Fruit Flavor Research Articles

Expression of the polyphenol oxidase gene MdPPO7 is modulated by MdWRKY3 to regulate browning in sliced apple fruit.

Browning is a pervasive problem in horticultural products, substantially diminishing the appearance, flavor and nutritional value of fruit, including important fruits like apple (Malus × domestica Borkh.). In this study, we compared the physiological characteristics of the browning-resistant line 'Rb-18' with the susceptible variety 'Fuji' and found that the polyphenol oxidase (PPO) enzyme activity and phenolic content of Rb-18 were significantly lower than those in Fuji. In addition, the PPO enzyme in Fuji showed a stronger affinity for its substrate, catechol, compared to Rb-18. Through transcriptome and RT-qPCR analyses, MdPPO7 expression was identified as contributing to flesh browning after cutting. Subsequent fruit injection and stable genetic transformation of the MdPPO7 gene into apple fruit and calli determined that syringic acid, procyanidin, phloridzin, chlorogenic acid, gallic acid, catechin, and caffeic act as its catalytic substrates in the process involved in browning. Furthermore, luciferase reporter, yeast one-hybrid, β-glucuronidase reporter assays and chip-qPCR analysis demonstrated that a WRKY transcription factor(MdWRKY3) binds to the promoter region of polyphenol oxidase gene (MdPPO7) and positively regulates its expression to promote apple flesh browning. This study provides insights into the molecular regulatory mechanisms of fruit browning in fresh-cut apples and provides a theoretical basis for the generation of high-quality apple germplasm resources.

Genomic analysis provides insights into the origin and divergence of fruit flavor and flesh color of pummelo.

Pummelo (Citrus maxima) is one of the most important citrus crops and have genetically contributed sweet orange, lemon and most citrus cultivars. It has been cultivated for c. 4000 years in China and is also distributed in many Southeast Asian countries. Nevertheless, the origin and dispersal of pummelo remain elusive. We conducted whole-genome sequencing for 290 pummelo accessions from China and Southeast Asia (SEA). Our findings indicated that pummelo was originated in Yunnan province. The divergence of the China-SEA accessions occurred c. 2000 years ago and the divergence was likely facilitated through the Maritime Silk Road. We detected the divergence of genomic regions associated with fruit flavor and color, indicating different selection by human activities in different regions. A gene encoding lycopene cyclase 2 (LCYB2) exhibited a high degree of divergence in expression and sequence between red-flesh and white-flesh pummelos. A SNP in the coding region of LCYB2 resulted in a reduction in lycopene β-cyclizing enzyme activity, leading to the accumulation of lycopene and the development of the red-flesh trait. This study reveals the origin and evolutionary history of pummelo and provides insights into the genomic basis for the divergence of fruit flavor and color.

Impacts of Five Different Drying Methods on Volatile Organic Compounds in Mulberry Fruits.

The mulberry fruit is edible and medicinal, and it is commonly referred to as the "best health product of the 21st century". The purpose of this study was to find out whether different drying methods affect the quality of mulberry fruits and the main nature of the volatile organic compounds (VOCs) they contain. This study used vacuum freeze-drying (VFD), vacuum drying (VD), sun drying (SD), hot-air drying (HAD), and microwave drying (MD) to treat fresh mulberry fruits. Gas-phase ion mobility spectrometry (GC-IMS) was used to detect and analyze the VOCs in mulberry fruit samples treated with the different drying methods. There were 47 VOCs detected, with aldehydes and alcohols dominating. The obtained data were subjected to principal component analysis (PCA), cluster analysis (CA), nearest neighbor fingerprint analysis, and partial least-squares regression analysis (PLS-DA). The conclusion was drawn that fresh mulberry fruits contain abundant VOCs, and mulberry fruits after VD contain many aldehydes; thus, VD promoted the synthesis of phellandrene and other compounds widely used in the preparation of cosmetics such as perfume and soap. HAD promoted the synthesis of esters commonly used in the preparation of fruit flavor and wine essence. The higher (E)-2-heptenal content with SD was conducive to the Maillard reaction. MD promoted the synthesis of heptanal and valeraldehyde with aroma characteristics such as fatty, green, fruity, grassy, and floral. According to the VIP results, VOCs (E)-2-heptenal, pentanal D, cyclohexanone, and 2-hexanone D influenced the VOCs in most of the mulberry fruit samples. The findings of this study provide an important reference for drying mulberry fruits, which, in turn, will help to ensure the safety and effectiveness of processed mulberry fruit products.

