Lotus Rhizome Research Articles

Optimization of slow-release fertilizer application improves lotus rhizome quality by affecting the physicochemical properties of starch

To achieve the dual goals of high yield and good quality with low environmental costs, slow-release fertilizer (SRF) has been widely used in lotus cultivation as new type of fertilizer instead of traditional nitrogen fertilizer. However, the optimal amount of SRF and how it would promote lotus rhizome quality remain unclear. This study was designed to investigate the photosynthetic characteristics and the synthesis, accumulation, and physicochemical properties of lotus rhizome starches under six SRF levels (CK, S1, S2, S3, S4, and S5). Compared with CK (0 kg ha–1), the net photosynthetic rate (Pn) and SPAD values of leaves remained at higher levels under SRF treatment. Further research showed that SRF increased the lotus rhizome yield, the contents of amylose, amylopectin, and total starch, and the number of starch granules. Among the six SRF levels, S3 (1 035 kg ha–1) showed the greatest difference from CK and produced the highest levels. With the increasing SRF levels, the peak, hot and final viscosities decreased at first and then increased, but the setback viscosity and pasting temperature increased. In order to interpret these changes at the molecular level, the activities of key enzymes and relative expression levels of starch accumulation related genes were analyzed. Each of these parameters also increased under SRF treatment, especially under the S3 treatment. The results of this study show that SRF, especially S3 (1 035 kg ha–1), is a suitable fertilizer option for lotus planting which can improve lotus rhizome quality by affecting starch accumulations related enzymes and genes. These results will be useful for SRF application to high-quality lotus rhizome production with low environmental costs.

Molecular mechanisms of antidiabetic effect of betulinic acid in lotus rhizome.

To explain the bio-physiological mechanisms of the antidiabetic effect of betulinic acid in Lotus rhizome. Even though Sri Lankan native medicine uses Lotus rhizome as a medicinal food for diabetes mellitus, its antidiabetic property has not been scientifically explained yet. It is found to compose several medicinally active components with antidiabetic properties, including Betulinic acid. A narrator review was conducted with a literature search in PubMed and Google Scholar databases using the search terms "Nelumbo nucifera rhizome", "Lotus rhizome", "phytochemicals", "antidiabetic effect", "hypoglycaemic effect" "Betulinic acid", and "molecular mechanism". The triterpenoid, Betulinic acid exerts its antidiabetic effect via seven bio-physiological mechanisms including, inhibiting α-glucosidase and α-amylase, upregulating the expression of peroxisome proliferator-activated receptor gamma coactivator-1 α, enhancing AS160 protein phosphorylation, stimulating adenosine monophosphate-activated protein kinase activation, stimulating Glucose transporter type 4 synthesis and translocation, inhibiting Protein Tyrosine Phosphatase 1 B activity preventing dephosphorylation of insulin receptor and stimulating Takeda-G-protein-receptor-5 resulting in an increased release of insulin from insulin-containing granulesCONCLUSION: The available scientific knowledge explains that betulinic acid in Lotus rhizome can improve glucose homeostasis contributing to the antidiabetic effect of this root (Tab. 1, Fig. 6, Ref. 29).

Nontarget Metabolites of Rhizomes of Edible Sacred Lotus Provide New Insights into Rhizome Browning

The “edible rhizome” variant of Nelumbo nucifera with various cultivars has a long history of use as a food in East Asia. In this study, 48 target metabolites were untargeted and identified in 212 rhizome cultivars (tropical and temperate types) using ultraperformance liquid chromatography-electrospray ionization quadrupole time-of-flight high-resolution mass spectrometry; among these, 32 compounds were newly reported in the rhizome. Combined with the browning phenotype of 212 lotus rhizomes, (epi) catechin, norarmepavine, and N-feruloyl-3-methoxytyramine were used as predominant chemical markers to separate different degrees of lotus rhizome browning. p-Coumaroyltyramine and N-trans-feruloyltyramine were selected as predominant chemical markers to investigate the differential expression between tropical and temperate lotus using principal component analysis and orthogonal partial least squares discriminant analysis. Shared and unique structure plots were used to compare the outcomes of the ecotype and browning OPLS model, showing that variation in tropical lotus rhizome browning is not obvious; this will be of great importance for genetic improvement by providing a hereditary basis.

Effect of Single and Dual Modifications on Properties of Lotus Rhizome Starch Modified by Microwave and γ-Irradiation: A Comparative Study.

