Thick Rind Research Articles

Molecular Markers and Marker-Assisted Selection Provide Genetic Insights for Identifying Key Quantitative Trait Locus for Watermelon Rind Thickness.

Rind thickness (RT) is an important agronomic trait in watermelon [Citrullus lanatus (Thunb.) Mansf.] and affects watermelon storability. However, genetic studies on this trait, as well as gene regulation studies, are scarce and of limited production significance. We constructed a temporary F2 generation using the highly differentiated thick-rind watermelon 'XiaoXiGua-4' and the thin-rind watermelon 'DuanMan' as parents and localized the Cla97C02G044120 gene, which controls the thickness of watermelon rind, to the intervals of chromosome 2, CL2-32303995 and CL2-32316840, through 2 years of genetic analysis. No exonic mutations were found in this gene, but two promoter mutations resulted in changes in the promoter progenitor. Fluorescence quantitative PCR analysis revealed highly significant differences in expression at 1 d and 28 d, and the expression was significantly lower in thick-skinned watermelon varieties. Marker-assisted selection (MAS) for this trait was performed using the Caps marker CL2-32303995 and the InDel marker CL2-32316840, which not only verified the stability of the localization interval but also distinguished thick rind from thin rind. These results can be used for germplasm resource screening and have strong breeding significance.

Development of a unified framework of low-rank approximation and deep neural networks for predicting the spatial variability of SSC in `Spania' watermelons using vis/NIR hyperspectral imaging

Soluble Solids Content (SSC) is an important quality attribute that represents the internal quality of fruits. Visible and near-infrared (Vis/NIR) combined with chemometric algorithms are now popular methods for non-invasive measurement and visualization of SSC. However, in fruits with a thick rind and a large flesh volume, such as watermelon, SSC is not evenly distributed across the fruit. The variability in SSC across the fruit flesh may have an adverse effect on the accuracy of quality analysis algorithms. Thus, this paper presents an accurate and efficient approach for predicting the spatial variation of SSC in watermelons using a combined framework of low-rank approximation and deep neural networks. Watermelon ‘Spania’ was selected for this study, and hyperspectral images of each watermelon were taken from various views, including the top, bottom, and two lateral views. The low-rank property is employed as a constraint in this approach to eliminate the unwanted variations in the spectral data. The low-rank component of the spectral data, free of unwanted variations, is then fed into a fully connected neural network (FNN) for the prediction of watermelon SSC values. The proposed approach obtained optimal performance in calibration and prediction with RC2=0.982, RMSEP = 0.132, and RP2=0.945, RMSEP = 0.195 respectively. Further, the prediction outcomes of the proposed method were compared with state-of-the-art such as Partial Least Square Regression (PLSR), Support Vector Regression (SVR), Multiple Linear Regression (MLR), Decision Tree (DT), and Random Forest (RF). The overall results showed that combining HSI data with a low-rank and deep neural network framework is an efficient method for accurately predicting SSC in watermelons as well as correctly predicting spatial variability of SSC in individual fruits.

Advancement of non-destructive spectral measurements for the quality of major tropical fruits and vegetables: a review.

The quality of tropical fruits and vegetables and the expanding global interest in eating healthy foods have resulted in the continual development of reliable, quick, and cost-effective quality assurance methods. The present review discusses the advancement of non-destructive spectral measurements for evaluating the quality of major tropical fruits and vegetables. Fourier transform infrared (FTIR), Near-infrared (NIR), Raman spectroscopy, and hyperspectral imaging (HSI) were used to monitor the external and internal parameters of papaya, pineapple, avocado, mango, and banana. The ability of HSI to detect both spectral and spatial dimensions proved its efficiency in measuring external qualities such as grading 516 bananas, and defects in 10 mangoes and 10 avocados with 98.45%, 97.95%, and 99.9%, respectively. All of the techniques effectively assessed internal characteristics such as total soluble solids (TSS), soluble solid content (SSC), and moisture content (MC), with the exception of NIR, which was found to have limited penetration depth for fruits and vegetables with thick rinds or skins, including avocado, pineapple, and banana. The appropriate selection of NIR optical geometry and wavelength range can help to improve the prediction accuracy of these crops. The advancement of spectral measurements combined with machine learning and deep learning technologies have increased the efficiency of estimating the six maturity stages of papaya fruit, from the unripe to the overripe stages, with F1 scores of up to 0.90 by feature concatenation of data developed by HSI and visible light. The presented findings in the technological advancements of non-destructive spectral measurements offer promising quality assurance for tropical fruits and vegetables.