Solid-state fermentation with lactic acid bacteria of citric acid degrading for hawthorn fruit improvement: sensory, flavor, antioxidant properties

Hawthorn fruit with high citric acid content leads to sour taste, and compacted flesht is not conducive to process into juice. To solve these problems, Leuconostoc citreum, Lactobacillus casei, and Lactobacillus brevis were screened out for compounding, by which the rate of degradation of citric acid reached 81.147% after solid-state fermentation (SSF). Results show that pectin solubility is improved, the cell-wall structure is dissolved and loosened, the fruit becomes softer, and the juice yield is increased to 60.63%, while the surface color is slightly affected after fermentation. Meanwhile pH value of fermented hawthorn fruit grows to 5.05, the content of citric acid reduces to 1.54 mg/kg, and the solidity-acid ratio is increased to 11.55, so sourness and astringency are alleviated and the taste is apparently improved. Additionally, total phenolics and total flavones are released and the antioxidant activity is enhanced by a factor of 1.2 ∼ 1.6. Besides, the contents of undesirable flavor substances such as acids and sulpho-compounds are reduced in fermented hawthorn fruit, while the content and diversity of flavor substances including esters, phenolics, and aldehydes are increased. This is positive for improving the flavor of hawthorn fruit. Based on the KEGG(Kyoto Encyclopedia of Genes and Genomes)results, it is proven that seven pathways are mainly involved in the fermentative metabolism, in which nine metabolites are produced. Therein, the phenylalanine metabolism pathway involving benzeneacetaldehyde shows the highest enrichment. Therefor, SSF of compound LAB is feasible in improving the processing quality and the suitability of hawthorn fruit.

ZF protein C2H2-71 regulates soluble solids content by inhibiting LIN5 in tomato

Soluble solids content (SSC) plays an important role in determining the flavor of tomato fruits. Tomato fruit SSC has been shown to be transcriptionally regulated via sugar metabolism. Previous studies have been predominantly focused on the role of C2H2-type zinc finger proteins in tomato growth and development. However, the specific regulatory mechanism of C2H2 in the accumulation of soluble solids in tomato fruits are yet to be fully understood. This study involved the selection of eight tomato accessions with varying levels of SSC to study the expression of SlC2H2 family genes in red ripe fruits. The study found that the levels of SlC2H2-71 expressions were significantly reduced in high-SSC accessions compared to low-SSC accessions. The Slc2h2-71 mutant lines were developed using the CRISPR-Cas9 system, leading to elevated levels of soluble solids, fructose, glucose, malic, and citric acids in mature red ripe fruits. However, sucrose content in the edited Slc2h2-71 mutant lines generally decreased. RNA-seq analysis revealed that fruits from the mutant lines had altered expression of genes related to sugar and acid metabolic pathways, which was further confirmed by quantitative real time PCR. Specifically, there was an observed increase in the expression of SlLIN5 encoding the cell wall invertase (CWIN). The yeast one-hybrid (Y1H) assay, 35S::UAS-GUS, dual-luciferase reporter systems and electrophoretic mobility shift assay (EMSA) demonstrated that SlC2H2-71 regulates tomato sugar metabolism by directly binding to the promoter region of SlLIN5, culminating in the repression of its transcriptional activity. The activity of acid invertase in the SlC2H2-71 knock-out lines exhibited a significantly higher level compared to that observed in the control lines. In summary, the regulation of tomato fruit SSC by SlC2H2-71 involves the inhibition of SlLIN5 expression.