A comparative study between two novel starch modification technologies, i.e., microwave (MI) and γ-irradiation (IR), is of important significance for their applications. The objective of this work is to compare the changes in lotus rhizome starch (LRS) subjected to single modifications by MI (thermal treatment) and IR (non-thermal treatment), and dual modification by changing the treatment sequence, i.e., microwave followed by irradiation (MI-IR) and irradiation followed by microwave (IR-MI). The amylose content of native and modified LRS varied from 14.68 to 18.94%, the highest and lowest values found for native and MI-LRS, respectively. IR-treated LRS showed the lowest swelling power (4.13 g/g) but highest solubility (86.9%) among native and modified LRS. An increase in light transmittance value suggested a lower retrogradation rate for dual-modified starches, making them more suitable for food application at refrigeration and frozen temperatures. Dual-modified LRS showed the development of fissures and dents on the surface of granules as well as the reduction in peak intensities of OH and CH2 groups in FTIR spectra. Combined modifications (MI and IR) reduced values of pasting parameters and gelatinization properties compared to native and microwaved LRS and showed improved stability to shear thinning during cooking and thermal processing. The sequence of modification also affected the rheological properties; the G′ and G″ of MI-IR LRS were lower (357.41 Pa and 50.16 Pa, respectively) than the IR-MI sample (511.96 Pa and 70.09 Pa, respectively), giving it a soft gel texture. Nevertheless, dual modification of LRS by combining MI and IR made more significant changes in starch characteristics than single modifications.

Evaluation of physicochemical properties and shelf life of regular‐fat model sausages by wrapping with sodium alginate active film containing different levels and drying method of lotus rhizome root powder

The objective of this study was to investigate shelf-life effect of regular-fat model sausages (RFMSs) wrapped with sodium alginate films (SAFs) containing 1% dried lotus rhizome root powder (LRRP) with different drying methods. After SAFs wrapping, the pH, moisture content, and expressible moisture of RFMSs were decreased, but the crude protein and fat contents tended to increase. 1% oven-dried LRRP was added to SAFs to make the SAFO, and its wrapping decreased total bacterial counts in RFMSs on day 21 and day 35. The microbial counts of Enterobacteriaceae of RFMSs wrapped with SAFO were lower than those of control RFMSs from day of 28 to day 35. RFMSs wrapped with SAFs containing LRRP had higher chewiness and cohesiveness than those of control RFMSs (p < 0.05). Therefore, SAFO wrapping can retard microbial growth and prolong the shelf-life of RFMSs since SAFs prevented microbial growth and LRRP had an antimicrobial activity.

Effects of different concentrations of ascorbic acid on the stability of (+) – Catechin under enzymatic conditions

A series of incubation systems of (+) - catechin (Cat), ascorbic acid (AA) and polyphenol oxidase (PPO) of lotus rhizome at 40 °C were performed to investigate the effect and oxidation pathway of AA on the stability of Cat. The results showed that after the enzymatic or non-enzymatic oxidation of Cat, the products of the two reactions were the same, namely epicatechin, catechin dimer and dehydrogenated catechin dimer. After adding AA, the protective effect of AA on catechin increased first and then decreased with the increase of AA concentration. 0.1 mmolL(exp)-1 AA can inhibit PPO activity in a short time. Within 24 h, 1 mmolL(exp)-1 AA can keep Cat content at 87.88 %. At the concentration of 10 mmolL(exp)-1 AA, excessive AA is oxidized to form a large amount of dehydroascorbic acid (DHAA), which forms an adduct with Cat, promoting the consumption of Cat. The effect of AA on the stability of Cat is time-dependent and dose-dependent.

Evaluation of antioxidant activities of lotus rhizome root powder prepared by different drying conditions and its application to raw and cooked pork patties

