Lycopene Yield Research Articles

Valorization of tomato processing by-products: Predictive modeling and optimization for ultrasound-assisted lycopene extraction

Lycopene is a carotenoid highly valuable to the food, pharmaceutical, dye, and cosmetic industries, present in ripe tomatoes and other fruits with a distinctive red color. The main source of lycopene is tomato crops. This bioactive component can be successfully isolated from tomato processing waste, commonly called tomato pomace, mostly made from tomato skins, seeds, and some residual tomato tissue. The main investigative focus in this work was the application of green engineering principles in each stage of the optimized ultrasound-assisted extraction (UAE) of enzymatically treated tomato skins to obtain functional extracts rich in lycopene. The experimental plan was designed to determine the influence of studied operating parameters: enzymatic reaction time (60, 120, and 180 min), extraction time (0, 5, 10, 15, 30, 60, and 120 min), and temperature (25, 35 and 45 ℃) on lycopene yield. Process optimization was performed based on the yield of lycopene [1018, 1067, and 1120 mg/kg] achieved at optimal operating conditions. An artificial neural network (ANN) model was developed and trained for predictive modeling of the closed extraction system, with operating parameters used as input neurons and experimentally obtained values for lycopene content defined as the output neural layer. Applied ANN architecture provided a high correlation of experimental output with ANN-generated data (R=0.99914) with a model deviation error for the entire data set of RMSE=5.3 mg/kg. The k-Nearest Neighbor algorithm was introduced to predict lycopene yield using experimental key features: operating temperature, extraction time, and time of enzymatic treatment, split into training and testing sets with an 85/15 ratio. The model interpretation was conducted through the SHAP (SHapley Additive exPlanations) methodology.

Characteristics of the existing methods for obtaining carotenes from carotenoid concentrates

Carotenes, which simultaneously have the properties of natural dyes and biologically active substances that have a positive effect on human health and life expectancy, are becoming increasingly widespread in the food, pharmacological and cosmetic industries. This necessitates an increase in the production of carotenes on an industrial scale. For use in food technologies, an encapsulated form of carotenes is recommended, which requires their high purity. The purpose of this study is to analyze domestic and foreign scientific, technical and patent information on existing methods for obtaining carotenes from carotenoid concentrates to determine the direction of research for the development of technology for the production of carotenes, in particular lycopene, ensuring the production of high purity lycopene from carotenoid concentrates, as well as increasing release of lycopene. The issues of using chromatographic methods for isolating lycopene, their advantages and disadvantages, as well as the use of non-polar and low-polar organic solvents for isolating lycopene from carotenoid concentrate are considered. The promising direction of research on the use of adsorption resins in the isolation of lycopene from carotenoid concentrates is noted.It has been concluded that the currently existing methods for obtaining carotenes from carotenoid concentrates, in particular lycopene, are quite technically complex and time-consuming. Some of the mallow the production of high purity lycopene, but the yield of lycopene is so low that their industrial scaling seems impractical. Taking this into account, research is being updated in the field of developing a technology for producing lycopene from a carotenoid concentrate, providing a high yield of high purity lycopene, with the possibility of its implementation on an industrial scale.

Expanding the CRISPR Toolbox for Engineering Lycopene Biosynthesis in Corynebacterium glutamicum.

