Effects of pre and post-harvest treatments on the phenolic compounds and antioxidant activity of different onion varieties

Onion (Allium cepa L.) is an important vegetable crop with an annual production of around 66 million tonnes worldwide. Onion and its by-products have the highest amount of quercetin content compared to other fruits and vegetables, which makes it a good free radical scavenging ability, contributing to its antioxidant capacity. Phytochemicals and antioxidants of onion are predominantly important for human health since phytochemicals have multiple compounds, including phenolics, flavonoids, anthocyanins, and quercetin. The total phenolic content of onions is not only higher than its fellow allium vegetables, such as garlic and leeks, but also higher than that of other common vegetables, such as carrots and red bell pepper. The main objective of this study was to investigate phenolic contents and antioxidant activity of different onion varieties by using different pre-harvest (soil, sunlight, climate, and fertiliser) and post-harvest (processing and storage) methods. In order to achieve this, several experiments have been designed and carried out among different onion varieties, particularly between organic and conventional ones. The first experimental chapter aimed to compare the total phenolic contents, total flavonoid contents, and antioxidant activity in onions grown under organic, conventional, and mixed cultivation practices in a multi-year experiment. ‘Hyskin’ and ‘Red Baron’ varieties had significantly higher phenolic contents and antioxidant properties in organic than in conventional production in most years. This study further investigated storage potential of organic and conventional onions at different storage conditions (-20 oC, 5 oC, and 25 oC with 60–75% relative humidity) for 10 weeks in the second experimental chapter. The findings suggested the fresh conventional onions were stored at -20 oC and 5 oC showed no significant quality (total phenolics, total flavonoids, flavonol, and antioxidant activity) loss. Meanwhile, the quality of dried organic onions remained stable during 10 weeks at -20 oC and 5 oC. Moreover, the third and fourth experimental chapters aimed to evaluate the effects of food thermal processing technologies on organic onions nutritional (the levels of phenolic compounds, colour and antioxidant properties). More specifically, this study firstly investigated the quality change in onions dried by different drying methods (freeze-drying, hot-air drying, vacuum oven drying, and oven drying) in comparison with fresh samples. Results indicated that the dried onion showed significantly higher total phenolic contents and antioxidant activity than those of undried onions. In order to reduce the energy involved and reducing the drying time in onion drying methods, blanching as a pre-treatment method optimizes the onion drying process. Therefore, the combination of a fast blanching and hot-air oven drying (60 oC) as a pre-treatment may be favorable since the application of heat treatment is the most common strategy for stabilising foods due to its capacity of destroying microorganisms and inactive enzymes. Since thermal processing, particularly blanching for a long time can negatively affect levels of phytochemicals in onions by experiencing a thermal breakdown or leakage of components, there is a growing interest in identifying new non-thermal strategies for the food industry. Finally, the last part of this thesis aimed to investigate the effects of ultrasonic pre-treatment (non-thermal) and blanching prior to hot-air or freeze-drying of onions on the retention of phenolic compounds. These results showed that ultrasound pre-treatment is a potential alternative to conventional blanching pre-treatment in the different drying onion slices. It may be used in a combination with other processing techniques to obtain high nutritive dehydrated onions compared to that of the products dried without the pre-treatment. In general, the research conducted in this thesis makes a notable contribution to the existing knowledge because it gives insights into pre and post- harvest conditions that contribute to high phenolic content and antioxidant activity in onions. The pre-harvest treatments and the novel approach to the post-harvest processing methods (blanching and ultrasound) can serve as ‘recommendations and guidelines’ for the industry or the agriculture authorities at a national level

Effect of storage, food processing and novel extraction technologies on onions flavonoid content: A review

peer-reviewedOnions play an important part in the daily diet for most populations around the world owing to their nutritional composition and their unique capacity to naturally flavor dishes. Onions contain quercetin and its derivatives - the predominant flavonoid in onions that exert a great contribution to the effective bioactive properties of onion, including its derived products. The present paper comprehensively reviewed flavonoids (with a specific focus on quercetin in onions): their chemical composition, distribution, bioactivities in onion, and impacting factors with a focus on how they can be affected by various post-harvest conditions (storage and food processing). In addition, research on the extraction of flavonoid compounds from onions using a number of novel technologies was also reviewed

Higher Antioxidant Activity, Total Flavonols, and Specific Quercetin Glucosides in Two Different Onion (Allium cepa L.) Varieties Grown under Organic Production: Results from a 6‑Year Field Study

We carried out a 6-year study to assess the effect of conventional, organic, and mixed cultivation practices on bioactive compounds (flavonoids, anthocyanins) and antioxidant capacity in onion. Total flavonoids, total anthocyanins, individual flavonols, individual anthocyanins, and antioxidant activity were measured in two varieties (‘Hyskin’ and ‘Red Baron’) grown in a long-term split-plot factorial systems comparison trial. This is the first report of repeated measurements of bioactive content over an extensive time period in a single crop type within the same trial. Antioxidant activity (DPPH and FRAP), total flavonol content, and levels of Q 3,4′ D and Q 3 G were higher in both varieties under fully organic compared to fully conventional management. Total flavonoids were higher in ‘Red Baron’ and when onions were grown under organic soil treatment. Differences were primarily due to different soil management practices used in organic agriculture rather than pesticide/ herbicide application

