The shelf life extension of fresh strawberries using an oxygen absorber in the biobased package

Characterization and application of the nanocompiste packaging films containing clay and TiO2 on preservation of tomato fruit under cold storage

BACKGROUND

Tomato (Lycopersicon esculentum), a valuable economic crop worldwide, often goes to waste due to improper packaging and handling. In the present study, three types of low-density polyethylene nanocomposite films containing 3% clay (Closite 20A), 3% TiO2 nanoparticles, and their combination were synthesized using melt blending method, and evaluated on the quality parameters of tomato fruit during 42 days of storage at 4 °C.

RESULTS

Transmission electron microscopy confirmed the degree of dispersion and exfoliation of the nanoparticles. The TiO2/clay-nanocomposite films exhibited notable enhancements in Young's modulus and tensile strength compared to conventional films. The addition of clay and TiO2 nanoparticles resulted in reduced permeability to CO2, O2, and water vapor. Fruits packed with clay/TiO2 nanocomposite films showed decreased ethylene production, mitigated weight loss, and maintained pH, titratable acidity, total soluble solids, and firmness. Furthermore, clay/TiO2 nanocomposite films enhanced membrane stability, decreased membrane lipid peroxidation, and enhanced catalase and ascorbate peroxidase enzyme activity in fruits.

CONCLUSIONS

The relatively good exfoliation of clay nanoparticles and the proper dispersion of TiO2 nanoparticles, which were confirmed by TEM, led to an increase in mechanical and physical properties in the Clay/TiO2 nanocomposite. This film displayed more potential in maintaining the quality properties of tomato fruit during cold storage. Therefore, this film can be considered a practical solution for minimizing pathogen risks and contamination, and enhancing the overall quality of tomato fruit.

Influence of chitin nanofibers and gallic acid on physical-chemical and biological performances of chitosan-based films

In this work, chitosan films loaded with gallic acid and different content of chitin nanofibers were prepared and subjected to different characterization techniques. The results showed that the inclusion of gallic acid to chitosan films caused moderate decrease in water vapor permeability (by 29 %) and increased tensile strength of films (by 169 %) in comparison to the neat chitosan films. Furthermore, it was found that the addition of chitin nanofibers up to 30 % into chitosan/gallic acid films additionally improved tensile strength (by 474 %) and reduced plasticity of films (by 171 %), when compared to the chitosan/gallic acid films. Increased concentration of chitin nanofibers in films reduced the overall water vapor permeability of films by 51 %. In addition, gallic acid and chitin nanofibers had synergic effect on high chitosan film's antioxidant and antifungal activity toward Botrytis cinerea (both above 95 %). Finally, chitosan/gallic acid/chitin nanofibers films reduced decay incidence of strawberries, increased total soluble solid content, and promoted high production of some polyphenols during cold storage, in comparison to the control chitosan films and uncoated strawberry samples. Hence, these results suggest that chitosan/gallic acid/chitin nanofibers can present eco-sustainable approach for preservation of strawberries, giving them additional nutritional value.

Regulation mechanism of magnetic field on pectinase and its preliminary application in postharvest sapodilla (Manilkara zapota)

In this study, regulation mechanism of magnetic field on pectinase was investigated and it was preliminarily applied in postharvest sapodilla. Results indicated pectinase activity decreased by 44 % when treated by magnetic field (3 mT, 0.5 h) with kinetic parameters V_max/K_m decreasing from 0.799 to 0.366 min. The optimal temperature (48 °C) and pH (4.8) of pectinase was not altered by magnetic field but Ca²⁺ at 0.05 mol/L strengthened its regulation effect. Ultraviolet and fluorescence spectra suggested tyrosine and tryptophan residues in treated pectinase became more hydrophobic while opposite in phenylalanine. CO, CNH, COO^- groups in pectinase were also influenced, resulting in decreased β-sheet (from 53 % to 49 %), increased random coil (from 20 % to 22 %) and β-turn content (from 27 % to 29 %). More importantly, the firmness of treated sapodilla remained 45 % of maximum at 12 days' storage. Our findings provided new insights to illustrate the role of magnetic field in fruit preservation.

