Peach Flesh Research Articles

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.

Study on visualization of impact damage characteristics of honey peaches based on finite element method.

The study of visualization of impact damage of fruit under different thicknesses of buffer materials can provide more efficient transportation and packaging solutions, and thus the economic losses caused by fruit damage can be reduced. Pearl cotton (EPE) is commonly used as a buffer material in the market, and the impact damage behavior of honey peaches under different thicknesses of EPE buffer material was studied by using the finite element method. Firstly, the damage area, maximum contact force and damage volume during the collision of honey peaches with EPE materials of different thicknesses (2, 4, and 6mm) were obtained by the single pendulum device, and then the Modulus of elasticity and Poisson's ratio of peach flesh were obtained by compression test. Finally, the finite element model of honey peach was built and the collision simulations were performed. The results of the study showed that the values of mechanical parameters of honey peach decreased with the increase of the thickness of the buffer material. When the collision angle was below 60°, the honey peaches were not damaged in the collision with the EPE material with a thickness of 4mm or more. By comparing the tested values with the simulated values, it was found that the errors of the damage area, damage volume and maximum contact force were less than 19.71%, 26.82%, and 25.88%, respectively. The study not only proves the possibility of the finite element method in the quantitative prediction of honey peaches damage but also provides rational support for the packaging design of honey peaches.

Quantitative lipidomics reveals lipid differences among peach (Prunus persica L. Batsch) fruits with varying textures

In this study, we aimed to identify potentially different lipids in ripe peaches with different textures through a comprehensive, quantitative lipidomic analysis using LC-MS/MS. By analyzing 27 different cultivars, we detected 282 lipid species across 23 subclasses, including 118 significantly different lipids (DLs) among the different fruit texture groups. Lipids primarily consist of fatty acyls, followed by glycerophospholipids, glycerolipids, sphingolipids, and sterol lipids. PCA and OPLS-DA analyses demonstrated that peach fruit lipids differed significantly depending on flesh texture. Four phosphatidylethanolamines, three phosphatidylcholines, one lysophosphatidylethanolamine, one sterol ester, one sterol glycoside, and four ceramides were highly correlated with peach flesh firmness, crispness, and compactness. Glycerolipid and glycerophospholipid metabolism are the most prominent metabolic pathways for DLs, followed by sphingolipid and inositol phosphate metabolism. Our study helps identify novel targets for fruit texture improvement and provides new perspectives on the regulation of peach storage and transportation quality.

Metabolic Response of Peach Fruit to Invasive Brown Marmorated Stink Bug (Halyomorpha halys Stål.)'s Infestation.

The brown marmorated stink bug (BMSB; Halyomorpha halys Stål.) is a highly destructive and polyphagous invasive pest that poses a serious threat to more than a hundred reported host plants. In the current study, the metabolic response of peach fruit of two cultivars-'Maria Marta' and 'Redhaven'-to BMSB infestation was studied using high-performance liquid chromatography (HPLC) and mass spectrometry (MS). In general, a strong phenolic response to BMSB infestation in peach flesh in the injury zone was observed, with flavanol content increasing by 2.4-fold, hydroxycinnamic acid content by 5.0-fold, flavonol content by 3.2-fold, flavanone content by 11.3-fold, and dihydrochalcones content by 3.2-fold compared with the undamaged tissue in the cultivar 'Maria Marta'. The phenolic response in the 'Redhaven' cultivar was even stronger. Consequently, the total phenolic content in the injured flesh also increased, 3.3-fold in 'Maria Marta' and 6.9-fold in 'Redhaven', compared with the uninjured flesh. Infestation with BMSB induced the synthesis of cyanidin-3-glucoside, which is not normally present in peach flesh. In comparison, the phenolic response was lower in peach peel, especially in the cultivar 'Maria Marta'. The study showed that both peach cultivars reacted to BMSB infestation with an increase in phenolic content in the peach flesh, but in a limited area of injury.

