1 nm) and more uniform distribution of oil droplets. After six days of storage, pullulan-CEO nanoemulsion coating remarkably lowered the loss in fruit mass, firmness, total soluble solids and titratable acidity of strawberries. In addition, pullulan-based nanoemulsion coated strawberries showed the strongest antimicrobial activity against bacteria and molds (2.544 and 1.958 log CFU/g, respectively) compared to control and pure pullulan coating groups. It is mainly due to the antimicrobial activities of CEO dispersed in nano size in pullulan matrix. This study revealed that pullulan-CEO nanoemulsion coating showed great potential to prolong the shelf life of fresh strawberries during room storage.

Effect of salep‐based edible coating enriched with grape seed extract on postharvest shelf life of fresh strawberries

AbstractEffects of novel edible coatings based on salep solution (SS) enriched with grape seed extract (GSE) (1.5% SS, 1.5% SS + 0.5% GSE, 1.5% SS + 1.5% GSE, 1.5% SS + 3% GSE) on the quality characteristics of fresh strawberries were monitored after 0, 4, 8, 12, 16, and 20 days of storage (1°C, 95% RH). The lowest growth of microorganisms, weight loss, softening and ascorbic acid, phenol and anthocyanin degradation was measured in strawberries coated with 1.5% SS + 3% GSE. The highest superoxide dismutase activity and the lowest peroxidase activity were determined in strawberries coated with 1.5% SS + 3% GSE. Moreover, they received the highest ranked sensory attributes. Incorporating GSE into the SS coating formulation as a new hurdle increased its antimicrobial properties and extended the shelf life of coated strawberries compared to uncoated by up to 20 days.

Modelling the biochemical and sensory changes of strawberries during storage under diverse relative humidity conditions

Many studies stress the importance of keeping strawberries at high relative humidity conditions during postharvest storage. However, the effect of deviations occurring across the supply chain on the appearance, acceptability and biochemical properties of strawberries has not been adequately explored or quantified to date using kinetic modelling applications. This study investigated the effect of relative humidity (RH) on degradation kinetics of quality and biochemical properties of ‘Strawberry Festival’, during 7 days of storage at 2 °C, using zero, first-order and Weibull models. The strawberries were stored at 40, 60, 70, 80 or 90% RH and were evaluated using subjective quality evaluation, weight loss monitoring and biochemical analysis. The shelf life was established based on current industry practices using subjective quality evaluation, namely shrivelling and colour scores. The Weibull model was found to better fit the experimental chemical analysis data compared to zero and first order kinetics models. The analysis of the rate constants quantified the significant effect of RH conditions on the weight loss and degradation rate of chemical components. Storage at low RH conditions accelerated the loss of ascorbic acid, and anthocyanins and negatively affect the in vitro antioxidant activity. The overall appearance of strawberries was modelled with zero-order kinetic model and the results revealed that lower RH conditions can limit the remaining shelf life of fresh strawberries by increasing the rate of appearance deterioration. Using RH and time as predictors in a logistic regression model, the waste occurring due to unacceptable strawberry quality, was predicted; highlighting the importance of using RH in predictive modelling when designing supply chains with the view to minimise losses.

Effect of Sonication Duration in the Performance of Polyvinyl Alcohol/Chitosan Bilayer Films and Their Effect on Strawberry Preservation.

In this study, we fabricated polyvinyl alcohol (PVA)/chitosan (CS) bilayer films by casting and investigated the effects of preparation conditions and CS content (2, 2.5, or 3 wt.%) on the ability of these films to preserve packaged strawberries. The best performance was achieved at a CS loading of 2.5 wt.% (ultrasound time, 25 min); the strain and stress values were 143.15 ± 6.43% and 70.67 ± 0.85 MPa, respectively, oxygen permeability was 0.16 ± 0.08 cm2·m2·day−1·MPa−1, water vapor permeability was 14.93 ± 4.09 g·cm−1·s−1·Pa−1, and the shelf life of fresh strawberries packaged in the PVA/CS 2.5 wt.% bilayer film was determined to be 21 days at 5 ± 2 °C and a relative humidity of 60 ± 5%. Treatment with PVA/CS bilayer films prevented the decrease in the firmness of strawberries during storage (21 days). The evaluated physicochemical parameters (weight loss, decay, firmness, titratable acidity, soluble solid content, ascorbic acid content, and color) indicated that treatment with PVA/CS bilayer films led to better maintenance of the fruit quality. We believe that our study makes a significant contribution to literature because it paves the way to the fabrication of smart packaging materials and facilitates the commercialization of fresh strawberries as an important health food.

