Comprehensive physicochemical indicators analysis and quality evaluation model construction for the post-harvest ripening rapeseeds.

Rapeseed (Brassica napus L.) is the second largest globally cultivated oil crop, but the effects of post-harvested ripening on rapeseed quality is unclear and unpredictable. This study reveals the relationship between post-harvest ripening periods (PHR) and physicochemical quality of different rapeseed cultivars using comprehensive physicochemical indicators analysis. The results indicate that PHR led to a gradual decrease in chlorophyll, carotenoid and moisture content but continually increased oil and total phenol content (TPC). Besides, 295 lipid molecules from 13 lipid subclasses were identified, revealing that the relative content of triacylglycerol (TG) was progressively increased while diacylglycerol (DG) demonstrated a consistent decline throughout the PHR. Correlation analysis, hierarchical cluster analysis (HCA) and principal component analysis (PCA) were employed to construct and verify the comprehensive quality evaluation model for rapeseeds in PHR. This paper develops a comprehensive quality evaluation model for post-harvest ripening rapeseeds and advances the development of agricultural products.

Post-harvest ripening affects drying behavior, antioxidant capacity and flavor release of peach via alteration of cell wall polysaccharides content and nanostructures, water distribution and status.

Effect of post-harvest ripening on cell wall polysaccharides nanostructures, water status, physiochemical properties of peaches and drying behavior under hot air-infrared drying was evaluated. Results showed that the content of water soluble pectins (WSP) increased by 94 %, while the contents of chelate-soluble pectins (CSP), Na2CO3-soluble pectins (NSP) and hemicelluloses (HE) decreased during post-harvest ripening by 60 %, 43 %, and 61 %, respectively. The drying time increased from 3.5 to 5.5 h when the post-harvest time increased from 0 to 6 days. Atomic force microscope analysis showed that depolymerization of hemicelluloses and pectin occurred during post-harvest ripening. Time Domain -NMR observations indicated that reorganization of cell wall polysaccharides nanostructure changed water spatial distribution and cell internal structure, facilitated moisture migration, and affected antioxidant capacity of peaches during drying. This leads to the redistribution of flavor substances (heptanal, n-nonanal dimer and n-nonanal monomer). The current work elucidates the effect of post-harvest ripening on the physiochemical properties and drying behavior of peaches.

Systems Biology Applied to the Study of Papaya Fruit Ripening: The Influence of Ethylene on Pulp Softening.

Papaya is a fleshy fruit that undergoes fast ethylene-induced modifications. The fruit becomes edible, but the fast pulp softening is the main factor that limits the post-harvest period. Papaya fast pulp softening occurs due to cell wall disassembling coordinated by ethylene triggering that massively expresses pectinases. In this work, RNA-seq analysis of ethylene-treated and non-treated papayas enabled a wide transcriptome overview that indicated the role of ethylene during ripening at the gene expression level. Several families of transcription factors (AP2/ERF, NAC, and MADS-box) were differentially expressed. ACO, ACS, and SAM-Mtase genes were upregulated, indicating a high rate of ethylene biosynthesis after ethylene treatment. The correlation among gene expression and physiological data demonstrated ethylene treatment can indeed simulate ripening, and regulation of changes in fruit color, aroma, and flavor could be attributed to the coordinated expression of several related genes. Especially about pulp firmness, the identification of 157 expressed genes related to cell wall metabolism demonstrated that pulp softening is accomplished by a coordinated action of several different cell wall-related enzymes. The mechanism is different from other commercially important fruits, such as strawberry, tomato, kiwifruit, and apple. The observed behavior of this new transcriptomic data confirms ethylene triggering is the main event that elicits fast pulp softening in papayas.

Comparative transcriptome analysis reveals the mechanism involving ethylene and cell wall modification related genes in Diospyros kaki fruit firmness during ripening.

Rapid loss of firmness is a major handicap for persimmon (Diospyros kaki Thunb.) transportation and retail. The present study employed a comparative transcriptomic approach to elucidate the mechanism involving ethylene and cell wall modification related genes in fruit firmness control of two cultivars during post harvest ripening. In contrast to the short shelf life cultivar (Mopan), the long shelf life cultivar (Yoho) kept high firmness during ripening. Extensive loss of firmness in Mopan drove an intense transcriptional activity. Globally, Mopan and Yoho shared very few common differentially expressed structural genes and regulators. Yoho strongly repressed the expression of ACC synthase and several classes of cell wall degradation genes at the onset of ripening and only induced them during late ripening period. Various ERF, WRKY, MYB, bHLH transcription factors were found highly active during fruit ripening. Overall, this study generates novel gene resources as important tools for extending persimmon shelf life.

Insights into profiling of volatile ester and LOX-pathway related gene families accompanying post-harvest ripening of 'Nanguo' pears.

'Nanguo' pear is particularly renowned for its fragrance. Esters are the main components of its aroma, which are synthesized primarily by the LOX pathway. We identified the main volatile esters and critical gene family members involved in the LOX pathway by monitoring their variation accompanying post-harvest ripening and examining their roles through principal component analysis (PCA), partial least-square regression (PLSR), and correlation analysis. In pears ripening to the optimum taste period (OTP), components and contents of volatile esters reached a peak, of which ethyl butanoate, ethyl hexanoate, and hexyl acetate were most prominent. Linoleic acid and linolenic acid contents rose greatly until OTP and then declined; the activities of LOX, alcohol dehydrogenase (ADH), and alcohol acyltransferase (AAT) increased progressively until the OTP. Among the genes involved in LOX-pathway, the expressions of PuLOX3, PuADH3, and PuAAT contributed most to changes of total ester and main esters in 'Nanguo' pears.