This study was to investigate the antioxidant activities of lotus rhizome root powders (LRRPs) prepared by different drying conditions and with different particle sizes, and the effect of LRRP on the physicochemical properties and shelf-life of raw and cooked patties. The total phenolic contents (TPCs) and total flavonoid contents (TFCs) of oven-dried LRRP (ODLRRP) at 100°C were higher than those of freeze-dried LRRPs (FDLRRPs) and ODLRRP at 60 or 80°C. TPCs, TFCs and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) values of LRRPs increased with increasing temperatures and decreasing particle sizes. The 2-thiobarbituric acid reactive substance (TBARS) values and volatile basic nitrogen (VBN) contents of raw patties with LRRPs added were decreased. Lightness, microbial counts of total bacteria and Enterobacteriaceae in raw patties, and the total bacterial counts of cooked patties with 1% ODLRRP at 100°C added were decreased. The redness of raw patties with FDLRRP added was increased, whereas the yellowness was increased by 100°C ODLRRPs addition. The color, TBARS, and VBN values of cooked patties with LRRPs added were decreased. The cooking process increased the TBARS and VBN but reduced microbial counts. Therefore, 1% 100°C ODLRRPs (< 150 μm) was effective in extending the shelf-life of raw and cooked patties during storage.

Sleep-promoting activity of lotus (Nelumbo nucifera) rhizome water extract via GABAA receptors

Context The sleep-promoting activity of Nelumbo nucifera Gaertn. (Nymphaeaceae) alkaloids in leaves or seeds are well known. However, the sleep-promoting activity of the lotus rhizome (LE), which is used mainly as food, has not yet been evaluated. Objective We investigated the sleep-promoting activity of LE water extract. Materials and methods Institute of Cancer Research (ICR) mice (n = 8) were subject to a pentobarbital-induced sleep test to assess changes in sleep latency and duration following the administration of LE (80–150 mg/kg). In addition, electroencephalography analysis was performed to determine the sleep quality after LE treatment as well as the sleep recovery effect of LE using a caffeine-induced insomnia SD rat model. Real-time PCR and western blot analysis were performed to investigate the expression of neurotransmitter receptors, and the GABAA receptor antagonists were used for receptor binding analysis. Results An oral administration of 150 mg/kg LE significantly increased sleep duration by 24% compared to the control. Furthermore, LE increased nonrapid eye movement (NREM) sleep by increasing theta and delta powers. In the insomnia model, LE increased sleep time by increasing NREM sleep. Moreover, treatment with picrotoxin and flumazenil decreased the sleep time by 33% and 23%, respectively, indicating an involvement of the GABAA receptor in the sleep-enhancing activity of LE. The expression of GABAA receptors and the concentration of GABA in the brain were increased by LE. Discussion and conclusions The results suggest that the sleep-promoting activity of LE was via the GABAA receptor. Collectively, these data show that LE may promote sleep.

Characterization of bacterial cellulose produced by Acetobacter pasteurianus MGC-N8819 utilizing lotus rhizome

Bacterial cellulose (BC) and its bacterial producers have been employed in valuable applications in the biomaterial, biomedicine and food industries. In this study, three novel strains were isolated from traditional rice vinegar and confirmed to be capable of producing BC, among which Acetobacter pasteurianus MGC-N8819 exhibited a relative high BC yield of 6.6 g/L in the Hestrin-Schramm (HS) medium. Furthermore, the agricultural lotus rhizome and its byproducts were investigated as an alternative source for BC synthesis by the novel strain. The combination of alpha-amylase and glucoamylase treatments effectively increased the release of the reduced sugar from rhizome byproducts, achieving a BC yield of 2.1 g/L and BC productivity of 0.26 g/(L·day). Though the BC yields of rhizome media were lower than that of the control HS medium, the rhizome-derived BC exhibited much better quality with great fiber diameter (57 nm), high crystallinity index (90.5%), tensile strength (82 MPa), elongation at break (26%) and thermal stability, indicating that the rhizome media promoted both the bacterial growth and specific BC synthesis. A. pasteurianus MGC-N8819 represents a valuable candidate for BC production and lotus rhizome byproducts can be reutilized for valuable BC production, which promises the wastes reduction during the lotus rhizome-related food processes.

Integrated mRNA and Small RNA Sequencing Reveals a microRNA Regulatory Network Associated with Starch Biosynthesis in Lotus (Nelumbo nucifera Gaertn.) Rhizomes.

