Enhancing Acid Resistance of Aspergillus niger Pectin Lyase through Surface Charge Design for Improved Application in Juice Clarification.

Pectin lyases (PNLs) can enhance juice clarity and flavor by degrading pectin in highly esterified fruits, but their inadequate acid resistance leads to rapid activity loss in juice. This study aimed to improve the acid resistance of Aspergillus niger PNL pelA through surface charge design. A modification platform was established by fusing pelA with a protein tag and expressing the fusion enzyme in Escherichia coli. Four single-point mutants were identified to increase the surface charge using computational tools. Moreover, the combined mutant M6 (S514D/S538E) exhibited 99.8% residual activity at pH 3.0. The M6 gene was then integrated into the A. niger genome using a multigene integration system to obtain the recombinant PNL AM6. Notably, AM6 improved the light transmittance of orange juice to 45.3%, which was 8.39 times higher than that of pelA. In conclusion, AM6 demonstrated the best-reported acid resistance, making it a promising candidate for industrial juice clarification.

An antifouling electrochemical biosensor using self-signal for Salmonella typhimurium direct detection in food sample.

Eating food contaminated by foodborne pathogens can lead to illness. The development of electrochemical sensors for pathogen detection has received widespread attention. However, the analytical performance of electrochemical sensors is inevitably affected by the non-specific adsorption of molecules in the sample. Moreover, the external signal probes might be affected by the complex components in the sample accompanied with signal suppression. This work presents an electrochemical aptasensor for Salmonella typhimurium detection based on the self-signal of poly-xanthurenic acid and the antifouling ability of chondroitin sulfate. The detection time was 60 min. The linear range was from 101 to 107 CFU/mL, and the detection limit was 3 CFU/mL. The biosensors presented good repeatability and storage stability. And the biosensors has been successfully applied in milk and orange juice. This strategy is expected to be applied in the design of other antifouling biosensors, to achieve rapid detection of pathogens and ensure food safety.

Synergistic effect of seaweed extract and boric acid and/or calcium chloride on productivity and physico-chemical properties of Valencia orange.

Many citrus species and cultivars are grown successfully in tropical and subtropical countries, as well as in arid and semi-arid regions with low levels of organic matter and low cation exchange, resulting in lower nutrient uptake by the plant. The essential nutrients needed for citrus flowering and fruit set are limited in winter due to a reduction in transpiration rate, negatively effecting vegetative growth, flowering, yield, and fruit quality. The present investigation was carried out to assess the nutritional status, fruit yield parameters, and fruit quality of Valencia orange trees after foliar spraying of seaweed extract (SW) combined with calcium chloride and boric acid and their combinations in the 2020/2021 and 2021/2022 seasons. The treatments were arranged in a split-plot design (three levels spraying seaweed extract × four levels spraying calcium chloride and boric acid and their combinations × four replicates × one tree/replicate). The results indicated that all of the characteristics measured, including leaf chlorophyll, leaf mineral contents, fruit yield parameters, fruit physical properties, and fruit chemical properties, were significantly affected by the foliar spraying of seaweed extract (SW) combined with calcium chloride and boric acid and their combinations. Although all treatments increased the productivity and the physical and chemical properties of Valencia orange fruits compared to the control, a treatment of 10 g/L SW combined with 0.5 g/L boric acid and 1 g/L calcium chloride produced superior results. This ratio of SW, boric acid, and calcium chloride is therefore recommended to enhance productivity and improve the physico-chemical properties of Valencia orange for greater fruit yield.

A critical evaluation on the valorization strategies to reduce and reuse orange waste in bakery industry.

Tons of orange by-products (OBPs) are generated during industrial orange processing. Currently, OBPs management is challenging due to their high amounts, physico-chemical characteristics (high water content, low pH, presence of essential oils) and seasonal nature of the production. Whereas agro-industrial OBPs can be highly valuable due to their abundant sources of bioactive compounds, which can add value to novel bakery products (e.g. bread, biscuits, cakes). This review covers the most recent research issues linked to the use of OBPs in bakery products, with a focus on available stabilization methods and on the main challenges to designing improved products. The application of OBPs improved the nutritional quality of bakery products, offering interesting sustainability benefits but also critical challenges. The valorization of OBPs may open new routes for the development of new natural ingredients for the food industry and lower food processing waste.

