Preharvest application of MeJA enhancing the quality of postharvest grape berries via regulating terpenes biosynthesis and phenylpropanoid metabolisms

Methyl jasmonate (MeJA) is an important phytohormone that regulates the development of grape, but the effect and underpin mechanism of its preharvest application on secondary metabolites accumulation in postharvest grape berries are still unclear. In this study, the transcriptome profiles combined with metabolic components analysis were used to determine the effect of preharvest MeJA application on the quality formation of postharvest rose-flavor table grape Shine Muscat. The results indicated that preharvest MeJA treatment had no significant effect on TSS content, but had a down-regulation effect on the accumulation of reducing sugar and titratable acid in the berries. The content of chlorophylls and carotenoids in treated berries was significantly higher than that of the control. Many phenolic components, such as trans-ferulic acid, resveratrol, quercetin, and kaempferol, were sensitive to MeJA and their contents were also significantly higher than that of the control under MeJA treatments during the shelf life. Compared with other volatile aroma components, terpenoid components were more sensitive to preharvest MeJA signals, the content of which presented an overall upward trend with increasing MeJA concentration and prolonging storage time. Furthermore, most of the differentially expressed genes in the general phenylpropanoid pathway and terpenoid biosynthesis pathway were up-regulated responding to MeJA signals. The most upregulated regulatory factors, such as VvWRKY72, VvMYB24, and VvWRI1, may be involved in MeJA signal transduction and regulation. Preharvest MeJA may be an effective technique for enhancing the quality of postharvest Shine Muscat grape berries, with its positive effect on enhancing the characteristic aroma and nutritional components.

Optimizing the extraction of phenolic antioxidants from date palm fruit by simplex-centroid solvent mixture design

Date palm (Phoenix dactylifera L.) fruits are rich in various bioactive compounds, such as phenolic acids, hydroxycinnamates, flavonoid glycosides, coumarins, alkaloids, and proanthocyanidin oligomers. The focus of this study was to develop a simplex-centroid mix design method to identify the most suitable mixture of solvents (water, acetone, and methanol) to extract bioactive compounds from date fruits. Three extraction solvents (water, methanol, and acetone) were investigated during this study to determine, total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (free radical DPPH) and ferric reduction ability (FRAP). The results showed that polar mixtures were effective in extracting antioxidant phenolics. The optimum solvent for extraction was Binary mixture water-acetone (50%) presenting TPC, TFC, DPPH and FRAP values of 502.88 mg GAE.100 g^-1 DW, 206.23 mg QE.100 g^-1 DW, 77 0.01% and 1688.66 μmol.100 g^-1 respectively. The results also confirmed a strong correlation between the amount of polyphenols in a given extract and the antioxidant activities observed in the DPPH and FRAP assays. This study presents a pragmatic and efficient way to choose a solvent combination to extract polyphenols from date palm fruits.

HPLC and high-throughput sequencing revealed higher tea-leaves quality, soil fertility and microbial community diversity in ancient tea plantations: compared with modern tea plantations

BACKGROUND

Ancient tea plantations with an age over 100 years still reserved at Mengku Town in Lincang Region of Yunan Province, China. However, the characteristic of soil chemicophysical properties and microbial ecosystem in the ancient tea plantations and their correlation with tea-leaves chemical components remained unclear. Tea-leaves chemical components including free amino acids, phenolic compounds and purine alkaloids collected from modern and ancient tea plantations in five geographic sites (i.e. Bingdao, Baqishan, Banuo, Dongguo and Jiulong) were determined by high performance liquid chromatography (HPLC), while their soil microbial community structure was analyzed by high-throughput sequencing, respectively. Additionally, soil microbial quantity and chemicophysical properties including pH, cation exchange capacity (CEC), soil organic matter (SOM), soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), alkali-hydrolyzable nitrogen (AN), available phosphorous (AP) and available potassium (AK) were determined in modern and ancient tea plantations.

RESULTS

Tea-leaves chemical components, soil chemicophysical properties and microbial community structures including bacterial and fungal community abundance and diversity evaluated by Chao 1 and Shannon varied with geographic location and tea plantation type. Ancient tea plantations were observed to possess significantly (P < 0.05) higher free amino acids, gallic acid, caffeine and epigallocatechin (EGC) in tea-leaves, as well as soil fertility. The bacterial community structure kept stable, while fungal community abundance and diversity significantly (P < 0.05) increased in ancient tea plantation because of higher soil fertility and lower pH. The long-term plantation in natural cultivation way might significantly (P < 0.05) improve the abundances of Nitrospirota, Methylomirabilota, Ascomycota and Mortierellomycota phyla.

CONCLUSIONS

Due to the natural cultivation way, the ancient tea plantations still maintained relatively higher soil fertility and soil microbial ecosystem, which contributed to the sustainable development of tea-leaves with higher quality.