Integrated analysis of HSP20 genes in the developing flesh of peach: identification, expression profiling, and subcellular localization

BackgroundPlant HSP20s are not only synthesized in response to heat stress but are also involved in plant biotic and abiotic stress resistance, normal metabolism, development, differentiation, survival, ripening, and death. Thus, HSP20 family genes play very important and diverse roles in plants. To our knowledge, HSP20 family genes in peach have not yet been characterized in detail, and little is known about their possible function in the development of red flesh in peach.ResultsIn total, 44 PpHSP20 members were identified in the peach genome in this study. Forty-four PpHSP20s were classified into 10 subfamilies, CI, CII, CIII, CV, CVI, CVII, MII, CP, ER, and Po, containing 18, 2, 2, 10, 5, 1, 1, 2, 1, and 2 proteins, respectively. Among the 44 PpHSP20 genes, 6, 4, 4, 3, 7, 11, 5, and 4 PpHSP20 genes were located on chromosomes 1 to 8, respectively. In particular, approximately 15 PpHSP20 genes were located at both termini or one terminus of each chromosome. A total of 15 tandem PpHSP20 genes were found in the peach genome, which belonged to five tandemly duplicated groups. Overall, among the three cultivars, the number of PpHSP20 genes with higher expression levels in red flesh was greater than that in yellow or white flesh. The expression profiling for most of the PpHSP20 genes in the red-fleshed ‘BJ’ was higher overall at the S3 stage than at the S2, S4-1, and S4-2 stages, with the S3 stage being a very important period of transformation from a white color to the gradual anthocyanin accumulation in the flesh of this cultivar. The subcellular localizations of 16 out of 19 selected PpHSP20 proteins were in accordance with the corresponding subfamily classification and naming. Additionally, to our knowledge, Prupe.3G034800.1 is the first HSP20 found in plants that has the dual targets of both the endoplasmic reticulum and nucleus.ConclusionsThis study provides a comprehensive understanding of PpHSP20s, lays a foundation for future analyses of the unknown function of PpHSP20 family genes in red-fleshed peach fruit and advances our understanding of plant HSP20 genes.

Elucidating Softening Mechanism of Honey Peach (Prunus persica L.) Stored at Ambient Temperature Using Untargeted Metabolomics Based on Liquid Chromatography-Mass Spectrometry

Peach fruit softening is the result of a series of complex physiological and biochemical reactions that influence shelf life and consumer acceptance; however, the precise mechanisms underlying softening remain unclear. We conducted a metabolomic study of the flesh and peel of the honey peach (Prunus persica L.) to identify critical metabolites before and after fruit softening. Compared to the pre-softening profiles, 155 peel metabolites and 91 flesh metabolites exhibited significant changes after softening (|log2(FC)| &gt; 1; p &lt; 0.05). These metabolites were mainly associated with carbohydrate metabolism, respiratory chain and energy metabolism (citrate cycle, pantothenate and CoA biosynthesis, nicotinate and nicotinamide metabolism, and pentose and glucuronate interconversions), reactive oxygen species (ROS) metabolism, amino acid metabolism, and pyrimidine metabolism. During peach fruit softening, energy supply, carbohydrate and amino acid metabolism, oxidative damage, and plant hormone metabolism were enhanced, whereas amino acid biosynthesis and cell growth declined. These findings contribute to our understanding of the complex mechanisms of postharvest fruit softening, and may assist breeding programs in improving peach fruit quality during storage.

Metabolome, Plant Hormone, and Transcriptome Analyses Reveal the Mechanism of Spatial Accumulation Pattern of Anthocyanins in Peach Flesh.

