Water-soluble Pectin Research Articles

Indole-3-acetic acid treatment promotes postharvest kiwifruit softening by regulating starch and cell wall metabolism

The softening process of postharvest kiwifruit is a critical aspect of fruit quality that has been extensively studied. However, the impact of indole-3-acetic acid (IAA) treatment on this process remains largely unexplored. In this study, we examined the effect of IAA treatment on the softening of postharvest kiwifruit. The results depicted that kiwifruit treated with IAA exhibited decreased firmness and increased ethylene production. Treatment with IAA upregulated the expression of starch decomposition genes, including AcSEX and AcBAM, resulting in a reduction in starch content. Additionally, IAA treatment induced cell wall breakdown, attributed to the enhanced transcript levels of cell wall-related degradation genes such as AcPE, AcPG, AcPL, and AcCX compared to the control. Consequently, IAA-treated kiwifruit displayed lower levels of cellulose and protopectin but higher levels of water-soluble pectin. In summary, our findings indicate that exogenous IAA promoted postharvest starch and cell wall biodegradation in kiwifruit, which reduced fruit firmness and accelerated fruit softening.

Elucidation of pineapple softening based on cell wall polysaccharides degradation during storage

The degradation of cell wall polysaccharides in pineapple fruit during softening was investigated in the present study. Two pectin fractions and two hemicellulose fractions were extracted from the cell wall materials of ‘Comte de Paris’ pineapple fruit at five softening stages, and their compositional changes were subsequently analyzed. The process of softening of the fruit corresponded to an increase in the water-soluble pectin (WSP) and 1 M KOH-soluble hemicellulose (HC1) fractions, and a decrease in the acid-soluble pectin (ASP) fraction, which suggested the solubilization and conversion of cellular wall components. However, the content of 4 M KOH-soluble hemicellulose (HC2) decreased and then returned to the initial level. Furthermore, WSP, ASP, and HC1 showed an increment in the content of low molecular weight polymers while a decline in the high molecular weight polymers throughout softening, and not significant change in the contents of different molecular polymers of HC2 was observed. Moreover, the galacturonic acid (GalA) content in the main chain of WSP was maintained at a relatively constant level, but the major branch monosaccharide galactose (Gal) in WSP decreased. Different from WSP, the molar percentages of Gal and GalA in ASP decreased. The Gal or Arabinose (Ara) in HC1 exhibited a gradual decline while the molar percentages of xylose (Xyl) and glucose (Glu) in the main chain increased. These suggested that the main chain of ASP degraded while the branched chains of ASP, WSP and HC1 depolymerized during pineapple softening. Overall, fruit softening of ‘Comte de Paris’ pineapple was found to be the result of differential modification of pectin and hemicellulose.

Development and evaluation of a precision heat treatment device for delaying postharvest softening of muskmelon

To extend the limited commercial storage of muskmelons due to insufficient shelf life, a heat treatment device with precise temperature control was designed and applied to three muskmelon varieties: "Xizhou Mi 25" (XZM), "Jinmi 3" (JM), and "Jiashi" (JS). The effectiveness of this device and the effect of heat treatment on the softening of muskmelons during storage were evaluated. The results indicated no significant difference between the temperatures set by the control system and the actual measured temperatures (p > 0.05), demonstrating the high accuracy of the temperature control system. After optimization of the heat treatment device, no thermal damage was observed in the heat-treated group of muskmelons. The energy consumption of the heat treatment device was only half that of the insulated tank. By the 18th day of storage, the protopectin (PP) content in the heat-treated group was significantly lower than in the control group. Correlation analysis showed that hardness was positively correlated with PP content and negatively correlated with water-soluble pectin (WSP). Additionally, cell wall metabolism-related enzyme activities were negatively correlated with PP content. These results indicated that the heat treatment effectively delayed muskmelon softening during postharvest storage. This study provides technical support for the industrial application of heat treatment devices in muskmelon preservation.