Electronic nicotine delivery system flavors, devices, and brands used by adults in the United States who smoke and formerly smoked in 2022: Findings from the United States International Tobacco Control Four Country Smoking and Vaping Survey

ObjectiveThis study estimated prevalence of current electronic nicotine delivery systems (ENDS) used by US adults who smoked cigarettes or formerly smoked in 2022 and assessed ENDS flavors, devices, and brands used most often. MethodsData are from the 2022 US ITC Smoking and Vaping Survey. Respondents were recruited from a web panel of a nationally representative sample of US adults ages 18+ who smoked, formerly smoked, and/or vaped ENDS. Using weighted data, we estimated prevalence of current vaping among adults who smoke or formerly smoked (N = 2,016). Among the subset who vaped (n = 554), we assessed flavors and devices used most often. Using unweighted data, we assessed the frequency (count) of reported brands used most often. ResultsIn 2022, 22.0 % of US adults who smoked or formerly smoked were vaping at least monthly. A significantly higher proportion of adults who formerly smoked and/or were younger (18–39) were vaping than adults who were smoking and/or were older (40+) (both p < 0.001). Tank devices were used most often (34.7 %), followed by disposables (27.4 %), pre-filled pods/cartridges (23.0 %), and refillable pods/cartridges (14.9 %). The five most commonly used flavors were fruit (33.9 %), tobacco (20.1 %), menthol (12.2 %), candy/sweets (10.8 %), and mixed ice flavors (10.0 %). The top 5 brands were JUUL, Smok, Vuse, Geekvape, and Blu. ConclusionsIn 2022, a majority of adults who smoked cigarettes or who had quit smoking used a variety of flavors and devices that go beyond the choices that FDA currently has authorized for sale.

Effects of Postharvest SO2 Treatment on Longan Aril Flavor and Glucosinolate Metabolites.

SO2 fumigation treatment (commonly known as sulfur treatment, ST) is a key method in the postharvest preservation of imported and exported fresh longan fruits, effectively reducing pericarp browning and enhancing color. Nonetheless, distinctive aromas, often referred to as "sulfur flavor", may develop in the aril during the extended preservation period. This study employed "Caopu" longan as the test material and patented SO2-releasing paper (ZL201610227848.7) as a treatment to perform a 35-day low-temperature (5 °C) storage of the fruit. The changes in glucosinolates (GSLs) and associated metabolites in the aril of treated fruit (ST) were examined utilizing ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) detection and widely targeted metabolomics technology. The findings indicated that following 35 days of storage, nearly all control (CK) fruit pericarp turned to brown, resulting in an edible fruit rate of 75.41% and a commercial fruit rate of 0%. In contrast, the treated (ST) fruit demonstrated an edible fruit rate and a commercial rate of 99.44%, while the pericarp color changed from dark yellow-brown to light earthy yellow. The sulfur-containing metabolites identified in longan fruit aril predominantly consist of amino acids and their derivatives (60.44%), followed by alkaloids (15.38%), nucleotides and their derivatives (1.10%), and other types (23.08%), which include GSLs. SO2 treatment significantly reduced the content of oxidized glutathione in fruit aril but increased the content of GSLs and related amino acids and their derivatives. Via screening, 19 differential sulfur-containing metabolites were obtained between ST and CK, including 11 GSLs. The identified differential metabolites of GSLs were all increased, primarily comprising aliphatic GSLs, such as 1-hydroxymethyl glucosinolate, 2-Propenyl glucosinolate (Sinigrin), and 4-Methylsulfinylbutyl glucosinolate (Glucoraphanin). Pathway analysis showed that these differential metabolites were mainly involved in coenzyme factor synthesis, cysteine and methionine metabolism, and amino acid synthesis, among other pathways. To the best of our knowledge, this is the first study to reveal the causes of the special flavor of longan aril after SO2 treatment, which is a great concern for longan consumers. Moreover, this study provides a scientific basis for exploring the reasons and mechanisms for the development of the sulfur flavor in the SO2-treated fruits during postharvest storage.

Identification and Functional Analysis of Key Genes Regulating Organic Acid Metabolism in Jujube Fruit

Organic acids are crucial indicators of fruit flavor quality, but the metabolic characteristics and regulatory genes of organic acids during jujube fruit development remain largely unexplored. In this study, the cultivar ‘Heigeda’ with a high organic acid content was used as the experimental material. The organic acid content was quantified, and key candidate genes were identified through transcriptome analysis. The results indicated that malic acid and citric acid were the main organic acid content in jujube fruit and increased gradually with fruit development. Transcriptome analysis identified nine genes associated with malic acid and seven with citric acid, with four genes co-regulating malic acid and citric acid. Functional assays by transient overexpression and silencing of these four genes in the jujube fruits revealed that overexpression significantly upregulated the malic and citric acid content. However, only the silencing of aconitase1 (ZjACO1) and aconitase3 (ZjACO3) significantly downregulated the content of malic and citric acids. Therefore, aconitase1 (ZjACO1) and aconitase3 (ZjACO3) are considered the key genes that regulate the metabolism of citric acid and malic acid in jujube fruits. Our study can enrich the regulation mechanism of the organic acid metabolism of jujube fruit and provide theoretical support for the efficient cultivation of jujube fruit.