Transcriptomic response for revealing the molecular mechanism of oat flowering under different photoperiods

Proper flowering is essential for the reproduction of all kinds of plants. Oat is an important cereal and forage crop; however, its cultivation is limited because it is a long-day plant. The molecular mechanism by which oats respond to different photoperiods is still unclear. In this study, oat plants were treated under long-day and short-day photoperiods for 10 days, 15 days, 20 days, 25 days, 30 days, 40 days and 50 days, respectively. Under the long-day treatment, oats entered the reproductive stage, while oats remained vegetative under the short-day treatment. Forty-two samples were subjected to RNA-Seq to compare the gene expression patterns of oat under long- and short-day photoperiods. A total of 634-5,974 differentially expressed genes (DEGs) were identified for each time point, while the floral organ primordium differentiation stage showed the largest number of DEGs, and the spikelet differentiation stage showed the smallest number. Gene Ontology (GO) analysis showed that the plant hormone signaling transduction and hormone metabolism processes significantly changed in the photoperiod regulation of flowering time in oat. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Mapman analysis revealed that the DEGs were mainly concentrated in the circadian rhythm, protein antenna pathways and sucrose metabolism process. Additionally, transcription factors (TFs) involved in various flowering pathways were explored. Combining all this information, we established a molecular model of oat flowering induced by a long-day photoperiod. Taken together, the long-day photoperiod has a large effect at both the morphological and transcriptomic levels, and these responses ultimately promote flowering in oat. Our findings expand the understanding of oat as a long-day plant, and the explored genes could be used in molecular breeding to help break its cultivation limitations in the future

Association of brain morphology and phenotypic profile in patients with unruptured intracranial aneurysm

IntroductionStudies have found a varying degree of cognitive, psychosocial, and functional impairments in patients with unruptured intracranial aneurysms (UIAs), whereas the neural correlates underlying these impairments remain unknown.MethodsTo examine the brain morphological alterations and white matter lesions in patients with UIA, we performed a range of structural analyses to examine the brain morphological alterations in patients with UIA compared with healthy controls (HCs). Twenty-one patients with UIA and 23 HCs were prospectively enrolled into this study. Study assessment consisted of a brain magnetic resonance imaging (MRI) scan with high-resolution T1-weighted and T2-weighted imaging data, a Montreal Cognitive Assessment (MoCA), and laboratory tests including blood inflammatory markers and serum lipids. Brain MRI data were processed for cortical thickness, local gyrification index (LGI), volume and shape of subcortical nuclei, and white matter lesions.ResultsCompared to the HCs, patients with UIA showed no significant differences in cortical thickness but decreased LGI values in the right posterior cingulate cortex, retrosplenial cortex, cuneus, and lingual gyrus. In addition, decreased LGI values correlated with decreased MoCA score (r = 0.498, p = 0.021) and increased white matter lesion scores (r = −0.497, p = 0.022). The LGI values were correlated with laboratory values such as inflammatory markers and serum lipids. Patients with UIA also showed significant regional atrophy in bilateral thalami as compared to the HCs. Moreover, the LGI values were significantly correlated with thalamic volume in the HCs (r = 0.4728, p = 0.0227) but not in the patients with UIA (r = 0.11, p = 0.6350).DiscussionThe decreased cortical gyrification, increased white matter lesions, and regional thalamic atrophy in patients with UIA might be potential neural correlates of cognitive changes in UIA

Molecular Mechanisms and Applications of Polyphenol-Protein Complexes with Antioxidant Properties: A Review

Proteins have been extensively studied for their outstanding functional properties, while polyphenols have been shown to possess biological activities such as antioxidant properties. There is increasing clarity about the enhanced functional properties as well as the potential application prospects for the polyphenol–protein complexes with antioxidant properties. It is both a means of protein modification to provide enhanced antioxidant capacity and a way to deliver or protect polyphenols from degradation. This review shows that polyphenol–protein complexes could be formed via non-covalent or covalent interactions. The methods to assess the complex’s antioxidant capacity, including scavenging free radicals and preventing lipid peroxidation, are summarized. The combination mode, the type of protein or polyphenol, and the external conditions will be the factors affecting the antioxidant properties of the complexes. There are several food systems that can benefit from the enhanced antioxidant properties of polyphenol–protein complexes, including emulsions, gels, packaging films, and bioactive substance delivery systems. Further validation of the cellular and in vivo safety of the complexes and further expansion of the types and sources of proteins and polyphenols for forming complexes are urgently needed to be addressed. The review will provide effective information for expanding applications of proteins and polyphenols in the food industry

