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Tomato is one of the most important vegetable crops in the world and is a model plant used to study the ripening of climacteric fleshy fruit. During the ripening process of tomato fruit, flavor and aroma metabolites, color, texture and plant hormones undergo significant changes. However, low temperatures delayed the ripening process of tomato fruit, inhibiting flavor compounds and ethylene production. Metabolomics and transcriptomics analyses of tomato fruit stored under low temperature (LT, 5°C) and room temperature (RT, 25°C) were carried out to investigate the effects of storage temperature on the physiological changes in tomato fruit after harvest. The results of transcriptomics changes revealed that the differentially expressed genes (DEGs) involved in tomato fruit ripening, including several kinds of transcription factors (TFs) (TCP, WRKY, MYB and bZIP), enzymes involved in cell wall metabolism [beta-galactosidase (β-GAL), pectinesterase (PE) and pectate lyase (PL), cellulose and cellulose synthase (CESA)], enzymes associated with fruit flavor and aroma [acetyltransferase (AT), malic enzyme (ME), lipoxygenase(LOX), aldehyde dehydrogenase (ALDH), alcohol dehydrogenase (ADH) and hexokinase (HK)], genes associated with heat stress protein 70 and genes involved in the production of plant hormones such as Ethylene responsive factor 1 (ERF1), Auxin/indoleacetic acids protein (AUX/IAA), gibberellin regulated protein. Based on the above results, we constructed a regulatory network model of the effects of different temperatures during the fruit ripening process. According to the analysis of the metabolomics results, it was found that the contents of many metabolites in tomato fruit were greatly affected by storage temperature, including, organic acids (L-tartaric acid, a-hydroxyisobutyric acid and 4-acetamidobutyric acid), sugars (melezitose, beta-D-lactose, D-sedoheptulose 7-phosphate, 2-deoxyribose 1-phosphate and raffinose) and phenols (coniferin, curcumin and feruloylputrescine). This study revealed the effects of storage temperature on postharvest tomato fruit and provided a basis for further understanding of the molecular biology and biochemistry of fruit ripening.

The increasing incidence and rapid spread of bacterial resistance to conventional antibiotics are a serious global threat to public health, highlighting the need to develop new antimicrobial alternatives. Antimicrobial peptides (AMPs) represent a class of promising natural antibiotic candidates due to their broad-spectrum activity and low tendency to induce resistance. However, the development of AMPs for medical use is hampered by several obstacles, such as moderate activity, lability to proteolytic degradation, and low bioavailability. To date, many researchers have focussed on the optimization or design of novel artificial AMPs with desired properties. Unnatural amino acids (UAAs) are valuable building blocks in the manufacture of a variety of pharmaceuticals, and have been used to develop artificial AMPs with specific structural and physicochemical properties. Rational incorporation of UAAs has become a very promising approach to endow AMPs with strong and long-lasting activity but no toxicity. This review aims to summarize key approaches that have been used to incorporate UAAs to develop novel AMPs with improved properties and better performance. It is anticipated that this review will guide future design considerations for UAA-based antimicrobial applications.

Phycoerythrin (PE) is a natural water-soluble pigment protein with characteristic phycobilins and is sensitive to thermal and light environmental changes. In this study, PE was extracted from Porphyra haitanensis and PE-oligochitosan complexes (POC) were fabricated by a self-assembly approach. The effects of cationic oligochitosan on the binding interaction, structure, size distribution, and color stability of PE were evaluated. The stoichiometric number n was calculated to be 21.67 ± 2.65 (oligochitosan/PE) and the binding constant K was (6.47 ± 0.48) × 105 M-1. Cationic oligochitosan could electrostatically interact with PE and affect the PE structure by increasing the α-helix content. In addition, high concentrations of oligochitosan led to the formation of dense phycoerythrin protein granules. Moreover, at a reaction ratio of 20.0:1 (oligochitosan/PE), being approximately the predicted stoichiometric number n, the thermal stability (40-80 °C), natural light stability, and ultraviolet light irradiation (254 nm) stability of the POC were improved. This study provides an approach to reduce the susceptibility of PE upon environmental changes by forming a stable self-assembly complex, which will promote the application of PE as a natural pigment protein in food and chemical applications.