Different drying methods' effects on the nutritional components and flavor of fruits

With the continuous development of food processing technologies, drying techniques have become increasingly important in fruit processing. Different drying methods have significant impacts on the nutritional components and flavor of fruits, directly affecting the nutritional value and market competitiveness of the products. This paper reviews the principles, technical characteristics, and effects of four main drying technologies—hot air drying, freeze drying, vacuum drying, and microwave drying—on the nutritional components and flavor of fruits. By comparing the retention effects of these drying methods on vitamins, minerals, dietary fibers, and antioxidants, the paper explores future research directions and suggests technical optimization strategies. The study indicates that different drying technologies have varying advantages and disadvantages in terms of nutrient retention, flavor preservation, and drying efficiency. Strategies such as multi-factor optimization, technological combinations, and exploration of new drying technologies are proposed to provide valuable references and guidance for the fruit processing industry.

Preclinical evidence of the effects of sweet flavors: Sweetness increases nicotine intake and seeking.

The influence of early exposure to sweet and fruit flavors on subsequent nicotine use behaviors during adolescence remains poorly understood. To address this gap, we utilized a rodent model to simulate childhood flavor exposure and examine its effects on later nicotine use behaviors. We employed a two-bottle choice paradigm in weanling rats to mimic human childhood flavor exposure. Subsequently, we investigated the impact of early exposure to sweet (saccharin) and cherry fruit (benzaldehyde) flavors on adolescent nicotine use behaviors. This included assessing subsequent nicotine acquisition, maintenance, and seeking behaviors using intraoral flavor and intravenous nicotine self-administration. Our findings reveal that rats exposed to saccharin during early development exhibited altered patterns of nicotine intake and seeking behaviors during adolescence. Specifically, rats demonstrated increased nicotine intake and seeking of saccharin flavored solutions when paired with nicotine, indicating a potential predisposition towards nicotine use following childhood flavor exposure. Intraoral benzaldehyde did not affect nicotine reinforcement in early sessions of self-administration, but significantly decreased nicotine reinforcement during later sessions. Both saccharin exposure alone or in combination with benzaldehyde promoted nicotine reinforcement. No significant sex differences in nicotine-related behaviors were observed. This study highlights the significance of early flavor exposure in shaping adolescent nicotine use behaviors. The findings suggest that childhood exposure to sweet flavors may contribute to heightened susceptibility to nicotine use and addiction later in life. Understanding these early influences is crucial for developing targeted interventions to prevent the onset of nicotine addiction during adolescence. Our study highlights the importance of how sweetness can contribute to and possibly even alter the effects of the flavor itself. The sweetness of a tobacco product does not solely stem from sweeteners, but it is also influenced by other components such as the PG/VG ratio (e.g., higher VG) and the inclusion of flavors associated with sweetness (e.g., vanillin and ethyl maltol). Therefore, sweet-associated constituents in tobacco products should be investigated further to inform regulatory policy. We believe that our findings can inform regulatory decisions on controlling sweet associated constituents in tobacco products.

Identification of key gene networks controlling organic acid and sugar metabolism during star fruit (Averrhoa carambola) development

The sugar and organic acid content significantly impacts the flavor quality of star fruit, and it undergoes dynamic changes during development. However, the metabolic network and molecular mechanisms governing the formation of sugar and organic acid in star fruit remain unclear. In this study, 23 of 743 components were detected by metabonomic analysis. The highest metabolites contents were organic acids and derivatives. The highest sugar content in the fruit was fructose and glucose, followed by sucrose, which proved that A. carambola is a hexose accumulation type fruit. Genome identification preliminarily screened 141 genes related to glucose metabolism and 67 genes related to acid metabolism. A total of 7,881 unigenes were found in transcriptome data, 6,124 differentially expressed genes were screened, with more up-regulated than down-regulated genes. Transcriptome and metabolome association analysis screened seven core candidate genes related to glucose metabolism and 17 core genes highly related to organic acid pathway, and eight differentially expressed sugar and acid genes were selected for qRT-PCR verification. In addition, 29 bHLHs and eight bZIPs transcription factors were predicted in the glucose metabolism pathway, and 23 MYBs, nine C2H2s transcription factors and one GRAS transcription factor was predicted in the acid metabolism pathway, and transcription factors have both positive and negative regulatory effects on sugar and acid structure genes. This study increased our understanding of A. carambola fruit flavor and provided basic information for further exploring the ornamental and edible values of star fruit.