Sensitivity of Salmonella Typhimurium to nisin in vitro and in orange juice under refrigeration.

The influence of environmental factors on Salmonella sensitivity to nisin in vitro and in refrigerated orange juice were investigated. Nisin activity was observed in the different conditions, but the highest efficiency was achieved at lower pH (4.0) and with higher bacteriocin concentration (174 µM). Moreover, the bactericidal action was directly proportional to the incubation period. When tested in orange juice, nisin caused a reduction of up to 4.05 logarithm cycles in the Salmonella population. So, environmental factors such as low pH and low temperature favored the sensitization of Salmonella cells to the bactericidal action of nisin. Therefore, this may represent an alternative to control Salmonella in refrigerated foods.

Enhancing the Quality of Low-Alcohol Navel Orange Wine through Simultaneous Co-Fermentation Using Saccharomyces cerevisiae SC-125, Angel Yeast SY, and Lactiplantibacillus plantarum BC114.

To date, there has been limited research on the interactive effects of yeast and lactic acid bacteria (LAB) on the sensory qualities of navel orange wine. In this study, using Jintang navel orange juice as the raw material, multi-microbial fermentation was conducted with Saccharomyces cerevisiae SC-125 and Angel yeast SY, as well as Lactiplantibacillus plantarum BC114. Single yeast and co-fermentation with Lactiplantibacillus plantarum were used as the control groups. The research aimed to investigate the physicochemical parameters of navel orange wine during fermentation. Additionally, headspace solid-phase microextraction gas chromatography-mass spectrometry (HP-SPME-GC-MS) was employed to determine and analyze the types and levels of flavor compounds in the navel orange wines produced through the different fermentation methods. The co-fermentation using the three strains significantly enhanced both the quantity and variety of volatile compounds in the navel orange wine, concomitant with heightened total phenol and flavonoid levels. Furthermore, a notable improvement was observed in the free radical scavenging activity. A sensory evaluation was carried out to analyze the differences among the various navel orange wines, shedding light on the impact of different wine yeasts and co-fermentation with LAB on the quality of navel orange wines.

Enhancing pectin extraction from orange peel through citric acid-assisted optimization based on a dual response.

Pectin is widely used in several products in the industry. Conventionally, strong and harmful acids are used for its extraction. This study optimized the extraction of orange peel's pectin using citric acid, considering yield and degree of esterification (DE) as response variables. Proximal analyses were performed, and the samples were subjected to a Box-Behnken design on three central points, considering as variables the temperature, time, and pH. The results of proximate analyses of the orange peels revealed 11.76 % moisture content, 87.26 % volatiles, 0.09 % ash, 50.45 % soluble carbohydrates, 70.60 % total carbohydrates, 0.89 % fixed carbon, 5.35 % lipids, and 36.75 mg GAE/g of phenolic compounds. The resulting second-order polynomial model described the relation of the input and output variables related to each other. The best performance to obtain a higher yield (18.18 %) of high methoxyl pectin (DE 50 %) was set at 100 °C/30 min/pH 2.48. Pectin showed antioxidant properties by ABTS and DPPH assays and similar thermal properties to the commercial polymer. Its equivalent weight was 1219.51 mol/g, and the methoxyl and anhydrouronic acid were 2.23 and 67.10 %, respectively. Hence, pectin extraction with citric acid results in a high-quality polymer and could be used as a gelling agent, stabilizer, or texturizer in food products.

Carnauba wax-based edible coatings retain quality enhancement of orange (Citrus sinensis cv. Moro) fruits during storage.

