Strawberry Storage Research Articles

A combined analysis of transcriptome and proteome reveals the regulation mechanism of alginate oligosaccharides on alleviating energy deficit in postharvest strawberry

Strawberry exhibits a very short shelf life due to its rapid softening and decay, resulting in postharvest loss. Our previous study showed that AOS, an eco-friendly nontoxic natural product, plays a role in preserving the freshness of strawberries by regulating ABA content and its signaling pathway. Considering the critical role that energy deficit plays in the senescence process of fruits, coupled with the potential influence of plant hormones on energy metabolism. In this study, the molecular mechanism of strawberry postharvest senescence in response to AOS treatment was further explored from the perspective of energy metabolism regulation. This was achieved through a two-layered approach, integrating the direct determination of energy-related substances with a comprehensive joint analysis of transcriptome and proteome data. AOS treatment significantly delayed the loss of ATP, ADP, and AMP contents compared to control fruit, implying that maintaining cell energy is a crucial factor in AOS postponing senescence in strawberry. Subsequently, the mechanisms were further revealed by transcriptome and proteome analysis. Overall, 255 DEGs were screened from the AOS group, mainly related to carbohydrate and energy metabolism, defense, plant hormone, and secondary metabolism. Additionally, A total of 227 proteins were identified that were differentially expressed in the AOS group, and the majority were related to carbohydrate and energy metabolism (85 proteins). Two omics data implied that AOS could effectively regulate the energy metabolism system to maintain the cellular energy level of harvested strawberry during storage, ultimately leading to longer shelf life. Therefore, our findings provide comprehensive information regarding the molecular mechanism underlying the postharvest storage of strawberry treated with AOS. From our results, it can be concluded that AOS postharvest treatment is very useful for keeping fruit quality and extending shelf life by maintaining a higher energy level.

Surfactant hydrophilic modification of expanded graphite to fabricate water-based composite phase change material with high latent heat for cold energy storage

Glycine water-based (GW) phase change material (PCM) is considered a promising candidate for cold energy storage due to its lower cost and high latent heat. However, low thermal conductivity hinders its practical application. Adding high thermal conductive fillers can effectively enhance the thermal conductivity of PCM, but it also leads to a decrease in enthalpy. Thus, the study employed a non-covalent functionalization method to modify the thermal conductivity filler of expanded graphite (EG) using the surfactant Triton X-100 (TX-100) in this study. The hydrophilic groups in TX-100 facilitated the formation of hydrogen bonds between modified expanded graphite (MEG) and GW PCM, thereby inhibiting the enthalpy loss of GW/MEG materials. The prepared GW/MEG composites containing 2 to 8 wt% of MEG exhibited thermal conductivities ranging from 0.88 to 1.28 W/(m·K), representing an increase of 46.47 % ∼ 113.35 %. Simultaneously, the melting temperature ranged from −5.35 to −5.65 °C, with a high melting latent heat of 284.6 to 264.5 J/g. After 100 thermal cycles, only minor fluctuations in melting temperature (−1.62 % ∼ +2.20 %) and latent heat (−2.18 % ∼ −4.66 %) were observed. Furthermore, the application of GW/MEG2 in cold storage of strawberries resulted in a significant reduction in pre-cooling time by 56.60 % compared to that of ice storage. The GW/MEG2 materials allow strawberries to be refrigerated for up to 17.86 h within the temperature range of 1.54 ∼ 3.39 °C. This study provides an effective solution for short-distance transportation of perishable food within cold chain logistics system.