Internode starch biosynthesis is one of the most important traits in lotus rhizome because of its relation to crop productivity. Understanding the microRNA (miRNA) and mRNA expression profiles related to lotus internode starch biosynthesis would help develop molecular improvement strategies, but they are not yet well-investigated. To identify genes and miRNAs involved in internode starch biosynthesis, the cDNA and small RNA libraries of Z6-1, Z6-2, and Z6-3 were sequenced, and their expression were further studied. Through combined analyses of transcriptome data and small RNA sequencing data, a complex co-expression regulatory network was constructed, in which 20 miRNAs could modulate starch biosynthesis in different internodes by tuning the expression of 10 target genes. QRT-PCR analysis, transient co-expression experiment and dual luciferase assay comprehensively confirmed that NnumiR396a down-regulated the expression of NnSS2 and ultimately prevents the synthesis of amylopectin, and NnumiR396b down-regulated the expression of NnPGM2 and ultimately prevents the synthesis of total starch. Our results suggest that miRNAs play a critical role in starch biosynthesis in lotus rhizome, and that miRNA-mediated networks could modulate starch biosynthesis in this tissue. These results have provided important insights into the molecular mechanism of starch biosynthesis in developing lotus rhizome.

Genome and Transcriptome Sequencing Analysis of Fusarium commune Provides Insights into the Pathogenic Mechanisms of the Lotus Rhizome Rot.

ABSTRACTFusarium wilt, a vascular wilt caused by F. commune, has been a serious problem for the lotus. Although some F. commune isolate genomes have been sequenced, little is known about the genomic information of the strain that causes Fusarium wilt of aquatic plants. In this study, the genome of F. commune FCN23 isolated from lotuses in China was sequenced using Illumina and PacBio sequencing platforms. The FCN23 genome consisted of 53 scaffolds with a combined size of 46,211,149 bp. According to the reference genome, F. oxysporum f. sp. lycopersici 4287 isolated from tomato, it was finally assembled into 14 putative chromosomes, including 10 core and 4 lineage-specific chromosomes. The genome contains about 3.45% repeats and encodes 14,698 putative protein-coding genes. Among these, 1,038 and 296 proteins were potentially secreted proteins and candidate effector proteins, respectively. Comparative genomic analysis showed that the CAZyme-coding genes and secondary metabolite biosynthesis genes of FCN23 were similar to those of other Ascomycetes. Additionally, the transcriptome of FCN23 during infection of lotus was analyzed and 7,013 differentially expressed genes were identified. Eight putative effectors that were upregulated in the infection stage were cloned. Among them, F23a002499 exhibited strong hypersensitive response after transiently expressed in Nicotiana benthamiana leaves. Our results provide a valuable genetic basis for understanding the molecular mechanism of the interaction between F. commune and aquatic plants.IMPORTANCE Fusarium commune is an important soilborne pathogen with a wide range of hosts and can cause Fusarium wilt of land plants. However, there are few studies on Fusarium wilt of aquatic plants. Lotus rhizome rot mainly caused by F. commune is a devastating disease that causes extensive yield and quality losses in China. Here, we obtained high-quality genomic information of the FCN23 using Illumina NovaSeq and the third-generation sequencing technology PacBio Sequel II. Compared to the reference genome F. oxysporum f. sp. lycopersici strain 4287, it contains 11 core and 3 lineage-specific chromosomes. Many differentially expressed genes associated with pathogenicity were identified by RNA sequencing. The genome and transcriptome sequences of FCN23 will provide important genomic information and insights into the infection mechanisms of F. commune on aquatic plants.

Effect of sodium alginate active film incorporating different lotus rhizome root powders on the physicochemical properties and shelf-life of low-fat model sausages

Low-fat model sausages (LFMSs) were wrapped in sodium alginate films (SAF) with different lotus rhizome root powders (LRRP) and their effects on the physicochemical properties and shelf-life effects of LFMSs were investigated. Oven-dried LRRP (OD LRRP) at 100 °C had the highest antioxidant activity among all LRRP. The pH values of SAF with 1% freeze-dried LRRP added were increased but decreased with 1% OD LRRP added. The lightness and thickness of the SAF decreased, but redness, yellowness, total color difference, and swelling ratio increased by the addition of LRRP. The antioxidant activity of SAF with 1% OD LRRP (SAFO) added were the best among all treatments. The 2-thiobarbituric acid reactive substances, total bacterial count, and Enterobacteriaceae of LFMSs wrapped in SAFO were decreased. The texture profile of LFMSs wrapped in SAF increased but the expressible moisture decreased. Therefore, LFMSs wrapped in SAFO might retard microbial growth and lipid oxidation during storage.