Currently, the use of synthetic pigments in foods is restricted since synthetic pigments are proven and suspected to be harmful to human health. Phycobiliproteins (PBPs), existed in phycobilisomes (PBSs) of algae, are a kind of pigment-proteins with intense color. The specific color of PBPs (red and blue) is given by the water-soluble open-chained tetrapyrrole chromophore (phycobilin) that covalently attaches to the apo-protein

Tomato fruit are sensitive to chilling injury (CI) during cold storage. Several factors have been discovered to be involved in chilling injury of tomato fruit. Plant hormones play an important regulatory role, however, the relationship between chilling injury and N6-methyladenosine (m6A) methylation of transcripts in plant hormone pathways has not been reported yet. In order to clarify the complex regulatory mechanism of m6A methylation on chilling injury in tomato fruit, Nanopore direct RNA sequencing was employed. A large number of enzymes and transcription factors were found to be involved in the regulation process of fruit chilling injury, which were associated with plant hormone, such as 1-aminocyclopropane 1-carboxylate synthase (ACS), aspartate aminotransferase (AST), auxin response factor (ARF2), ethylene response factor 2 (ERF2), gibberellin 20-oxidase-3 (GA20ox) and jasmonic acid (JA). By conjoint analysis of the differential expression transcripts related to chilling injury and m6A methylation differential expression transcripts 41 differential expression transcripts were identified involved in chilling injury including 1-aminocyclopropane-1-carboxylate oxidase (ACO) and pectinesterase (PE) were down-regulated and heat shock cognate 70 kD protein 2 (cpHSC70), HSP70-binding protein (HspBP) and salicylic acid-binding protein 2 (SABP2) were up-regulated. Our results will provide a deeper understanding for chilling injury regulatory mechanism and post-harvest cold storage of tomato fruit.

Basic helix-loop-helix (bHLH) transcription factors (TFs) are widely distributed in eukaryotes and play an important role in biological growth and development. The identification and functional analyses of bHLH genes/proteins in edible mushrooms (Agaricus bisporus) have yet to be reported. In the present study, we identified 10 putative bHLH members carrying the conserved bHLH domains. Phylogenetic analyses revealed that the 10 AbbHLHs were the closest to sequences of species belonging to 7 different fungal subgroups, which was supported by loop length, intron patterns, and key amino acid residues. The substantial increase after harvest and continuously elevated expression of AbbHLH1 during the development until the disruption of mushroom velum, and the preferential expression in cap and gill tissues suggest the important function of AbbHLH1 in postharvest development of A. bisporus. The relationship of arginine catabolism-related genes with the early stage of postharvest continuing development also was revealed by expression determination. Subcellular localization showed that AbbHLH1 could be localized in nucleus. Importantly, the electrophoretic mobility shift and dual-luciferase reporter assays showed that AbbHLH1 activated the promoters of AbOAT, AbSPDS, and AbSAMDC and suppressed the expression of AbARG, AbUREA, and AbODC, probably for the modulation of arginine catabolism and thus control of postharvest mushroom development. Taken together, the available data provide valuable functional insight into the role of AbbHLH proteins in postharvest mushrooms.

Plant ferritin has a natural cage-like nanospace for carrying bioactive ingredients. By taking advantage of the calcium binding ability of casein phosphopeptide (CPP) and the cage-like conformation of plant ferritin, a ferritin–CPP shell–core complex (FC) was fabricated with the reversible self-assembly character of ferritin induced by a pH 2.0/7.0 transition strategy. The FC–calcium composite (FCC) was further fabricated by binding of the FC with calcium ions. When the same amount of calcium was loaded, the calcium binding capacity of the FCC was 28.13 ± 1.65%, which was significantly higher than that of ferritin and CPP alone. Fluorescence and Fourier transform infrared analysis indicated that the CPP encapsulation and the calcium binding in the FCC influenced the ferritin structure. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) results showed that the spherical morphology and the 12 nm-diameter size were sustained in the FC and FCC. Moreover, the FCC as a transport carrier could increase the precipitation time of calcium phosphate, and the encapsulated calcium could be released in a more sustained manner as compared with ferritin and CPP under simulated in vitro gastrointestinal conditions. This study presents a novel calcium delivery strategy based on the ferritin cage and CPP, which will improve the applicability of ferritin and CPP and enhance the bioavailability of calcium ions.

Ferritin is a cage-like carrier protein with multiple interfaces, allowing for the encapsulation and delivery of biologically active molecules. In this study, hesperetin was covalently conjugated to the outer surface of ferritin to fabricate hesperetin covalently modified ferritin (HFRT) at pH 9.0. This conjugation resulted in a binding equivalent of hesperetin to ferritin of 12.33 ± 0.56 nmol/mg. After covalent binding, the free amino content of HFRT decreased and the secondary and tertiary structures of HFRT were changed relative to the structure of control ferritin. In addition, HFRT successfully retained the cage-like structure of ferritin and exhibited reversible self-assembly property regulated by pH shifts. Taking advantage of this property, quercetin was encapsulated into the inner surface of HFRT with an encapsulation ratio of 14.0 ± 1.36% (w/w). The modification with hesperetin improved the digestive stability of ferritin and enhanced the stability of encapsulated quercetin against thermal treatment compared to unmodified ferritin. This study explored the functions of the double interfaces of ferritin by covalent and non-covalent binding of two different bioactive compounds. The results can help guide the functionalization of the ferritin cage as a nanocarrier in food application.

In plants, spermidine synthase (SPE) received detailed investigation due to its key roles in the biosynthesis of spermidine, a major form of polyamine. However, there is no report on the identifica...