The effect of polylactic acid-based blend films modified with various biodegradable polymers on the preservation of strawberries

Polylactic acid (PLA) has garnered much attention in the field of fruit and vegetable packaging. Despite its poor flexibility and water resistance, PLA film faces challenges in being used for strawberry storage and freshness preservation due to its inability to maintain flavor quality. In this study, a series of PLA-based modified films was produced by melt blending and extrusion cast processing with PLA as the main component, along with flexible biodegradable polyesters or polycarbonate as the secondary component. First, five different biodegradable polymers were used to investigate the effect of the flexibility and barrier properties of different dispersed phases on the morphology, mechanical properties, and water vapor barrier of PLA-based blend films. Next, the impact on the freshness of strawberries was assessed through examination of fruit color and weight, as well as the levels of O2 and CO2 in the packaging bags. The results showed that the size of the dispersed phase and interfacial bonding with PLA were the key factors determining the mechanical and barrier properties of the blend films. The PLA-polycaprolactone (PCL) blend showed the best compatibility among them, with PCL having the smallest dispersion size (D=0.58 µm), higher toughness than the other four PLA blends, and greater enhancement of PLA. Additionally, it exhibited a similar rate of quality loss in strawberry preservation compared to commercial PE. As a result, the color and luster were more completely preserved. The results of this study may help the future development of degradable plastics, to reduce environmental pollution.

Strawberry Post-Harvest Anthocyanin Development to Improve the Colour Stability of Strawberry Nectars

Strawberry nectars have increased colour stability when produced from overripe, darker, and redder strawberries, with a high anthocyanin concentration. The post-harvest storage of strawberries has been shown to develop these properties. Nectars are frequently produced from strawberries rejected for fresh sale due to poor colour, which are insufficiently ripe to produce colour-stable nectars. This study investigated post-harvest anthocyanin development in strawberries to improve the colour and colour stability of nectars, which is the first time these developments were studied for beverage production. Strawberries at five ripeness stages were stored at 20 °C for 1 and 2 days prior to nectar production. The anthocyanin content of nectars was determined by a pH-differential method, and the colour stability was tracked for 12 weeks using a consumer Acceptance Factor, derived from CIELAB colour components. The anthocyanin content and colour stability were highly correlated, and both were dependent on ripening, with larger increases observed in under-ripe strawberries, and small to no improvement in overripe samples. Stored partially coloured strawberries produced nectars with equivalent colour stability to non-stored strawberries of normal ripeness. This allowed strawberries that were previously unsuitable for both fresh sale and nectar production to be used as a feedstock for nectar production, reducing food waste.

Red LED light affects the physicochemical responses of strawberries during storage

This study aimed to evaluate the effect of the storage of strawberries under LED lights on ‘Albion’ strawberry quality. The treatments were applied as follows; (1) storage under continuous blue, red, and ultraviolet-A (UVA) LED light, (2) storage in the dark conditions (control), and (3) storage in the dark conditions after 1 h UVA (UVAh) LED lighting. Strawberries were stored at a temperature of 4±1oC with 85-90% relative humidity for 10 days. In the study, analyses were conducted on the total anthocyanin content, color (L*, hue angle, redness index), total soluble solids (TSS), fructose, glucose, total sugar content, titratable acidity (TA), fruit firmness (N), and weight loss at the start of the experiment and at 2-day intervals during storage. According to the results, the storage of strawberries under continuous red-LED light was successful in improving the anthocyanin and TSS contents, while preserving fruit firmness and reducing weight loss. Moreover, UVA treatment was effective in maintaining the L*, a*, and b* color values, whereas UVAh was effective on the hue angle and redness index. Furthermore, UVAh treatment caused a decrease in the glucose, fructose, and total sugar content and, in the titratable acidity of the strawberries.

Application of plasma-activated hydrogen peroxide solution synergized with Ag@SiO2 modified polyvinyl alcohol coating for strawberry preservation

To extend the postharvest storage time of strawberries, this study aims to prepare a composite coating using plasma-activated hydrogen peroxide solution (PAH) synergized with nano-Ag@SiO2 by blending method to modify polyvinyl alcohol (PVA) solution. Results showed that the viscosity and the swelling rate of PVA significantly decreased with the addition of Ag@SiO2 at 0.18 %. Meanwhile, the elongation at break and the tensile strength of PVA increased to 0.87 MPa and 214 %. When the addition of Ag@SiO2 was 0.18 % and the composite ratio of PAH to PVA was 1:1, the composites could inactivate the pathogenic bacteria at 2 h. During the storage of strawberries, the initial colony counts on the surface of strawberries could be reduced by about 1 lg CFU/g after coating with the composite film. Moreover, with the extension of the storage time to 7 d, the respiratory intensity, colony counts, and rot index in the strawberries were 65.7 mg/(kg•h), 4.05 log CFU/g, and 38.7 %. Meanwhile, the superoxide dismutase activity and Vc content were 944 U/g and 690 μg/g, respectively. Overall, this study provides ideas and the theoretical basis for applying composite films in fruit preservation.