Lycopene represents one of the central compounds in the carotenoid pathway and it exhibits a potent antioxidant ability with wide potential applications in medicine, food, and cosmetics. The microbial production of lycopene has received increasing concern in recent years. Corynebacterium glutamicum (C. glutamicum) is considered to be a safe and beneficial industrial production platform, naturally endowed with the ability to produce lycopene. However, the scarcity of efficient genetic tools and the challenge of identifying crucial metabolic genes impede further research on C. glutamicum for achieving high-yield lycopene production. To address these challenges, a novel genetic editing toolkit, CRISPR/MAD7 system, was established and developed. By optimizing the promoter, ORI and PAM sequences, the CRISPR/MAD7 system facilitated highly efficient gene deletion and exhibited a broad spectrum of PAM sites. Notably, 25 kb of DNA from the genome was successfully deleted. In addition, the CRISPR/MAD7 system was effectively utilized in the metabolic engineering of C. glutamicum, allowing for the simultaneous knockout of crtEb and crtR genes in one step to enhance the accumulation of lycopene by blocking the branching pathway. Through screening crucial genes such as crtE, crtB, crtI, idsA, idi, and cg0722, an optimal carotenogenic gene combination was obtained. Particularly, cg0722, a membrane protein gene, was found to play a vital role in lycopene production. Therefore, the CBIEbR strain was obtained by overexpressing cg0722, crtB, and crtI while strategically blocking the by-products of the lycopene pathway. As a result, the final engineered strain produced lycopene at 405.02 mg/L (9.52 mg/g dry cell weight, DCW) in fed-batch fermentation, representing the highest reported lycopene yield in C. glutamicum to date. In this study, a powerful and precise genetic tool was used to engineer C. glutamicum for lycopene production. Through the modifications between the host cell and the carotenogenic pathway, the lycopene yield was stepwise improved by 102-fold as compared to the starting strain. This study highlights the usefulness of the CRISPR/MAD7 toolbox, demonstrating its practical applications in the metabolic engineering of industrially robust C. glutamicum.

Global rewiring of lipid metabolism to produce carotenoid by deleting the transcription factor genes ino2/ino4 in Saccharomyces cerevisiae

The transcription factor complex INO2 and INO4 in Saccharomyces cerevisiae plays a vital role in lipid biosynthesis by activating multiple genes in the biosynthetic pathways of phospholipid, fatty acid, and sterol. Previous studies have reported conflicting results regarding the effects of ino2 and ino4 gene expression levels on target chemicals. Therefore, this study aimed to examine the influence of different ino2 and ino4 expression levels on carotenoid production (e.g., lycopene), which shares a common precursor, acetyl-CoA, with lipid metabolism. Surprisingly, 2.6- and 1.8-fold increase in lycopene yield in the ino2 and ino4 deletion strains were found, respectively. In contrast, ino2 overexpression did not promote lycopene accumulation. Additionally, there was a decrease in intracellular free fatty acids in the ino2 deletion strain. Comparative transcriptome analysis revealed a significant downregulation of genes related to lipid biosynthesis in the ino2 deletion strain. To our knowledge, this is the first report showing that deletion of transcription factor genes ino2 and ino4 can facilitate lycopene accumulation. These findings hold significant implications for the development of metabolically engineered S. cerevisiae with enhanced carotenoid production.

Enhancement of Lycopene Synthesis via Low-Frequency Alternating Magnetic Field in Brassica trispora

In recent years, magnetic fields have emerged as a non-thermophysical treatment with a significant impact on microbial fermentation processes. Brassica trispora is a microorganism known for its industrial-scale production of lycopene and high yield of single cells. This study aimed to investigate the impact of low-frequency magnetic fields on lycopene synthesis by Brassica trispora and elucidate the underlying mechanism for enhancing lycopene yield. The results indicate that both the intensity and duration of the magnetic field treatment influenced the cells. Exposing the cells to a 0.5 mT magnetic field for 48 h on the second day of fermentation resulted in a lycopene yield of 25.36 mg/g, representing a remarkable increase of 244.6% compared to the control group. Transcriptome analysis revealed that the alternating magnetic field significantly upregulated genes related to ROS and the cell membrane structure, leading to a substantial increase in lycopene production. Scanning electron microscopy revealed that the magnetic field treatment resulted in a rough, loose, and wrinkled surface morphology of the mycelium, along with a few micropores, thereby altering the cell membrane permeability to some extent. Moreover, there was a significant increase in intracellular ROS content, cell membrane permeability, key enzyme activity involved in lycopene metabolism, and ROS-related enzyme activity. In conclusion, the alternating frequency magnetic field can activate a self-protective mechanism that enhances lycopene synthesis by modulating intracellular ROS content and the cell membrane structure. These findings not only deepen our understanding of the impact of magnetic fields on microbial growth and metabolism but also provide valuable insights for developing innovative approaches to enhance carotenoid fermentation.