Shiitake cultivation as biological preprocessing of lignocellulosic feedstocks - Substrate changes in crystallinity, syringyl/guaiacyl lignin and degradation-derived by-products

Formulation of substrates based on three hardwood species combined with modulation of nitrogen content by whey addition (0-2%) was investigated in an experiment designed in D-optimal model for their effects on biological preproceesing of lignocellulosic feedstock by shiitake mushroom (Lentinula edodes) cultivation. Nitrogen loading was shown a more significant role than wood species for both mushroom production and lignocellulose degradation. The fastest mycelial colonisation occurred with no nitrogen supplementation, but the highest mushroom yields were achieved when 1% whey was added. Low nitrogen content resulted in increased delignification and minimal glucan consumption. Delignification was correlated with degradation of syringyl lignin unit, as indicated by a significant reduction (41.5%) of the syringyl-to-guaiacyl ratio after cultivation. No significant changes in substrate crystallinity were observed. The formation of furan aldehydes and aliphatic acids was negligible during the pasteurisation and fungal cultivation, while the content of soluble phenolics increased up to seven-fold.

Effect of soaking and germination treatments on nutritional, anti-nutritional, and bioactive properties of amaranth (Amaranthus hypochondriacus L.), quinoa (Chenopodium quinoa L.), and buckwheat (Fagopyrum esculentum L.)

Pseudocereals have attracted the attention of nutritionists and food technologists due to their high nutritional value. In addition to their richness in nutritional and bioactive components, these are deficient in gluten and can serve as valuable food for persons suffering from gluten allergies. Processing treatments are considered an effective way to enhance the quality of food grains. Soaking and germination are traditional and most effective treatments for enhancing the nutritional and bioactive potential as well as reducing the anti-nutritional components in food grains. This study reflects the effect of soaking and germination treatments on nutritional, bioactive, and anti-nutritional characteristics of pseudocereals. There was a significant (p ≤ 0.05) increase in nutritional and bioactive components such as crude fiber, crude protein, phenolic components, antioxidant activity, and mineral content but reduced the anti-nutrients such as tannin and phytic acid. In amaranth, there was a significant increase (p ≤ 0.05) of 7.01, 74.67, 126.62, and 87.47% in crude protein, crude fiber, phenolic content, and antioxidant activity but significant (p ≤ 0.05) reduction of 32.30% and 29.57% in tannin and phytic acid contents, respectively. Similar changes in values of crude proteins, crude fiber, phenolic content, and antioxidant activity were observed in buckwheat and quinoa. While the anti-nutritional components such as tannin and phytic acid decreased by 59.91 and 17.42%, in buckwheat and 27.08% and 47.57%, in quinoa, respectively. Therefore, soaking and germination proved to be excellent techniques to minimize the anti-nutritional component and enhance the nutritional, bioactive, and antioxidant potential of these underutilized grains.

•

Pseudocereals were found to be a rich source of nutritional and bioactive components.

•

Processing treatments (soaking and germination) were found effective in improving the nutritional as well as bioactive components.

•

The anti-nutrients such as tannin and phytic acid contents decreased significantly thereby enhancing the nutritional potential of these underutilized grains.

The impact of different extracts of six Lamiaceae species on deleterious effects of oxidative stress assessed in acellular, prokaryotic and eukaryotic models in vitro

The main objective of this research was to evaluate the impact of methanolic, ethanolic and aqueous extracts of Origanum majorana L., Origanum vulgare L., Teucrium chamaedrys L., Teucrium montanum L., Thymus serpyllum L. and Thymus vulgaris L. (Lamiaceae) on the effects of free radicals using different model systems. The extracts were characterized on the basis of the contents of total phenolics, phenolic acids, flavonoids and flavonols, and also using high-performance liquid chromatography with diode-array detection. Antioxidant activity in vitro was assessed using DPPH assay. The genoprotective properties were tested using plasmid relaxation assay on pUC19 E. coli XL1-Blue, while SOS/umuC assay on Salmonella typhimurium TA1535/pSK1002 and Comet assay on human lung fibroblasts were used to assess the antigenotoxicity of the extracts. Ethanolic extracts had the most phenolics (up to 236.20 mg GAE/g at 0.5 mg/mL), flavonoids (up to 42.47 mg QE/g at 0.5 mg/mL) and flavonols (up to 16.56 mg QE/g at 0.5 mg/mL), and they exhibited the highest DPPH activity (up to 92.16% at 0.25 mg/mL). Interestingly enough, aqueous extracts provided the best protection of plasmid DNA (the lowest IC₅₀ value was 0.17 mg/mL). Methanolic extracts, on the other hand, most efficiently protected the prokaryotic DNA, while all the extracts had a significant impact against genomic damages inflicted on human fibroblasts. O. vulgare extracts are considered to be the most promising in preserving the overall DNA integrity against oxidative genomic damages. Moreover, HPLC-DAD analysis highlighted rosmarinic acid as the most abundant in the investigated samples (551.45 mg/mL in total in all the extracts), followed by luteolin-7-O-glucoside (150.19 mg/mL in total), while their presence correlates with most of the displayed activities. The novelty of this study is reflected in the application of a prokaryotic model for testing the antigenotoxic effects of Lamiaceae species, as no previous reports have yet been published on the genoprotective potential of these species.

