Metal-organic frameworks-based moisture responsive essential oil hydrogel beads for fresh-cut pineapple preservation.

The preservation of fresh-cut fruits and vegetables has attracted attention to the shelf-life reduction caused by high humidity. Herein, alginate/copper ions cross-linking, in-situ growth and self-assembly techniques of metal-organic frameworks (MOFs) were utilized to prepare a moisture responsive hydrogel bead (HKUST-1@ALG). As the multistage porous structure formation, tea tree essential oil (TTO) load capacity in hydrogel bead (TTO-HKUST-1@ALG) was increased from 6.1% to 21.6%. TTO-HKUST-1@ALG had excellent moisture response performance, and the release rates of TTO increased from 33.89% to 70.98% with moisture increasing from 45% to 95%. Besides, TTO-HKUST-1@ALG exhibited excellent antimicrobial, antioxidant capacity, and biocompatibility. During storage, TTO-HKUST-1@ALG effectively improved the cell membrane integrity by maintaining the balance of reactive oxygen species metabolism. The degradation of cell wall structure and tissue softening were delayed by inhibiting the cell wall-degrading enzymes activity. Briefly, TTO-HKUST-1@ALG improved the storage quality and extended shelf-life of fresh-cut pineapple, which was a promising preservative.

Polyphenols functionalized MOF encapsulated BPQDs for synergistic photothermal/photodynamic antibacterial properties and multifunctional food preservation.

Active antibacterial materials play an important role in solving food safety problems caused by pathogen contamination. In this study, a composite active antibacterial material with the synergistic antibacterial effectiveness of photothermal, photodynamic and the surface charge of polyphenols was developed, where the multi-porous polyphenol functionalized metal-organic frameworks (ZIF-8-TA) were used as the framework carrier, and black phosphorus quantum dots (BPQDs) were used as the photosensitive source. The resulted ZIF-8-TA/PBQDs possesses excellent photothermal conversion efficiency (27.92%), photodynamic performance and surface charge, and these factors ensure the outstanding broad-spectrum antibacterial performance (100%). Multifunctional characteristics and excellent biocompatibility endow the materials with vast potential for foodstuff packaging. The results showed that the composite antibacterial film produced by doping ZIF-8-TA/PBQDs into chitosan could effectively prolong the shelf life of foodstuff compared with commercial membrane. The successful implementation of this research provides a new idea for controlling microbial contamination and developing multifunctional antibacterial materials.

Effects of quercetin- and Lactiplantibacillus plantarum-containing bioactive films on physicochemical properties and microbial safety of grass carp.

In this study, the electrospinning technique was used to co-encapsulate Quercetin (Qu) and Lactiplantibacillus plantarum 1-24-LJ in PVA-based nanofibers, and the effect of bioactive films on fish preservation was evaluated at the first time. The findings indicated that both Lpb. plantarum 1-24-LJ and Qu were successfully in the fibers, and co-loaded fibers considerably outperformed single-loaded fiber in terms of bacterial survival and antioxidant activity. Following fish preservation using the loaded fibers, significant reductions were observed in TVB-N, TBARS, and microbial complexity compared to the control group. Additionally, the co-loaded fibers more effectively reduced the counts of H2S-producing bacteria and Pseudomonas. In the future, fibers with both active substances and LAB hold promise as a novel approach for fish preservation.

Continuous-Flow High-Pressure Homogenization of Blueberry Juice Enhances Anthocyanin and Ascorbic Acid Stability during Cold Storage.

Blueberries (Vaccinium section Cyanococcus) have a wealth of bioactive compounds, including anthocyanins and other antioxidants, that offer significant health benefits. Preserving these compounds and maintaining the sensory and nutritional qualities of blueberry products such as juice during cold market storage is critical to meet consumer expectations for nutritious, safe, and minimally processed food. In this study, we compared the effects of two preservation processing techniques, high-temperature short-time (HTST) and continuous flow high-pressure homogenization (CFHPH), on blueberry juice quality during storage at 4 °C. Our findings revealed that inlet temperature (Tin) of CFHPH processing at 4 °C favored anthocyanin retention, whereas Tin at 22 °C favored ascorbic acid retention. After 45 days of storage, CFHPH (300 MPa, 1.5 L/min, 4 °C) juice retained up to 54% more anthocyanins compared to control at 0 day. In contrast, HTST treatment (95 °C, 15 s) initially increased anthocyanin concentrations but led to their subsequent degradation over time, while also significantly degrading ascorbic acid. Furthermore, CFHPH (300 MPa, 4 °C) juice had significantly lower polyphenol oxidase activity (>80% less than control), contributing to the overall quality of the juice. This innovative processing technique has the potential to improve commercial blueberry juice, and help meet the rising demand for healthy and appealing food choices.