Anthocyanins are important secondary metabolites in fruits, and anthocyanin accumulation in the flesh of peach exhibits a spatial pattern, but the relevant mechanism is still unknown. In this study, the yellow-fleshed peach, cv. 'Jinxiu', with anthocyanin accumulation in the mesocarp around the stone was used as the experimental material. Red flesh (RF) and yellow flesh (YF) were sampled separately for flavonoid metabolite (mainly anthocyanins), plant hormone, and transcriptome analyses. The results showed that the red coloration in the mesocarp was due to the accumulation of cyanidin-3-O-glucoside, with an up-regulation of anthocyanin biosynthetic genes (F3H, F3'H, DFR, and ANS), transportation gene GST, and regulatory genes (MYB10.1 and bHLH3). Eleven ERFs, nine WRKYs, and eight NACs were also defined as the candidate regulators of anthocyanin biosynthesis in peach via RNA-seq. Auxin, cytokinin, abscisic acid (ABA), salicylic acid (SA), and 1-aminocyclopropane-1-carboxylic acid (ACC, ethylene precursor) were enriched in the peach flesh, with auxin, cytokinin, ACC, and SA being highly accumulated in the RF, but ABA was mainly distributed in the YF. The activators and repressors in the auxin and cytokinin signaling transduction pathways were mostly up-regulated and down-regulated, respectively. Our results provide new insights into the regulation of spatial accumulation pattern of anthocyanins in peach flesh.

PpHY5 is involved in anthocyanin coloration in the peach flesh surrounding the stone.

Red coloration around the stone (Cs) is an important trait of canned peaches (Prunus persica). In this study, an elongated hypocotyl 5 gene in peach termed PpHY5 was identified to participate in the regulation of the Cs trait. The E3 ubiquitin ligase PpCOP1 was expressed in the flesh around the stone and could interact with PpHY5. Although HY5 is known to be degraded by COP1 in darkness, the PpHY5 gene was activated in the flesh tissue surrounding the stone at the ripening stages and its expression was consistent with anthocyanin accumulation. PpHY5 was able to promote the transcription of PpMYB10.1 through interacting with its partner PpBBX10. Silencing of PpHY5 in the flesh around the stone caused a reduction in anthocyanin pigmentation, while transient overexpression of PpHY5 and PpBBX10 resulted in anthocyanin accumulation in peach fruits. Moreover, transgenic Arabidopsis seedlings overexpressing PpHY5 showed increased anthocyanin accumulation in leaves. Our results improve our understanding of the mechanisms of anthocyanin coloration in plants.

Yogurt Products Fortified with Microwave-Extracted Peach Polyphenols.

Pectin and polyphenols have been obtained from choice peach flesh using microwave extraction, with the resulting extracts used in functionalizing strained yogurt gels. A Box-Behnken design was utilized in order to co-optimize the extraction process. Soluble solid content, total phenolic content, and particle size distributions were measured in the extracts. Extraction at pH 1 yielded the highest phenolic content, while increases in the liquid-to-solid ratio resulted in a decrease in soluble solids and an increase in particle diameter. Selected extracts were then incorporated into strained yogurt, and the resulting gel products were assessed for color and texture over a two-week period. All samples were darker and had more red tones than the control set yogurt, while exhibiting less yellow tones. The cohesiveness of all samples remained stable over the gels' aging of two weeks (break-up times always remaining within 6 s and 9 s), which is close to the expected shelf-life of such products. The work required for the deformation of most samples increases with time, indicating that the products became firmer due to the macromolecular rearrangements in the gel matrix. The extracts obtained with the highest microwave power (700 W) give less firm samples. This was due to the microwave-induced loss of conformation and self-assembly of the extracted pectins. The hardness of all samples increased over time, gaining from 20 to 50% of the initial hardness due to the rearrangement of the pectin and yogurt proteins over time. The products with pectin extracted at 700 W were again exceptions, losing hardness or remaining stable after some time. Overall, this work combines the sourcing of polyphenols and pectin from choice fruit; it uses MAE for isolating the materials of interest; it mechanically examines the resulting gels; and it performs all the above under a specifically-set experimental design aiming towards optimizing the overall process.

Inheritance of Fruit Red-Flesh Patterns in Peach.

Fruit color is an important trait in peach from the point of view of consumer preference, nutritional content, and diversification of fruit typologies. Several genes and phenotypes have been described for peach flesh and skin color, and although peach color knowledge has increased in the last few years, some fruit color patterns observed in peach breeding programs have not been carefully described. In this work, we first describe some peach mesocarp color patterns that have not yet been described in a collection of commercial peach cultivars, and we also study the genetic inheritance of the red dots present in the flesh (RDF) and red color around the stone (CAS) in several intra- and interspecific segregating populations for both traits. For RDF, we identified a QTL at the beginning of G5 in two intraspecific populations, and for CAS we identified a major QTL in G4 in both an intraspecific and an interspecific population between almond and peach. Finally, we discuss the interaction between these QTLs and some other genes previously identified in peach, such as dominant blood flesh (DBF), color around the stone (Cs), subacid (D) and the maturity date (MD), and the implications for peach breeding. The results obtained here will help peach germplasm curators and breeders to better characterize their plant materials and to develop an integrated system of molecular markers to select these traits.