Fruit coatings serve a dual purpose in preserving the quality of fruits. Not only do they act as a barrier against water evaporation and fungal infiltration, but they also enhance the fruit's visual appeal in the market. Yet, their influence on the fruit's quality components, which play a crucial role in determining its nutritional value, taste, and overall flavor, has remained relatively unexplored. This study aimed to evaluate the effects of carnauba wax coating on the quality of Moro oranges during storage. The selected fruits were meticulously chosen for uniformity in size. The experiment involved applying carnauba wax, a commonly used type among local producers, at four different concentrations: 0%, 0.5%, 1%, and 1.5%. These treatments were applied during various storage periods, including immediately after fruits were harvested and after 40 and 80 days. Following the application of these treatments, the oranges were stored in a controlled environment (morgue) at a temperature of 4 ± 1 °C. Subsequently, several physicochemical parameters of both the fruit flesh and skin were examined. The results unveiled a decline in the overall ascorbic acid content of the fruits. In terms of phenol content, a general decreasing trend was observed after harvesting. At each sampling interval during storage, the phenol content in uncoated fruits consistently exceeded that of their waxed counterparts. Significant reduction in fruit weight was observed throughout the storage period. Both vitamin C and total acidity levels in the fruit exhibited decreases during the storage period. As time passed, fruit firmness gradually declined, while fruit decay increased during the 40- and 80-day storage periods for untreated Moro oranges. The anthocyanin content showed an increasing trend. The study also unveiled a decline in the antioxidant capacity of citrus fruits during storage. Strong significant positive correlations were observed between total phenol content and key parameters, such as antioxidant activity (0.941**), MDA (0.364*), vitamin C content, and total carbohydrate content (0.475**). Skin radiance showed a perfect correlation with chroma and hue (1.000**). Principal component analysis revealed that the first principal component accounted for 34.27% of the total variance, out of a total of five principal components that explained 77.14% of the variance. Through cluster analysis, the variables were categorized into three distinct groups; one associated with weight loss and another with ion leakage. Considering these findings, carnauba wax-based coating emerges as a promising solution for preserving Moro oranges. It effectively mitigates fruit weight loss and helps maintain fruit firmness during storage, making it a valuable tool for fruit preservation.

Chemical and genetic basis of orange flavor.

Sweet orange (Citrus sinensis) exhibits limited genetic diversity and high susceptibility to Huanglongbing (HLB). Breeding HLB-tolerant orange-like hybrids is in dire need. However, our understanding of the key compounds responsible for orange flavor and their genetic regulation remains elusive. Evaluating 179 juice samples, including oranges, mandarins, Poncirus trifoliata, and hybrids, distinct volatile compositions were found. A random forest model predicted untrained samples with 78% accuracy and identified 26 compounds crucial for orange flavor. Notably, seven esters differentiated orange from mandarin flavor. Cluster analysis showed six esters with shared genetic control. Differential gene expression analysis identified C. sinensis alcohol acyltransferase 1 (CsAAT1) responsible for ester production in orange. Its activity was validated through overexpression assays. Phylogeny revealed the functional allele was inherited from pummelo. A SNP-based DNA marker in the coding region accurately predicted phenotypes. This study enhances our understanding of orange flavor compounds and their biosynthetic pathways and expands breeding options for orange-like cultivars.

Comparison of vitamin C and flavanones between freshly squeezed orange juices and commercial 100% orange juices from four European countries.

Knowing the true levels of nutrients and dietary bioactives in fruit juices at the point of consumption is key to properly understand their potential health benefits. The objective was to characterise the vitamin C and flavanone content in commercial orange juices consumed in Europe, compared with fresh-squeezed juices. Commercial juices were a rich source of vitamin C (>30% of the Nutrient Reference Value). Vitamin C in fresh-squeezed juices, at the end of their shelf-life, remained 33% higher than the levels found in the commercial juices. Flavanones had similar values from both commercial and fresh juices, except for fresh samples stored for 48 h, where fresh juices had higher values (22.36 mg/100 mL). Thus, orange juices preserve their bioactive compounds during storage, with very little influence of the brand, country, industrial process or storage conditions. Main bioactive compounds in commercial juices are present at nutritionally significant levels to the freshly-squeezed ones.

Comparison of green solvents for the revalorization of orange by-products: Carotenoid extraction and in vitro antioxidant activity.