H2O2-mediated cell wall remodeling and pectin demethylesterification are involved in maintaining postharvest texture of table grape by sulfur dioxide

Berry texture affects consumer acceptance and postharvest shelf life of table grapes. This study elucidates how sulfur dioxide (SO2) treatment maintains grape texture quality, focusing on the role of hydrogen peroxide (H2O2)-mediated cell wall modifications. SO2 treatment exhibited effects similar to those of H2O2 treatment, resulting in firmer berries with more intact cell wall structures, higher contents of chelate-soluble pectin, sodium carbonate-soluble pectin, hemicellulose, and cellulose, with lower levels of water-soluble pectin compared to untreated fruit. Moreover, it delays pectin nanostructure disassembly and reduces degree of pectin methylesterification, which facilitates the formation of calcium bridges between demethylesterified pectin and increased calcium ions, thereby strengthening the cell wall and weakening enzymatic pectin degradation. Conversely, combining ROS generation inhibitors with SO2 mitigated these effects. Overall, these findings highlight the role of H2O2-mediated cell wall modification in maintaining grape postharvest texture through SO2 treatment, providing new insights for managing grape postharvest softening.

Physiological and Microstructure Analysis Reveals the Mechanism by Which Formic Acid Delays Postharvest Physiological Deterioration of Cassava.

Formic acid is reported to act as a food preservative and feed additive, but its effects on controlling postharvest physiological deterioration (PPD) development in cassava are unclear. In this study, we assessed the effectiveness of different concentrations of formic acid in attenuating PPD occurrence in fresh-cut cassava. The results showed that the concentration of 0.1% (v/v) formic acid could significantly delay the occurrence of PPD, and that the higher the concentration of formic acid supplied, the later the occurrence of PPD symptoms. The physiological and biochemical analysis of 0.5%-formic-acid-treated cassava slices revealed that formic acid decreased the degradation of starch, inhibited the accumulation of hydrogen peroxide (H2O2), malondialdehyde (MDA), and water-soluble pectin in cassava slices with PPD development, and increased the activities of the antioxidant enzymes ascorbate peroxidase (APX) and glutathione reductase (GR). A microscopic observation showed that the formic acid treatment inhibited the enlargement of the intercellular space during the cassava PPD process, which suggests that the formation of an intercellular layer of the cell wall was inhibited by formic acid. This study thus revealed the mechanism used by formic acid to extend the cassava shelf life; however, a detailed evaluation of the possible side effects on, for example, the cyanide content will be needed to categorically ensure the safety of this method.

Impacts of Fruit Frosting Coverage on Postharvest Softening of Prunes under Vibration Stress

The surface of prune fruit has a thick layer of frosting, which is easily damaged and lost during prunes harvest or postharvest handling, and there is no clear information on the effect of prune surface frost on postharvest storage quality. To investigate the effect of fruit frosting on the softening of prune fruits during storage under vibration stress, prunes were divided into three grades according to fruit frosting in this study and were vibrated for 8 h at a frequency of 5 Hz at 4 °C; then, samples were selected once every 8 d. The results showed that the heavy fruit frosting (HFF) group maintained higher hardness (21.47%), L* (20.85%), and total soluble solids (12.79%) levels at the end of storage and inhibited cell wall-modifying enzyme activities (polygalacturonase, pectin methylesterase, glycosidase, β-glucosidase, and cellulase) compared to frosting-less fruit (FF) group. This group also showed improved expression of key cell wall-modification genes (ADPG2, PME31, CESA1, BGAL3, XTH33, BGLU41) as well as chelate-soluble pectin (72.11%), Na2CO3-soluble pectin (42.83%), and cellulose (36.89%) solubilization and maintained lower water-soluble pectin (34.23%). Microscopic observations showed that the fruit frosting could delay the dissolution of pectin components and protect the cell wall structure. In summary, fruit frosting can effectively inhibit fruit softening and maintain fruit quality.