Characterizing of carotenoid diversity in peach fruits affected by the maturation and varieties

Although peach fruits are known to exhibit high carotenoid content, the effect of maturation and variety on the carotenoid diversity has not been investigated in detail. Herein, carotenoids in 35 varieties of peach were qualitatively and quantitatively analyzed by ultra-high-performance liquid chromatography combined with atmospheric pressure chemical-tandem mass spectrometry (UHPLC-APCI-MS/MS), and 12 carotenoids were identified in every peach flesh. The results suggest that lutein was the main carotenoid, accounting for over 63.6 % of the total carotenoid pool in both white- and yellow-fleshed peach varieties at the immature stage. In contrast, at the mature stage, phytoene was the major carotenoid with a contribution of more than 51.1 %. In addition, the main carotenoids present in 30 yellow-fleshed peach varieties were β-carotene, β-cryptoxanthin, (E/Z)-phytoene, lutein, and zeaxanthin, with their content varying from 5.07 to 28.9, 2.19–88.05, 0.41–8.8, 0.83–10.8, and 1.33–19.08 µg/g DW, respectively. The results obtained suggest the rich diversity of carotenoid profiles in peaches. • The main carotenoids are β-carotene, β-cryptoxanthin, phytoene, lutein, and zeaxanthin. • Lutein is the main carotenoid at the immature stage. • Phytoene is the major carotenoid at the mature stage. • The carotenoid diversity and content are affected by maturation and variety factors.

Identification and Analysis of Long Non-Coding RNAs Related to UV-B-Induced Anthocyanin Biosynthesis During Blood-Fleshed Peach (Prunus persica) Ripening.

Blood flesh is a key fruit trait in peaches (Prunus persica) and can be attributed to the accumulation of anthocyanins. The roles of long non-coding RNAs (lncRNAs) have been highlighted by multiple studies in regulating fruit ripening, anthocyanin accumulation, and abiotic stress responses in many flowering plants. Such regulatory functions of lncRNAs in Prunus persica, nonetheless, have not been reported. In this research, we sequenced and analyzed the complete transcriptome of C3-20 (a blood-fleshed peach) fruit at four developmental stages. Analyses of the correlated genes and differentially expressed lncRNA target genes helped to forecast lncRNAs’ possible functions. The RNA-seq data were generated using high-throughput sequencing. In total, 17,456 putative lncRNAs, including 4,800 intergenic lncRNAs, 2,199 antisense lncRNAs, and 10,439 intronic lncRNAs were discovered, of which 4,871 differentially expressed lncRNAs (DE-lncRNAs) were annotated in the fruit developmental processes. The target genes of these DE-lncRNAs and their regulatory relationship identifying 21,795 cis-regulated and 18,271 trans-regulated targets of the DE-lncRNAs were in a similar way predicted by us. The enriched GO terms for the target genes included anthocyanin biosynthesis. Flavonoid biosynthesis and plant hormone signal transduction were also included in the enriched KEGG pathways. Co-expression network construction demonstrated that the highly expressed genes might co-regulate multiple other genes associated with auxin signal transduction and take effect in equal pathways. We discovered that lncRNAs, including LNC_000987, LNC_000693, LNC_001323, LNC_003610, LNC_001263, and LNC_003380, correlated with fruit that ripened and could take part in ethylene biosynthesis and metabolism and the ABA signaling pathway. Several essential transcription factors, such as ERFs, WRKY70, NAC56, and NAC72, may in a similar way regulate fruit ripening. Three DE-lncRNAs, XLOC_011933, XLOC_001865, and XLOC_042291, are involved in UV-B-induced anthocyanin biosynthesis and positively regulating UVR8 and COP10, were identified and characterized. Our discovery and characterization of XLOC_011933, XLOC_001865, and XLOC_042291 provide a more precise understanding and preliminarily establishes a theoretical framework for UV-B-induced flesh anthocyanin biosynthesis. This phenomenon might encourage more in-depth investigations to study the molecular mechanisms underlying peach flesh coloring.