Effect of Temperature and Humidity on Oil Quality of Harvested Torreya grandis cv. Merrillii Nuts During the After-Ripening Stage.

Temperature and relative humidity (RH) influence post-harvest ripening, a crucial stage for quality promotion in some oil plants or fruits. Torreya grandis cv. Merrillii nuts, which are rich in unsaturated fatty acids (UFA), are easily affected by temperature and humidity, and they oxidize quickly during the post-harvest ripening stage, leading to the deterioration of nut quality. In this study, the main nutraceutical components, fatty acid composition, and related metabolic parameters of lipid rancidity under four treatments (20°C and 70% RH, T20-LH; 30°C and 70% RH, T30-LH; 20°C and 90% RH, T20-HH; 30°C and 90% RH, T30-HH) were measured. The post-harvest ripening process was advanced under HH treatments (T20-HH and T30-HH) compared to LH treatments (T20-LH and T30-LH) and was associated with a shorter time for the seed coat to turn dark black and a faster reduction in starch content. The amount of unsaturated fatty acids significantly increased under the T20-HH treatment, but significantly decreased under the T30-HH treatment from 12 to 16 d of ripening time. The acid value (AV) and lipase activity under the T30-HH treatment remained virtually constant from 12 to 16 d of ripening time, and this was accompanied by a dramatic increase in peroxide value (POV), lipoxygenase (LOX) activity, and relative expression of the LOX2 gene. Meanwhile, a significant positive correlation between LOX activity and POV, malondialdehyde (MDA) content, and O2⋅- content was observed. The results imply that the lower amount of oxidative rancidity induced by the T20-HH treatment is related to the LOX activity induced by down-regulation of the LOX2 gene during the late after-ripening stage. Therefore, the T20-HH treatment not only promoted the post-harvest process of T. grandis 'Merrillii' nuts but also delayed lipid oxidation, which was ultimately associated with better oil quality at the late after-ripening stage.

Identification of calcium carbide-ripened sapota (Achras sapota) fruit by headspace SPME-GC-MS.

The effect of post-harvest ripening by ethylene and calcium carbide was studied by headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) method. Sapota (sapodilla) fruits were ripened with ethylene gas, technical grade calcium carbide and pure calcium carbide ripeners and the samples were homogenised after complete ripening. The samples were subjected to HS-SPME-GC-MS and the obtained results showed the presence of various alcohols, aldehydes, acids, ketones and esters which were commonly present in the samples. The fruit samples ripened with technical grade calcium carbide showed the presence of 3,5-dimethyl-1,2,4-trithiolane isomers, which can be used as markers to identify sapota fruits ripened with technical grade calcium carbide. The technical grade calcium carbide contains divinyl sulphide which might have been transformed into the trithiolane isomers. These isomers were not observed in the fruits ripened with pure calcium carbide and also with ethylene gas. Hence the formation of trithiolane residues may be attributed to the presence of divinyl sulphide impurity present in calcium carbide and its conversion due to the action of ethylene releasing enzymes present in the fruits.

Hydrogen Sulfide Maintained the Good Appearance and Nutrition in Post-harvest Tomato Fruits by Antagonizing the Effect of Ethylene.

Hydrogen sulfide (H2S) could act as a versatile signaling molecule in delaying fruit ripening and senescence. Ethylene (C2H4) also plays a key role in climacteric fruit ripening, but little attention has been given to its interaction with H2S in modulating fruit ripening and senescence. To study the role of H2S treatment on the fruit quality and nutrient metabolism, tomato fruits at white mature stage were treated with ethylene and ethylene plus H2S. By comparing to C2H4 treatment, we found that additional H2S significantly delayed the color change of tomato fruit, and maintained higher chlorophyll and lower flavonoids during storage. Moreover, H2S could inhibit the activity of protease, maintained higher levels of nutritional-related metabolites, such as anthocyanin, starch, soluble protein, ascorbic acid by comparing to C2H4 treatment. Gene expression analysis showed that additional H2S attenuated the expression of beta-amylase encoding gene BAM3, UDP-glycosyltransferase encoding genes, ethylene-responsive transcription factor ERF003 and DOF22. Furthermore, principal component analysis suggested that starch, titratable acids, and ascorbic acid were important factors for affecting the tomato storage quality, and the correlation analysis further showed that H2S affected pigments metabolism and the transformation of macromolecular to small molecular metabolites. These results showed that additional H2S could maintain the better appearance and nutritional quality than C2H4 treatment alone, and prolong the storage period of post-harvest tomato fruits.

New sights into lipid metabolism regulation by low temperature in harvested Torreya grandis nuts.

BACKGROUND: Torreya grandis, a large evergreen coniferous tree with oil-rich nuts, undergoes a crucial ripening stage after harvest that results in oil accumulation, finally giving rise to the nut that is edible in roasted form. To understand lipid metabolism in T. grandis nuts during the post-harvest ripening period, the effects of low temperature on lipid content, fatty acid composition, lipid biosynthesis and degradation were investigated. RESULTS: The lipid content increased during ripening at room temperature and a low temperature slowed down this increase. Linoleic acid content increased at low temperature, which was accompanied by an increase in the microsomal oleate desaturase (FAD2) activity and FAD2 expression. Furthermore, a low temperature attenuated lipid peroxidation as indicated by lower contents of malondialdehyde, hydroperoxide and total free fatty acid in T. grandis nuts during the ripening stage, as well as the down-regulation of gene expression of lipid degradation-related enzymes such as phospholipase D and lipoxygenases. CONCLUSION: The findings of the present study indicate that a low temperature increased polyunsaturated fatty acid contents by increasing FAD2 biosynthesis and decreasing lipid peroxidation, thereby improving the oil yield in T. grandis nuts during the post-harvest ripening period. © 2019 Society of Chemical Industry.