Изменение состава пектиновых веществ при замораживании и хранении растительной продукции

To keep up with the growing demand, producers of frozen plant products have to develop new freezing technologies that would preserve the sensory and biological properties of fruits and vegetables. Pectins are important structural and moisturebinding components of plant cells that improve their stability at high and low temperatures. The research objective was to study the effect of blanching and various freezing methods on the composition of pectin substances during long-term storage of fruits and vegetables. The research featured scorzonera, salsify, kohlrabi, apples, and plums. The freezing modes included two temperature modes (–24 and –35°C) and three freezing methods, i.e., blanching, air-freezing represented by natural air-freezing, artificial convection, and fluidization, and immersion in a mix of water, ethyl alcohol, sucrose, and sodium chloride. The frozen samples were stored in sealed bags at –18°C for 7–12 months. The water-soluble pectin, intermediate fraction, and protopectin obtained by extraction were determined using the colorimetric carbazole method. The qu alitative analysis relied on infrared spectroscopy. Blanching reduced the pectin content by 2–10% in vegetables and by 18–21% in apples. Fluidization and immersion freezing had the least damaging effect on pectins. Air-freezing with natural convection caused the greatest damage to protopectin. During storage, the maximal loss of pectins (66%) occurred in the salsify sample subjected to natural air convection at –24°C. The least damage (9%) was detected in the kohlrabi sample frozen at –24°C in ice environment. A higher moisture content in the native state correlated with minimal losses of pectins by the end of refrigerated storage. The research also included identification of absorption bands for pectic substances in fro zen scorzonera and salsify. In this study, pectin content depended on moisture content in tissues, blanching process, and freezing method. All frozen samples demonstrated losses of protopectin and an increase in the intermediate fraction. An intense freezing process had a positive effect on the pectin content during long-term storage. However, after six months of storage, the samples demonstrated significant fractional changes and pectin losses.

Sequential extraction of hawthorn pectin: An attempt to reveal their original mode of being in plants and functional properties

Hawthorn is rich in pectin, which is much higher than most cultivated fruits, but conventional extraction methods do not meet the requirements of low energy consumption and green production. Pectin in hawthorn is divided into soluble and insoluble parts, and with the ripening of hawthorn, the original pectin is converted into soluble pectin and pectic acid under the action of enzymes. Therefore, based on the characteristics of hawthorn pectin, this study sequentially extracted hawthorn pectin using water-soluble pectin (WSP) and hot acid-soluble pectin (HAP) method, verifying the feasibility of extracting hawthorn pectin with pure water at room temperature, and systematically analyzing and comparing the physicochemical properties and functional characteristics of the two methods. The combination of texture analysis and gel rheology revealed that WSP formed a more uniform and dense network structure during the gelation process. Additionally, microscopic observations and emulsification index results indicated that the emulsion prepared with WSP (WSE) had a smaller particle size and better stability. This indicates that hawthorn pectin is suitable for extraction with pure water at room temperature, which can maintain its good physical properties while reducing energy consumption, providing a new approach for the large-scale extraction of pectin in the food industry.

Structure formation mechanism of pectin-soy protein isolate gels: Unraveling the role of peach pectin fractions.

This study investigated the macro & micro properties of the composite gels formed by soy protein isolate (SPI) and peach pectin fractions: water-soluble pectin (WSP), chelator-soluble pectin (CSP), and sodium carbonate soluble pectin (NSP). Specially, the interaction between pectin fractions and SPI was studied to explain the formation mechanism of the composite gels. WSP, as a high methoxyl pectin, exhibited rich branching (sugar ratio B=3.10). CSP, as a low methoxyl pectin, depicted a high linearity. NSP, with low linearity (sugar ratio A=6.14), contained numerous side chains. Due to the strong interaction between pectin fractions and SPI, the new composites with excellent dense network microstructures were formed, accompanied by increased apparent viscosity, higher G' and G'', and reduced particle size. XRD and FT-IR analysis highlighted the modifications in gel structures. SEM-dispersive X-ray spectroscopy observed elemental distribution and framework composition in pectin-SPI gels. Hydrophobic interaction was the most important chemical force in pectin-SPI binding. Molecular docking results indicated that galacturonic acid in pectin bound more strongly to 7S than to 11S, with tighter hydrogen bonds. Notably, WSP-SPI showed the lowest turbidity, indicating enhanced solubility and particle dispersion, which helped prevent aggregation. CSP-SPI demonstrated the highest G' and G'', ascribing to the high linearity and abundant carboxyl groups in CSP. NSP-SPI showed the highest apparent viscosity and irregular structure. Overall, the texture properties of pectin-SPI gels were driven by pectin's structure properties, which would provide new and valuable information for texture control in gel formulation.