Orange peels contain a considerable number of bioactive compounds such as carotenoids, that can be used as ingredients in high-value products. The aim of this study was to compare orange peel extracts obtained with different green solvents (vegetable oils, fatty acids, and deep eutectic solvents (DES)). In addition, the chemical characterization of a new hydrophobic DES formed by octanoic acid and l-proline (C8:Pro) was performed. The extracts were compared in terms of carotenoid extraction, antioxidant activity by three methods, color, and environmental impact. The results confirmed that the mixture of C8:Pro is a DES and showed the highest carotenoid extraction (46.01 µg/g) compared to hexane (39.28 µg/g). The antioxidant activity was also the highest in C8:Pro (2438.8 µM TE/mL). Finally, two assessment models were used to evaluate the greenness and sustainability of the proposed extractions. These results demonstrated the potential use of orange peels in the circular economy and industry.

Plasma proteome profiling reveals molecular mechanisms underlying the effects of daily consumption of 'Bahia' and 'Cara Cara' orange juices.

Orange juice is an important food source of bioactive compounds, mainly the flavanones hesperidin and narirutin. This study aimed to investigate the underlying molecular mechanisms of action of orange juice's health properties by analyzing changes in the plasma proteome of healthy Brazilian volunteers after consuming juices made from 'Bahia' (BOJ-source of flavanones) and 'Cara Cara' (CCOJ-source of flavanones and carotenoids) oranges cultivated in Brazil. We used an untargeted proteomic approach, with a particular emphasis on the juices' effects on blood coagulant activity. We identified 247 differentially expressed proteins, of which 170 significantly increased or decreased after BOJ consumption and 145 after CCOJ. These proteins are involved in 105 processes that can significantly regulate cell adhesion, cell signaling, cell metabolism, inflammation, or others. Bioinformatic analysis evidenced proteins with major cellular regulatory capacity (e.g., FN1 and GAPDH) and predicted transcription factors (TFs) (e.g., SP1 and CEBPA) and miRNAs (e.g., miR-1-3p and miR-615-3p) that could be involved in the regulation of differentially expressed proteins. In-silico docking analyses between flavanone metabolites and TFs evidenced the higher binding capacity of narirutin phase II metabolites with akt1 and p38, interactions that suggest how the expression of genes of differentially expressed proteins were activated or inhibited. Moreover, the study shed light on proteins of coagulation cascade that presented expression modulated by both juices, proposing the modulation of blood coagulant activity as a potential benefit of OJ (mainly CCOJ) consumption. Taken together, this study revealed that BOJ and CCOJ consumption affected plasma proteome in healthy individuals, suggesting potential molecular targets and mechanisms of OJ bioactive compounds in humans.

Multitargeted molecular docking and dynamics simulation studies of flavonoids and volatile components from the peel of Citrus sinensis L. (Osbeck) against specific tumor protein markers.

Citrus sinensis (L.) Osbeck (Rutaceae), commonly known as the sweet orange, is a popular and widely consumed fruit with several medicinal properties. The present study aimed to perform the in silico screening of 18 flavonoids and eight volatile components from the peel of C. sinensis against apoptotic and inflammatory proteins, metalloprotease, and tumor suppressor markers. Flavonoids obtained higher probabilities than volatile components against selected anti-cancer drug targets. Hence, the data from the binding energies against the essential apoptotic and cell proliferation proteins substantiate that they may be promising compounds in developing effective candidates to block cell growth, proliferation, and induced cell death by activating the apoptotic pathway. Further, the binding stability of the selected targets and the corresponding molecules were analyzed by 100 ns molecular dynamics (MD) simulations. Chlorogenic acid has the most binding affinity against the important anti-cancer targets iNOS, MMP-9, and p53. The congruent binding mode to different drug targets focused on cancer shown by chlorogenic acid suggests that it may be a compound with significant therapeutic potential. Moreover, the binding energy predictions indicated that the compound had stable electrostatic and van der Waal energies. Thus, our data reinforce the medicinal importance of flavonoids from C. sinensis and expand the need for more studies, seeking to optimize results and amplify the impacts of further in vitro and in vivo studies. Communicated by Ramaswamy H. Sarma.