Multi-modular metabolic engineering and efflux engineering for enhanced lycopene production in recombinant Saccharomyces cerevisiae.

In this research, lycopene production in yeast was markedly enhanced by integrating a multi-modular approach, acetate signaling-based down-regulation of competitive pathways, and an efflux optimization strategy.

Metabolic Engineering of Pichia pastoris for High-Level Production of Lycopene.

Lycopene is widely used in cosmetics, food, and nutritional supplements. Microbial production of lycopene has been intensively studied. However, few metabolic engineering studies on Pichia pastoris have been aimed at achieving high-yield lycopene production. In this study, the CRISPR/Cpf1-based gene repression system was developed and the gene editing system was optimized, which were applied to improve lycopene production successfully. In addition, the sterol regulatory element-binding protein SREBP (Sre) was used for the regulation of lipid metabolic pathways to promote lycopene overproduction in P. pastoris for the first time. The final engineered strain produced lycopene at 7.24 g/L and 75.48 mg/g DCW in fed-batch fermentation, representing the highest lycopene yield in P. pastoris reported to date. These findings provide effective strategies for extended metabolic engineering assisted by the CRISPR/Cpf1 system and new insights into metabolic engineering through transcriptional regulation of related metabolic pathways to enhance carotenoid production in P. pastoris.

Optimization of antioxidant and lycopene extraction from tomato pomace using Hansen solubility parameters and its application in chicken meat preservation.

Tomato pomace, composed of peels and seeds, is often discarded or used as animal feed. However, it contains valuable phytochemicals, including lycopene. Lycopene, a natural pigment, is an antioxidant known for reducing the risk of chronic diseases like cardiovascular ailments and cancer. In this study, we aimed to study the possibility of valorizing tomato pomace by quantifying phenolic compounds, evaluating the antioxidant activity of their extracts, as well as extracting and quantifying lycopene, and studying the effect of tomato peel extract on the oxidative stability of chicken patties during storage. The effectiveness of different solvent mixtures for the extraction of lycopene was evaluated using Hansen solubility parameters (HSPs). The obtained results showed that the best solvent mixture was hexane/acetone (50/50) with a Hansen theoretical distance of 7.2, indicating its favorable solvation power. It also achieved a notable extraction yield of 3.12% and the highest lycopene yield of 20.05mg/100g. This combination demonstrated the highest values in terms of total phenolic (24.06mg equivalent gallic acid/100g dry matter) and flavonoid content (30.55mg equivalent catechin/100g dry matter), indicating a significant presence of these compounds. However, its 1,1-diphenyl-2-picrylhydrazyl (13.51µg/mL) and ABTS, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid, (8.52µg/mL) IC50 values were comparatively lower than the other mixes. The use of this fraction as a food additive and antioxidant showed significant competitiveness with the conventional preservative, 2,6-di-tert-butyl-4-methylphenol. Tomato extract can be considered a potential natural preservative in food preparations due to its high lycopene content. PRACTICAL APPLICATION: This research provides valuable insights into optimizing the extraction of antioxidants from tomato pomace, using HSPs. The findings have the potential to benefit the food industry by developing improved methods for preserving chicken meat through the application of these optimized antioxidant extracts. By enhancing the preservation process, this study may contribute to extending the shelf life and maintaining the quality of chicken meat, leading to reduced food waste and improved consumer satisfaction.