Phytoferritin has a natural cagelike architecture for carrying bioactive molecules, and it is uniquely suited to function as a carrier due to its multiple interfaces and channels. In this study, a novel approach was proposed to prepare ferritin-salvianolic acid B-epigallocatechin gallate (EGCG) three-layer nanoparticles (FSE) through the steric hindrance of ferritin channels. Urea (30 mM) could expand the ferritin channel size evidenced by the improved iron release rate vo and promote the EGCG penetration into the ferritin cavity without disassembly of the ferritin cage. The encapsulation ratio of EGCG was 16.0 ± 0.14% (w/w). Salvianolic acid B attached to the outer interface of ferritin through weak bonds with a binding constant of (2.91 ± 0.04) × 105 M-1. The FSE maintained a spherical structure with a diameter of 12 nm. Moreover, when subjected to heat (40-70 °C) there was a significant increase in the stability of EGCG in the FSE due to the binding of salvianolic acid B. Through this interesting approach, two molecules are simultaneously attached and encapsulated in ferritin in a multilayer form under moderate conditions, which is conducive to the protection of unstable molecules for potential encapsulation and delivery utilization.

Ferritin is a cage-like protein with a modifiable exterior surface. In this study, transglutaminase was applied to catalyze the glycosylation of oligochitosan onto the apo-red bean seed ferritin (apoRBF) to fabricate an oligochitosan-modified apoRBF nanoparticle (OFN). Results indicated that the oligochitosan glycosylation retained the shell-like structure of ferritin and improved its thermal stability. The reversible assembly of OFN regulated by pH and urea transition was successfully retained. By using this assembly routine, rutin can be encapsulated within the OFN either by pH 2.0/7.0 transition or urea (8.0 M/0 M) transition, and the size distribution of rutin-loaded OFN was mainly about 12 nm. Moreover, the thermal stability of the rutin in the OFN was significantly improved as compared with that in apoRBF. The present study will be beneficial for extension of chitosan and Transglutaminase applications in protein modification, and will improve ferritin functionalization as a nanocarrier for food bioactive molecules.

Ferritin is a multisubunit protein with a hollow interior interface and modifiable surfaces. In this study, the manothermosonication (MTS) technology was applied to apo-red bean seed ferritin (apoRBF) to produce the MTS-treated apoRBF (MTFS). MTS treatment (200 kPa, 50 °C, and 40 s) maintained the spherical morphology of apoRBF (12 nm), but reduced the content of α-helix structure and increased the content of random coil structure, and correspondingly decreased the ferritin stability. The MTS treatment also affected the ferritin's iron storage function by decreasing its iron oxidative deposition activity and increasing the iron release activity. Importantly, the disassembly and reassembly properties of the MTFS induced by pH changes were retained, which facilitated its usage in encapsulation of tea polyphenol-epigallocatechin gallate (EGCG) into the ferritin by a relatively benign pH conversion routine (pH 3.0/6.8). In addition, the water solubility of the MTFS was increased, leading to the improved encapsulation efficiency of the EGCG molecules. This study will facilitate the ferritin modification and functionalization by MTS to design a protein variant to be used as new scaffold for iron and bioactive compounds.

Lipoarabinomannan (LAM) is a major structural surface component of Mycobacterium tuberculosis. This study describes the synthesis of the well-defined lipoarabinomannan (LAM) specific dodecasaccharide-protein conjugate and immunological studies. Arabinomannan (AM) dodecasaccharide has been efficiently synthesized and covalently conjugated to carrier proteins, including cross reactive mutant (CRM197) diphtheria toxoid and bovine serum albumin (BSA) for novel neoglycoconjugates, creating a potent T-dependent conjugate vaccine. Preliminary mice immunization studies on the neoglycoconjugate revealed that it could give rise to a strong IgG antibody titer in mice at 4.0 μg dose with an aluminum phosphate adjuvant. AM-CRM197 shows potential as an excellent candidate for a new carbohydrate-based vaccine that would be capable of eliciting a protective immune response against tuberculosis.

Leguminous proteins are important nutritional components in leguminous plants, and they have different structures and functions depending on their sources. Due to their specific structures and physicochemical properties, leguminous proteins have received much attention in food and nutritional applications, and they can be applied as various carriers for binding/encapsulation and delivery of food bioactive compounds. In this review, we systematically summarize the different structures and functional properties of several leguminous proteins which can be classified as ferritin, trypsin inhibitor, β-conglycinin, glycinin, and various leguminous proteins isolates. Moreover, we review the development of leguminous proteins as carriers of food bioactive compounds, and emphasize the functions of leguminous protein-based binding/encapsulation and delivery in overcoming the low bioavailability, instability and low absorption efficiency of food bioactive compounds. The limitations and challenges of the utilization of leguminous proteins as carriers of food bioactive compounds are also discussed. Possible approaches to resolve the limitations of applying leguminous proteins such as instability of proteins and poor absorption of bioactive compounds are recommended.