What is the role of active packaging in the future of food sustainability? A systematic review

Nowadays, the strong increase in products consumption, the purchase of products on online platforms as well as the requirements for greater safety and food protection are a concern for food and packaging industries. Active packaging brings huge advances in the extension of product shelf-life and food degradation and losses reduction. This systematic work aims to collect and evaluate all existing strategies and technologies of active packaging that can be applied in food products, with a global view of new possibilities for food preservation. Oxygen scavengers, carbon dioxide emitters/absorbers, ethylene scavengers, antimicrobial and antioxidant active packaging, and other active systems and technologies are summarized including the products commercially available and the respective mechanisms of action. © 2022 Society of Chemical Industry.

Effects of resveratrol treatment on quality and antioxidant properties of postharvest strawberry fruit

Strawberry fruit is one of people's favorite fruits. It has high nutritional value and health care effects. Strawberries lose their edible value quickly after being picked because of their thin skin, which is easily damaged. In order to find a method to maintain the quality of strawberries, the effects of resveratrol treatment on the nutritional quality and antioxidant metabolism of strawberry fruit were studied. The result indicated that 100 μM resveratrol was the optimal concentration to delay the occurrence of decay. Strawberry fruit treated with resveratrol delayed the decrease in firmness, total soluble solids (TSS), total phenolics content (TPC), total flavonoid content (TFC), vitamin C (Vc) content,1,1-diphenyl-2-picrylhydrazyl (DPPH), and 2,2'-azino-bis (3-ethylbezothi- azot-hiazoline-6-sulfonic acid) (ABTS) radical scavenging capacities. The malondialdehyde (MDA) content, hydrogen peroxide (H₂ O₂ ) content, and superoxide anion (O₂ ^•- ) production of control fruit were significantly higher than those of treated fruit. Strawberry fruit treated with resveratrol also increased the activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) during storage. Therefore, resveratrol has been proved to effectively improve the nutritional quality and antioxidant properties of strawberry fruit. PRACTICAL APPLICATIONS: Strawberry fruit is rich in nutrients, which is beneficial to human health. But strawberry fruit has high water content and soft tissue, which is easy to be damaged and decayed. Therefore, it is particularly important to find a way to maintain strawberry fruit quality. In this study, resveratrol has good antioxidant, health care, and antibacterial properties. Resveratrol treatment can maintain the nutritional quality of strawberry fruit and can be used as an effective method for strawberry fruit preservation.

Development of Microcapsule Bioactive Paper Loaded with Chinese Fir Essential Oil to Improve the Quality of Strawberries

Essential oils are natural antibacterial substances and have potential value for application in fruit and vegetable packaging. In this study, Chinese fir essential oil (CFEO) was microencapsulated to prepare food packaging materials for the first time to overcome its volatilization and oxidation shortcomings and to obtain a sustained-release form of the oil. CFEO was effectively encapsulated in gelatin and chitosan using the complex coacervation method, and the encapsulation efficiency, microstructure, infrared spectrum and thermal stability of the microcapsules were evaluated. Experiments confirmed that the microcapsules had some antibacterial activity. A bioactive paper was developed by combining CFEO microcapsules (CFEO-Ms) with paper-based material using the film-forming property of polyvinyl alcohol (PVA). The coated paper showed good mechanical, air permeability and moisture permeability properties. Environmental scanning electron microscopy confirmed that CFEO-Ms bonded well with PVA and was successfully introduced into the paper fiber after coating, forming an obvious coating film on the surface to facilitate the continuous release of CFEO. The shelf life of strawberries was significantly prolonged when the PVA-coated paper mixed with 3% CFEO-Ms was used for packaging. The results demonstrated that the CFEO-Ms coated paper has the potential to become an effective packaging material for the preservation of strawberries.

