Comprehensive responses of aroma production in 'Benihoppe' strawberry to low oxygen associated with the changes of key gene expressions and energy levels.

BACKGROUND: The influence of low oxygen on the biosynthesis of aroma-related esters and alcohols in strawberries has been well revealed. However, how low-oxygen conditions affect other volatile compounds, such as terpenes and furans, is still to be elucidated. RESULTS: The effects of 2 kPa O2 low oxygen on the biosynthesis of aroma in 'Benihoppe' strawberries were comprehensively investigated in this study. The results showed that, like esters, the accumulations of key terpene alcohols and furans in strawberries were also inhibited by 2 kPa O2 low oxygen during storage and subsequent shelf life, which was associated with the down-regulation of expression of FaNES1 (nerolidol synthase) and FaOMT (O-methyltransferase). However, no anaerobic fermentation occurred in 'Benihoppe' strawberries since no ethanol and acetaldehyde were produced under the 2 kPa O2 condition. As expected, the 2 kPa O2 condition suppressed the respiratory intensity and lowered the energy charge to maintain the quality of strawberries. The negative effects of low-oxygen storage on aroma accumulations and the energy charge of strawberries were more pronounced when transferred to the period of shelf life. CONCLUSION: The 2 kPa O2 condition caused a full-scale loss of aroma in 'Benihoppe' strawberries, including esters and alcohols as well as terpenes and furans, which was mainly reflected in the reduction of aroma emissions rather than the production of off-flavor, probably due to the reduced expressions of related genes and energy charge. © 2022 Society of Chemical Industry.

[Research progress in Raman spectra and its test sample pretreatment].

It is generally accepted that Raman spectroscopy is an advanced method with simple operation, small amount of specimens needed as well as rapid on-line screening, detection and identification. However, in the technology of determination, sample preparation is also an significant factor during analysis process. It would affect the accuracy and precision of the results, and normally involved complicated procedure. Developing a rapid and effective sample preparation method coupled with Raman detective technology is a method worth study. In the present paper, the simply basic principle, the origin and development of generating Raman spectra were introduced, some Raman technology, such as the surface-enhanced Raman spectroscopy, tip-enhanced Raman spectroscopy, shell-isolated nanoparticle enhanced Raman spectroscopy and the sample preparation were discussed.

Involvement of limonene hydroperoxides formed after oil gland injury in the induction of defense response against Penicillium digitatum in lemon fruit.

The effects of wounding oil glands of lemon [Citrus limon (L.) Burm.] fruit were investigated. Young mature-green lemons demonstrated significantly lower decay incidence than older yellow fruit when their oil glands were punctured in the presence of postharvest wound pathogen Penicillium digitatum Sacc. Contact with the released gland content on the green lemon surface reduced the viability of P. digitatum spores approximately twice. Wounding caused rapid production of limonene hydroperoxides that persisted for only a few minutes. The magnitude depended on the physiological maturity of the fruit; mature-green fruit produced much higher levels than did yellow lemons. Furthermore, wounding of the oil glands or injection of limonene hydroperoxides into the lemon peel elicited the production of the citrus fruit phytoalexins, scoparone and scopoletin, to levels known to be effective in reducing decay caused by P. digitatum. The mature-green fruit produced about twice as much of these phytoalexins as the older yellow fruit. This induced defensive elicitation of phytoalexin production, as well as the direct effects of these antifungal compounds, markedly inhibited the pathogen in mature-green fruits but was ineffective in older yellow ones.

Opposite Effects of Two-Derived Antioxidants from Physalis pubescens L. on Hepatocellular Carcinoma Cell Line Malhavu.

Physalis pubescens L. (P. pubescens) is an edible plant used in folk medicine in China. There is traditional, but not scientific, evidence for the anti-tumour effects of P. pubescens. This study aimed to identify whether, or not, antioxidants rich in phenols and flavonoids from fruits and calyxes of P. pubescens can be the candidates for further development of an anti-hepatoma fraction, and if such biological effects coupled with reactive oxygen species (ROS) changes, can provide a direction for subsequent biological action. The effects of calyx-origin (or fruit-origin) total phenol and flavonoid (CTPF or FTPF) from P. pubescens on Malhavu cell viability were evaluated by using a counting-kit-8 (CCK-8) method. Morphological characterisation of cells was undertaken and the structures were photographed (200 × magnification) using Hoechst 3348 staining after exposure to different concentrations of CTPF or FTPF. Induced-apoptosis activity was determined using flow cytometry (FC) after Annexin VFITC/ PI staining. The corresponding ROS changes in Malhavu cells were observed and quantified by the uploading of 2', 7'-dichlorofluorescin diacetate (DCFH-DA). Anti-oxidation was evaluated by a cellular oxidation-stress model and chemical assessments for DPPH, hydroxyl radial, super-oxide radicals, and reducing power. Result shows that CTPF led to significant anti-proliferation in a time- and dosedependent manner. However, FTPF promoted cell viability at 100-1000 µg/mL with a dose-response manner in 24 h. With the extension of exposure time to 48 h, the cell viability did not increase with the growth of FTPF. Morphological characterisation and FC assay both demonstrated that CTPF, and not FTPF possessed induced-apoptotic activity. CTPF potentially induced cell apoptosis by promoting oxidative stress. FTPF indicated pro-oxidation at a concentration of 10 µg/mL and anti-oxidation capabilities at higher concentrations. ROS scavenging assay by oxidation-stress model indicated that CTPF (10 - 400 µg/mL) had ROS inhibitory capacity (R2 = 0.5156, p < 0.0001). FTPF (10 - 100 µg/mL) boosted the level of ROS (p < 0.0001) and inhibited the generation of ROS at 100-400 µg/mL (R2 = 0.5951, p < 0.0001). CTPF is a potential candidate requiring further exploration for the development of antihepatoma ingredients. The down-regulation of cell viability was related to production and reduction of cellular ROS.

Modulation of Actinidia arguta fruit ripening by three ethylene biosynthesis inhibitors.

The purpose of this study was to investigate the effect of postharvest application of 1-methylecyclopropene (1-MCP), 1-pentylcyclopropene (1-PentCP) and 1-octylcyclopropene (1-OCP), two structural analogues of 1-MCP, on Actinidia arguta (Siebold et Zucc.) Planch. ex. Miq. Fruit post-harvest ripening and antioxidant activity. The results showed that these two structural analogues, just as 1-MCP, exerted their effect in a concentration-dependent manner. The most effective concentration of 1-MCP, 1-PentCP or 1-OCP treatment was 1.2 µl L(-1), 1.2 µl L(-1) and 0.8 µl L(-1), respectively. But, 0.8 µl L(-1) 1-OCP was found to be more potent in postponing the appearances of respiration rate peak and ethylene production peak, delaying the softening and weight loss, suppressing the activities of ACC synthase (ACS) and ACC oxidase (ACO), maintaining higher glutathione (GSH) content, activities of glutathione reductase (GR) and ascorbate peroxidase (APX), though slightly inferior to 1.2 µl L(-1) 1-MCP.