Enzymatic hydrolysis and glycosylation were successively applied to modify soybean protein isolate (SPI) and rheological and textural properties of acid-induced SPI gel added with the obtained SPI hydrolysates and their glycosylated products were then investigated. The incorporation of SPI hydrolysates decreased the elastic modulus (G') and hardness of SPI gel, which might be related to the random aggregation between SPI hydrolysates and native SPI molecules via hydrophobic interactions. In addition, as the molecular weight of SPI hydrolysates decreased, the reduction in G' and hardness became more significant. Although glycosylation of SPI hydrolysates weakened the adverse effects of hydrolysates on the SPI gel formation to some extent, the glycosylated SPI hydrolysates were still unable to improve the gel quality compared with the control. However, results of this research may provide important information for understanding the influencing mechanism of SPI hydrolysates and their glycosylated products on the formation of SPI gel.

Ferritin, a protein with an 8-nm cage structure, can encapsulate and deliver bioactive molecules. In this study, succinylation was adopted to modify plant ferritin to fabricate succinylated red been ferritin (SRBF) at pH 8.0. The SRBF was retained as a cage-like shape (12 nm diameter), while its secondary structure was altered, rendering higher negative charge accompanies by decreased surface hydrophobicity. The SRBF also demonstrated favorable property of reversible assembly regulated by pH-transitions (pH 2.0/7.0), thus enabled successful encapsulation of epigallocatechin gallate (EGCG) for fabrication of EGCG-loaded SRBF complexes with a diameter of ~12 nm. Succinylation enhanced the thermal stabilities of ferritin and the embedded EGCG. Moreover, SRBF markedly improved the transport efficiency of EGCG in Caco-2 monolayers relative to EGCG and that encapsulated in unmodified ferritin. These findings have extended the succinylation reaction for the cage-like protein modification, and facilitated the usage of ferritin variant in delivery of bioactive molecules.

Background The functionality of pea proteins is relatively weak relative to that of soybean proteins, which limits the application of pea proteins in food and nutritional applications. Glycosylation is a promising approach to influence the protein structure and in turn change the functional properties of pea proteins. Results In this study, the effect of transglutaminase-induced oligochitosan glycosylation on the structural and functional properties of pea seed legumin was studied. Different oligochitosan-modified legumin complexes (OLCs) were prepared by applying different molar ratios of legumin to oligochitosan (1:1 to 1:4) induced by transglutaminase (10 U g-1 protein). Results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), glucosamine, and free amino analysis showed that the legumin could be covalently bonded with the oligochitosan and were influenced by the applying dose of the oligochitosan. Infrared spectroscopy, fluorescence, and scanning electron microscopy analysis indicated that the structure of the different OLC samples could be changed to different extents. Moreover, although the emulsifying activity decreased, the emulsification stability, thermal stability, and in vitro digestive stability of the OLCs were remarkably improved relative to that of the untreated legumin. Conclusion Oligochitosan glycosylation could change the structure of the legumin and consequently improve its emulsification stability, thermal stability, and in vitro digestive stability. This study will facilitate the legumin functionalization by the glycosylation approach to fabricate protein-oligochitosan complex for potential food and nutritional applications. © 2020 Society of Chemical Industry.

Enrichment of multiple bioactive components with different characters into one food substrate simultaneously is a challenge. In this study, the hydrophilic epigallocatechin gallate (EGCG) and the hydrophobic quercetin were simultaneously enriched in the cavity of phytoferritin from red bean seed deprived of iron (apoRBF), a cagelike protein. The interactions of apoRBF with EGCG and quercetin were evaluated by UV/visible absorption, fluorescence, and circular dichroism technologies. By combination of the reversible assembly and urea induced approaches, both EGCG and quercetin were successfully coencapsulated in apoRBF to fabricate four kinds of apoRBF-EGCG-quercetin nanocomplexes FEQ (FEQ1, FEQ2, FEQ3, and FEQ4) with good solubility in aqueous solution. All FEQ samples maintained the typically spherical morphology of ferritin cage with a diameter around 12 nm. Among the four FEQ samples, the FEQ1 prepared by involving a pH 2.0/6.7 transition scheme was more effective in encapsulating EGCG and quercetin molecules than that by the urea induced method. Furthermore, all FEQs facilitated the stability of EGCG and quercetin molecules relative to free ones, and simultaneous coencapsulation of EGCG and quercetin could significantly improve the quercetin stability as compared with that of the free one and quercetin-loaded ferritin (p < 0.05), respectively. This work provides a new scheme to design and fabricate the ferritin based carrier for encapsulation of multiple bioactive components, and it is beneficial for the intensification of multifunction in one food substrate.