Comparison of Aroma Trait of the White-Fleshed Peach ‘Hu Jing Mi Lu’ and the Yellow-Fleshed Peach ‘Jin Yuan’ Based on Odor Activity Value and Odor Characteristics

Peach flesh colors and aromas impact greatly on consumer behaviors and these two traits are closely associated in white- and yellow-fleshed peaches. However, current understanding of their aromas is rather limited and confined to the concentration differences of some volatiles. Therefore, this study aims to compare the overall aromas of the white-fleshed peach ‘Hu Jing Mi Lu’ (HJML) and yellow-fleshed peach ‘Jin Yuan’ (JY), two fresh cultivars with intense aromas and industrial influence by applications such as HS-SPME/GC-MS analysis, odor activity value evaluations, and odor note analysis. The significant contributions of 26 odor-active compounds to their aromas were revealed. Among which, 15 compounds showed no concentration differences and contributed to the fruity, floral, sweet, etc., odors in both HJML and JY; (E)-2-nonenal, 1-pentanol, and styrene showed significantly higher concentrations in HJML and conveyed much stronger fusel-like and balsamic odors; likewise, (Z)-3-hexenyl acetate, octanal, nonanal, and 3,5-octadien-2-one showed significantly higher concentrations in JY and conveyed much stronger banana, citrus-like, and honey odors; besides, benzyl alcohol, 1-heptanol, 1-octen-3-ol, and 3-octanone with woody, earthy, mushroom, and lavender odors were exclusively detected in HJML. Overall, apart from the common and stronger specific odors in either the white- or yellow-fleshed peach cultivar, the white-fleshed peach was endowed with a unique aroma.

English

Carotenoids are important substances for the yellow color of peach flesh. In this study, the contents of carotenoids in two yellow flesh peach varieties ('Zhongtao Jinmi' and 'Jinxiang') and one white flesh peach variety ('Bairuyu') were determined by high-performance liquid chromatography. The results showed that the carotenoid content in the two yellow flesh peach varieties increased with fruit development and reached the maximum of 25.80 and 27.63 μg.g-1 at the mature stage, while that of the white flesh peach variety remained at a very low level during the whole fruit development period. Furthermore, transcriptome sequencing was performed to analyze the differentially expressed genes (DEGs) during fruit development among the three peach varieties. Among these DEGs, four candidate genes were identified to be potentially involved in the biosynthesis of carotenoids, including LOC18774744 (encoding UDP-glycosyltransferase 87A1 (UGT87A1)), LOC18792568 (encoding the carotenoid cleavage dioxygenase 4 gene (CCD4)), LOC109949966 (an unannotated gene), and LOC18779468 (encoding xyloglucan endoglucosylase/hydrolase protein 8. qRT-PCR confirmed that the expression of LOC109949966 and LOC18779468 in two yellow flesh varieties was significantly higher than that in the white flesh variety, while it was the opposite case for UGT87A1 and CCD4. Therefore, we speculate that CCD4 is directly involved in regulating carotenoid synthesis, while other three genes may play some indirect roles in the process. Our findings are expected to improve the understanding on the mechanism of carotenoid biosynthesis in peach. © 2022 Friends Science Publishers

Differentiation of peach cultivars by image analysis based on the skin, flesh, stone and seed textures