New gas sensitive films containing anthocyanin/curcumin for real-time monitoring of strawberries quality

Gas sensitive films (GSFs) of polyvinyl alcohol (PA), soluble starch (SS), and polyethylene glycol bis (3-aminopropyl) ether (PGE) containing blueberry anthocyanin (BA), curcumin (CU), and anthocyanin/curcumin complexes were created to monitor the quality changes of strawberries during storage (room temperature, 24 ± 2 °C). Using headspace-gas chromatography-mass spectrometry (HS-GC-MS), the volatile aroma gases released during storage of strawberries were analyzed. Results showed that the release of aldehydes was more closely associated to the quality of the strawberries. The BA, CU and BA/CU complexes (mass ratio: 1:2 and 2:1) were well dispersed in GSFs and improved the films' hydrophilicity, however, there was no effect on the water vapor permeability. The four GSFs were employed to monitor strawberry quality changes over the course of storage. The results showed that the changes in color of the four GSFs had a strong correlation with the quality of strawberries, which could be classified as fresh, sub-fresh and spoiled.

Edible chitosan-based Pickering emulsion coatings: Preparation, characteristics, and application in strawberry preservation

The long-term application of plant essential oils in food preservation coatings is limited by their poor water solubility and high volatility, despite their recognized synergistic antimicrobial effects in postharvest fruit preservation. To overcome these limitations, a Pickering emulsion loaded with thyme essential oil (TEO) was developed by utilizing hydrogen bonding and electrostatic interactions to induce cross-linking of chitosan particles. This novel emulsion was subsequently applied in the postharvest storage of strawberries. The shear-thinning behavior (flow index <1) and elastic gel-like characteristics of the emulsion made it highly suitable for spray application. Regarding TEO release, the headspace concentration of TEO increased from 0.21 g/L for pure TEO to 1.86 g/L after two instances of gas release due to the stabilizing effect of the chitosan particles at the oil-water interface. Notably, no phase separation was observed during the 10-day storage of the emulsion. Consequently, the emulsion was successfully employed for the postharvest storage of strawberries, effectively preventing undesirable phenomena such as weight loss, a decrease in firmness, an increase in pH, and microbial growth. In conclusion, the developed Pickering emulsion coating exhibits significant potential for fruit preservation applications, particularly for extending the shelf life of strawberries.

Ultrasonic preparation of citral/hydroxypropyl-β-cyclodextrin inclusion complex: Application as a potential antifungal preservative in strawberry storage

Ultrasonic preparation of citral/hydroxypropyl-β-cyclodextrin inclusion complex: Application as a potential antifungal preservative in strawberry storage

Efficient Strategies for Strawberry (Fragaria x ananassa Duchesne) Storage on Farms

Strawberry (Fragaria x ananassa Duchesne) is fruit that's enjoyed by many people worldwide. However, like most fruit varieties, this fruit also faces challenges regarding its storage. Although this is the case, strawberry storage protocols are well established. Nevertheless, on farms, the storage of this culinary fruit is important so that the challenges to obtain good quality fruits are avoided at some costs. Like we have seen with pineapple fruits, storage protocols are essential and ought to be effective so that the produce obtained is superior in quality, irrespective of the variety being transported. In this article, efficient storage strategies of strawberries on farms will be discussed as this is considered to be an essential requirement for strawberries having an extended shelf life, as well as a process for producing superior produce to consumers.

Effect of Yogurt Addition on the Stability of Anthocyanin during Cold Storage of Strawberry, Raspberry, and Blueberry Smoothies.