Possible Application of Hydrocolloid Edible Coating Layer to Enhance the Quality of Fried Lotus Rhizome

There is an increasing demand for healthier and functional products. Lotus (Nelumbonucifera) rhizome is as a case in point. It’s well naturally adapted in swamp regions as one of major crops in Mekong delta, Vietnam. It is rich in carbohydrates, essential minerals, soluble fibers, antioxidants, phytochemical constituents such as polyphenolics and oligomeric procyanidines. It’s extensively utilized as a traditional herbal medicine due to its strong antioxidant effect. Very small portion of total lotus rhizome cultivation undergo industrial processing. The processing of lotus parts into value added products must be encouraged to improve the market efficiency, generating employment for local laborers and accelerating income for rural farmers. During frying, oil absorption leads to negative effects in its flavour, odour and general organoleptic properties. The aim of this research was to investigate the in? uence of various hydrocolloids such as carrageenan, carboxymethyl cellulose, sodium alginate as edible coating layer to enhance the quality of fried lotus rhizome with respect to moisture reduction, oil uptake and overall acceptance. Different edible coating substances such as carrageenan, carboxymethyl cellulose, alginate in different concentrations (0.75%, 1.0%, 1.25%, 1.5% w/v) were examined on the lotus rhizome before frying at 190oC for 2.5 minutes in sunflower oil. Our results revealed that 1.25% carboxymethyl cellulose was appropriate for coating of the lotus rhizome. From this investigation it was hoped that, the functional and economic values of lotus rhizome would be enhanced.

Identification of QTLs and a putative candidate gene involved in rhizome enlargement of Asian lotus (Nelumbo nucifera).

QTL mapping studies identified threereliable QTLs of rhizome enlargement in lotus. NnBEL6 located within the confidence interval of the major QTL cqREI-LG2 is a key candidate gene enhancing rhizome enlargement. Lotus (Nelumbo) is perennial aquatic plant with nutritional, pharmacological, and ornamental significance. Rhizome is an underground lotus stem that acts as a storage organ and as a reproductive tissue for asexual production. The enlargement of lotus rhizome is an important adaptive strategy for surviving the cold winter. The aims of this study were to identify quantitative trait loci (QTLs) for rhizome enlargement traits including rhizome enlargement index (REI) and number of enlarged rhizome (NER), and to uncover their associated candidate genes. A high-density genetic linkage map was constructed, consisting of 2935 markers binned from 236,840 SNPs. A total of 14 significant QTLs were detected for REI and NER, which explained 6.7-22.3% of trait variance. Three QTL regions were repeatedly identified in at least 2years, and a major QTL, designated cqREI-LG2, with a rhizome-enlargement effect and about 20% of the phenotypic contribution was identified across the 3 climatic years. A candidate NnBEL6 gene located within the confidence interval of cqREI-LG2 was considered to be putatively involved in lotus rhizome enlargement. The expression of NnBEL6 was exclusively induced by rhizome swelling. Sequence comparison of NnBEL6 among lotus cultivars revealed a functional Indel site in its promoter that likely initiates the rhizome enlargement process. Transgenic potato assay was used to confirm the role of NnBEL6 in inducing tuberization. The successful identification QTLs and functional validation of NnBEL6 gene reported in this study will enrich our knowledge on the genetic basis of rhizome enlargement in lotus.

Mechanism of bluish pigment formation in lotus rhizome starch with ferrous sulfate and its application in rapid detection of adulteration

ABSTRACT Lotus rhizome starch (LRS) is an important traditional processed product of lotus rhizome in China due to its good taste and high nutritional value. However, adulterated lotus rhizome starches are prevalent on the market. In this study, a novel method for the rapid detection of adulteration in LRS based on color reaction between ferrous sulfate (FS) and (-)-gallocatechin (GC) in LRS was studied. The polyphenols in LRS were analyzed by liquid chromatography-mass spectrometry (LC-MS/MS) as GC and (+)-catechin, and GC could show a bluish color with FS solution. LRS showed a bluish color when FS solution (0.01 mol/L) was used as the chromogenic agent, which was not observed for other ten kinds of starches tested in this work. There was an obvious color gradient when FS solution was used to react with adulterated LRS at different proportions, and the change in blue color was obvious when maize starch or cassava starch was adulterated in LRS at the ratio of 6:4. Then, a semi-quantitative method was used to make a color card according to the color gradient, which was then successfully used to detect the adulteration of four kinds of commercial LRS. The results indicate that the proposed method may facilitate the simple, effective and efficient detection of adulteration in LRS.