The peaches belonging to different cultivars can be characterized by differentiation in properties. The aim of this study was to evaluate the usefulness of individual parts of fruit (skin, flesh, stone and seed) for cultivar discrimination of peaches based on textures determined using image analysis. Discriminant analysis was performed using the classifiers of Bayes net, logistic, SMO, multi-class classifier and random forest based on a set of combined textures selected from all color channels R, G, B, L, a, b, X, Y, Z and for textures selected separately for RGB, Lab and XYZ color spaces. In the case of sets of textures selected from all color channels (R, G, B, L, a, b, X, Y, Z), the accuracy of 100% was observed for flesh, stones and seeds for selected classifiers. The sets of textures selected from RGB color space produced the correctness equal to 100% in the case of flesh and seeds of peaches. In the case of Lab and XYZ color spaces, slightly lower accuracies than for RGB color space were obtained and the accuracy reaching 100% was noted only for the discrimination of seeds of peaches. The research proved the usefulness of selected texture parameters of fruit flesh, stones and seeds for successful discrimination of peach cultivars with an accuracy of 100%. The distinguishing between cultivars may be important for breeders, consumers and the peach industry for ensuring adequate processing conditions and equipment parameters. The cultivar identification of fruit by human may be characterized by large errors. The molecular or chemical methods may require special equipment or be time-consuming. The image analysis may ensure objective, rapid and relatively inexpensive procedure and high accuracy for peach cultivar discrimination.

Identification of DNA Methylation and Transcriptomic Profiles Associated With Fruit Mealiness in Prunus persica (L.) Batsch.

Peach (Prunus persica) fruits have a fast ripening process and a shelf-life of days, presenting a challenge for long-distance consuming markets. To prolong shelf-life, peach fruits are stored at low temperatures (0 to 7 °C) for at least two weeks, which can lead to the development of mealiness, a physiological disorder that reduces fruit quality and decreases consumer acceptance. Several studies have been made to understand this disorder, however, the molecular mechanisms underlying mealiness are not fully understood. Epigenetic factors, such as DNA methylation, modulate gene expression according to the genetic background and environmental conditions. In this sense, the aim of this work was to identify differentially methylated regions (DMRs) that could affect gene expression in contrasting individuals for mealiness. Peach flesh was studied at harvest time (E1 stage) and after cold storage (E3 stage) for 30 days. The distribution of DNA methylations within the eight chromosomes of P. persica showed higher methylation levels in pericentromeric regions and most differences between mealy and normal fruits were at Chr1, Chr4, and Chr8. Notably, differences in Chr4 co-localized with previous QTLs associated with mealiness. Additionally, the number of DMRs was higher in CHH cytosines of normal and mealy fruits at E3; however, most DMRs were attributed to mealy fruits from E1, increasing at E3. From RNA-Seq data, we observed that differentially expressed genes (DEGs) between normal and mealy fruits were associated with ethylene signaling, cell wall modification, lipid metabolism, oxidative stress and iron homeostasis. When integrating the annotation of DMRs and DEGs, we identified a CYP450 82A and an UDP-ARABINOSE 4 EPIMERASE 1 gene that were downregulated and hypermethylated in mealy fruits, coinciding with the co-localization of a transposable element (TE). Altogether, this study indicates that genetic differences between tolerant and susceptible individuals is predominantly affecting epigenetic regulation over gene expression, which could contribute to a metabolic alteration from earlier stages of development, resulting in mealiness at later stages. Finally, this epigenetic mark should be further studied for the development of new molecular tools in support of breeding programs.

Quantitative determination of sugar profiles in peach fruit during storage by an integrating sphere system

This work describes the optical approach for the quantitative description of sugar profiles in peaches during storage by using single integrating sphere (SIS). The spectral profiles for the optical properties (light absorption coefficient μa and reduced scattering coefficient μ’s) were measured. Correlation analysis between the optical properties and the sugar profiles showed that higher correlated values, with r > 0.640, were found. Furthermore, quantitative models were constructed by Partial Least Squares Regression (PLSR) based on μa and μ’s datasets to predict the sugar composition in peach flesh. The predicted results for the sucrose content based on μa datasets by PLSR were better than those based on the μ’s. For fructose and glucose contents, the predicted models were not very satisfactory due to low concentration in peach flesh, with Rp2 of 0.721, RMSEP of 0.817 g kg−1 for fructose and Rp2 of 0.753 and RMSEP of 0.604 g kg−1 for glucose, respectively. The models established by SIS present a simple and efficient strategy for quantitative analysis and may be used as alternative methods for evaluating the quality attributes of different types of fruit.