The addition of yogurt to fruit smoothies enhances their nutritional value by introducing components not naturally found in fruit products. However, the addition of fermented products can affect the stability of fruit bioactive components in fruits, such as anthocyanins. This study aimed to evaluate the effect of varying yogurt additions (0, 10, 20, and 30%) on the stability of anthocyanins during a 4-week refrigerated storage period. The smoothies were obtained from purees of strawberry, raspberry, and blueberry, combined with apple juice and apple puree. In addition, to elucidate the causes of the observed changes in the smoothies, model studies were conducted using purified anthocyanin extracts obtained from the analyzed fruits. We assessed the effects of pH, hydrogen peroxide concentration, and the addition of cell-free extracts from Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus on changes in anthocyanin content during storage. We found that adding yogurt led to a decrease in anthocyanin stability during the 4-week cold storage period. Specifically, a 30% yogurt addition decreased anthocyanin stability in all tested beverages, while a 20% yogurt addition impacted the strawberry and raspberry smoothies. The degree to which yogurt affected anthocyanin stability was dependent on the source of the raw material. The most notable impact was observed in strawberry smoothies and the least in blueberry smoothies. The variability could be attributed to differences in anthocyanin profiles among the fruits, the chemical composition of the beverages, and the observed difference in the survival rates of lactic acid bacteria. Model studies showed that during the storage of anthocyanin extracts, the addition of hydrogen peroxide and cell-free extract had a significant effect, whereas pH within the examined range (3.0-4.5) did not affect anthocyanin stability.

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.

Effect of drainage ratio during strawberry cultivation:The volatilomics-based shelf-life indicators for strawberry fruit.

The metabolome of strawberries at harvest determines their storage capacity. Therefore, dynamics of volatile production during storage of strawberry cultivated under diverse drainage ratios, T1 (12.0%), T2 (25.3%), T3 (36.4%), and T4 (56.5%), were evaluated. Among the various non-target VOCs analysis, there were some groups including aldehydes, esters, and furans occupied over 5% with exhibiting high coefficient of determination (R2 ) following the days after storage (DAS). Aldehydes content decreased over the storage period, while the esters (methyl butanoate, methyl hexanoate, ethyl hexanoate, and benzyl acetate) and furanones (furaneol and mesifuran) were increased as representing aroma compounds in strawberry ripening. Even on the same day, it was investigated that the release of VOCs linked to fruit decay was delayed in the groups (T1 and T2) that were given relatively little water compared to T3 and T4. The hexanal and ethyl hexanoate as an over-ripened signal showed a rapid increase from 4 DAS to 5 DAS in T3 and T4, respectively, while T1 and T2 showed significant increase from 5 DAS to 6 DAS. Relatively slower over-ripening tendency of T1 and T2 was supported by changes of firmness, total soluble solid content, anthocyanin content, and antioxidant activity during storage. T1 and T2 showed higher antioxidant activity at the harvest time and lower anthocyanin accumulation than T3 and T4. The present study elucidated that the preharvest drainage changes during cultivation was involved in fruit quality during strawberry storage. Besides, volatilomics analysis depicted that T2 as an optimal ratio, could delay the occurrence of stress and senescence, and guaranteed the strawberry yield. In conclusion, this study provided evidence that the practical application of drainage ratios could improve horticultural product quality even with low water use and VOCs might be considered an early indicator for strawberry fruit shelf-life.

High hydrostatic pressure (HHP) reinforces solid encapsulation of d-limonene into V-type starch and its application in strawberry storage

The formation of inclusion complexes (ICs) between V-type starch and flavors is traditionally conducted in an aqueous system. In this study, limonene was solid encapsulated into V6-starch under ambient pressure (AP) and high hydrostatic pressure (HHP). The maximum loading capacity reached 639.0 mg/g after HHP treatment, and the highest encapsulation efficiency was 79.9 %. X-ray Diffraction (XRD) results showed that the ordered structure of V6-starch was ameliorated with limonene, which avoided the reduction of the space between adjacent helices within V6-starch generated by HHP treatment. Notably, HHP treatment may force molecular permeation of limonene from amorphous regions into inter-crystalline amorphous regions and crystalline regions as the Small-angle X-ray scattering (SAXS) patterns indicated, leading to better controlled-release behavior. Thermogravimetry analysis (TGA) revealed that the solid encapsulation of V-type starch improved the thermal stability of limonene. Further, the release kinetics study showed that a complex prepared with a mass ratio of 2:1 under HHP treatment sustainably released limonene over 96 h and exhibited a preferable antimicrobial effect, which could extend the shelf life of strawberries.