LC-ESI-QTOF-MS/MS Characterization and Estimation of the Antioxidant Potential of Phenolic Compounds from Different Parts of the Lotus (Nelumbo nucifera) Seed and Rhizome.

Edible lotus (Nelumbo nucifera G.) is widely consumed in Asian countries and treated as a functional food and traditional medicinal herb due to its abundant bioactive compounds. Lotus rhizome peels, rhizome knots, and seed embryos are important byproducts and processing waste of edible lotus (Nelumbo nucifera G.) with commercial significance. Nevertheless, the comprehensive phenolic profiling of different parts of lotus is still scarce. Thus, this study aimed to review the phenolic contents and antioxidant potential in lotus seeds (embryo and cotyledon) and rhizomes (peel, knot, and pulp) grown in Australia. In the phenolic content and antioxidant potential estimation assays by comparing to the corresponding reference standards, the lotus seed embryo exhibited the highest total phenolic content (10.77 ± 0.66 mg GAE/gf.w.), total flavonoid content (1.61 ± 0.03 mg QE/gf.w.), 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity (9.66 ± 0.10 mg AAE/gf.w.), 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) scavenging activity (14.35 ± 0.20 mg AAE/gf.w.), and total antioxidant capacity (6.46 ± 0.30 mg AAE/g), while the highest value of ferric ion reducing antioxidant power (FRAP) activity and total tannin content was present in the lotus rhizome knot (2.30 ± 0.13 mg AAE/gf.w.). A total of 86 phenolic compounds were identified in five parts of lotus by liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS/MS), including phenolic acids (20), flavonoids (51), lignans (3), stilbenes (2), and other polyphenols (10). The most phenolic compounds, reaching up to 68%, were present in the lotus seed embryo (59). Furthermore, the lotus rhizome peel and lotus seed embryo exhibit significantly higher contents of selected polyphenols than other lotus parts according to high-performance liquid chromatography (HPLC) quantification analysis. The results highlighted that byproducts and processing waste of edible lotus are rich sources of phenolic compounds, which may be good candidates for further exploitation and utilization in food, animal feeding, and pharmaceutical industries.

The Effect of Nitrogen Fertilizer on Rhizome Quality and Starch Physicochemical Properties in Nelumbo nucifera

Optimal nitrogen (N) supply significantly increases the starch content, components, and yield of Nelumbo nucifera. However, the underlying transcriptional mechanism and starch accumulation under dose-dependent nitrogen fertilizer are poorly understood. In this study, we found that the optimal nitrogen fertilizer (N2, 30 kg/667 m2) was more beneficial to improve the stomatal conductance (Gs), leaf intercellular CO2 concentration (Ci), transpiration rate (Tr), net photosynthetic rates (Pn), chlorophyll content, starch content, and plot yield. What is more, N2-fertilizer treatment induced a higher number of starch granule, AP2 content, and RVA curve peaks. Then, the transcriptomic analyses performed in control (CK) and N2-fertilizer treatment (N2) showed that the expressions of many differentially expressed genes (DEGs) were significantly induced by N2. KEGG and GO enrichment analysis showed that these DEGs were significantly enriched in biosynthesis of secondary metabolites, phenylpropanoid biosynthesis, carbon metabolism, carbon fixation in photosynthetic organisms, plant hormone signal transduction, and starch and sucrose metabolisms, suggesting that nitrogen fertilizer induced alterations of photosynthesis- and starch accumulation-related gene expression profiles. Finally, six photosynthesis-related genes and fourteen starch synthesis-related genes were confirmed to be required for starch accumulation in the Nelumbo nucifera development. qPCR analysis of six starch accumulation-related genes demonstrated the accuracy of the transcriptome. Hence, our study provides valuable resource for future studies on molecular mechanisms underlying starch accumulation in Nelumbo nucifera rhizome under N-fertilizer treatment.

Effects of lotus rhizome root powder made by different levels and drying methods on the physicochemical properties and antioxidant activity of regular‐fat model sausages

SummaryThe effects on physicochemical properties and shelf‐life of regular‐fat model sausages (RFMSs) added with oven‐dried or freeze‐dried lotus rhizome root powder (LRRP, ≤150 µm) at two different concentrations (0.5% or 1%) were investigated in this study. RFMSs added with LRRP showed decreased lightness (L*), reduced microbial counts, and thiobarbituric acid‐reactive substances (TBARS), but increased redness (a*), yellowness (b*), hardness, and cohesiveness. The changes in L*, a*, and b* of RFMSs treated with 1% oven‐dried LRRP were the largest. Furthermore, addition of 1% oven‐dried LRRP to the RFMSs minimised the TBARS value and the microbial count. RFMSs treated with LRRP had a denser and more compact microstructure than RFMSs without LRRP based on low‐vacuum scanning electron microscopy analysis. Therefore, LRRP improved the shelf‐life of RFMSs, especially 1% oven‐dried LRRP inhibited the maximum lipid oxidation and microbial growth.