Fabrication of Three Bio-Adsorbents from Different Parts of Rape Straw

This work describes the novel approach for the quantitative description of sugar profiles in peaches during storage by using single-integrating sphere (SIS). The spectral profiles for the optical properties (light absorption coefficient μa and reduced scattering coefficient μ's) were measured. Correlation analysis between the optical properties and the sugar profiles showed that higher correlated values, with r > 0.640, were found. Furthermore, quantitative models were constructed by partial least squares regression (PLSR) based on μa and μ's datasets to predict the sugar composition in peach flesh. The predicted results for the sucrose content based on μa datasets by PLSR were better (Rp2 = 0.796 at wavelengths of 600 to 1050 nm) than those based on the μ's datasets. The models established by SIS present a simple and efficient strategy for quantitative analysis and may be used as alternative methods for evaluating the quality attributes of different types of fruit.

The outer influences the inner: Postharvest UV-B irradiation modulates peach flesh metabolome although shielded by the skin

UV-B-driven modulation of secondary metabolism in peach fruit by enhancing the biosynthesis of specific phenolic subclasses, is attracting interest among consumers. However, current literature explored the UV-B-induced metabolic changes only in peach skin subjected to direct UV-B irradiation. Accordingly, this study aimed to understand whether UV-B radiation penetrates the fruit skin and is able to induce metabolic changes also within the inner flesh. Peaches were UV-B-irradiated either 10 or 60 min, and the flesh was sampled after 24 and 36 h. Non-targeted metabolomics revealed that UV-B has a strong impact on peach flesh metabolome, determining an initial decrease after 24 h, followed by an overall increase after 36 h, particularly for terpenoids, phenylpropanoids, phytoalexins and fatty acids in the 60 min UV-B-treated samples (+150.02, +99.14, +43.79 and +25.44 log2FC, respectively). Transmittance analysis indicated that UV-B radiation does not penetrate below the skin, suggesting a possible signalling pathway between tissues.

Hybrid Label-Free Molecular Microscopies for Simultaneous Visualization of Changes in Cell Wall Polysaccharides of Peach at Single- and Multiple-Cell Levels during Postharvest Storage.

Softening of fruit during the postharvest storage, which is mainly associated with both compositional and spatial changes of polysaccharides within cell wall, affects the texture and quality of fruit. Current research on the fruit softening mechanism lacks an understanding of the overall softening at the cell level. The objective of this work was to investigate the change in the spatial distribution of cell wall polysaccharides in peach flesh cells at both single- and multiple-cell levels in a label-free way during the postharvest storage. Nonmelting peaches (Prunus persica L. Batsch cv.”Zhonghuashoutao”) at commercial maturity were stored at 0 °C and 20 °C. Firmness measurement and chemical analysis were performed at each storage time. In addition, three molecular imaging techniques, namely confocal Raman microspectroscopy (CRM), Fourier transform infrared microspectroscopy (FTIRM), and stimulated Raman scattering microscopy (SRS) were used to visualize changes in the spatial distribution of cell wall polysaccharides of peach fruit in a label-free way during the postharvest storage. The combination of CRM and FTIRM provided complementary spectral information to visualize the spatial changes of cellulose, hemicellulose, and pectin in the cell wall of peach flesh during softening at the single-cell level, and found that the cell wall polysaccharides tended to be concentrated in the cell corner of parenchymal cells at the late stage. Furthermore, SRS, which is an ultrafast Raman imaging technique (approximately three or four orders of magnitude faster than CRM), was used for high-throughput cell wall phenotypes measurement. Different degradation degrees of parenchymal cells during fruit softening were found based on the gray-scale statistical analysis of SRS data. In general, cell wall polysaccharides decreased during softening and tended to be concentrated in the cell corner for most parenchymal cells at the late stage, but there were also some cells not in line with the whole softening trends. The results show that there were differences in the content and spatial changes of cell wall polysaccharides among parenchymal cells of peach fruit during the softening process, and the hybrid use of CRM, FTIRM, and SRS is a promising method for simultaneous visualization of changes in cell wall polysaccharides of peach.