Improving hawthorn fruit pulp processing and quality through optimized freeze-thaw cycles

Hawthorn fruit is firm, making it difficult to process into fruit pulp. To improve the processing suitability of hawthorn fruit pulp, one, two, and three freeze-thaw cycles (FTCs, frozen at −18 °C for 24 h, then thawed at 5 °C or 25° C for 6 h) were performed on hawthorn fruit in this study. Using unfrozen specimens as the controls, the study assessed fruit softening characteristics and rheological properties, taste traits, and nutritional components of the fruit pulp. Freeze-thaw treatments decreased fruit firmness and cell-wall stability, increased juice yield during pulp processing, and reduced the viscosity, sourness, and astringency of hawthorn fruit pulp, likely by enhancing pectin solubility. The treatment effect was influenced by both FTC number and thawing temperature. Two FTCs with a thawing temperature of 5 °C were most effective, promoting the transformation of protopectin into water-soluble pectin (WSP) to the fullest extent. The treatment reduced firmness to about 25 % of the initial value, increased juice yield by about 22 %, increased the sugar-acid ratio to 11.6, and reduced the sourness and astringency of the fruit pulp. It increased the contents of total flavones and anthocyanidins without affecting the contents of vitamin C. Therefore, the use of two FTCs with a thawing temperature of 5 °C can facilitate the preparation of hawthorn fruit pulp while preserving its nutritional properties and improving its taste profile.

Effects of Changes in Pectin Constitution on Optical Properties and Firmness of Peach Flesh during Storage.

Understanding the fundamental light-sample interaction process is a crucial step toward the development of vibrational spectroscopy to determine fruit texture (i.e., firmness). This study aimed to investigate the effect of pectin constitution, including total pectin, water-soluble pectin, protopectin contents, and protopectin index (PI), on the optical properties and firmness of 'Baifeng' and 'Xiahui 8' peach flesh at the different softening degrees during postharvest storage of 6 days at 20 °C. The firmness of 'Baifeng' and 'Xiahui 8' peaches significantly (p < 0.05) changed with a decreasing rate from 90.3% to 92.2%. Peach firmness of these two cultivars correlated well with PI contents (r > 0.912) and showed good internal correlations with optical scattering properties. The light absorption coefficient (μa) and reduced scattering coefficient (μ's) at 600-1600 nm were measured using a single integrating sphere system combined with an inversion algorithm. This relationship of μa and μ's with peach firmness and pectin constitution was first analyzed. Notably, the specific μ's at 660 nm, 950 nm, 1203 nm, and 1453 nm showed a satisfactory prediction of peach firmness and PI of 'Xiahui 8' (R2 ≥ 0.926) and 'Baifeng' peaches (R2 ≥ 0.764), respectively. Furthermore, the prediction models were established based on partial least squares regression coupled with optical properties, and considerable prediction performances were obtained for tissue firmness (Rp2 ≥ 0.863) and PI based on μ's (Rp2 ≥ 0.802). Consequently, these results further verified that the spectroscopic prediction model for peach firmness could be related to the high correlations between PI in tissues and their optical scattering properties. Future research interests could include the development of optical absorption and scattering sensors for rapid and efficient determination of peach firmness.

Effect of magnetic field treatment on the softening of green chilies (Capsicum annuum L.) during storage