Effect of basil seed gum based edible coating enriched with echinacea extract on the postharvest shelf life of fresh strawberries

Effects of novel edible coatings based on bail seed gum (BSG) enriched with echinacea extract (EE) (3% BSG, 3% BSG + 0.5% EE, 3% BSG + 1.5% EE, 3% BSG + 3% EE) on the quality characteristics of fresh strawberries were monitored after 0, 4, 8, 12, 16 and 20 days of storage (1C, 95% RH). The lowest growth of microorganisms, weight loss, softening and ascorbic acid, phenol and anthocyanin degradation were measured in strawberries coated with 3% BSG + 3% EE. Moreover, the strawberries coated with 3% BSG + 3% EE showed the highest antioxidant and superoxide dismutase activity, the lowest peroxidase activity and received the highest ranked sensory attributes. Incorporating EE into the BSG solution coating formulation as a new hurdle increased its antimicrobial properties and extended the shelf life of coated strawberries compared to uncoated by up to 20 days. These achievements paved the way for hurdle technology applications involving medicinal plant extract such as echinacea extract combined with other technologies like coating technology in the preservation of fresh or process foods.

Development of antimicrobial edible coating based on modified chitosan for the improvement of strawberries shelf life

Edible antimicrobial coating produced from chitosan (CS) and its derivative was applied to improve the shelf life of fresh strawberries at 10°C. Fruits treated with coating solution was stored at 10°C and evaluated for weight loss, visual decay and microbiological analysis. Results indicated that the percentage weight loss and the decay were significantly (p<0.05) lower for chitosan-monomethyl fumaric acid (CS-MFA) than that of CS and control samples. The total aerobic count for CS-MFA was 3.32 log CFU/fruit and was considerably lowered (p<0.05) than CS (3.83 log CFU/fruit) and control (5.31 log CFU/fruit) at the end of storage. Fruit coated with CS-MFA showed significantly lowered (p<0.05) count of yeast and molds when compared with CS. In conclusion, the antimicrobial edible coating based on modified CS improved microbiological characteristics and increased the shelf life from 4 (control) to 8days (coated fruits).

Preparation and Application of LDPE/ZnO Nanocomposites for Extending Shelf Life of Fresh Strawberries.

Strawberries have a very short post-harvest life mostly due to their relatively high water content, intense metabolic activity and susceptibility to microbial rot. Antimicrobial low-density polyethylene nanocomposite films containing ZnO nanoparticles at different mass fractions were prepared by melt mixing and followed by compression moulding using a hot press machine. Fresh strawberries were packed in nanocomposite films and stored at 4 °C. Their microbial stability, ascorbic acid content and titratable acidity were evaluated after 0, 4, 8, 12 and 16 days of storage. Microbial growth rate was significantly reduced up to 16 days as a result of the use of nanocomposite packaging material containing ZnO nanoparticles. By increasing the ZnO nanoparticle mass fraction to 5%, the antimicrobial activity of the film increased. All packages containing the ZnO nanoparticles kept the microbial load of fresh strawberries below the level that affects shelf life (5 log CFU/g) up to 16 days. The lowest degradation of ascorbic acid content (6.55 mg per 100 g), and loss of acidity (0.68%) were observed in packages containing 3% of ZnO nanoparticles with 10% polyethylene-grafted maleic anhydride.