Long-Term Operation of a Pilot-Scale Sulfur-Based Autotrophic Denitrification System for Deep Nitrogen Removal

Sulfur-based autotrophic denitrification is a novel biological denitrification process characterized by the absence of an organic carbon source, a short reaction time, a high denitrification rate, a low treatment cost, and a small footprint. However, the technique is facing challenges with respect to engineering applications. In this study, a pilot-scale sulfur-based autotrophic denitrification system was established with an optimal hydraulic retention time (HRT) of 0.21 h, which achieved the highest denitrification load of 1158 mg/(L·d) and a denitrification rate of 164 gNO3−-N/(m3·h). Effective backwashing is the basis for the long-term stable and efficient nitrogen removal performance, which recovered its normal nitrogen removal performance within 0.5 h. In addition, the operation cost is merely 0.013 $/t, indicating that the sulfur-based autotrophic denitrification process presents good economic applicability, and the relatively low operation cost will lay a foundation for practical application

Evaluation of polyphenolic content and antioxidant activity in two onion varieties grown under organic and conventional production systems

BACKGROUND: Onions contain a number of bioactive compounds, in particular polyphenols. They are rich sources of such compounds in the human diet and offer significant health benefits to the consumer. Demand for organic crops is steadily increasing partly based on the expected health benefits of organic food consumption. The current study examines the influence of organic and conventional crop management practices on bioactive polyphenolic content of onion. RESULTS: We examined the effect of conventional, organic, and mixed cultivation practices on the content of total phenolics, total flavonoids and antioxidant activity in two varieties of onion grown over 4 years in a split-plot factorial systems comparison trial. Levels of total phenolics and total flavonoids showed a significant year-on-year variation and were significantly different between organic and conventional production systems. The levels of total phenolics, total flavonoids and antioxidant activity in general were significantly higher (P < 0.05) under fully organic compared to fully conventional management. CONCLUSION: Organic cultivation practices resulted in significantly higher levels of potential bioactive compounds in onion

A Multifrequency Brain Network-Based Deep Learning Framework for Motor Imagery Decoding

Motor imagery (MI) is an important part of brain-computer interface (BCI) research, which could decode the subject’s intention and help remodel the neural system of stroke patients. Therefore, accurate decoding of electroencephalography- (EEG-) based motion imagination has received a lot of attention, especially in the research of rehabilitation training. We propose a novel multifrequency brain network-based deep learning framework for motor imagery decoding. Firstly, a multifrequency brain network is constructed from the multichannel MI-related EEG signals, and each layer corresponds to a specific brain frequency band. The structure of the multifrequency brain network matches the activity profile of the brain properly, which combines the information of channel and multifrequency. The filter bank common spatial pattern (FBCSP) algorithm filters the MI-based EEG signals in the spatial domain to extract features. Further, a multilayer convolutional network model is designed to distinguish different MI tasks accurately, which allows extracting and exploiting the topology in the multifrequency brain network. We use the public BCI competition IV dataset 2a and the public BCI competition III dataset IIIa to evaluate our framework and get state-of-the-art results in the first dataset, i.e., the average accuracy is 83.83% and the value of kappa is 0.784 for the BCI competition IV dataset 2a, and the accuracy is 89.45% and the value of kappa is 0.859 for the BCI competition III dataset IIIa. All these results demonstrate that our framework can classify different MI tasks from multichannel EEG signals effectively and show great potential in the study of remodelling the neural system of stroke patients

Development and validation of a nomogram based on preoperative variables for predicting recurrence‐free survival in stage IA lung adenocarcinoma

Abstract Background This study aimed to establish a nomogram for predicting risk of recurrence and provide a model for decision‐making between lobectomy and sublobar resection in patients with stage IA lung adenocarcinoma. Methods Patients diagnosed with stage IA lung adenocarcinoma (LUAD) between December 2010 and October 2018 from Cancer Hospital Chinese Academy of Medical Sciences were included. Patients were randomly assigned to training and validation cohorts, accounting for 70% and 30% of the total cases, respectively. We collected laboratory variables before surgery. Univariate and multivariate analyses were performed in the training cohort to identify variables significantly associated with recurrence‐free survival (RFS) which were subsequently used to construct a nomogram. Validation was conducted in both cohorts. A receiver operating characteristic curve was used to determine the optional cutoff values of the scores calculated from the nomogram. Patients were then divided into low‐ and high‐risk groups. Survival was performed to determine if the nomogram could guide the operation method. Results A total of 543 patients were included in this study. Gender, albumin level, carcinoembryonic antigen level and cytokeratin‐19‐fragment level were included in the nomogram. In both cohorts, the nomogram stratified the patients into high‐ and low‐risk groups in terms of RFS. In particular, there was a significant difference in RFS between lobectomy and sublobar resection in the high‐risk group. Conclusions Gender, albumin level, carcinoembryonic antigen level and cytokeratin‐19‐fragment level are valuable markers in predicting recurrence and can guide surgical practice in patients with stage IA LUAD