Modelling strawberry quality in a longitudinal study under the marketing concept of branding

Background

Marketing strategies, such as branding, redefine how consumers perceive quality and create new requirements related to season length and quality homogeneity, among others. For short-day (SD) strawberry cultivar brands, the commercial season is short due to a dependency on temperature and photoperiod. A plausible strategy to extend the commercialization period is to use different varieties within a single brand; however, this has led to inconsistent quality in other fruit crops. A form of quality assessment to evaluate the impact of a multi-varietal brand on sensory quality is a critical longitudinal study with several sources of variability, such as the inherent variation among assessors and fruit replicates that can affect the reliability of the results. Therefore, this study aimed to develop a methodology to assess the sensorial and physicochemical quality of strawberry brands in two contexts: a short-term season composed of two SD cultivars and a long-term season with one SD and one day-neutral (DN) cultivar.

Results

New statistical models are proposed in this study. An ANOVA mixed model with assessors and replicates as random terms and a multiple factor analysis highlighted a lack of homogeneity with regard to texture parameters and sourness, while partial least square models identified aroma and sweetness as the best quality indicators.

Conclusions

This work has successfully illustrated a methodology that is capable of handling critical aspects of longitudinal studies by using univariate models that account for different sources of variability and constrained multivariate models to relate parameters with overall liking. A long-term brand is a viable solution to valorise strawberries, as parameter heterogeneity did not affect overall quality.

The Influence of Packaging on Palatability and Shelf Life Stability of Horse Treats

Horse treat packaging may be composed of materials including plastic and paper which protect the product from the environment to improve shelf life. Objectives of this research were to 1) assess the impact of packaging on shelf life of horse treats and 2) evaluate the impact of packaging on horse preferences. Three packaging treatments (control, poly, and paper) were examined at five time points over a 12 month period. Treatments were analyzed for moisture, water activity, mold, yeast, pH, and volatile organic acids. Horse preference testing evaluated first treatment sniffed, consumed, and finished as well as number of treats consumed. Significance was set at P < .05 and trends at P < .10. Moisture content and water activity increased in all treatments (P < .01) from month 0 to month 12, with paper packaging providing a greater fluctuation and containing visible mold at month 12 (P < .01). No difference was observed for first treatment sniffed, consumed, or finished during preference testing. However a trend (P = .09) for the period∗treatment interaction was observed for number of treats consumed, with poly increasing while paper decreased. These data indicate that packaging impacts shelf life and horse preference of treats.

Effects of ozone treatment on the antioxidant capacity of postharvest strawberry

Strawberries are highly popular around the world because of their juicy flesh and unique taste. However, they are delicate and extremely susceptible to peroxidation of their membrane lipids during storage, which induces water loss and rotting of the fruit. This study investigated the effects of ozone treatment on the physiological traits, active oxygen metabolism, and the antioxidant properties of postharvest strawberry. The results revealed that the weight loss (WL) and respiration rate (RR) of strawberry were inhibited by ozone treatment (OT), while the decline of firmness (FIR) and total soluble solids (TSS) were delayed. Ozone also reduced the generation rate of superoxide radical anions , and the content of hydrogen peroxide (H₂O₂) enhanced the activity of superoxidase (SOD), catalase (CAT), ascorbate peroxidase (APX), and monodehydroascorbate reductase (MDHAR), as well as promoted the accumulation of ascorbic acid (ASA), glutathione (GSH), and ferric reducing/antioxidant power (FRAP). In addition, a total of 29 antioxidant-related proteins were changed between the OT group and control (CK) group as detected by label-free proteomics during the storage time, and the abundance associated with ASA–GSH cycle was higher in the OT group at the later stage of storage, and the qRT-PCR results were consistent with those of proteomics. The improvement of the antioxidant capacity of postharvest strawberry treated with ozone may be achieved by enhancing the activity of the antioxidant enzymes and increasing the expression of the antioxidant proteins related to the ascorbic acid–glutathione (ASA–GSH) cycle.

Strawberries are highly popular around the world because of their juicy flesh and unique taste.