Adenosine monophosphate boosts the cryoprotection of ultrasound-assisted freezing to frozen surimi: Insights into protein structures and gelling behaviors.

Ultrasound-assisted freezing (UAF) is a clean technique for meat cryoprotections; however, its effectiveness is still limited compared to conventional cryoprotectants, e.g., sugars, polyols, especially at high dosages. To resolve this problem, a synergistic cryoprotection strategy was developed in this study. Adenosine monophosphate (AMP), an adenosine-type food additive, was introduced into frozen surimi at a considerably reduced content (0.08%), yet substantially enhanced the efficiency of UAF to comparable levels of commercial cryoprotectant (4% sucrose with 4% sorbitol). Specifically, UAF/AMP treatment retarded denaturation of surimi myofibrillar protein (MP) during 60-day frozen storage, as evidenced by its increased solubility, Ca2+-ATPase activity, sulfhydryl content, declined surface hydrophobicity, particle size, and stabilized protein conformation. Gels of UAF/AMP-treated surimi also demonstrated more stabilized microstructures, uniform water distributions, enhanced mechanical properties and water-holding capacities. This study provided a feasible approach to boost the cryoprotective performance of UAF, thus expanding its potential applications in frozen food industry.

An effective preserving strategy for strawberries by constructing pectin/starch coatings reinforced with functionalized eggshell fillers.

Food waste occurs frequently worldwide, though hunger and malnutrition issues have received global attention. Short-term spoilage of perishable foods causes a significant proportion of food waste. Developing simple, green, and low-cost strategies to preserve the freshness of perishable foods is important to address this issue and improving food safety. By using strawberries as the model perishable fruit, this study reported a pectin/carboxy methyl starch sodium (PC) based coating using epigallocatechin gallate-loaded eggshell powder (ES@EGCG) as the functional fillers. In comparison to PC coating, the PC-ES@EGCG coating displayed much-enhanced performance, such as enhanced mechanical (2 folds) and barrier (water vapor & oxygen) properties. This composite coating reduced the weight loss of strawberries from over 60% to around 30% after 7-day storage. Coated strawberries exhibit better freshness retention, which achieves the purpose of preserving strawberries during storage. This study provided a cost-effective and eco-friendly coating strategy for reducing food waste.

The improvement of water barrier property in gelatin/carboxymethyl cellulose composite film by electrostatic interaction regulation and its application in strawberry preservation.

Gelatin (GL) and carboxymethyl cellulose (CMC) are common natural components for edible films, but their water barrier performance are finite as hydrophilic polymers. In this study, a GL/CMC water barrier film was prepared, characterized and applied. The microstructure results showed that complex coacervation at pH 2.0 and cross-linking effect of sodium benzoate resulted in strong interaction forces and dense structure of this film. Compared with pure GL or CMC film, this novel composite film decreased water vapor permeability by approximately 90%, and possessed applicable water solubility (51.5%) and stronger barrier to oxygen and UV light. Acidic environment and sodium benzoate endowed antibacterial activity. Furthermore, the water barrier coating film decreased water loss by 47.8% and improved overall quality of fresh strawberries stored at 25 °C for 6 d. Therefore, the novel water barrier film based on complex coacervation and cross-linking is promising to control the postharvest quality of perishable berries.

Preparation and characterization of quercetin@ZIF-L/GO@AgNPs nanocomposite film for room-temperature strawberry preservation.

Fresh strawberries are easily contaminated by microorganisms after picking. Therefore, how to effectively store and keep fresh strawberries has been a hot topic for scientists to study. In this study, we prepared a leaf shaped metal organic framework nanomaterial loaded with quercetin (Quercetin@ZIF-L) at first, which can achieve effective loading of quercetin (96%) within 45 min and has a controlled release effect under acidic conditions. In addition, by cleverly combining satellite graphene oxide @ silver nanoparticles (GO@AgNPs) with slow precipitation performance, Quercetin@ZIF-L/GO@AgNPs nanocomposite film with larger pore size and larger specific surface area was prepared by scraping method. The characterization data of water flux, retention rate, flux recovery rate and water vapor permeability show that the composite film has good physical properties. The experiment of film packaging showed that the fresh life of strawberry could be extended from 3 to 8 days, which significantly improved the storage and freshness cycle of strawberry. At the same time, the metal migration test proved that the residual amount of silver ion in strawberry met the EU standard and zinc ions are beneficial to the health, enriching the types of high-performance fresh-keeping materials and broadening the application.