Magnetic field delays the senescence of strawberries by maintaining energy state and regulating respiratory metabolism

Strawberries are prone to rapid quality deterioration after harvest. Research has confirmed that a magnetic field can improve fruit quality during postharvest storage. However, how the magnetic field impacts the postharvest physiology of strawberries is far from being explored. In this study, the magnetic field (MF, 4 mT, and 50 Hz) was employed during the storage of strawberries at 4 °C for 1, 3, 5, 7, 10, and 15 d, and conventional refrigeration (CR) was used as the control. The results showed that the MF maintained better fruit quality, as indicated by lower decay incidence, declined weight loss, and greater firmness retention. The decrease in soluble solids content and titratable acidity of strawberries caused by respiratory depletion was also alleviated by MF. Furthermore, an improvement in the adenosine triphosphate level, energy charge, activity of enzymes (H+-ATPase, Ca2+-ATPase, succinate dehydrogenase, and cytochrome oxidase) involved in the respiratory metabolism, as well as primary respiratory metabolites (D-glucose, succinic acid, fumaric acid, and citric acid) were observed for the strawberries of MF group. Accumulations of hydrogen peroxide, superoxide anion, and malondialdehyde were suppressed with the application of MF. Overall, the MF contributed to maintaining higher energy and membrane integrity and function, regulating the levels of energy metabolism enzymes, and mitigating reactive oxygen species accumulation, which might be a part of the mechanism involved in retarding the senescence and decay of harvested strawberries.

Effect of Some Sanitizing Treatments on Strawberry Fruit Quality during Cold Storage

The present research was conducted to evaluate the effect of dipping treatments with 2% citric acid, 0.2% benzoic acid, 0.2% sorbic acid and acidic electrolyzed water on the quality of strawberries ("Malvina" cultivar) during 21 days storage at 8 °C. The following analyses were performed on the control and sanitized strawberry fruits at 1, 7, 14 and 21 days of storage: weight loss, firmness, decay incidence, soluble solids content, titratable acidity, total phenolics content, total anthocyanins content and DPPH antioxidant activity. All sanitizing treatments significantly (P&lt;0.05) reduced weight loss and fruit decay during strawberry storage. Dipping strawberries in 0.2% sorbic acid or 0.2% benzoic acid aqueous solutions were the most effective treatments for maintaining firmness and phytochemical content and for delaying the decay of strawberries during cold storage.

Changes in Volatile Compounds in Short-Term High CO2-Treated 'Seolhyang' Strawberry (Fragaria × ananassa) Fruit during Cold Storage.

‘Seolhyang’ strawberry is harvested before it is fully ripened and treated with CO2 to extend the shelf-life. However, the volatile changes in the ‘Seolhyang’ strawberry after short-term CO2 treatment have not been investigated, although the volatile profile is an important quality attribute. Herein, we investigated the effect of short-term high CO2 treatment on the changes in the composition of volatile compounds in ‘Seolhyang’ strawberries at two ripening stages (i.e., half-red and bright-red) during cold storage using headspace solid-phase microextraction and gas chromatography-mass spectrometry. Furthermore, the effect of CO2 treatment on fruit quality with respect to the aroma was investigated. A total of 30 volatile compounds were identified. Storage increased the volatile compound concentrations, and the total concentration of volatiles in the CO2-treated strawberries was lower than that of the untreated strawberries during storage. The production of some characteristic strawberry volatiles (e.g., 4-methoxy-2,5-dimethyl-3(2H)-furanone) was inhibited in CO2-treated strawberries. However, CO2 treatment helped maintain the concentrations of hexanal and 2-hexenal, which are responsible for the fresh odor in strawberries. Interestingly, CO2 treatment suppressed the production of off-odor volatiles, acetaldehyde, and hexanoic acid during strawberry storage. Thus, short-term CO2 treatment may help maintain the fresh aroma of strawberries during cold storage.