Performance of colored capsicums as affected by plant training systems in a naturally ventilated polyhouse

ABSTRACT The yield and quality of capsicum fruit is affected by plant training system due to the number of branches and fruit retained. More branches on a plant result in nutritional imbalance in fruit, lowering yield and fruit quality. Developing an appropriate plant training system for bell pepper (Capsicum annuum L. var. grossum Sendt.) under protected structures may help obtain the highest yield. A two-year (2018–2019, 2019–2020) study was undertaken to monitor the performance of bell pepper (green = “Indra,” red = “Inspiration,” and yellow = “Bachata”) cultivated in a naturally ventilated polyhouse as affected by training systems (T1 = un-trained, T2 = two-shoot, T3 = three-shoot and T4 = four-shoot). A benefit-cost analysis was also included. Among training systems, T1 had taller plants, larger and heavier fruit, thicker rinds and longer self-life, but fewer fruit; T4 had the highest yield of 3.54, 2.66 and 2.93 kg/plant for “Indra,” “Inspiration” and “Bachata,” respectively. Among cultivars, “Indra” had the tallest plants, longest shelf-life, and “Bachata” had the earliest flowering and thickest rind. The cost:benefit values for T4 and T2 were 1.31–1.1.55 and 1.39–1.61, respectively, indicating economic viability.

Pomelo Juice–Drug Interactions: A Word of Caution

The main of this article is to study the interactions of certain commonly used drugs with pomelo juice which is commonly consumed as easily available fruit or fruit juice in certain parts of India. Relevant literature was identified by searching PubMed and other articles on the web. Various search words which were used are “Grapefruit,” “pomelo,” “drug interactions,” and “juice-drug interactions.” Inclusion criteria included grapefruit juice–drug interaction studies and pomelo juice–drug interactions. Exclusion criteria were articles actually irrelevant to the juice–drug interaction topics. After reviewing the summary of each article, few articles were directly excluded because of actually irrelevant topics. Finally, eight articles were selected as reference articles and certain data were obtained and our opinion about the same is mentioned in the present article. The full text of each included article was critically reviewed, and valuable information was summarized by data interpretation. Pomelo “(Citrus maxima/Citrus grandis)” is the largest citrus fruit from the family Rutaceae and the principal ancestor of the grapefruit. It is a natural, nonhybrid citrus fruit native to Southeast Asia. Pomelo is commonly consumed and used for festive occasions throughout Southeast Asia. It has also been found to have drug interactions similar to grapefruit. The fruit is large, 15–25 cm in diameter, and weighing 1–2 kg. It has a thicker rind than the grapefruit and is divided into 11–18 segments. Pomelo is closely related to grapefruit and extensively studied and contains furanocoumarins which have been identified as inhibitors of cytochrome P450 3A4 in grapefruit juice in vitro. The fruit was first described in 1750 by Griffith Hughes, and in 1789, Patrick Browne referred to it as “forbidden fruit” or “smaller shaddock.” Its taste also varies from sour or bitter to sweet. The fruit is nearly round or slightly pear shaped in clusters similar to grapes, 10–15 cm wide with smooth, finely dotted peel, up to 1 cm thick. The pulp is yellow or pink to red, which has 11–14 segments with thin membrane. The fruit is very juicy. The fruit presents with pointed seeds about 1.25 cm in length. In Karnataka, a type of pomelo named Devanahalli pomelo (Gi registered) is exclusively grown in the region around Devanahalli taluk, Bangalore, as an exotic crop variety. It is locally known as chakkota. Besides, pomelo has many names such as batabi lebu or jambura in Bengali and chakotra in Hindi-speaking states. In the present pandemic outbreak, in-home consumption of packaged fruit juices has increased among people in the cities, whereas in-home consumption of easily grown and easily available fruits such as pomelo, grapes, apples, and their juices has increased among people in the villages. Hence, caution is required while consuming pomelo juice (similar to grapefruit juice) with certain drugs.

The Essential Oil of Citrus lumia Risso and Poit. 'Pyriformis' Shows Promising Antioxidant, Anti-Inflammatory, and Neuromodulatory Effects.