Textural formation of instant controlled pressure drop-dried peach chips: Investigation of the electrical, thermal, and textural properties of predried peach slices with osmotic dehydration pretreatment.

In this study, the effect of osmotic dehydration (OD) pretreatment with various sugar (erythritol, glucose, and trehalose) on the quality of hot-air-predried peach slices was investigated, particularly focusing on electrical properties, texture, thermal stability, and cell wall strength. Furthermore, the correlation between the properties of predried peach slices and the texture of the instant controlled pressure drop (DIC) dried peach chips was explored. OD pretreatments improved the stability and integrity of the cell wall and cell membrane of pre-dried peach slices, which inhibited the excessive expansion of samples during DIC drying. Especially, peach chips with trehalose-OD exhibited the highest crispiness (1.05 mm), the highest hardness (101.34 N) was obtained in erythritol-OD samples. Overall, the type of osmotic agents affected the texture of DIC peach chips with OD pretreatments. It should be noted that trehalose is a promising osmotic agent for controlling and regulating the quality of DIC peach chips.

3D printed cinnamon essential oil/banana peel carbon dots loaded corn starch/gelatin bilayer film with enhanced functionality for food packaging application.

Using 3D printing technology, a gelatin-polyvinyl alcohol­carbon dots (GPC) layer+corn starch-polyvinyl alcohol-cinnamon essential oil (CPC) layer active bilayer film with an external barrier function and an internal controlled-release effect was successfully produced for food preservation. The GPC film was provided with potent antioxidant and UV blocking properties by the banana peel carbon dots (CDs). The cinnamon essential oil (CEO) had the strongest interaction with the film matrix at 3% (w/w), causing the CPC film having the lowest surface wettability, good integrity, and lowest crystallinity. The CEO's stability and releasing effectiveness were greatly enhanced by the creation of a bilayer film. At 60% filling rate of the CPC layer, the bilayer film showed the highest CEO retention after drying and the best CEO release performance. Finally, the created active bilayer film was found to significantly improve the sensory quality stability of the spicy essential oil microcapsule powders. It also successfully extended the mangoes' shelf life by delaying browning and rot.

Development of ultra-thin poly(L-lactic acid)-based films integrating toughness, barrier properties, and gas selectivity: Towards gas-permeation controllable green food packaging.

High costs and low performance have constrained the application of bio-based materials in food packaging. Herein, a series of ultra-thin poly(L-lactic acid-iconic acid N-diol) (P(LA-NI)) copolymer films were developed using a "one-step" polycondensation process with integrated toughness, barrier properties, gas selectivity, and quality control features. The massive branched structure and gg conformers in P(LA-NI) act as "internal chain expansion" and "internal plasticization". Meanwhile, P(LA-NI) contains numerous polar groups and unique nanoscale microphase structures to realize excellent CO2, O2 barrier, CO2/O2 selectivity, anti-fogging, and UV shielding functions. The atmosphere within the package spontaneously achieves the desirable low O2 and high CO2 levels when packaging button mushrooms with high respiratory metabolism. Eventually, the shelf life of button mushrooms reached 24 days, >3-fold extended. This PLLA-based film meets "dual carbon" and "food safety" goals and has vast potential for fresh food preservation.

A biodegradable pH-response packaging film with blueberry extract: Blown-extrusion fabrication, multifunctional activity, and kinetic investigation.

This work proposed a novel strategy for manufacturing biodegradable pH-response packaging. Briefly, to minimize the amount and thermal processing times of blueberry extract (BE), ethanol-dissolved BE (≤ 3‰ w/w) was sprayed onto the starch/poly(butylene adipate-co-terephthalate) (PBAT) pellets before extrusion blowing. BE was well-integrated into the matrix, forming uniformly colored films. The films with BE exhibited superior mechanical (7.85 MPa of strength, 606.53% of elongation) and enhanced barrier capabilities against ultraviolet light, moisture, and gas. Additionally, they exhibited good antioxidant capacity (68.69%), antibacterial activity (72.40%), and maintained color stability. The film with 3‰ w/w BE presented excellent color responsiveness (ΔE⁎ ≥ 15) in the alkaline range, and successfully monitored the spoilage of shrimp. The pigments in the film had the maximum migration degree (≥ 70%) and rate in 50% ethanol simulation, following a first-order kinetic behavior dominated by Fickian diffusion. Findings supported the application of this strategy in the fabrication of starch/PBAT/BE films for pH-response intelligent packaging.

Mitigating quality deterioration in chilled pork by combining cinnamaldehyde nanoemulsions and a high-voltage electrostatic field.