The commercial Hβ (25, 50), HY (11) and HZSM-5(50) were dealuminated by acid leaching and subsequent calcination to improve their hydrophobic nature for the removal of bisphenol A (BPA). The structure and properties of the raw zeolites and the modified ones (labelled as T-Hβ (25, 50), T-HY (11), T-HZSM-5(50)) have been investigated comparatively by XRD, BET, SEM, XRF and contact angle test (CA). The results indicated that HY (11) and T-HY (11) had poor adsorption capacity for hydrophobic BPA because of destroyed crystalline phase of T-HY (11) and hydrophilic nature of HY (11). HZSM-5(50) and T-HZSM-5(50) also had poor adsorption ability for BPA molecules because larger BPA molecules cannot enter smaller pores of HZSM-5(50) and T-HZSM-5(50). However, the T-Hβ (25, 50) zeolites exhibited significantly higher adsorption capacity for BPA because their larger pore size remained than molecule size of BPA and larger water contact angles and molar ratios of SiO2/Al2O3 of T-Hβ (25, 50) than Hβ (25, 50), respectively. BPA removal mechanism study showed that hydrophobic interaction force between BPA and T-Hβ (25, 50) should be a main driving force. The adsorption process conformed to pseudo-second order model and the three-parameter Redlich-Peterson model. The adsorption rate of BPA over T-Hβ (50) (0.01050 ​g ​mg−1 ​min−1) was 2.29 times faster than that over Hβ (50) (0.004581 ​g ​mg−1 min−1), and the maximum adsorption capacity of BPA on T-Hβ (50) (117.62 ​mg ​g−1) was 3.5 times than that on Hβ (50) (33.78 ​mg ​g−1). The acid treatment-calcination method is feasible and appropriate for modification of Hβ in order to remove hydrophobic organic pollutants.

Ferritin is characterized by a shell-like structure and a reversible self-assembly property. In this study, atmospheric cold plasma (ACP) was applied to red bean seed ferritin (RBF) to prepare an ACP-treated RBF (ACPF). Results indicated that the ACP treatment retained the shell-like structure of ferritin but reduced the α-helix/β-sheet contents and thermal stability. Iron oxidative deposition and release activities were also markedly changed. The ACPF could be disassembled at pH 4.0 and then assembled into an intact ferritin cage when pH was increased to 7.0, which was a more benign transition condition than that of the traditional method (pH 2.0/7.0 transition). By using this assembly routine, curcumin was successfully encapsulated within the ACPF with a size distribution of 12 nm. Moreover, the encapsulation ratio of curcumin in the ACPF reached 12.7% (w/w). This finding can be used to expand the application of ACP and improve the functionalization of the ferritin.

Background: In the present study, we investigated the role of ornithine decarboxylase (ODC) in the methyl jasmonate (MeJA)-regulated postharvest quality maintenance of Agaricus bisporus (J. E. Kange) Imbach button mushrooms by pretreating mushrooms with a specific irreversible inhibitor called α-difluoromethylornithine (DFMO) before exposure to MeJA vapor.; Results: Mushrooms were treated with 0 or 100 µmol L-1 MeJA or a combination of 120 µmol L-1 DFMO and 100 µmol L-1 MeJA, respectively, before storage at 4 °C for 21 days. Treatment with MeJA alone induced the increase in ODC activity whereas this effect was greatly suppressed by pretreatment with DFMO. α-Difluoromethylornithine strongly attenuated the effect of MeJA on decreasing cap opening, slowing the decline rate of soluble protein and total sugar, and accumulating total phenolics and flavonoids. α-Difluoromethylornithine pretreatment also counteracted the ability of MeJA to inhibit polyphenol oxidase and lipoxygenase activities, and malondialdehyde production, and to stimulate superoxide dismutase and catalase activities. It also largely downregulated MeJA-induced accumulation of free putrescine (Put).; Conclusion: These results reveal that ODC is involved in MeJA-regulated postharvest quality retention of button mushrooms, and this involvement is likely to be associated with Put levels. © 2018 Society of Chemical Industry.; © 2018 Society of Chemical Industry.

The inner surface and outer surface of ferritin cage provide interfaces for the encapsulation and delivery of food nutrients. Traditional methods to fabricate ferritin-nutrients shell-core nanoparticle usually apply acid/alkaline pH transition, which may cause the activity loss of the food nutrients or the formation of insoluble aggregates. In attempt to tackle these limitations, a simple one-step method was utilized to prepare the red bean seed ferritin (RBF)-epigallocatechin (EGC)-chitosan nanoparticle (REC) by thermal treatment at 55 °C. Results indicated that the apoRBF was partially uncoiled with a decrease of 5.3% of α-helix content induced by 55 °C treatment, and the EGC molecules could spontaneously permeate into the inner cavity of the ferritin with an encapsulation ratio of 11.8% (w/w). Meanwhile, the thermal treatment facilitated the chitosan attaching onto the outer surface of the ferritin by electrostatic interactions with a binding constant of 4.7 × 105 M−1. Transmission electron microscope and dynamic light scattering results indicated that the REC was mono-dispersedly distributed, with a diameter of 12 nm and a hydrodynamic radius (RH) of 7.3 nm. In addition, the chitosan decorating onto the apoRBF improved the EGC stability by weakening the degradation of apoRBF against digestive enzymes in simulated gastrointestinal tract. This work is a novel attempt to fabricate shell-core nanoparticle in the encapsulation and delivery of functional molecules based on the ferritin cage in a benign condition without extreme pH changes.