Citrus lumia Risso and Poit. 'Pyriformis' are horticultural varieties of Citrus lumia Risso. The fruit is very fragrant and pear-shaped, with a bitter juice, a floral flavor, and a very thick rind. The flavedo shows enlarged (0.74 × 1.16 mm), spherical and ellipsoidal secretory cavities containing the essential oil (EO), visible using light microscopy, and more evident using scanning electron microscopy. The GC-FID and GC-MS analyses of the EO showed a phytochemical profile characterized by the predominance of D-limonene (93.67%). The EO showed interesting antioxidant and anti-inflammatory activities (IC50 0.07-2.06 mg/mL), as evaluated by the in vitro cell-free enzymatic and non-enzymatic assays. To evaluate the effect on the neuronal functional activity, the embryonic cortical neuronal networks grown on multi-electrode array chips were exposed to non-cytotoxic concentrations of the EO (5-200 µg/mL). The spontaneous neuronal activity was recorded and the mean firing rate, mean burst rate, percentage of spikes in a burst, mean burst durations and inter-spike intervals within a burst parameter were calculated. The EO induced strong and concentration-dependent neuroinhibitory effects, with IC50 ranging between 11.4-31.1 µg/mL. Furthermore, it showed an acetylcholinesterase inhibitory activity (IC50 0.19 mg/mL), which is promising for controlling some of the key symptoms of neurodegenerative diseases such as memory and cognitive concerns.

Determination of moisture loss of pomegranate cultivars under cold and shelf storage conditions and control strategies

Pomegranates are prone to moisture loss, despite having a thick rind.

"THE HEALTH BENEFITS OF WATERMELON "

"Watermelon (Citrulus lantus) is an important horticultural crop which belongs to the Curcubitaceae family. The nutraceutical potential of watermelon has been illustrated by several researchers, which makes it a better choice of functional food. Watermelon has been used to treat various ailments, such as cardio-vascular diseases, aging related ailments, obesity, diabetes, ulcers, and various types of cancers. The medicinal properties of watermelon are attributed by the presence of important phytochemicals with pharmaceutical values such as lycopene, citrulline, and other polyphenolic compounds. Watermelon acts as vital source of l-citrulline, a neutral-alpha amino acid which is the precursor of l-arginine, an essential amino acid necessary for protein synthesis. Watermelon is a natural product that contains high level of antioxidants and may prevent oxidative damage in tissues due to free radical generation following an exposure to ionizing radiation. The present study aimed to investigate the radioprotective effects of watermelon. Watermelon is a member of the Cucurbitaceae family native to tropical areas of Africa near Kalahari Desert. Botanists refer it as a «pepo» which is a fruit having a thick rind and fleshy center. It is largely consumed as refreshing summer fruit, much appreciated by the consumers because of its refreshing capability, attractive color, delicate taste, and high water content to quench the summer thirst. According to Oberoi, D. and Sogi S., watermelon fruits yield 55.3 % juice, 31.5 % rind, and 10.4 % pomace. Carotenoids such as lycopene and β-carotene are responsible for the red and orange colors of the watermelon, respectively The sweetness of watermelon is mainly due to a combination of sucrose, glucose, and fructose. Sucrose and glucose account for 20–40 % and fructose for 30–50 % of total sugars in a ripe watermelon. Keywords: watermelon, nutrients, antioxidants, diseases, and consumption. "

High-Throughput Phenotyping of Cross-Sectional Morphology to Assess Stalk Mechanical Properties in Sorghum

Lodging is one of the major constraints in attaining high yield in crop production. Major factors associated with stalk lodging involve morphological traits and anatomical features along with the chemical composition of the stem. However, little relevant research has been carried out in sorghum, particularly on the anatomical aspects. In this study, with a high-throughput procedure newly developed by our research group, the nine parameters related to stem regions and vascular bundles were generated in 58 sorghum germplasm accessions grown in two successive seasons. Correlation analysis and principal component analysis were conducted to investigate the relationship between anatomical aspects and stalk mechanical traits (breaking force, stalk strength and lodging index). It was found that most vascular parameters were positively associated with breaking force and lodging index with the correlation coefficient r varying from −0.46 to 0.64, whereas stalk strength was only associated with rind area with the r = 0.38. The germplasm resources can be divided into two contrasting categories (classes I with 23 accessions and II with 30 accessions). Compared to class II, the class I was characterized by a larger number (+40.7%) and bigger vascular bundle (+30%), thicker stem (+19.6%) and thicker rind (+36.0%) but shorter internode (plant) (−91.0%). This study provides the methodology and information for the studies of the stem anatomical parameters in crops and facilitates the selective breeding of sorghum.