Optimization of extraction of lycopene from carrot and determination of its antioxidant activity

Background: Lycopene is a carotenoid which is abundant in mature red plant fruits, especially in tomato, carrot and watermelon. This study investigated lycopene extraction from carrots and its antioxidant properties. Methods and results: Through an orthogonal experiment (L9 (3)3), lycopene extraction was optimized and its antioxidant capacity was assessed by DPPH, ABTS, and hydroxyl radical scavenging assay. The results showed that the maximum yield of lycopene was obtained when the extraction temperature, extraction time and solid-liquid ratio were 40℃, 125 min and 1:2 g/mL, and the influence on the extraction yield of lycopene decreased in the order: solid-liquid ratio > extraction time > extraction temperature. The antioxidant activity test showed that lycopene had strong scavenging ability on DPPH and ABTS free radicals, but poor scavenging ability on hydroxyl radicals. Conclusion: The maximum extraction yield of lycopene is 50.82 ± 0.18 µg/g. Lycopene has good antioxidant capacity. This study provides a theoretical framework and statistical support for the continued development of the lycopene from carrots, which is projected to be exploited as a natural antioxidant or health supplement in the food and cosmetics industries.

Development of Terminator-Promoter Bifunctional Elements for Application in Saccharomyces cerevisiae Pathway Engineering.

The construction of a genetic circuit requires the substitution and redesign of different promoters and terminators. The assembly efficiency of exogenous pathways will also decrease significantly when the number of regulatory elements and genes is increased. We speculated that a novel bifunctional element with promoter and terminator functions could be created via the fusion of a termination signal with a promoter sequence. In this study, the elements from a Saccharomyces cerevisiae promoter and terminator were employed to design a synthetic bifunctional element. The promoter strength of the synthetic element is apparently regulated through a spacer sequence and an upstream activating sequence (UAS) with a ~5-fold increase, and the terminator strength could be finely regulated by the efficiency element, with a ~5-fold increase. Furthermore, the use of a TATA box-like sequence resulted in the adequate execution of both functions of the TATA box and the efficiency element. By regulating the TATA box-like sequence, UAS, and spacer sequence, the strengths of the promoter-like and terminator-like bifunctional elements were optimally fine-tuned with ~8-fold and ~7-fold increases, respectively. The application of bifunctional elements in the lycopene biosynthetic pathway showed an improved pathway assembly efficiency and higher lycopene yield. The designed bifunctional elements effectively simplified pathway construction and can serve as a useful toolbox for yeast synthetic biology.

Machine learning-guided prediction of potential engineering targets for microbial production of lycopene

The process of designing streamlined workflows for developing microbial strains using classical methods from vast amounts of biological big data has reached its limits. With the continuous increase in the amount of biological big data, data-driven machine learning approaches are being used to overcome the limits of classical approaches for strain development. Here, machine learning-guided engineering of Deinococcus radiodurans R1 for high-yield production of lycopene was demonstrated. The multilayer perceptron models were first trained using the mRNA expression levels of the key genes along with lycopene titers and yields obtained from 17 strains. Then, the potential overexpression targets from 2,047 possible combinations were predicted by the multilayer perceptron combined with a genetic algorithm. Through the machine learning-aided fine-tuning of the predicted genes, the final-engineered LY04 strain resulted in an 8-fold increase in the lycopene production, up to 1.25 g/L from glycerol, and a 6-fold increase in the lycopene yield.

Lycopene extraction from industrial tomato processing waste using emerging technologies, and its application in enriched beverage development

SummaryThe present study aimed to extract lycopene from the industrial tomato processing waste (peel) using emerging technologies such as power ultrasound‐assisted extraction (UAE), low‐temperature microwave‐assisted extraction (MAE), pulsed electric field (PEF)‐assisted extraction (PAE), combined low‐temperature microwave‐power ultrasound‐assisted extraction (MUAE) and combined ultrasound‐pulsed electric field‐assisted extraction (UPAE). A green solvent (ethanol: ethyl acetate, 2:3, v/v) was used for the recovery of lycopene and a mass transfer kinetic approach was used to understand the extraction kinetics of various extraction methods. The highest extraction yield was observed for UPAE treatment with the lycopene yield of 3.56% followed by MUAE with 3.49%. UPAE had the highest antioxidant capacity (87.09% DPPH) compared to other methods. Thus, the green solvent and combination UPAE technology are environmentally sustainable techniques and present a good scope for lycopene recovery. Further, the extracted lycopene was entrapped in oil in water emulsion to develop an enriched lemon juice beverage.