Equilibrium modified atmosphere packaging on postharvest quality and antioxidant activity of strawberry

SummaryMicroporous film and MAP were evaluated to find the optimal method for extending the postharvest storage of strawberry. To determine the most suitable MAP system for strawberry, fruits were stored in controlled atmospheres (O2/CO2 partial pressures in kPa: 5/10; 10/10; 5/15), and in a separate experiment, strawberries were sealed in the container with different microporous PET/PE films. Results showed that the optimum atmosphere of strawberries was 10 kPa O2 + 10 kPa CO2 which could be achieved and maintained by using the microporous film with four perforations of 100 μm. By maintaining the optimal atmosphere, active EMAP could increase polyphenol compounds accumulation, with total phenolic content increased by 25% and the content of anthocyanin and total flavonoid was 13% and 29% higher than control at the end of storage. Meanwhile, active EMAP significantly increased CAT PAL and APX activities and the shelf‐life was prolonged for 6 and 3 days, respectively, compared with strawberries packed in control and passive EMAP.

Postharvest Application of Aloe Vera Gel Improved Shelf Life and Quality of Strawberry (Fragaria x ananassa Duch.)

Strawberry is highly appreciated for its aroma and texture, but rapid detrimental changes lead to decay and loss of quality in strawberries, which are the main reasons for huge economic losses. To tackle this major concern, this research focused on assessing the efficacy of edible coatings based on aloe vera (AV) gel to maintain quality parameters and postharvest storage of strawberries. Fruits were coated with gel containing one of five different concentrations of AV gel (0%, 20%, 40%, 60% and 80%) and stored at 1 °C and 95% relative humidity (RH) for up to 20 days. The weight loss, total soluble solids and malondialdehyde content was higher in untreated fruits, whilst these parameters were reduced in treated fruits. The AV gel treated fruits also maintained firmness, titratable acidity, ascorbic acid and total antioxidant activity, whereas, a significant decrease in these parameters was observed in untreated fruits. Furthermore, AV gel coated fruits had better superoxide dismutase, catalase and ascorbate peroxidase activities than uncoated fruits. Additionally, AV gel coatings reduced the rate of loss of total phenolic and flavonoid contents during storage. Consequently, it is concluded that AV gel edible coating is recommended for improving postharvest life and for maintaining maximum quality characteristics of strawberry stored for 20 days stored at 1 °C and 95% RH. Among all treatments, 80% AV gel revealed the best results in maintaining the overall fruit quality and delaying ripening throughout the storage period

Isolation and characterization of a new strain of Bacillus amyloliquefaciens and its effect on strawberry preservation

Bacillus amyloliquefaciens has been widely used in agriculture these years for its high efficiency in biological control of postharvest fruits. Aiming to look for efficient biopreservative of fruits and vegetables, a new strain PJ which isolated from Litopenaeus vannamei, was identified as B. amyloliquefaciens based on morphological, physiological, biochemical characteristics, and phylogenetic relationships. Subsequently, the antimicrobial peptide (termed PJAP) was isolated and purified. At last, the bioactivities and functional application of this peptide were evaluated through the determination of the antibacterial activity and the preservation effect on strawberries. Results indicated that the molecular mass of PJAP was approximately 3.3 kDa. PJAP had antagonistic effect on foodborne pathogens (minimal inhibitory concentrations, MIC values = 62.5–250 μg/mL), and electron microscopy and flow cytometry revealed that PJAP caused an increase of cell membrane permeability in Staphylococcus aureus. The rate of strawberry weight loss and titratable acid level during low temperature storage were delayed after strawberries were treated with PJAP. Consequently, this study indicated that B. amyloliquefaciens PJ and related bacteriostatic substance may have potential applications as the natural preservative for the storage of strawberry after harvest.