Cinnamaldehyde nanoemulsion (CNE) was obtained through ultrasonication, using Tween 80 as an emulsifier. The CNE was then applied to chilled pork in conjunction with a high-voltage electrostatic field (HVEF) to mitigate quality deterioration during refrigerated storage. The particle size of CNE ranged from 60 to 150 nm and was positively correlated with the amount of added cinnamaldehyde. The polydispersity index and zeta potential of CNE ranged from 0.25 to 0.30 and - 12 to -11 mV, respectively, indicating a narrow size distribution and stability. The CNE released the odor specific to cinnamaldehyde to pork in the first 4 days of chilling; however, it had little effect on the taste. HVEF pretreatment reduced the initial total viable count (TVC) in pork by 1.14 log cycle. The combination of CNE with HVEF successfully slowed down the loss of moisture, decrease in pH, and accumulation of total volatile basic nitrogen in pork during refrigeration. Furthermore, it mitigated the increase in TVC of pork. Therefore, this integrated method appears to be suitable for extending the shelf life of chilled pork.

Facile fabrication of microfibrillated cellulose-based aerogels incorporated with nisin/ß-cyclodextrin microcapsule for channel catfish preservation.

In this study, a hydrophobic and antibacterial pad was prepared to preserve Channel Catfish (Ictalurus punctatus). The pad composite the microfibrillated cellulose and ß-cyclodextrin/nisin microcapsules. The hydrophobic pad ensures a dry surface in contact with the fish, reducing microbial contamination. The pad has a low density and high porosity, making it lightweight and suitable for packaging applications, while also providing a large surface area for antibacterial activity. Results demonstrated that this antibacterial pad exhibits an ultralow density of 9.0 mg/cm3 and an ultrahigh porosity of 99.10%. It can extend the shelf life of Channel Catfish fillets to 9 days at 4 °C, with a total volatile base nitrogen below 20 mg/100 g. The study proposes a novel solution for preserving aquatic products by combining antibacterial substances with the natural base material aerogel. This approach also extends the utilization of aerogel and nisin in food packaging.

Preservation of soy protein-based meat analogues by using PLA/PBAT antimicrobial packaging film.

This study aimed to reveal the quality changes of soy protein-based meat analogues at 4 °C, and to investigate the efficacy of antimicrobial packaging on maintaining the qualities of meat analogues during 10 days of storage. Cinnamaldehyde (CI) or tea polyphenols (TP) were incorporated in polylactic acid (PLA), polybutylene adipate (PBAT) and starch blends by extrusion technique to prepare antimicrobial packaging. The changes of meat analogues were characterized for morphology, water distribution, texture properties and microbiological analysis during 10 days of storage. Cinnamaldehyde loaded PLA/PBAT film effective retarded the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) at 4 °C, giving an average reduction of E. coli and S. aureus of 3.6 and 4.1 log CFU/g on day 10, respectively. Results suggest that PLA/PBAT-CI film successfully prevents moisture from evaporation, maintains the texture properties and ensures the quality and safety of meat analogues.

Effect of calcium hydroxide mixed with preservatives on physicochemical characteristics and sensory shelf-life of corn tortilla.

BACKGROUND: The objective of the study was to evaluate the physicochemical characteristics and shelf-life of corn tortilla stored at room temperature (25 °C) using aw modifiers (propylene glycol and glycerol) and pH modifiers (fumaric acid and sodium benzoate) as preservatives combined with calcium hydroxide. Detection thresholds were used to determine the maximum preservative concentration and calcium hydroxide. Physicochemical characterization and sensory evaluation were used to determine the stability and sensory shelf-life of tortillas. RESULTS: Control, calcium hydroxide, calcium hydroxide + fumaric acid, calcium hydroxide + glycerol, calcium hydroxide + propylene glycol, and calcium hydroxide + sodium benzoate treatments had rounded half-lives of 1, 2, 1, 2, 2, and 2 days respectively. Glycerol combined with calcium hydroxide resulted in tortillas with lower pH variations over time. Mold presence was the critical attribute causing tortilla rejection. CONCLUSION: The use of aw modifiers had a better effect in preserving corn tortilla, as the concentration of pH modifiers at detection threshold levels was not able to reach an optimum performance when combined with calcium hydroxide. © 2021 Society of Chemical Industry.

Performances of the barrel kiln used in cottage industry for fish processing and effects on physicochemical characteristics and safety of smoked fish products.