The mechanism of interaction between lotus rhizome polyphenol oxidase and ascorbic acid: Inhibitory activity, thermodynamics, and conformation analysis.

In this study, the interaction between lotus rhizome polyphenol oxidase (PPO) and ascorbic acid (AA) was discussed from the aspects of inhibitory activity, thermodynamics, and conformation. Results showed that PPO was purified from lotus rhizome by DEAE-52 anion exchange chromatography and Sephadex G-100 gel filtration chromatography, with its optimum substrate being determined as pyrogallic acid. Spectrophotometric and polarographic assays demonstrated that AA exhibited strong inhibitory activity against PPO. Thermodynamics, fluorescence, and circular dichroism spectral analysis showed that hydrophobic interactions caused the formation of AA-PPO complex, leading to the remarkable fluorescence quenching and conformational change of PPO. Atomic force microscopic analysis revealed that binding to AA induced significant changes in the surface morphology and molecular aggregation of PPO molecules. In this study, the interaction mechanism between PPO and AA was proposed for the first time, which provided a theoretical basis for AA to inhibit lotus rhizome browning. PRACTICAL APPLICATIONS: Lotus rhizome, an aquatic vegetable, is prone to enzymatic browning in processing operations, which leads to a decrease in market value and economic loss. At present, ascorbic acid (AA) is widely used in industries as an excellent antioxidant because of its good antibrowning effect and relatively low cost. However, the interaction between the enzymatic browning-related polyphenol oxidase (PPO) from lotus rhizome and ascorbic acid has not been clearly studied. Understanding the mechanism of inhibiting PPO will help to prevent vegetable browning, especially fresh-cut products. The inhibitory effect of AA on PPO in lotus rhizome favors simultaneous use with other types of PPO inhibitors because of their likely synergistic effects.

Drying of lotus rhizome slices: Influence of drying conditions on Fourier transform infrared spectroscopy, rheology, functional, and physicochemical characteristics of lotus rhizome powder

AbstractFresh lotus rhizome has a limited harvesting duration and is prone to browning leading to fast decomposition. Lotus rhizome powder (LRP) can be an innovative substitute to unravel this difficulty, valorize the product and improve its export potential. Microwave blanched lotus rhizome (LR) slices revealed the logarithmic model as the best drying model of fresh LR slices. Water activity (Aw) portrayed strong dependence on drying time; color parameters, a* increased, while L* and b* decreased with slice thickness. Water and oil absorption capacity (WAC and OAC) of lotus rhizome powder (LRP) changed from 4.95 to 1.68 g/g and 2.99 to 0.52 g/g, respectively, with a sharp increase in OAC of samples dried at 80°C. Storage modulus (G′) was higher than loss modulus (G″). Samples of 3 mm thickness dried at 50, 60 and, 70°C had the lowest flow behavior index (n) of 0.2219. Fourier transform infrared spectra of LRP displayed regions of polyphenols with slight deviations for different drying temperatures. It was concluded that 3 mm thick slices dried at 60–80°C required lesser time and possessed better WAC, OAC, and color values.Practical ApplicationsRecently, vegetable powders have driven the attention of food process engineers due to their stability and wide nutritional gamut. Thus, it is attempted to develop and characterize the Lotus (Nelumbo nucifera Gaertn) rhizome powder which will not only make it readily available but will find its practical utilization as an ingredient in food formulations. Lotus rhizome powder is a unique blend of nutrients and bioactive components; therefore, it is important to understand its properties, drying behavior, and engineer the powder development with maximum functionality. Primarily, the lotus rhizome being a perishable vegetable, can be improved for shelf‐life stability and safety. Secondarily, the lotus rhizome powder can be incorporated as the functional ingredient, in flavoring, food, and pharmaceutical industry. Therefore, it is of prime significance to add value to this aquatic vegetable to make it an ideal food resource in the future.