Postharvest diseases result in major losses in fruits. Tomato is susceptible to postharvest rot caused by Botrytis cinerea and is regarded as a good model system to study postharvest disease and quality deterioration in fruit. To develop a safe and effective technique to alleviate disease and maintain fruit quality, the effects of methyl salicylate (MeSA) and 1-methylcyclopropene (1-MCP) either separately or combined on quality and gray mold caused by B. cinerea in tomato fruit were investigated.; Results: The results showed that application of MeSA (0.05 mmol L-1 ) delayed fruit ripening and reduced gray mold. Compared with MeSA treatment, 1-MCP (0.5 µL L-1 ) effectively delayed fruit ripening. Further, MeSA combined with 1-MCP treatment was more effective in inhibiting fungal decay during storage than MeSA treatment alone. The combined treatment not only enhanced pathogenesis-related protein 1 (PR1) expression, activities of defense enzymes and total phenolic content but also inhibited the increase in electrical conductivity and malondialdehyde content. The combined treatment was also more effective in retaining firmness, color change and titratable acidity content than MeSA treatment alone.; Conclusion: MeSA combined with 1-MCP treatment was a useful technique to maintain quality and alleviate gray mold in postharvest tomato fruit during storage. © 2018 Society of Chemical Industry.; © 2018 Society of Chemical Industry.

Ferritin is an iron-containing protein and functions in the maintenance of iron balance in organisms. Currently the interaction among ferritin, ion iron, and food bioactive compounds is still unclear. In this study, the mechanism underlying the interaction of ferritin, ion iron, and chlorogenic acid was investigated, as well as the effect of chlorogenic acid on the physicochemical properties of ferritin. The results showed that chlorogenic acid could interact with Fe(III) to form chlorogenic acid-Fe(III) complexes, which then bonded with ferritin via hydrogen bonds in the ferritin-chlorogenic acid-Fe(III) complexes. The chlorogenic acid showed a high efficiency in Fe(II) chelation and hydroxyl radical (•OH) capture, and could promote iron oxidation and iron release induced by ferritin. Chlorogenic acid could also effectively reduce the polymerization extent of ferritin induced by Fe(III) and Fe(II). This study elucidates the interactions of multiple components in foodstuffs by using a protein-metal-polyphenol model.

The antibacterial peptide mytichitin-CB has been highly expressed in Pichia pastoris. In this study, we aim to investigate its potential for application in pork preservation. P. pastoris-derived mytichitin-CB exhibited broad and potent antibacterial activity against four common foodborne bacterial pathogens and two food spoilage bacteria of Pseudomonas spp. with low minimal inhibition concentrations of 0.23–1.24 μg/mL. Mytichitin-CB effectively suppressed the growth of the microflora and significantly reduced the increases in pH, drip loss, total volatile basic nitrogen (TVB-N), and thiobarbituric acid reactive substances (TBARS) of fresh pork during storage at 4 °C. Consequently, the fresh pork maintained its desirable sensory properties. Mytichitin-CB could also effectively inhibit the growth of Staphylococcus aureus, Escherichia coli O157, and Pseudomonas fluorescens in a pork spoilage model. Combining mytichitin-CB with chitosan and nisin at the optimal proportion further enhanced the antibacterial activity and effects of food preservation on fresh pork, as evidenced by improved sensory properties, lowered drip loss and TVB-N production, and reduced change in pH during storage. However, combining these three agents failed to further increase antioxidant activity against lipid oxidation. Overall, the combination of 4 mg/L of mytichitin-CB with 10 g/L of chitosan incorporated with 300 mg/L of nisin exhibited the best performance in fresh pork preservation. The combined findings suggest that treatment with mytichitin-CB alone or in combination with chitosan and nisin has considerable potential in the preservation of fresh meat products to extend the shelf life and assure the quality and safety of meat.