Incorporation of pomegranate rind powder extract and pomegranate juice into frozen burgers: oxidative stability, sensorial and microbiological characteristics

This study was aimed to evaluate the antibacterial and antioxidant characteristics of incorporated pomegranate juice (PJ) and pomegranate rind powder extract (PRPE) into meat burgers. The peroxide value, thiobarbituric acid reactive substances, and metmyoglobin content for different burgers during 90 days storage at - 18 °C were evaluated. Total anthocyanin content, total phenolic content (TPC) and free radical scavenging activity (RSA or IC50) for PJ and PRPE were measured as 18.90 (mg/mL), 4380 ppm, 0.136 (mg/mL) and 0.40 (mg/mL), 5598 ppm, 0.084(mg/mL), respectively. Incorporation of PRPE with a high concentration of TPC resulted in less oxidation of lipid in comparison with other formulations. The highest and lowest scores in the sensory analysis and total acceptance at the 90th day corresponded to burgers containing PJ and control, respectively. Butylated hydroxytoluene may be substituted in whole or part with PJ and PRPE due to their desired effects on burgers' properties.

Nano-silicon alters antioxidant activities of soybean seedlings under salt toxicity

Materials with a particle size less than 100 nm are classified as nano-materials. The physical and chemical properties of nano-materials can vary considerably from those of bulk materials of the same composition. Silicon (Si) still fails to get recognized as an essential nutrient for plant growth and development, however the beneficial effects in terms of growth, biotic and abiotic stress resistance have been indicated in a variety of plant species for their growth. The aim of this study was to investigate the effects of different nano-silicon rates on the growth and antioxidant activities of soybean (Glycine max L. cv. M7) under salt stress. The results showed that salinity decreased shoot and root dry weight, potassium (K+) concentration in the root and leaf; however, increased sodium (Na+) concentration, catalase, peroxidase, ascorbate peroxidase and superoxide dismutase activities, phenolic components, ascorbic acid and α-tocopherol contents, lipid peroxidation, hydrogen peroxide, and oxygen radical's concentration. Between the treatments, 0.5 and 1 mM of nanosilicon oxide (nano-SiO2) improved shoot and root growth of seedlings. In contrast, a foliar application of SiO2 at 2 mM reduced the soybean growth. Overall, exogenous nano-silicon alleviated the salt stress by increase in K+ concentration, antioxidant activities, non-enzymatic compounds and decreasing of Na+ concentration, lipid peroxidation, and reactive oxygen species production.

Profiling of lipophilic and phenolic phytochemicals of four cultivars from cherimoya (Annona cherimola Mill.)

The lipophilic and phenolic extractives of the ripe mesocarp of four cherimoya cultivars ('Perry Vidal', 'Mateus I', 'Mateus III' and 'Funchal') from Madeira Island, were studied for the first time. The predominant lipophilic compounds are kaurene diterpenes (42.2-59.6%), fatty acids (18.0-35.6%) and sterols (9.6-23.7%). Kaur-16-en-19-oic acid is the major lipophilic component of all cultivars accounting between 554 and 1350mgkg(-1) of dry material. The studied fruits also contain a high variety of flavan-3-ols, including galloylated and non-galloylated compounds. Five phenolic compounds were identified for the first time: catechin, (epi)catechin-(epi)gallocatechin, (epi)gallocatechin, (epi)afzelechin-(epi)catechin and procyanidin tetramer. 'Mateus I' and 'Mateus III' cultivars present the highest content of phenolic compounds (6299 and 9603mgkg(-1) of dry weight, respectively). These results support the use of this fruit as a rich source of health-promoting components, with the capacity to prevent or delay the progress of oxidative-stress related disorders.

Components of a standardised olive leaf dry extract (Ph. Eur.) promote hypothiocyanite production by lactoperoxidase

We investigated in vitro the ability of a standardised olive leaf dry extract (Ph. Eur.) (OLE) as well as of its single components to circumvent the hydrogen peroxide-induced inhibition of the hypothiocyanite-producing activity of lactoperoxidase (LPO). The rate of hypothiocyanite (⁻OSCN) formation by LPO was quantified by spectrophotometric detection of the oxidation of 5-thio-2-nitrobenzoic acid (TNB). By using excess hydrogen peroxide, we forced the accumulation of inactive enzymatic intermediates which are unable to promote the two-electronic oxidation of thiocyanate. Both OLE and certain extract components showed a strong LPO-reactivating effect. Thereby an o-hydroxyphenolic moiety emerged to be essential for a good reactivity with the inactive LPO redox states. This basic moiety is found in the main OLE components oleuropein, oleacein, hydroxytyrosol, caffeic acid as well as in different other constituents including the OLE flavone luteolin. As LPO is a key player in the humoral immune response, these results propose a new mode of action regarding the well-known bacteriostatic and anti-inflammatory properties of the leaf extract of Olea europaea L.