In this study, effects of magnetic field treatment on the softening of green chilies during storage (0–30 d at 10 °C) were investigated, and the cell wall polysaccharide content, modifying enzyme activities, water distribution, and cell wall structure were determined. After 30 d of storage, the weight loss of the green chilies in conventional refrigeration (CR) group reached 35.40 %, whereas it was 20.96 % and 29.85 % in the static (SMF; 4 mT) and alternating magnetic field (AMF; 4 mT, 1 Hz) groups, respectively. Furthermore, magnetic field treatment maintained low levels of water-soluble pectin (WSP) and high levels of chelate-soluble pectin (CSP) and sodium carbonate-soluble pectin (NSP) in the green chilies. The degree of methylation (DE) values of WSP and NSP in the pre-treated samples were 0.37 and 0.18, respectively. Conversely, at the end of storage, the DE values of WSP and NSP in the CR, SMF, and AMF groups decreased to 0.12 and 0.05, 0.25 and 0.11, and 0.18 and 0.07, respectively, suggesting that magnetic field treatment had a negative influence on the demethylation of pectin. Magnetic field treatment also decreased the activities of pectin methyl esterase, polygalacturonase, and β-galactosidase in the green chilies, maintaining them at a low level. The magnetic field treatment resulted in a higher free water content in green chilies compared to the CR, exceeding the CR group’s content by 1.79 % and reaching 88.18 % at the terminal storage. Scanning electron microscopy results revealed that magnetic field treatment maintained the structural integrity of the cell wall in the green chilies. The results of this study confirmed the applicability of magnetic field treatment in maintaining the firmness and reducing the weight loss of the green chilies, thus prolonging their shelf life.

Extraction of cell wall pectins and hemicellulose from agro-industrial wastes: A sustainable alternative source

The efficient repurposing of agro-industrial waste has significantly enhanced the utilization of food resources. This study aims to propose a methodology for extracting cell wall polysaccharides from residues of mango (Mangifera indica), passion fruit (Passiflora edulis), and cashew (Anacardium occidentale). Polysaccharide fractions were obtained through sequential extraction protocols involving water, cyclohexane-trans-1,2-diamine tetracetate (CDTA), sodium carbonate:CDTA, and potassium hydroxide. These fractions were categorized as water-soluble pectin (WSP), CDTA-soluble pectin (CSP), sodium carbonate-soluble pectin (SSP), and hemicellulose (HC), respectively. Each polysaccharide fraction was characterized by Nuclear Magnetic Resonance (NMR) spectroscopy and Gel Permeation Chromatography (GPC). Monosaccharide composition was determined using Gas Chromatography-Mass Spectrometry (GC–MS). NMR spectra of WSP, CSP, and SSP fractions exhibited characteristic pectin features, while the HC fraction primarily comprised hemicellulose. Consequently, the proposed methodology demonstrates potential as a standardized protocol for the extraction of pectin and hemicellulose from various food sources.

Predictions of apple mechanical damage volume using micro-CT measurements and support vector regression(SVR)

Accurately calculating the damage volume and making clear the interconnected effects of the physical and chemical properties of apples on mechanical damage are crucial steps in reducing the possibility of apple damage. Tests have been conducted on apples at different maturity levels, including measuring the firmness, moisture content, water-soluble pectin (WSP) content, soluble solids content (SSC) of the flesh, and elastic modulus of the apple flesh and peel. Transient collisions were performed using a pendulum device to create damage zones under specific impact energies. Then, the X-ray micro-computed tomography (Micro-CT) was utilized to quantitatively analyse mechanical damage volumes, the effects of apple tissue characteristics and impact energy on the damage volume were analysed in detail. The results indicated that higher-maturity apples were more susceptible to mechanical damage, and Micro-CT measurements were more accurate when the impact energy ≥ 0.05 J, while the empirical formula showed greater deviation; the curvature radius at the impact point can be considered as a latent variable influencing the apple damage volume. Furthermore, a damage volume prediction model, based on bruise area calculated by the empirical formula, WSP content of the flesh, and elastic modulus of the apple flesh and peel, was established. With a testing dataset without anticipate in model training for verification, the developed model achieved a coefficient of determination of 0.9782, indicating that the model can predict damage volume effectively and reduce errors associated with the empirical formula, particularly at higher impact energies. The research can provide insights into potential applications in apple industry practices to reduce the mechanical damage.

Structural analysis and biological activity of cell wall polysaccharides and enzyme-extracted polysaccharides from pomelo (Citrus maxima (Burm.) Merr.)

