Effect of the ripening stage on the pulsed vacuum drying behavior of goji berry (Lycium barbarum L.): Ultrastructure, drying characteristics, and browning mechanism

In current work, the effect of ripening stages (I, II, and III) on pulsed vacuum drying (PVD) behavior of goji berry was explored. The shortest drying time of goji berry was observed at stage I (6.99 h) which was 13.95 %, and 28.85 % shorter than those at stages II, and III, respectively. This phenomenon was closely associated with the ripening stage, as contributed by the initial physiochemical differences, ultrastructure alterations, and moisture distribution. In addition, lower maturity suffered more severe browning, primarily due to the enzymatic and non-enzymatic reactions of phenolics, followed by pigment degradation and the Maillard reaction. Additionally, the PVD process promoted the rupture and transformation of the pectin fractions, also causing browning either directly or indirectly through participation in other chemical reactions. These findings suggest that the appropriate ripening stage of goji berry should be considered as having a significant impact on drying behaviors and quality attributes.

Comparison of phenolic composition in Australian-grown date fruit (Phoenix dactylifera L.) seeds from different varieties and ripening stages

In this research, different seeds of Australian-grown date palm (Phoenix dactylifera L.) were studied to evaluate the antioxidant potential and analyze their phenolic constituents. Phenolic compounds were extracted from seeds of various Australian-grown date varieties at different ripening stages. Eight varieties of date seeds (Zahidi, Medjool, Deglet nour, Thoory, Halawi, Barhee, Khadrawy, and Bau Strami) at three ripening stages (Kimri, Khalal, and Tamar) were investigated in this study. Date seeds at Khalal (9.87-16.93 mg GAE/g) and Tamar (9.20-27.87 mg GAE/g) stages showed higher total phenolic content than those at Kimri stage (1.81-5.99 mg GAE/g). For antioxidant assays like DPPH, FRAP, ABTS, RAP, FICA, and TAC, date seeds at Khalal and Tamar stages also showed higher antioxidant potential than Kimri stage. However, date seeds at Kimri stage (55.24-63.26 mg TE/g) expressed higher radical scavenging activity than Khalal (13.58-51.88 mg TE/g) and Tamar (11.06-50.92 mg TE/g) stages. Phenolic compounds were characterized using LC-ESI-QTOF-MS/MS, revealing the presence of 37 different phenolic compounds, including 8 phenolic acids, 18 flavonoids, and 11 other phenolic compounds. Further, phenolic compounds were quantified using LC-DAD, revealing that Zahidi variety of date seeds exhibited the highest content during the Kimri stage. In contrast, during the Khalal and Tamar stages, Deglet nour and Medjool date seeds displayed higher concentrations of phenolic compounds. The results indicated an increase in phenolic content in date seeds after the Kimri stage, with significant variations observed among different date varieties.

Characterization and metabolism pathway of volatile compounds in walnut oil obtained from various ripening stages via HS-GC-IMS and HS-SPME-GC-MS

Volatile organic compounds (VOCs) of walnut oil (WO) samples obtained from 5 ripening stages were analyzed by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and HS-solid phase microextraction-GC-mass spectrometry (HS-SPME-GC-MS). A total of 75 VOCs were identified in WO, of which 24 VOCs were found to be the key aroma-active compounds for WO by using odor activity values (OAVs) analysis. Based on chemometrics methods, flavor of WO samples can be characterized into three categories, i.e., early, mid-, and late stages. WO from early ripening stage had stronger green and sweet odor due to 1,8-cineole (OAV 280) and ethanol (OAV 134.5). While nonanal (OAV 181.82), (E)-2-octenol (OAV 160), and hexanal (OAV 103.78) were sources of intense fatty and oily odor in mid-ripening stage. For WO of later ripening stage, the flavor was affected by nonanal (OAV 192.28), 1-heptanol (OAV 150), heptanal (OAV 71.11) and some organic acids.