The objective of this study was to determine the effects of low-concentration acidic electrolyzed water (LcEW) combined with ultrasound (US) on fresh-sliced button mushrooms (Agaricus bisporus), by evaluating the enzymatic browning, physio-biochemical changes, and microbial loads. The sliced button mushrooms were divided randomly into three groups (control, LcEW, and LcEW+US) and treated separately with tap water, LcEW, and LcEW+US for 3 min, and afterwards, they were stored at 5 °C for 8 days. The results indicated that LcEW delayed surface browning and maintained the flesh firmness of fresh-cut mushrooms compared with the control, and ultrasound enhanced these effects. Moreover, LcEW+US slowed down the electrolyte leakage (EL) rate and malondialdehyde (MDA) content, which were 5.29% and 0.5227 μmol/fresh weight less than those in control at day 8, respectively. The combined treatment of LcEW and US also significantly inhibited the activities of polyphenol oxidase (PPO) and peroxidase (POD) and controlled the counts of total bacteria (TBC) and yeast and mold counts (Y&M). Meanwhile, LcEW+US maintained a high level of total soluble protein and total phenolic contents, which were 1.49 and 1.24 times higher than those in control at the end of the storage time, respectively, and the combined treatment was more effective than LcEW treatment alone. These results demonstrated that the combination of LcEW and US could be an effective pretreatment technology in maintaining the product quality and prolonging the shelf life of fresh-sliced button mushrooms.

It has been demonstrated that Agaricus bisporus (J.E. Kange) Imbach fruit body exerts enhanced postharvest quality retention when treated with 100 μmol L −1 exogenous methyl jasmonate (MeJA) vapor. In this study, fruit bodies of A. bisporus were treated with 100 μmol L −1 MeJA vapor or the combination of 100 μmol L −1 MeJA and 20 μmol L −1 N ω -hydroxy-nor- l -arginine (nor-NOHA, an inhibitor of arginase), respectively, before they were stored for 21 d at 4 °C. Our data showed that treatment with MeJA alone indeed induced the increased transcription and activity of arginase whereas this effect was largely inhibited by pretreatment with nor-NOHA. In correspondence to this observation, nor-NOHA suppressed the ability of MeJA to decrease open caps and to down-regulate malondialdehyde (MDA) production and polyphenol oxidase (PPO) and lipoxygenase (LOX) activities. Biochemical analysis further demonstrated that nor-NOHA counteracted the MeJA in stimulating antioxidant enzyme activities of catalase (CAT) and superoxide dismutase (SOD) and accumulating total phenolics and flavonoids. In addition, the effect of MeJA in slowing the decline rate of soluble protein and total sugar contents was also partially impaired by nor-NOHA. Taken together, our findings firmly showed that arginase acts as an important regulatory factor in maintaining the MeJA-induced mushroom quality retention during postharvest storage.

The effects of l-arginine (Arg, 1 mM) and/or methyl salicylate (MeSA, 0.05 mM) treatment on gray mold caused by Botrytis cinerea in tomato fruit were studied. Results indicated that Arg or MeSA alleviated the incidence and severity of fruit disease caused by B. cinerea, and that both Arg and MeSA (Arg + MeSA) further inhibited the development of fruit decay. Treatment with Arg + MeSA not only enhanced the activities of superoxide dismutase, catalase, and peroxidase but also promoted the expression levels of pathogenesis-related protein 1 gene and the activities of defense-related enzymes of phenylalanine ammonia-lyase, polyphenol oxidase, β-1,3-glucanase, and chitinase during most of the storage periods, which were associated with lower disease incidence and disease index. In addition, the combined treatment elevated the levels of total phenolics, polyamines, especially putrescine, and nitric oxide. These observations suggest that treatment of fruit with Arg + MeSA is an effective and promising way to alleviate postharvest decays on a commercial scale.

Chlamydomonas reinhardtii offers a great promise for large-scale production of multiple recombinant proteins of pharmaceutical and industrial interest. However, the nuclear-encoding transgenes usually are expressed at a low level, which severely hampers the use of this alga in molecular farming. In this study, the promoter of the endogenous intraflagellar transport 25 (IFT25) gene of C. reinhardtii was tested for its ability to drive the expression of green fluorescent protein (GFP), which functions as a readout for target gene expression. IFT25 promoter (IFT25P) alone was not able to drive GFP expression to a detectable level. IFT25P, however, can drive robust IFT25-GFP fusion protein expression when the intron-containing IFT25 gene was inserted between IFT25P and GFP cDNA. When an extended version of foot-and-mouth virus 2A protease (2AE) sequence was further inserted between the intron-containing IFT25 gene and the GFP cDNA, discrete GFP protein was observed to release from the IFT25-2AE-GFP polyprotein via 2A self-cleaving with a cleavage efficacy of approximately 99%. The monomer GFP was accumulated to a level of as high as 0.68% of total soluble proteins. To test whether the newly developed bicistronic IFT25P-IFT25-2AE expression system can be used to overexpress heterologous proteins of different origins and sizes, we inserted codon-optimized cDNAs encoding a Trichoderma reesei xylanase1 (25 kDa) and a Lachnospiraceae bacterium ND2006 type V CRISPR-Cas protein LbCpf1 (147 kDa) to the vector and found that the production of xylanase1 and LbCpf1 was as high as 0.69 and 0.49% of total soluble protein. Our result showed that IFT25P-IFT25-2AE system is more efficient to drive nuclear gene expression in C. reinhardtii than other conventionally used promoters, thus representing a novel efficient recombinant protein expression tool and has the potential to be scaled for commercial production of nuclear-encoded recombinant proteins of different sizes and origins in C. reinhardtii.