The effect of adding pomace on the bioactive composition and flavor volatiles in fermented orange juice with Lactobacillus.

BACKGROUND: The consumption of oranges generates huge amounts of pomaces, which are the potential raw materials to increase the nutritional value of the products. RESULTS: In this study, the bioactive composition and flavor volatiles in Lactobacillus fermented orange juice with added pomaces were researched. Results showed that the orange juices blended with pomaces were favorable substrates for Lactobacillus growth and the colony counts reached above 9.0 log CFU mL-1 , total phenolics, total flavonoids, and the antioxidant activity in orange juices were increased significantly after adding pomaces. Some amino acids, such as threonine (P < 0.0001), isoleucine (P < 0.01), and glycine (P < 0.01) were markedly higher in fermented orange juices with pomaces. The flavonoid diversity was more abundant by adding pomace fermentation and most flavonoids showed higher levels in fermented juices with the pomace, Lactobacillus fermentum 252 may transform some flavonoids through deglycosylation and reduction reaction. Furthermore, orange pomace mainly improved the flavor volatiles by increasing terpenoids and alcohol, such as d-limonene and benzyl alcohol, and decreasing volatile acids. CONCLUSION: This study presented a novelty in elevating the nutritional value of juice by the utilization of pomaces, its findings can provide a new way to mine the bioactive ingredient from Citrus by Lactobacillus, and can be used as a guide for the development of new Citrus processing technologies and functional foods. © 2023 Society of Chemical Industry.

Effects of irradiation on the aging and sensory quality of navel orange distilled spirits.

BACKGROUND: 60 Co-γ irradiation can simulate the effects of aging and enhance the flavor of distilled spirits. The present study aimed to investigate the effects of 0, 2, 4, 6, 8 and 10 kGy 60 Co-γ irradiation doses on the key aroma components in newly produced navel orange distilled spirits and thus determine the mechanism of their aging distilled spirits. RESULTS: The identification of aroma compounds demonstrated that ethyl hexanoate, d-limonene, ethyl octanoate, 3-methyl-1-butanol and linalool are the key aroma compounds in navel orange distilled spirits, which were increased except for linalool with irradiation doses of 2-6 kGy. Irradiation treatment simulated the effects of the aging of navel orange distilled spirits by promoting the content of total acids, total esters and aldehydes. Irradiation doses of 2-6 kGy increased the aroma intensity of navel orange distilled spirits, reaching an optimum at 6 kGy. However, irradiation doses as high as 8 and 10 kGy decreased the content of esters in navel orange distilled spirits, which led to a deterioration of the spirit flavor. CONCLUSION: Low doses of 60 Co-γ irradiation can simulate the effects of the aging by increasing the content of key aromatic compounds in navel orange distilled spirits. © 2023 Society of Chemical Industry.

Peracetic acid residues in orange juice can lead to a 5-vinylguaiacol-induced clove-like off-flavor via Baeyer-Villiger oxidation of hesperidin.

A balanced flavor is a major quality attribute of orange juice. Formation of 4-vinylguaiacol during storage can lead to an undesirable clove-like off-flavor. However, clove-like off-flavors were occasionally reported despite low 4-vinylguaiacol concentrations, suggesting an alternative molecular background. Application of gas chromatography-olfactometry and aroma extract dilution analysis to an orange juice with a pronounced clove-like off-flavor resulted in the identification of 5-vinylguaiacol. The compound showed the same odor as 4-vinylguaiacol, but was previously unknown in orange juice. In five of six commercial orange juices with clove-like off-flavors, 5-vinylguaiacol was even more odor-active than 4-vinylguaiacol. Spiking and model studies suggested that 5-vinylguaiacol is formed during pasteurization from the natural orange juice component hesperidin and residual peracetic acid used as cleaning agent by a Baeyer-Villiger oxidation. An activity-guided screening approach confirmed the role of hesperidin as 5-vinylguaiacol precursor. In conclusion, peracetic acid should no longer be used in orange juice processing plants.

Analysis of aroma components changes in Gannan navel orange at different growth stages by HS-SPME-GC-MS, OAV, and multivariate analysis.