BACKGROUND: In the traditional food sector, the smoking process and smoking-drying process are widely used to increase the shelf-life of seafood products. The smoking process and smoking-drying process are mainly performed using barrel kiln and wood as fuel in many West African countries. The present study evaluated the performances of the barrel kiln and its effects on physicochemical characteristics and safety of smoked fish (SF) and smoked-dried fish (SDF). Twelve follow-ups were conducted with three experimental processors and 24 samples of fish collected at different steps of processing were analyzed in a laboratory using standard methods. RESULTS: The extreme values of combustion temperature recorded during the smoking process (456.4 °C) and smoking-drying process (482.8 °C) were higher than 450 °C, the temperature at which wood pyrolysis generates polycyclic aromatic hydrocarbons (PAHs). Smoked fish were highly contaminated with PAHs, and showed maximal levels of benzo[a]pyrene (52.7 µg kg-1 ) and PAH4 (i.e. sum of benzo[a]pyrene, chrysene, benzo[b]fluoranthene and benz[a]anthracene) (290.9 µg kg-1 ) exceeding the European Union limits by about 25-fold. After smoking of Scomber scombrus and smoking-drying of Cypselurus cyanopterus, no significant differences were recorded for lipid, protein and biogenic amine contents between fresh and processed fish, even if the histamine content of both fish exceeded the limit fixed by the European Union regulation. CONCLUSION: The results obtained in the present study showed that smoked fish and smoked-dried fish produced using barrel kiln and wood fuel are highly contaminated by PAHs. Therefore, there is a need to improve the preservation practices of raw fish and smoking conditions to limit the contamination of end-products by PAHs known to be carcinogenic components for humans and to ensure consumer safety. © 2021 Society of Chemical Industry.

Green alternative methods for pretreatment of whole jujube before the drying process.

BACKGROUND: Jujube contains a waxy cuticle that acts as a barrier against fungal pathogens, prevents nutrition damage and leakage due to mechanical damage, and maintains water content. Chemical treatment before drying is the most commonly used method for whole jujube. Although chemical pretreatment can effectively enhance drying kinetics, it can lead to the loss of soluble nutrients and cause food safety issues due to chemical residues. Therefore, this study aimed to explore the effect of various pretreatments (cold plasma, cold plasma activated water, ultrasonics, thermosonication, and blanching) on the drying process and quality properties of whole jujube so as to find effective green alternatives to chemical pretreatment. RESULTS: The application of chemical, cold plasma, and thermosonication significantly altered the surface morphology of jujube by etching larger cracks and holes, which can facilitate the transfer of moisture, thereby improving the drying rate and the effective diffusivity. Chemical, cold plasma, and thermosonication pretreatment reduced drying time by 18%, 12%, and 7% respectively, thereby increasing the content of total phenolics by 13%, 12%, and 6% respectively, and enhancing antioxidant capacity (ferric reducing antioxidant power) by 13%, 11%, and 3% respectively. In addition, chemical and cold plasma pretreatment reduced the generation of 5-hydroxymethylfurfural by 25% and 15% respectively. CONCLUSION: Cold plasma is a promising green alternative method to chemical pretreatment for drying processes of whole jujube. © 2021 Society of Chemical Industry.

Role of thermal and non-thermal drying techniques on drying kinetics and the physicochemical properties of shiitake mushroom.

BACKGROUND: Fresh shiitake mushrooms are rich in nutrients, but have high water content, a fast metabolism after harvest, and deteriorate extremely easily. Therefore, the drying of shiitake mushrooms has become a research direction. However, the role of different drying techniques on shiitake mushroom quality is limited. Therefore, the purpose of this study was to investigate the effect of thermal and non-thermal drying on the drying kinetics, and the physicochemical properties of the end product. RESULTS: Results showed that shiitake mushroom treated with non-thermal drying (vacuum freeze-drying) had an attractive color, low shrinkage, and uniform honeycomb structure, while the drying time was the longest and not conducive to the formation of shiitake mushroom aroma. But shiitake mushroom treated with thermal drying presents an attractive fragrance. In thermal processing technology, compared with hot air convection drying (HAD), infrared hot air convection drying (IRHAD) shortens the drying time by 37.5%, and had the highest oxidation resistance, polysaccharide content and the lowest color change. Relative-humidity drying (RHD) samples had the lowest shrinkage compared with other thermal processing technology. The five polysaccharides exhibited similar preliminary structural characteristics, but the polysaccharides obtained by IRHAD have the highest antioxidant properties. CONCLUSION: These results showed that compared with thermal drying technology, non-thermal drying technology is not suitable for shiitake mushroom processing. In thermal processing technology, IRHAD is a potential drying method to obtain high-quality dried shiitake mushrooms and shiitake mushroom polysaccharide (SMP). However, it is necessary to increase the pretreatment technology to achieve the attractive appearance of non-thermal drying technology. © 2021 Society of Chemical Industry.