The 8 nm diameter cavity endows the ferritin cage with a natural space to encapsulate food components. In this work, urea was explored as a novel medium to facilitate the formation of ferritin–polyphenol co-assemblies. Results indicated that urea (20 mM) could expand the 4-fold channel size of apo-red bean ferritin (apoRBF) with an increased initial iron release rate υ0 (0.22 ± 0.02 μM min–1) and decreased α-helix content (5.6%). Moreover, urea (20 mM) could facilitate the permeation of EGCG into the apoRBF without destroying the ferritin structure and thus form ferritin–EGCG co-assemblies (FECs) with an encapsulation ratio and loading capacity of 17.6 and 2.1% (w/w), respectively. TEM exhibited that FECs maintained a spherical morphology with a 12 nm diameter in size. Fluorescence analysis showed that urea intervention could improve the binding constant K [(1.22 ± 0.8) × 104 M–1] of EGCG to apoRBF. Furthermore, the EGCG thermal stability was significantly improved (20–60 °C) compared with free EGCG. Addi...

Rice bran albumin protein (RAP) is sensitive to thermal changes and tends to degrade when exposed to high-temperature processing. In this work, RAP–epigallocatechin-3-gallate (EGCG) complex (RAPE) was prepared and the thermal stability was evaluated. Fluorescence results showed that EGCG could interact with RAP with a binding number n of 0.0885:1 (EGCG:RAP, w/w) and a binding constant Kof 1.02 (± 0.002) ×104/M, suggesting both hydrogen bonding and van der Waals forces played an important role. FTIR analysis demonstrated that EGCG could induce secondary structural changes in RAP above a ratio of 1.6:1 (EGCG:RAP, w/w). Interestingly, the secondary structure changes of RAPE at different temperatures (25, 50, 60, 70, and 80 °C) were inhibited compared with that for RAP, suggesting RAPE was more resistant and stable to the heat treatment. In addition, a dense porous structure of RAPE was achieved due to the EGCG binding after thermal treatment. Furthermore, the Tpeaktemperature of RAPE increased significantly from 64.58 to 74.16 °C and the enthalpy also increased from 85.53 to 138.52 J/g with a mass ratio increasing from 0 to 3.2 (EGCG:RAP, w/w), demonstrating the thermal stability of RAPE. In addition, the valine, methionine, and lysine content in RAPE were significantly higher than RAP following 80 °C treatment for 20 min (P< 0.05), exhibiting enhanced amino acid profiles, which might be due to EGCG–RAP interactions and microenvironment changes around relevant amino acids. These findings demonstrate that EGCG has the potential to improve the thermal stability of sensitive proteins and is beneficial for usage in the food industry. Rice bran albumin protein can be combined with the tea polyphenol-EGCG to achieve an improved thermal stability and amino acid profile. Therefore, tea polyphenols have potential usage in food resource protein stabilization during food processing.

The low solubility, instability, and low bioavailability of food bioactive compounds such as polyphenols and flavonoids, restrict their applications in the fields of food science and nutrition. Ferritin protein has received more and more attention in encapsulation and delivery of the bioactive compounds due to its nanosized shell-like structure and its reversible self-assembly character. After encapsulation, bioactive compounds can be functionalized by the ferritin vehicle to achieve stabilization, solubilization, and targeted delivery. In addition, the outer interfaces and the porous structure of ferritin are also artfully harnessed for encapsulation. This review focuses on the newest advances in the fabrication, characterization, and application of ferritin-based nano-carriers for bioactive compounds by the reversible self-assembly, outer-interface decoration methods, and the channel-directed approach. The functional improvements of food bioactive compounds, including their solubility, stability, and cellular uptake, are emphasized. The limitations that affect ferritin encapsulation are also examined.

Postharvest browning is the primary cause of a decrease in the shelf life of the white button mushroom (Agaricus bisporus). This study investigated the effect of postharvest brassinolide (BL) treatment on metabolism in relation to browning of the white button mushroom. Each harvested mushroom was dipped into one of three solutions containing 0, 1, or 3 μM BL for 5 min and stored in darkness at 4 °C for 16 days. Our results indicated that treatment with BL restrains browning development and reduces the total phenolic content and polyphenol oxidase activity. In addition, BL treatment maintains lower weight loss, electrolyte leakage, and malondialdehyde content and inhibits any increase in lipoxygenase activity compared with those of the control mushrooms. Furthermore, BL treatment significantly decreases the accumulation of reactive oxygen species (ROS) and induces the antioxidant enzyme system. Compared with 1 μM BL, treatment with 3 μM BL is more effective in reducing cap browning. The reduction of membrane oxidative damage and ROS levels induced by BL inhibits enzymatic browning reaction in the white button mushroom. These findings suggest that treatment with BL could have the potential of inhibiting browning and thus maintaining the mushroom’s commercial value.