Pomelo peel is a valuable source of pectin, but research on its cell wall polysaccharides is limited. This study compared the cell wall polysaccharides of pomelo peel, enzyme-extracted polysaccharides of pomelo peel, and enzyme-extracted polysaccharides of whole pomelo fruit. Cell wall polysaccharides, including water-soluble pectin (WSP), chelator-soluble pectin (CSP), sodium carbonate-soluble pectin (NSP), 1 mol/L KOH soluble hemicellulose (KSH-1), and 4 mol/L KOH soluble hemicellulose (KSH-2), were obtained by sequence-extraction method. Total polysaccharides from whole pomelo fruit (TP) and peel-polysaccharides from pomelo pericarps (PP) were obtained using enzyme-extraction method. The structural, thermal, rheological, antioxidant properties, and wound healing effect in vitro were described for each polysaccharide. WSP had a uniform molecular weight distribution and high uronic acid (UA) content, suitable for commercial pectin. NSP had the highest Rhamnose (Rha)/UA ratio and a rich side chain with highest viscosity and water retention. PP displayed the highest DPPH radical scavenging activity and reducing capacity at 0.1 to 2.0 mg/mL concentration range, with an IC50 of 1.05 mg/mL for DPPH free radicals. NSP also demonstrated the highest hydroxyl radical scavenging activity and promoted Human dermal keratinocyte proliferation and migration at 10 μg/mL, suggesting potential applications in daily chemical and pharmaceutical industries.

Preharvest methyl jasmonate application delays cell wall degradation and upregulates phenolic metabolism and antioxidant activities in cold stored raspberries

The effects of preharvest methyl jasmonate (MeJA) spray application on the physicochemical quality, metabolism of phenolics, and cell wall components in raspberries were investigated during a 10-day cold storage period. MeJA spray reduced firmness loss, decay incidence, and weight loss, while maintained higher levels of soluble solids content, ascorbic acid, anthocyanins and flavonoids in raspberries. Furthermore, MeJA application resulted in increased total pectin and protopectin levels, as well as lowered water-soluble pectin, and activities of pectin methyl esterase, polygalacturonase and cellulase enzymes. Additionally, MeJA treatment upregulated the phenylpropanoid pathway, leading to higher endogenous phenolics and activities of phenylalanine-ammonia lyase and shikimate dehydrogenase. In conclusion, preharvest MeJA spray application could be adopted to enhance the storage potential of cold-stored raspberries for 10 days by maintaining higher firmness, assuring better physicochemical quality, and increasing phenolic metabolism, while reducing cell wall hydrolysis.

MdWRKY31-MdNAC7 regulatory network: orchestrating fruit softening by modulating cell wall-modifying enzyme MdXTH2 in response to ethylene signalling.

Softening in fruit adversely impacts their edible quality and commercial value, leading to substantial economic losses during fruit ripening, long-term storage, long-distance transportation, and marketing. As the apple fruit demonstrates climacteric respiration, its firmness decreases with increasing ethylene release rate during fruit ripening and postharvest storage. However, the molecular mechanisms underlying ethylene-mediated regulation of fruit softening in apple remain poorly understood. In this study, we identified a WRKY transcription factor (TF) MdWRKY31, which is repressed by ethylene treatment. Using transgenic approaches, we found that overexpression of MdWRKY31 delays softening by negatively regulating xyloglucan endotransglucosylase/hydrolases 2 (MdXTH2) expression. Yeast one-hybrid (Y1H), electrophoretic mobility shift (EMSA), and dual-luciferase assays further suggested that MdWRKY31 directly binds to the MdXTH2 promoter via a W-box element and represses its transcription. Transient overexpression of ethylene-induced MdNAC7, a NAC TF, in apple fruit promoted softening by decreasing cellulose content and increasing water-soluble pectin content in fruit. MdNAC7 interacted with MdWRKY31 to form a protein complex, and their interaction decreased the transcriptional repression of MdWRKY31 on MdXTH2. Furthermore, MdNAC7 does not directly regulate MdXTH2 expression, but the protein complex formed with MdWRKY31 hinders MdWRKY31 from binding to the promoter of MdXTH2. Our findings underscore the significance of the regulatory complex NAC7-WRKY31 in ethylene-responsive signalling, connecting the ethylene signal to XTH2 expression to promote fruit softening. This sheds light on the intricate mechanisms governing apple fruit firmness and opens avenues for enhancing fruit quality and reducing economic losses associated with softening.