Preparation and characterization of Konjac glucomannan and pullulan composite films for strawberry preservation

The present study aims to develop the new composite films by blending Konjac glucomannan (KGM) and pullulan with different ratios and concentrations. The structural, physical, barrier properties and morphology of the films were investigated and the practical use on strawberry preservation at 4 ± 1 °C, 85 %±5% relative humidity (RH) and 25 ± 1 °C, 55 %±5% RH was evaluated. Fourier transform infrared and scanning electron microscopy indicated the well-dispersion of film matrix was due to the good compatibility of the components. The mechanical and barrier properties of blend films were markedly enhanced although the light transmittance of which were decreased slightly. It was a further proof that 1% (w/v) KGM/pullulan (with the mass ratio of 2:1) blend film could decrease the weight loss significantly and maintain the titratable acidity, soluble solids and skin color on the strawberry preservation, thus improving the qualities of strawberries during storage time and offering a potential alternative to synthetic materials.

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 Aloe vera Gel, Chitosan and Sodium Alginate Based Edible Coatings on Postharvest Quality of Refrigerated Strawberry Fruits of cv. Chandler

Strawberry is a non-climacteric fruit but exhibits very limited postharvest life due to rapid softening and decay. Therefore, the current study was carried out to evaluate the effects of different types of edible coatings to extend the postharvest life of strawberry fruit. The strawberry fruits of cultivar Chandler, grown under agro-climatic conditions of Multan, were coated with Aloe vera gel, chitosan (2%) or sodium alginate (2%) and kept in refrigerated storage at 5-7 °C with 50-60% RH for 12 days. The fruits were evaluated for sensory and biochemical quality attributes after every 4 days of storage. The results showed that overall coated fruits had prolonged storage life (8 days) as compared to non-coated fruits (4 days). Aloe vera gel coating maintained various quality attributes of strawberry fruits such as firmness, appearance, TSS (6.8°Brix), titratable acidity (1.14%), pH (3.27), ascorbic acid content (76 mg 100 mL-1), antioxidant activity (93%), anthocyanins (104 mg PE 100 g-1 FW) and total phenolic content (369.45 µg GE mL-1). Generally, all coatings prohibited the decay incidence. The results showed that edible coatings based on Aloe vera gel can be used as an effective alternative for other costly and synthetic chemicals.

Ultrasound Improves Antimicrobial Effect of Sodium Hypochlorite and Instrumental Texture on Fresh-Cut Yellow Melon

Ultrasound combined with sanitizers is efficient for the reduction of microbiological contaminants in fruits and vegetables. However, the physicochemical changes remain to be elucidated. Therefore, the isolated and combined effect of ultrasound (40 kHz, 500 W) and sodium hypochlorite (NaOCl) (100 mg/L) for 5 min in the bacterial microbiota and physicochemical changes on yellow melon (Cucumis melo L.) were evaluated. Mesophilic aerobic bacteria (MAB), pH, total titratable acidity (TTA), and texture profile were performed. No changes in pH and TTA (p>0.05) were obtained. Firmness, chewiness, cohesiveness, and gumminess increased (p<0.05) after the ultrasound application. A synergistic effect between ultrasound and NaOCl in the MAB reduction was achieved. Therefore, ultrasound improves the antimicrobial effect of NaOCl and texture profile without undesirable chemical changes.

Development of a Sulfite-Based Oxygen Scavenger and its Application in Kimchi Packaging to Prevent Oxygen-mediated Deterioration of Kimchi Quality