The ripe Gannan navel oranges have an appealing aroma, but few studies have reported the changes of these aromatic substances during the growth of navel oranges. In this study, changes of aroma components in Gannan navel orange from 119 to 245 days after flowering were systematically studied using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) coupled with multivariate analysis, including principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). A total of 43 and 54 aroma components were identified in pulp and peel of navel orange, respectively. The odor active value (OAV) results indicated that 14 substances were the key aroma components during the growth of navel orange. Among them, the contribution of linalool, ß-myrcene and limonene were the highest. The multivariate statistical analysis further confirmed that 14 and 18 compounds could be used as key markers to distinguish the pulp and peel at different growth stages, respectively. Results from this study contributed to a better understanding of the dynamic variation and retention of aroma compounds during navel orange growth, and have great potential for industrial application.

Effect of hydrocolloid concentration in low-calorie orange jellies on preservation of bioactive compounds and antioxidant capacity.

The purpose of this paper was to avaliate of the concentration of hydrocolloids (low methoxyl pectin [LMP], guar gum [GG], and carrageenan gum [CG]) in low-calorie orange jellies in order to maximize the amount of bioactive compounds and antioxidant capacity, and to study the influence on degradation these compounds. A mixture design with seven tests was used to analyze the total phenolic compounds, ascorbic acid (vitamin C) and antioxidant capacity (ABTS, DPPH and ß-carotene/linoleic acid methods). The results were analyzed by response surface methodology and the Scott-Knott mean test at a significance level of 5% (p ≤ 0.05). In general, the regions containing 0.5% GG and 0.5% GC had higher levels of the variables under study, and this combination preserved the bioactive compounds and antioxidant activity of jellies in relation to that of orange juice.

Ultrasound Treatment Improves Fruit Quality of Postharvest Blood Oranges (Citrus sinensis L. Osbeck): Anthocyanin Enrichment and Its Biosynthesis.

This study was to investigate the effects of different nonthermal treatments on quality attributes, anthocyanin profiles, and gene expressions related to anthocyanin biosynthesis during low-temperature storage, including pulsed light (PL), magnetic energy (ME), and ultrasound (US). Among these treatments, 1 min US treatment was the most effective method for improving fruit quality and increasing total anthocyanin contents (by 29.89 ± 3.32%) as well as individual anthocyanins during low-temperature storage of 28 days. This treatment resulted in high color intensity, intact cellular architectures, and positive sensory evaluation. In contrast, PL and ME treatments displayed negative effects on quality improvement, leading to the destruction of cell architectures and inhibiting anthocyanin levels. Furthermore, qPCR analysis revealed that the structural genes (C4H, CHS1, CHS2, CHI, F3H, ANS, and GST) related to anthocyanin biosynthesis and transport were the target genes and upregulated in response to the cavitation effect of US treatment.

Evaluation of chemical characterization and antihyperlipidemic potential of orange peel powder (Citrus sinensis) in male human subjects.

Citrus sinensis is an important member of the genus Citrus which contains phenolic compounds and bioflavonoids which have antihyperlipidemic and antiatherogenic effects. It also has the potential to reduce oxidative stress. To investigate the antihyperlipidemic effect of orange peel powder was encapsulated and analyzed in hyperlipidemic patients. Results showed that it contains moisture (12.2%), ash content (7.9%), crude fat (0.78%), crude protein (12.37%) and crude fiber (13.2%). Total phenolic content and total flavonoid content were observed as 163.17 mg and 17.23mg in quercetin equivalent per gram a dry weight basis. Furthermore, the Orange peel powder was given in the form of medicinal capsules to hyperlipidemia male subjects. The experimental groups (G1 and G2) were given orange peel powder in capsules 400mg/d to the G1 group and 800mg/d to the G2 group for the time of 45 days. The serum lipid profile of patients was measured before and after the experimental trial. The result showed that G1 and G2 showed a decrease in plasma lipid parameters and increased high-density lipoprotein content in blood substantially as compared to G0. Thus, it was concluded from the results that orange peel powder depicts a significant impact on treating hyperlipidemia.