The key metabolite of fruit flavor change in different ripening stages of Baccaure ramiflora

Baccaurea ramiflora has an unstable ripening period. Herein, five typical periods of fruit ripening of ‘LR’ Baccaurea ramiflora were analyzed by non-targeted metabolomics techniques. The results showed that ripening started 73 days after flowering and reached the ripening criterion at 93 days, a total of 451 differential metabolites were identified for the five periods. KEGG enrichment pathway showed that significant changes in citric acid were significantly correlated with changes in the downstream substance spermine (R2 = 0.9068, y = −5.49 + 0.66×), while citric acid (R2 = 0.9982) and spermine (R2 = 0.9841) were negatively correlated with the sugar-acid ratio. Citric acid was the main component of titratable acid and spermine (R2 = 0.9991) was positively correlated with titratable acid. We speculated that citric acid is a key taste marker for fruit ripening in ‘LR’ B. ramiflora. The results of the study provide new metabolic evidence for flavor changes and scientific basis for their quality improvement and exploitation in B. ramiflora.

Contribution of polyvinylpolypyrrolidone (PVPP) treatment to the distribution of polyphenols and the evolution of esters and higher alcohols in Rosa roxburghii Tratt wine

Polyvinylpolypyrrolidone (PVPP) is commonly employed for fining in fruit wine brewing. This study aimed to investigate the impact of PVPP pretreatment on the formation of fermentation aroma and polyphenol distribution in Rosa roxburghii Tratt (RRT) wine. A significant effect of PVPP on polyphenol adsorption was observed, and polyphenol families or subfamilies such as flavanols and flavonols showed specific affinity for PVPP, decreasing by over 19 % and 30 %, respectively. Furthermore, it was the first time to demonstrate a significant enhancement in the ester content of the corresponding RRT wine after PVPP treatment, particularly in imparting sweet and fruity esters (increased by over 40 %). In contrast, the RRT wine treated with PVPP exhibited a significant reduction of over 20 % in the concentration of higher alcohols, particularly reflected in the green and chemical aromas. This indicates that PVPP treatment could promote the transformation of RRT wine aroma from green and chemical to sweet and fruity. Correlation analysis revealed a positive relationship between the concentration of higher alcohols and most phenolic compounds in RRT wine, while quercetin 3-glucoside, rutin, and polydatin were negatively correlated with esters that can impart fruit flavor and floral aroma to fruit wine. As a practical insight into fruit wine fermentation, PVPP fining before fermentation is more likely to alter the phenolic compositions of RRT wine, thereby influencing its aroma characteristics. Specifically, polyphenols associated with energy metabolism of yeast could have stimulated the formed fluxes of esters. The association between the formation of esters and higher alcohols with phenolic compounds will provide new information on the impact of clarification treatments on yeast-derived volatile metabolites in RRT wine and hold promise in improving the aroma of RRT wine by modulating polyphenol composition through pre-clarification.

Reduced Fertilization and Magnesium Supplementation: Modulating Fruit Quality in Honey Pomelo (Citrus maxima (Burm.) Merr.)