Assessment of watermelon maturity using portable new generation NIR spectrophotometers

The non-destructive evaluation of internal maturity in watermelons, which are large fruits with a thick rind, during their development on the vine can be considered as a challenge for the growing sector. Near infrared spectroscopy (NIRS) was used to assess in situ soluble solid content (SSC), the main parameter to establish full maturity, in 249 intact watermelons, of which, 152 had a striped light green rind and 97 a solid dark green rind. Two handheld new generation spectrophotometers were compared for this purpose. Different pre-processing methods and the partial least squares (PLS) regression algorithm were used to build global calibration models and specific calibration models for each one of the two types of watermelon analysed. The results obtained for the global models showed that NIRS is a suitable technology for screening the fruit for maturity, and that the linear variable filters (LVF) sensor is the best equipment for this purpose (SECV = 1.02%; RPDp = 1.36). Moreover, the best results were obtained when different models were used depending on the type of watermelon. Additionally, near infrared (NIR) classification models were developed to discriminate the samples by stage of maturity for each type of watermelon available, using partial least squares discriminant analysis (PLS-DA). The optimum threshold values for the striped light green and solid dark green rind watermelons (0.82 and 0.65, respectively) were displaced from the mean value of the discriminant variable due to the differences in terms of number of samples per class used. A total of 66.4% and 82.2% of the striped light green and solid dark green rind watermelons, respectively, were correctly classified. The results of this study demonstrated the viability of using NIRS technology as a decision-making support tool to measure the maturity of watermelons and to establish the optimum harvest time of watermelons and therefore meet the consumers’ demand for sweet-tasting fruits. Further studies will be needed to improve calibration robustness, and to further interpret outdoor applications in fruits with thick rind.

Transcriptome analysis reveals the mechanism of internode development affecting maize stalk strength

BackgroundThe stalk rind is one of the important factors affecting maize stalk strength that is closely related to stalk lodging. However, the mechanism of rind development in maize is still largely unknown.ResultsIn this study, we analyzed the mechanical, anatomical, and biochemical properties of the third basal internode in one maize non-stiff-stalk (NSS) line and two stiff-stalk (SS) lines. Compared with the NSS line, the two SS lines had a significantly higher rind penetrometer resistance, thicker rind, and higher dry matter, hemicellulose, cellulose, and lignin weights per unit length. RNA-seq analysis was used to compare transcriptomes of the third basal internode of the two SS lines and the NSS line at the ninth leaf and tasseling stages. Gene Ontology (GO) enrichment analysis revealed that genes involved in hydrolase activity (hydrolyzing O-glycosyl compounds) and cytoskeleton organization were significantly up-regulated in the two SS lines at the ninth leaf stage and that microtubule process-related genes were significantly up-regulated in the two SS lines at the tasseling stage. Moreover, the two SS lines had enhanced expression of cell wall metabolism-related genes at the tasseling stage.ConclusionsThe synthesis of cell wall polysaccharides and the cytoskeleton might play important roles in internode development. Our results can be applied for screening lodging-resistant inbred lines and breeding lodging-resistant cultivars in maize.

Kidney Preservation and Wilms Tumor Development in Children with Diffuse Hyperplastic Perilobar Nephroblastomatosis: A Report from the Children's Oncology Group Study AREN0534.