A sulfite-based oxygen scavenger (SOS) was developed with sodium metabisulfite and applied to kimchi packaging in an attempt to prevent oxygen-mediated kimchi quality degradation. The results of the oxygen_- scavenging capacity test showed that the SOS had a competitive oxygen_- scavenging performance in comparison with commercial oxygen scavengers. The kimchi was packaged with and without the SOS and stored over 12 weeks at 0 and 10 °C for an SOS application test. The kimchi treated with the SOS showed a significantly lower (P < 0.05) headspace oxygen and carbon dioxide concentration and pressure inside the packages than the control. The pH and titratable acidity values indicated that the SOS did not retard the kimchi fermentation process. The Hunter L, a, and b values in the kimchi packaged with the SOS were significantly higher (P < 0.05) than those in the control. After 12 weeks of storage, the total aerobic bacteria counts were reduced by 1.32 and 2.97 log CFU/g, lactic acid bacteria counts were reduced by 2.22 and 4.42 log CFU/g, and total yeasts and molds counts were reduced by 1.76 and 3.04 log CFU/g at 0 and 10 °C, respectively, by the SOS compared to those in the control. These results demonstrated that the developed SOS inhibited oxygen-mediated deterioration of the kimchi, but did not affect the kimchi fermentation. Therefore, our SOS can be used as an active food-packaging technology for kimchi quality preservation. PRACTICAL APPLICATION: A newly designed sulfite-based oxygen scavenger was applied in kimchi packaging, and it showed remarkable preventive effects on the kimchi quality deterioration caused by oxygen. Accordingly, it can be used as an active food-packaging technology to maintain kimchi quality during the storage period. Moreover, it can also be effectively utilized in the packaging of other high-moisture foods such as meat, fish, fruits, vegetables, and dairy products.

A global visual method for measuring the deterioration of strawberries in MAP

Evaluating the quality changes of packed strawberries during storage requires multiple, time consuming and costly measurements such as sensorial, chemical and decay identification. In order to efficiently assess the quality of strawberries in Modified Atmosphere Packaging (MAP) while reducing the number of analysis done, we propose to gather the main visual quality changes under one unique, overall measurement. For this end, a protocol associated to a deterioration grid was built to evaluate surface deterioration as a function of time considering color change, texture softening and microorganism development. The developed method has permitted to build the deterioration kinetic of strawberries packed in different conditions (MAP or no MAP). It allows to mimic the quality analysis made by the consumer, at a glance, during purchase. To the best of our knowledge, the presented method is a breakthrough unlike most common usual methods mainly relying on the number of spoiled strawberries. •Global measurement of the deterioration encompassing microorganism development, color change and texture softening.•An annotation grid built to be used as reference for the attribution of the percentage of strawberries' deterioration.•Measurements of a percentage of surface deterioration was found more accurate than counting the number of rotten strawberries.

Effects of nano-TiO2 -LDPE packaging on postharvest quality and antioxidant capacity of strawberry (Fragaria ananassa Duch.) stored at refrigeration temperature

BACKGROUND

Nano-TiO₂ -low-density polyethylene (NTLDPE) packaging was prepared, and the effects of NTLDPE packaging on quality and antioxidant capacity of strawberry fruits were investigated.

RESULTS

With increased barrier properties, NTLDPE packaging quickly formed a relative lower O₂ and higher CO₂ air composition in comparison with LDPE. It was also more efficient in maintaining the overall quality of strawberry fruit, as reflected by lower decay rate and weight loss, as well as retarding the decrease in firmness and titratable acid. Meanwhile, reactive oxygen species (ROS) including superoxide anion and hydrogen peroxide in NTLDPE-packed fruits were 10.8% and 21.9% lower, respectively. Furthermore, the activities of antioxidant enzymes involved in ROS scavenging in NTLDPE-packed fruits were significantly higher at the later period of storage time. Anthocyanin accumulation was inhibited, whereas ascorbic acid and total phenolics contents were better retained and 1-diphenyl-2-picrylhydrazyl radical scavenging activity was 13.2% higher in NTLDPE-packed fruit by the end of storage.

CONCLUSION

These data indicate that the beneficial effects of NTLDPE packaging on postharvest quality and antioxidant capacity of strawberry are probably associated with the promotion of ROS scavenging and related antioxidant enzyme activities, and NTLDPE packaging together with refrigeration storage is a promising method for strawberry fruit preservation. © 2016 Society of Chemical Industry.