The excessive use of chemical fertilizers in the Guanxi honey pomelo production area has led to severe soil acidification and magnesium (Mg) deficiency, adversely affecting pomelo fruit quality. To address this issue, an integrated nutrient optimization model crucial for ensuring the sustainable and environmentally friendly development of the Guanxi honey pomelo industry has been explored. In a three-year experiment, two fertilizer treatments were implemented: a farmer fertilizer practice (FP) and an NPK reduction plus foliar Mg fertilizer (OPT + fMg). We investigated the impact of this integrated optimized fertilization measure on pomelo fruit quality from three aspects: flavor (sugars and organic acids), nutrition (vitamin C and mineral elements), and antioxidant properties (phenolics, flavonoids, and phytic acid). The results revealed that the OPT + fMg treatment improved fruit flavor by reducing acidity (titratable acid, citric acid, and quinine), while having a minimal impact on sugar components (sucrose, fructose, and glucose). Additionally, the OPT + fMg treatment increased the total phenolics, total flavonoids, and phytic acid in the fruit peel, enhancing its potential antioxidant quality. However, the OPT + fMg treatment reduced the mineral nutrient quality (excluding calcium) in the fruit. As for the fruit developmental period, the OPT + fMg treatment significantly increased the total flavonoid concentration in the peel from the mid-expansion fruit stage, followed by notable increases in phytic acid in the peel during the mid-to-late expansion fruit stage. The total phenolic concentration in the peel significantly rose only during the late fruit development stage. The most pronounced effect was observed on phytic acid in both peel and pulp. The influence of the OPT + fMg treatment on the mineral nutrients (excluding calcium) primarily occurred during the mid-to-late expansion fruit stage. Overall, the OPT + fMg treatment significantly improved the comprehensive nutritional quality of pomelo fruit, providing valuable insights for scientifically reducing fertilizer application while enhancing fruit quality.

Special Issue: ‘Advanced Studies in Maintaining Post-Harvest Quality of Fruits and Vegetables’

The characteristics of taste, flavor, nutrition, and safety in fruits and vegetables during post-harvest, minimal processing, fresh-cutting, fermenting, and processing are critical elements in the storage and sale of products [...]

Low soil pH enhances fruit acidity by inhibiting citric acid degradation in lemon (Citrus lemon L.)

Fruit acidity significantly influences fruit flavor, but the specific impact of soil pH on fruit acidity remains unclear. This study investigated the effects of various soil pH levels on fruit acidity and citric acid (CA) metabolism in lemon (Citrus limon L.). High soil pH (pH 8) decreased total soluble solids concentrations in lemon fruits, while low soil pH (pH 4) increased titratable acid and CA concentrations. Although low soil pH reduced the synthesis of CA due to the decreased citrate synthase and phosphoenolpyruvate carboxylase activities, the elevated fruit acidity under low soil pH conditions is not directly related to CA synthesis. Instead, low soil pH was found to suppress the activity of cytosolic aconitase (Cyt-ACO), an iron-dependent enzyme, indicating a potential role for CA degradation inhibition in low soil pH-induced CA accumulation. Furthermore, low soil pH significantly reduced cytosolic iron (Cyt-Fe) concentration, which was positively correlated with Cyt-ACO activity. In conclusion, low soil pH contributes to increasing fruit acidity in lemon, partially by inhibiting CA degradation due to the reduced Cyt-Fe concentrations. Our work unravels the influence of soil pH on CA accumulation and provides important clues for modulating CA levels through microelement fertilization in citrus.

Dynamic Analysis of the Fruit Sugar-Acid Profile in a Fresh-Sweet Mutant and Wild Type in 'Shatangju' (Citrus reticulata cv.).

Citrate is a major determinant of fruit flavor quality. Currently, citrus species and/or varieties with significant alterations in citrate level have greatly advanced the molecular basis of citrate accumulation in fruit. However, in-depth dissections of the molecular mechanism specific to citrate accumulation are still limited due to the lack of mutants, especially within one single variety. In this study, a fresh-sweet 'Shatangju' mutant (Citrus reticulata cv.) was obtained during a survey of citrus resources in Guangdong, China, and the phenotype, fruit morphology, and primary flavor profiles were comparatively analyzed. Unlike the wild-type 'Shatangju' (WT), the mutant (MT) material exhibited a dwarfed and multi-branched tree shape, delayed flowering and fruit ripening at maturity, a prolonged fruit tree-retention time, and a decreased single fruit weight at maturity. Dynamic measurement of the metabolite levels further suggested that the contents and fluctuation patterns of vitamin C, malate, quinate, and oxalate showed no obvious difference between MT and MT fruits, while the citrate level in MT fruits significantly decreased over various developmental stages, ranging from 0.356 to 1.91 mg g-1 FW. In addition, the accumulation patterns of the major soluble sugars (sucrose, fructose, and glucose), as well as the sugar/acid ratio, were also altered in MT fruits during development. Taken together, this study provides a novel acid-free 'Shatangju' mutant, which can serve as a powerful tool for the research of fruit flavor quality, especially for the comprehensive understanding of the molecular mechanism of citrate accumulation in fruits.