Diffuse hyperplastic perilobar nephroblastomatosis (DHPLN) represents a unique category of nephroblastomatosis. Treatment has ranged from observation to multiple regimens of chemotherapy. Wilms tumors (WTs) develop in 100% of untreated patients and between 32 and 52% of treated patients. Renal preservation rates have not been previously reported. An aim of the Children's Oncology Group (COG) study AREN0534 was to prospectively evaluate the efficacy of chemotherapy in preserving renal units and preventing WT development in children with DHPLN. Patients were enrolled through the COG protocol AREN03B2 with central radiological review. DHPLN was defined as the cortical surface of the kidney being composed of hyperplastic rests, with the entire nephrogenic zone involved, and with a thick rind capping all of one or both kidneys. Treatment was with vincristine and dactinomycin (regimen EE4A), with cross-sectional imaging at weeks 6 and 12. If the patient's disease was stable or decreasing, treatment was continued for 19 weeks. Renal preservation, WT development rates at 1year, and overall survival (OS) are reported. Nine patients were enrolled (five females and four males), with a median age at enrollment of 10.22months (range 2.92-29.11). One patient who was enrolled was deemed unevaluable because they did not meet the radiological criteria for DHPLN, resulting in eight evaluable patients. These eight patients had DHPLN confirmed via radiological criteria (all bilateral). Initial chemotherapy was EE4A for all eight patients, with seven of eight patients starting chemotherapy without tissue diagnosis.One patient who had an upfront partial nephrectomy was found to have DHPLN in the specimen and was subsequently treated with EE4A. All patients remained alive, with a median follow-up of 6.6years (range 4.5-9.1). No patients were anephric; 14 of 16 kidneys were functioning (87.5%). Six of eight patients (75%) did not have WT on therapy, but two of these patients relapsed within 6months of stopping therapy; both had favorable histology WT. One patient who was diagnosed with WT on therapy relapsed at 12 months (one of eight [12.5%]) and developed anaplastic histology. Chemotherapy for patients with DHPLN was effective in preserving kidney function. Five-year OS is excellent, however the ideal type and duration of chemotherapy to prevent WT development remains elusive.

Can light penetrate through pomelos and carry information for the non-destructive prediction of soluble solid content using Vis-NIRS?

The penetration depth of light and the distribution of components in fruit affect the accuracy of models in visible-near infrared spectroscopy (Vis-NIRS). These issues are particularly prominent for predicting the soluble solids content (SSC) of large fruit with thick rinds, such as pomelo. To describe the light penetration and distribution inside pomelos, three different modes of puncture measurement were performed by an original system with a puncture optical fiber. The asymmetrical changes and distribution of light intensity were observed in tissues. The semi-transmittance mode was adopted combined with the limited penetration depth, photon aggregation near the light source, and the distribution characteristics of SSC in pomelo. Subsequently, the multi-point spectra at six points in semi-transmittance mode were employed to evaluate the influence of the asymmetrical light and SSC distribution using cross-validation of partial least squares regression (PLSR). The models established by the mean spectra got good performances by eliminating the difference in light distribution. In addition, the probability distribution of SCC could affect the model performance more than the spatial distribution. Finally, the effective wavelengths were selected by competitive adaptive reweighted sampling (CARS) to establish the calibration model. The global model of CARS-PLSR using mean spectra and mean SSC of six points got the best performance in terms of root mean square error of prediction (RMSEP) and residual predictive deviation (RPD), with values of 0.25% and 2.62, respectively. Overall, multi-point detection in semi-transmittance mode could weaken the distribution difference caused by biological variability and allow the non-destructive prediction of SSC in pomelo. • An original system with a puncture optical fiber was designed. • The sensitive area and light distribution were explored by puncture measurement. • The influence of light and SSC distribution on multi-point detection were analyzed. • The mean spectra can effectively eliminate the influence of asymmetric light distribution on the model. • Pre-processing methods and wavelength selection by CARS were employed to improve the model.

Primary Lower-Limb Arterial Stent Infection Managed with Resection and in Situ Bovine Pericardial Revascularization

Peripheral arterial stent infection is a rare but morbid condition. We present the case of a patient with primary stent infection of his superficial femoral artery (SFA) and popliteal artery, managed with surgical explant and in situ reconstruction using rifampicin-soaked bovine pericardial tube graft. A 69-year-old man presented with a 3-day history of left groin pain. He had had stents placed into his SFA and popliteal artery in 6 months prior. Duplex ultrasound demonstrated a pseudoaneurysm of the common femoral artery (CFA), with ying-yang flow. A computed tomography angiogram confirmed this pseudoaneurysm, which had a thick rind of nonenhancing soft tissue. Blood cultures were positive for methicillin-sensitive Staphylococcus aureus. The patient was taken to the operating theater, and the CFA, profunda femoris artery, and SFA were exposed. After heparinization and clamp control, the pseudoaneurysm was incised, which revealed that the proximal SFA had been completely eroded. All infected tissues were resected. In situ arterial reconstruction was undertaken using a rifampicin-soaked bovine pericardium tube graft. A subsequent positron emission tomography scan revealed high fluorodeoxyglucose uptake around the patients remaining distal SFA and popliteal artery stents. These were explanted in the same manner described above. There is limited evidence regarding the prevention of infection when placing peripheral arterial stents. The Society of Interventional Radiology does not recommend routine prophylactic antibiotics when placing peripheral stents. In situ reconstruction using bovine pericardium is a well-described technique in the management of aortic graft infections, but there is limited experience in its use in a peripheral setting.