How does maturity stage affect seeds metabolome via UPLC/MS based molecular networking and chemometrics and in relation to antioxidant effect? A case study in 4 major cereals and legumes

Legumes and cereals as staple food are typically consumed at mature stage, though also consumed at earlier stages. UPLC/MS based molecular networking and chemometrics were employed for the first time to address metabolome composition heterogeneity amongst seeds in the context of their maturity stages. The study included 4 major cereal and leguminous seeds of different species, and cultivars i.e., Triticum aestivum, Hordeum vulgare, Vicia faba and Cicer arietinum. 146 Metabolites from various classes were identified of which several are first time to be reported. Supervised OPLS model of all datasets revealed that sugars and oxylipids were dominant in mature and immature seeds, respectively. DPPH and FRAP assays were assessed for differential secondary metabolites' correlation. Results were attributed to flavonoids, oxylipids, and amino acids/peptides. Mature barley seeds possessed the strongest antioxidant activity among examined seeds. This study provides novel insights on seeds' maturation process in context to holistic metabolic changes.

"Improved quality assessment of cornelian cherry (Cornus mas L.) fruit with regard to their processing potential"

The sensory properties and appropriateness of cornelian cherry (Cornus mas L.) for processing is very closely related to its ripening stage, recognizable by firmness and skin colour to some extent. Due to the non-uniform ripening on the trees the quality of the fruits offered on the market depends very much on the harvest-method. Today, processors, who usually do not buy fresh fruits but frozen fruits or puree on the market, don`t have a suitable means for the accurate quality assessment of the raw material they need for the processing of high-quality products. The results of this work show for the first time that from the selected parameters (carbohydrates, organic acids, phenols) only flavonols, especially kaempferol-3-glucoside is appropriate to determine the stage of ripeness of cornelian cherries properly independent from species, provenance and crop year. Kaempferol 3-O-glucoside of about 1.75 mg/Kg in wild genotypes and of about 0.80 mg/Kg in most big cornelian cherry species can serve as a reference for sufficient ripeness and therefore for high fruit quality.

Comparative metabolomics and sensory evaluation of pineapple (Ananas comosus) reveal the importance of ripening stage compared to cultivar

The pineapple ripening stage is determined at the time of harvest and can be classified into the C0 to C4 stage based on its peel color. C1 and C4 pineapples are the most commonly exported products with high demand. Pineapple also has many cultivars with different tastes and appearances. However, there are limited studies regarding the metabolite and taste profiles of pineapple from different cultivars and ripening stages using a metabolomics approach. Therefore, the objective of this study was to investigate the metabolite and sensory profiles of pineapple from different cultivars and different ripening stages. Three cultivars of pineapple (Red Spanish, Smooth Cayenne, and Queen) and C1, C3, and C4 stages from Indonesia, Japan, the Philippines, and Taiwan, respectively, were analyzed by gas chromatography/mass spectrometry (GC/MS). The data obtained from GC/MS analysis were combined with the data obtained from sensory evaluation, which showed that sourness and firmness contributed to C1 fruits with metabolites correlated to isocitric acid+citric acid, malic acid, ascorbic acid, and quinic acid, while sweetness, juiciness, and high acceptability contributed to C4 fruits with metabolites that correlated were asparagine, serine, glycine, threonic acid, sucrose, and 5-hydroxytryptamine. GC/MS analysis using different pineapple cultivars also showed characteristic metabolites for each cultivar. Prediction of the sensory profile was performed by investigating the relative intensity of taste-related metabolites. This information can provide a basis for improving pineapple taste quality related to metabolites, depending on the cultivar and ripening stage.