New insights into the relationship between optical response and physicochemical properties in apple flesh: Hyperspectral microscope imaging technology

Hyperspectral microscope imaging (HMI) technique was employed to assess the changes in physicochemical parameters and microstructure of ‘Golden Delicious’ apples flesh during storage. Four regions of interest (ROIs), including whole-cell ROI, intercellular space ROI, cytoplasm ROI, and cell wall ROI were investigated to assess their relationships with physicochemical parameters. Different ROIs presented similar vibrational profiles, but with slight differences in spectral intensity, especially in the range of 800–1000 nm. Spectral angle mapper (SAM) was applied to the HMI of apple tissues at different storage stages to clearly show the structural changes of parenchyma cells, while principal component analysis (PCA) could highlight the distribution of sugars, water and pigments in apple flesh at the cellular scale. Simultaneously with the degradation of acid-soluble pectin (ASP), middle lamella dissolution and increased intercellular space were observed using SEM and TEM. Single feature variables were used to construct linear models based on pearson correlation analysis, with R2 of 0.96 for moisture at 982 nm, 0.85 for water-soluble pectin (WSP) at 420 nm, 0.82 for L* at 946 nm, 0.77 for soluble solids content (SSC) at 484 nm, and 0.66 for firmness at 490 nm. This work demonstrated the great potential of HMI technology as a fast, accurate and efficient solution for assessing the quality of ‘Golden Delicious’ apples.

Detection of cell membrane disruption using electrical impedance spectroscopy and acceleration of cell wall modification in carrot processed under low temperature blanching

In this study, we evaluated relationships between cell membrane damage and cell wall modification in carrots by low temperature blanching. Electrical impedance analysis was carried out to elucidate the tissue condition during low temperature blanching. The obtained parameters suggested that cell membrane disruption and electrolyte outflow was promoted by low temperature blanching at 60 °C than that at 50 °C. Low temperature blanching at 60 °C for 40 min showed greater softening inhibition than that at 50 °C. Meanwhile, the activity of pectin methylesterase at 60 °C was lower than that at 50 °C. Regarding cell wall condition, increased insoluble pectin and decreased water-soluble pectin were confirmed at 60 °C rather than that at 50 °C. To conclude, cell membrane disruption is assumed to trigger cell wall modification by exposing the cell wall and middle lamella to intracellular ions.

Mitigating citrus fruit cracking: the efficacy of chelated calcium or silicon foliar fertilizers in 'Okitsu no. 58' citrus fruit.

The 'Okitsu No. 58' citrus variety is highly prone to fruit cracking, which jeopardizes yield and results in economic losses. In this study, we investigated the impacts of spraying 5 distinct concentrations (0.1, 0.2, 0.3, 0.4, and 0.5 g/L) of chelated calcium (Ca) or silicon (Si) fertilizers at the young fruit stage (60-90 days after flowering, DAF) on fruit cracking and quality in the citrus variety 'Okitsu No. 58'. The results showed either Ca or Si fertilizer treatments reduced fruit cracking. We found that all Ca and partial Si treatments (0.4 and 0.5 g/L) significantly promoted the accumulation of Ca content in the peel. Notably, Ca or Si treatments significantly reduced polygalacturonase (PG) activity and inhibited the production of water-soluble pectin (WSP) in the peel. Additionally, Ca or Si treatments elevated the superoxide dismutase (SOD) activity and decreased the malondialdehyde (MDA) content of the peels. Changes in these parameters likely contributed to strengthening the durability of peel cell wall constituents, thus enhancing the fruit's resistance to fruit cracking. Overall, except for the C3 (0.3 g/L of Ca), Ca or Si fertilizers contributed to fruit conventional quality, mainly in terms of higher soluble sugars (SS) and SS/TA (titratable acid). Therefore, our findings will provide a reference for the prevention and control of citrus fruit cracking and the development of new fertilizers.