Functional characterisation of lenticels, micro-cracks, wax patterns, peel tissue fractions and water loss of pomegranate fruit (cv. Wonderful) during storage

Pomegranate fruit is prone to moisture loss irrespective of its thick rind and tough leathery outer skin, resulting in compromised visual appearance and financial loss. The aim of this study was to identify and characterise structural changes in lenticels, micro-cracks, wax patterns and peel tissue fractions to aid the understanding of water loss trends in pomegranate fruit during storage. Fruit were stored at 7 °C and 90 % RH for 42 d and thereafter transferred to shelf conditions (23 °C and 58 % RH) for 8 d. Peel samples were obtained from the calyx-end, equatorial-region and stem-end of randomly selected fruit. Lenticels, micro-cracks, thickness of waxy cuticle and wax layer patterns were examined under scanning microscopes. The trends of water loss with respect to peel tissues and location on fruit were examined by monitoring changes in tissue thickness. Increased fragmentation of waxy cuticle and widening of micro-cracks were observed during fruit storage. Higher count of lenticels, larger lenticel size and generally low peel thickness were observed at the calyx-end and equatorial-region as compared to the stem-end of the fruit. A noticeable water loss trend was detectable with respect to region on the fruit, the calyx-end being more susceptible compared to the equatorial-region and stem-end.

A Comparative Study of Maize and Miscanthus Regarding Cell-Wall Composition and Stem Anatomy for Conversion into Bioethanol and Polymer Composites

Due to an increasing demand for environmentally sustainable products, miscanthus and maize stover represent interesting lignocellulosic resources for conversion into biofuels and biomaterials. The overall purpose was to compare miscanthus and maize regarding cell-wall composition and stem anatomy for conversion into bioethanol and polymer composites using partial least squares regressions. For each of the two crops, six contrasted genotypes were cultivated in complete block design, and harvested. Internodes below the main cob for maize, and on the first aboveground internode for miscanthus, were analyzed for biochemistry and anatomy. Their digestibility was predicted using crop-specific near infrared calibrations, and the mechanical properties were evaluated in stem-based composites. On average, the internode cross-section of miscanthus anatomy was characterized by a thick rind (26.2%) and few but dense pith-bundles (3.5 nb/mm2), while cell-wall constituted 95.2% of the dry matter with high lignin (243.2 mg/g) and cellulose concentrations (439.7 mg/g). Maize internode-anatomy showed large cross-sections (397.5 mm2), pith with the presence of numerous bundles and non-lignified-pith fractions (22.3% of the section). Its cell-wall biochemistry displayed high concentrations of hemicelluloses, galactose, arabinose, xylose, and ferulic acid. Cell-wall, lignin, and cellulose concentrations were positively correlated with rind-fraction and pith-bundle-density, which explained strong mechanical properties as shown in miscanthus. Hemicelluloses, galactose, arabinose, and ferulic acid concentrations were positively correlated with pith fraction and stem cross-section, revealing high digestibility as shown in maize. This underlines interesting traits for further comparative genetic studies, as maize represents a good model for digestibility and miscanthus for composites.

Dual-Frequency Sensor for Thick Rind Fruit Quality Assessment

This article proposes a novel multibeam dual-frequency sensor system to assess the quality of thick rind fruits based on phase difference between lower- and higher-frequency reflection coefficients (Φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> ). The proposed sensor system consists of five dual-band antennas and a customized circuit that approximates lower- and higher-frequency phase difference. The main components of the customized circuit are down-conversion mixers and a phase detector module. For comparison, simulations were initially carried out using single (1 GHz) and dual-frequency (1 GHz/2.3 GHz) sensor systems, and results indicated lower accuracy in classification of thick rind fruits of the single-frequency scheme. As a result, a dual-frequency sensor prototype was fabricated and experimented with normal and granulated plastic pomelo models and real pomelo fruits. The experimental results revealed that the average Φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> of the normal and granulated pomelos are almost identical, while the standard deviation (SD) of Φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> of the granulated pomelo is significantly larger than the normal pomelo. SD is thus used as the determinant of pomelo quality. The multibeam 1-GHz/2.3-GHz dual-frequency sensor system efficiently differentiates between normal and granulated pomelo fruits. As such, the proposed sensor system is operationally appropriate for quality control of thick rind fruits.