Fatty acid composition and oil content during coriander fruit development

Coriander contains petroselinic acid, an isomer fatty acid of oleic acid. Coriander seed oil has been proposed as novel food ingredient in the European Union. Field experiments were performed at Auch (France) during two seasons (2010 and 2011). From flowering to maturity, fruits were harvested weekly and oil content and fatty acid (FA) compositions were determined. Fruits presented 2% more oil in 2010 than in 2011. Petroselinic acid (PA) contents was higher in 2011 than in 2010. Oil accumulation began earlier after flowering (2 DAF) in 2011. A first step in accumulation was identified between two and 21 DAF characterized by high SFA and PUFA, which decreased 21 DAF. Subsequently, PA increased to its highest concentration (30-55 DAF) and SFA and PUFA reached their lowest. These results suggest that higher concentrations of PA can be achieved by collecting fruits before full maturity.

Influence of ripening stage and cultivar on physicochemical properties, sugar and organic acid profiles, and antioxidant compositions of strawberries

The current study compared the physicochemical properties, antioxidant compounds and activities, of unripe and ripe fruits of three cultivars (Seolhyang, Janghee, and Maehyang) of strawberries grown in Korea. As fruits matured, their soluble solids content increased and their organic acid content decreased. Total phenolic content (TPC) and total flavonoid content (TFC) did not differ between Seolhyang and Maehyang fruits, regardless of maturity, whereas unripe Janghee fruits showed higher TPC and TFC than ripe fruits. Total anthocyanin content was higher in ripe fruits than in unripe fruits. For total antioxidant activity, ripe and unripe Seolhyang fruits showed no differences, whereas unripe Janghee fruits showed significantly higher activity than ripe fruits. TPC and TFC were highly correlated, as were DPPH and ABTS radical scavenging activities. Thus, antioxidant contents and total antioxidant activities differed with variety and fruit ripeness at harvest. Unripe fruits show strong potential for use in functional food manufacturing.

Effects of ripening stage on physicochemical properties, drying kinetics, pectin polysaccharides contents and nanostructure of apricots

Effects of ripeness (four stages from the lowest to highest degree-I, II, III, and IV) on the physicochemical properties, pectin contents and nanostructure, and drying kinetics of apricots were investigated. The color values (L^*, a^*, and b^*) and total soluble solid content increased during ripening, while the titratable acidity content and hardness decreased. The water-soluble pectin content increased as ripening progressed, but the chelate- and sodium carbonate-soluble pectin contents gradually declined. Atomic force microscopy imaging indicated that the pectin depolymerization occurred during ripening. Fruits at stage III obtained the highest drying rate, and the drying time was reduced by 27.27%, 17.24%, and 7.69% compared to those of stage I, II and IV, respectively. Results showed that the ripeness had significant influence on the drying kinetics, which is related to the modification of physicochemical and pectic properties. The ripeness classification is an essential operation for achieving effective drying process.

Changes of the free and bound volatile compounds in Rubus corchorifolius L. f. fruit during ripening

The changes of free and bound volatile compounds in Rubus corchorifolius fruit during ripening were determined with a headspace SPME-GC-MS method. The results suggest that the free aldehydes, alcohols, esters and phenols increases, while that of free terpenoids decreases, with the ripening of the fruit. The bound aldehydes, alcohols, terpenoids, esters and phenols gradually decreases during ripening because these bound compounds are hydrolyzed to their free form. The characteristic free aroma compounds of ripened red fruit were found to be hexanal, 2-heptanone, ethyl hexanoate, 4-terpineol, geranial and methyleugenol. The free aroma compounds in red and yellow fruits exhibit similar odor profiles, and both of them are much sweeter, more floral and greener than the green fruit. The overall aroma of the fruits all ripening stages are mainly attributed to the free aroma compounds including β-damascenone, hexanal, 2-hexenal and linalool. The formation mechanisms of some volatile compounds were proposed.

Analysis of the distribution of assimilation products and the characteristics of transcriptomes in rice by submergence during the ripening stage

Background

Research on the submergence stress of rice has concentrated on the quiescence strategy to survive in long-term flooding conditions based on Submergence-1A (SUB1A). In the case of the ripening period, it is important that submergence stress can affect the quality as well as the survival of rice. Therefore, it is essential to understand the changes in the distribution of assimilation products in grain and ripening characteristics in submergence stress conditions. However, such studies have been insufficient at the physiological and molecular biological levels.