Active Packaging for Fresh Food Based on the Release of Carvacrol and Thymol

Active packaging is becoming an emerging food technology to improve quality and safety of food products. One of the most common approaches is based on the release of antioxidant/a ntimicrobial compounds from the packaging material. In this work an antifungal active packaging system based on the release of carvacrol and thymol was optimized to increase the post-harvest shelf life of fresh strawberries and bread during storage. Thermal properties of the developed packaging material were determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Volatile compounds in food samples contained in active packaging systems were monitored by using headspace solid phase microextraction followed by gas chromatography analysis (HS-SPME-GC-MS) at controlled conditions. The obtained results provided evidences that exposure to carvacrol and thymol is an effective way to enlarge the quality of strawberries and bread samples during distribution and sale.

Carvacrol and Thymol for Fresh Food Packaging

Active packaging is becoming an emerging food technology to improve quality and safety of food products. One of the most common approaches is based on the release of antioxidant/antimicrobial compounds from the packaging material. In this work an antifungal active packaging system based on the release of carvacrol and thymol was optimized to increase the post-harvest shelf life of fresh strawberries and bread during storage. Thermal properties of the developed packaging material were determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Volatile compounds in food samples contained in active packaging systems were monitored by using headspace solid phase microextraction followed by gas chromatography analysis (HS-SPME- GC-MS) at controlled conditions. The obtained results provided evidences that exposure to carvacrol and thymol is an effective way to enlarge the quality of strawberries and bread samples during distribution and sale.

MAINTAINING THE QUALITY OF STRAWBERRIES BY COMBINED EFFECT OF AQUEOUS CHLORINE DIOXIDE WITH MODIFIED ATMOSPHERE PACKAGING

ABSTRACT This study evaluated the efficiency of various concentrations (3, 6 and 9 ppm) of ClO2 and modified atmosphere packaging (MAP). Quality criteria of fresh strawberries were analyzed during storage. Highest CO2 and lowest O2 levels were observed inside the package for the control (without ClO2) group. ClO2 treatments were effective in retaining pH and titratable acidity. After 25 days, ClO2 groups exhibited low conductivity (3.4–3.5 µS/cm) and high L* values, around 30, compared with the control group. ClO2 was effective in maintaining the stability of anthocyanin. At day 6, the 9 ppm group had the highest a* value (30.06). Firmness values were in the range of 280–300 g for the ClO2-treated group and around 100 g for the control group at the end of storage. Fourier transform near-infrared spectra gave comprehensive information about the water and sugar contents of the strawberries. The overall results indicated that ClO2 treatment and MAP had significant effect on the postharvest quality of fresh strawberries. PRACTICAL APPLICATIONS Strawberries are highly perishable fruits due to high respiration rate, and require protection during storage. The present study demonstrated that combination of various ClO2 concentrations and modified atmosphere packaging technologies is capable of maintaining the shelf life of fresh strawberries and has been suggested as an interesting alternative to traditional sanitizers. Also, Fourier transform near-infrared measurements provided good estimates of the internal quality indices of the fresh strawberries.

Development of bioactive coatings based on γ-irradiated proteins to preserve strawberries

Gamma irradiation was applied for creating cross-linked proteins to enhance the physicochemical properties of edible films made of calcium caseinate, whey protein isolate and glycerol. The characteristics of γ irradiated cross-linked proteins were analyzed by Fourier Transform Infrared spectroscopy. A second derivative spectra exhibited changes in band intensities that were correlated to an increase of β-sheet structure and a decrease of α-helix and unordered fractions of γ irradiated-cross-linked proteins as compared to the control without irradiation. Furthermore, on addition of methylcellulose to the irradiated protein matrix it was found that it has potential in enhancing the puncture strength and has no detrimental effect on water vapor permeability of protein based films. Finally, these film formulations were used as bioactive edible coatings containing natural antimicrobial agents (limonene and peppermint) to preserve the shelf life of fresh strawberries during storage. The bioactive coatings containing peppermint was found to be more efficient as preserving coatings than the formulations containing limonene. Irradiated proteins/methylcellulose/peppermint formulation had only 40% of decay at day 8 while it was 65% for the control.