Targeted metabolic profiling indicates differences in primary and secondary metabolites in Kinnow mandarin (C. nobilis × C. deliciosa) from different climatic conditions

We studied the impact of climatic conditions on Kinnow juice metabolome by employing a targeted metabolomics approach. Fruit samples were evaluated in seven locations with different climatic conditions. A liquid chromatography tandem mass spectrometry (LC–MS/MS) technique was applied to identify and quantify primary and secondary metabolites, such as sugars, organic acids, vitamins, polyphenolics and limonoids. Results showed significant differences in the concentrations of several metabolites in the juice of fruit grown in the different subtypes of subtropical climate. Fruit from subtropical-humid (STH) climate favored more accumulation of polyphenolics (1047 μg/ mL) and limonoids (limonin: 2.90–3.25 μg/ mL) as compared to fruit from other climates (polyphenolics: 396–782 μg/mL; limonin: 0.07–1.56 μg/mL). Fruit from subtropical-arid (STA) climate favored fruit with a thick rind (4.09–4.44 mm) and juice with lower limonoids (limonin: 0.07–0.52 μg/mL) and better flavor. Principal component analysis (PCA) discriminated Kinnow fruit from different climatic conditions and identified primary and secondary metabolites responsible for this discrimination. Knowledge of the influence of climatic conditions on metabolic profiles can be useful for the industry to determine the suitability and sourcing of mandarin fruit for fresh and processing purposes.

Optimization of soluble solids content prediction models in ‘Hami’ melons by means of Vis-NIR spectroscopy and chemometric tools

Nondestructive assessment of internal quality in fruit with thick rind and large size was always a challenge in terms of the fruit quality automatic grading application. This study compared different spectral measurement positions and prediction models for determining soluble solids content (SSC) of ‘Hami’ melon. Visible and short wavelength near-infrared with the spectral range of 550–950 nm was used and three local positions (calyx, equator and stem regions) in each sample were selected for spectral collection, respectively. The partial least squares (PLS) was employed to establish three local calibration models (calyx-model, equator-model and stem-model) and calyx-model was proved to be optimal one for SSC prediction of ‘Hami’ melon. In order to optimize the calyx-model, four algorithms including successive projections algorithm (SPA), Monte Carlo-uninformative variable elimination (MC-UVE), competitive adaptive reweighted sampling (CARS) and combination algorithm MC-UVE-SPA were applied to select effective variables from full spectra, respectively. And, the non-linear least square support vector machine (LSSVM), linear multiple linear regression (MLR) and PLS models were also developed based on those selected effective variables, respectively. The results indicated that MC-UVE-SPA was the optimal method for selecting the effective variable. Based on 18 variables selected by MC-UVE-SPA, all established models including MC-UVE-SPA-PLS, MC-UVE-SPA-LSSVM and MC-UVE-SPA-MLR can successfully predict the SSC of all ‘Hami’ melon fruit samples with the prediction accuracy of RMSEP = 0.95–0.99 °Brix.

Optimizing genetic algorithm-partial least squares model of soluble solids content in Fukumoto navel orange based on visible-near-infrared transmittance spectroscopy using discrete wavelet transform.

The thick rind of Fukumoto navel orange is a great barrier to light penetration, which makes it difficult to evaluate the internal quality of Fukumoto navel orange accurately by visible-near-infrared (Vis-NIR) transmittance spectroscopy. The information carried by the transmission spectrum is limited. Thus, the application of genetic algorithm (GA) for variable selection may not reach the expected results, and selected variables may contain redundancy. In this paper, we present the use of discrete wavelet transforms for optimizing a GA-partial least squares (PLS) model based on Vis-NIR transmission spectra of Fukumoto navel orange. Haar, Db, Sym, Coif and Bior wavelets were used to compress the spectral data selected by GA. Then a PLS model was established based on the variables compressed by each wavelet function. The use of Db4, Sym4, Coif2 and Bior3.5 succeeded in further simplification of the GA-PLS model by reducing the number of variables by 40-44% without decreasing the prediction accuracy. The application of Bior3.5 not only could reduce the number of variables in the GA-PLS model by 40%, but also increase the value of correlation coefficient of prediction by 1% and decrease the value of root mean square error of prediction by 3%. The results indicated that the combination of GA and discrete wavelet transforms for variable selection in the internal quality assessment of Fukumoto navel orange by Vis-NIR transmittance spectroscopy was feasible. © 2019 Society of Chemical Industry.