Results

We confirmed that the distribution rate of assimilation products in grain was decreased by submergence treatment. These results were caused by an increase in the distribution rate of assimilation products to the stem according to escape strategy. To understand this phenomenon at the molecular level, we analyzed the relative expression levels of genes related to sucrose metabolism, and found that the sucrose phosphate synthase gene (OsSPS), which induces the accumulation of sucrose in tissues, was decreased in the seeds and leaves, but not in the stems. Furthermore, the sucrose transporter gene (OsSUT) related to sucrose transport decreased in the seeds and leaves, but increased in stems. We also analyzed the biological metabolic processes related to starch and sucrose synthesis, carbon fixation, and glycolysis using the KEGG mapper with selected differentially expressed genes (DEGs) in seeds, stems, and leaves caused by submergence treatment. We found that the expression of genes for each step related to starch and D-glucose synthesis was down-regulated in the seeds and leaves but up-regulated in the stem.

Conclusion

The results of this study provide basic data for the development of varieties and corresponding technologies adapted to submergence conditions, through understanding the action network of the elements that change in the submergence condition, as well as information regarding useful DEGs.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5320-7) contains supplementary material, which is available to authorized users.

Volatile aroma components and MS-based electronic nose profiles of dogfruit (Pithecellobium jiringa) and stink bean (Parkia speciosa)

Dogfruit (Pithecellobium jiringa) and stink bean (Parkia speciosa) are two typical smelly legumes from Southeast Asia that are widely used in the cuisines of this region. Headspace/gas chromatography/flame ionization detection analysis and mass spectrometry (MS)-based electronic nose techniques were applied to monitor ripening changes in the volatile flavor profiles of dogfruit and stink bean. Compositional analysis showed that the ripening process greatly influenced the composition and content of the volatile aroma profiles of these two smelly food materials, particularly their alcohol, aldehyde, and sulfur components. The quantity of predominant hexanal in stink bean significantly declined (P < 0.05) during the ripening process, whereas the major volatile components of dogfruit changed from 3-methylbutanal and methanol in the unripe state to acetaldehyde and ethanol in the ripe bean. Moreover, the amount of the typical volatile flavor compound 1,2,4-trithiolane significantly increased (P < 0.05) in both ripened dogfruit and stink bean from 1.70 and 0.93%, to relative amounts of 19.97 and 13.66%, respectively. MS-based nose profiling gave further detailed differentiation of the volatile profiles of dogfruit and stink bean of various ripening stages through multivariate statistical analysis, and provided discriminant ion masses, such as m/z 41, 43, 58, 78, and 124, as valuable “digital fingerprint” dataset that can be used for fast flavor monitoring of smelly food resources.

Impact of apple cultivar, ripening stage, fermentation type and yeast strain on phenolic composition of apple ciders

Hydroxycinnamic acids and flavonoids in apple juices and ciders were studied using liquid chromatography. Samples were produced from four different Estonian apple cultivars using unripe, ripe and overripe apples, and six different commercial yeasts including Saccharomyces cerevisiae, Saccharomyces bayanus, and Torulaspora delbrueckii strains. Part of the samples was additionally inoculated with malolactic bacteria, Oenococcus oeni. The most notable difference among the samples was the appearance of phloretin in malolactic ciders in comparison to conventional ciders and the juices. Furthermore, the apple cultivars were significantly different in their phenolic contents and compositions. Additionally, ciders and juices made from unripe apples contained more phenolic compounds than the ripe or overripe, but the effect was dependent on cultivar. The commercial yeast strains differed in the release of free HCAs, especially p-coumaric acid, during the yeast fermentation. In ciders inoculated with S. bayanus, the content was higher than in ciders fermented with S. cerevisiae.