Expansion and functional divergence of terpene synthase genes in angiosperms: a driving force of terpene diversity

Abstract Angiosperms are prolific producers of structurally diverse terpenes, which are essential for plant defense responses, as well as the formation of floral scents, fruit flavors, and medicinal constituents. Terpene synthase genes (TPSs) play crucial roles in the biosynthesis of terpenes. This study specifically focuses on the catalytic products of 222 functionally characterized TPSs in 24 angiosperms, which mainly comprise monoterpenes, sesquiterpenes, diterpenes, and sesterterpene. Our systematic analysis of these TPSs uncovered a significant expansion of the angiosperm-specific TPS-a, b, and g subfamilies in comparison to the TPS-e/f and c subfamilies. The expanded subfamilies can be further partitioned into distinct branches, within which considerable functional innovation and diversification have been observed. Numerous TPSs exhibit bifunctional or even trifunctional activities in vitro, yet they exhibit only a single activity in vivo, which may be largely determined by their inherent properties, subcellular localization, and the availabilities of endogenous substrates. Additionally, we explored the biological functions of terpenes in various organs and tissues of angiosperms. We propose that the expansion and functional divergence of TPSs contribute to the adaptability and diversity of angiosperms, facilitating the production of a broad spectrum of terpenes that enable diverse interactions with the environment and other organisms. Our findings provide a foundation for comprehending the correlation between the evolutionary features of TPSs and the diversity of terpenes in angiosperms, which is significant for terpene biosynthesis research.

Unveiling the effects of ZnO nanoparticle incorporated chitosan coating on postharvest quality of eggplant (Solanum melongena L.)

Due to rapid moisture loss, eggplant (Solanum melongena L.), a significant economic product, has a short postharvest shelf life. This study examined at 4 °C for 20 days at the effects of chitosan (CH) 1% and CH with micro ZnO (0.25 g/L) on eggplant quality. After 0, 5, 10, 15, and 20 days, coating effects on parameters (weight loss, pH, respiration rate, total acidity, soluble solids, firmness, total anthocyanin, antioxidant, phenolic, antioxidant enzymes superoxide dismutase, peroxidase and malondialdehyde activity), as well as microbiological count (total bacteria and yeast), were examined. When compared to the control, the coatings significantly affected the quality parameters, eggplant fruit coatings with CH (1 %) + nano ZnO (0.25 g/L) had the significantly least respiratory rate, weight loss, firmness, TAC, TPC, TAA and enzyme activity (P < 0.05). The microbial load during fruit preservation was suppressed by nano ZnO treatments (total bacterial and fungal count in control and eggplant treated with nano ZnO were 4.46, 4.33 and 3.96, 3.17 log CFU g−1 respectively). Treatments had little effect on fruit's flavour or aroma, but ZnO-treated fruit had improved texture, colour, and acceptance overall compared to control fruit. Finally, nano ZnO may offer a chance to preserve quality and limit deterioration during extended storage.

Consumer Acceptance of Novel Lucuma Fruit Ice Cream in the US Market.

This study explored the use of lucuma fruit powder in an ice cream formulation for the US market. Six ice cream prototypes were developed using five different lucuma fruit powder variants. A central location test was conducted with frequent ice cream consumers (n = 106) to assess acceptance, attribute intensity rating, ideal intensity levels, and purchase intent against a control sample with caramel flavor. The mean overall liking score for all lucuma ice creams was moderate. The overall, aroma, and flavor liking scores were significantly higher (p < 0.05) for lucuma ice cream samples, whereas the control sample was liked significantly more for texture. The Terrasoul variant of lucuma ice cream was the most liked among all samples, and the control was liked the least. Only the Terrasoul ice cream sample was successful in delivering significantly strong caramel, fruit, and sweet flavor levels; the other lucuma ice cream samples were more comparable to the control. The inclusion of lucuma powder increased powdery mouthfeel perception, negatively impacting texture liking. Consumers perceived all ice cream samples to be weak in flavor and fell short of delivering ideal levels. The US consumers had low-moderate food neophobia scores for lucuma fruit, with 57% showing interest in buying lucuma ice creams.