Content variations of triterpenic acid, nucleoside, nucleobase, and sugar in jujube (Ziziphus jujuba) fruit during ripening

Jujube (Ziziphus jujuba) fruit is widely consumed as food and traditional Chinese medicine in Asian countries due to its potential effects for human health. To facilitate selection of the maturity stage providing optimum health benefits, jujube fruits were analysed at six stages of growth (S1-6) for triterpenic acids, nucleosides, nucleobases, and sugars by UHPLC-MS/MS or HPLC-ELSD methods. The content levels of most triterpenic acids and sugars increased with ripening, and reached the highest at S5 and S6, respectively. The accumulation of the cyclic nucleotides (cAMP and cGMP) was mainly in the later stage of ripening (S5-6). Therefore, if taking triterpenic acids as the major quality indicator, S5 should be the ideal time to harvest jujube fruit, and the full ripen stage (S6) maybe the best choice when taking sugars and cyclic nucleotides as the most important components.

Effect of ripening stage on phytosterols and phytostanols composition

Changes in 4-desmethylsterol, 4-monomethylsterol, 4,4-dimethylsterol and phytostanol composition were quantitatively and qualitatively investigated during the ripening of three varieties of Tunisian-grown pecan nuts (Mahan, Moore and Burkett). These components have many health benefits, especially in lowering LDL-cholesterol and preventing heart disease. The phytosterol composition of whole pecan kernel was quantified by Gas Chromatography-Flame Ionisation Detection (GC-FID) and identified by Gas Chromatography-Mass Spectrometry (GC-MS). Fifteen phytosterols and one phytostanol were quantified. The greatest amount of phytosterols (2852.5mg/100g of oil) was detected in Mahan variety at 20 weeks after the flowering date (WAFD). Moore had the highest level of phytostanols (7.3mg/100g of oil) at 20 WAFD. Phytosterol and phytostanol contents showed a steep decrease during pecan nut development. Results from the quantitative characterisation of pecan nut oils revealed that β-sitosterol, Δ5-avenasterol, and campesterol were the most abundant phytosterol compounds at all ripening stages.

Changes in resistant starch from two banana cultivars during postharvest storage

Banana resistant starch samples were extracted and isolated from two banana cultivars (Musa AAA group, Cavendish subgroup and Musa ABB group, Pisang Awak subgroup) at seven ripening stages during postharvest storage. The structures of the resistant starch samples were analysed by light microscopy, polarising microscopy, scanning electron microscopy, X-ray diffraction, and infrared spectroscopy. Physicochemical properties (e.g., water-holding capacity, solubility, swelling power, transparency, starch-iodine absorption spectrum, and Brabender microviscoamylograph profile) were determined. The results revealed significant differences in microstructure and physicochemical characteristics among the banana resistant starch samples during different ripening stages. The results of this study provide valuable information for the potential applications of banana resistant starches.

Chemical composition and oxidative stability of Tunisian monovarietal virgin olive oils with regard to fruit ripening

The chemical composition of virgin olive oil may be influenced by genotype and different agronomic (i.e. fruit ripeness degree, water supply) and technological factors. This article reports the evaluation of the influence of the olive ripening stage on the quality indices, the major and the minor components and the oxidative stability of the two main monovarietal Tunisian cultivars (cvv. Chétoui and Chemlali) virgin olive oils. Moreover, the olives cv. Chétoui were tested in a rain-fed control and an irrigation regime. The oils sampled at five different ripeness stages were submitted to liquid chromatographic determination (HPLC-DAD/MSD) of their quali-quantitative phenolic and tocopherolic profiles. Moreover, the triacylglycerol and fatty acid compositions, and minor components such as squalene, pigments and their relation with the oil oxidative stability were evaluated. The tested oils showed very good correlation between the oxidative stability and the concentrations of total phenols, practically secoiridoids and α-tocopherol.