Flux decline and fouling analysis in reverse osmosis of watermelon juice

AbstractIn this article, the concentration of watermelon juice by HR98PP membrane was investigated at 30 and 40 bar of operating pressure. The semi‐empirical model of permeate flux was determined. The predominant fouling mechanism in the concentration was found to be complete blocking by Hermia's model. Recovery yield and content of total solid, lycopene and antioxidant capacity in concentrate was analyzed. Results indicated that, concentration of watermelon juice by HR98PP at 40 bar exhibited the higher effectiveness than that at 30 bar. At 40 bar and 2.25 of CF, contents of total sugar (TS), lycopene, and antioxidant capacity in concentrate were 171.31 g/L, 83.9 mg/L, and 124.74 mg TEAC/L, respectively. Recovery yields of TS, lycopene, and antioxidant capacity in concentrate were 98.67%, 90.03%, and 82.39%, respectively. Maximum CF value of concentration at 40 bar of operating pressure was 2.64. The mathematical model was built for estimation of the change in contents of lycopene and TS versus time. Maximum theoretical content of lycopene and TS at 40 bar were estimated as 185 mg/L and 341 g/L, respectively. The cleaning procedure with NaOH solution at pH 10 could fully recovery permeate flux after the concentration. Results imply that, concentration of watermelon juice by HR98PP was feasible.Practical ApplicationsRO filtration is a method that is commonly used for concentration of fruit juice. In this study, the watermelon juice was concentrated with RO to increase concentration of substances. This solution can be applied in factories producing concentrated juice, fruit powder. Operating pressure and models have been evaluated. Fouling mechanism and flux model have also been researched. From the mathematical model studies, influence of process parameters on the concentration process and operating time were derived which will be helpful to apply and scale‐up in industry.

A tunable metabolic valve for precise growth control and increased product formation in Pseudomonas putida

Metabolic engineering of microorganisms aims to design strains capable of producing valuable compounds under relevant industrial conditions and in an economically competitive manner. From this perspective, and beyond the need for a catalyst, biomass is essentially a cost-intensive, abundant by-product of a microbial conversion. Yet, few broadly applicable strategies focus on the optimal balance between product and biomass formation. Here, we present a genetic control module that can be used to precisely modulate growth of the industrial bacterial chassis Pseudomonas putida KT2440. The strategy is based on the controllable expression of the key metabolic enzyme complex pyruvate dehydrogenase (PDH) which functions as a metabolic valve. By tuning the PDH activity, we accurately controlled biomass formation, resulting in six distinct growth rates with parallel overproduction of excess pyruvate. We deployed this strategy to identify optimal growth patterns that improved the production yield of 2-ketoisovalerate and lycopene by 2.5- and 1.38-fold, respectively. This ability to dynamically steer fluxes to balance growth and production substantially enhances the potential of this remarkable microbial chassis for a wide range of industrial applications.

Optimizing the downstream MVA pathway using a combination optimization strategy to increase lycopene yield in Escherichia coli

BackgroundLycopene is increasing in demand due to its widespread use in the pharmaceutical and food industries. Metabolic engineering and synthetic biology technologies have been widely used to overexpress the heterologous mevalonate pathway and lycopene pathway in Escherichia coli to produce lycopene. However, due to the tedious metabolic pathways and complicated metabolic background, optimizing the lycopene synthetic pathway using reasonable design approaches becomes difficult.ResultsIn this study, the heterologous lycopene metabolic pathway was introduced into E. coli and divided into three modules, with mevalonate and DMAPP serving as connecting nodes. The module containing the genes (MVK, PMK, MVD, IDI) of downstream MVA pathway was adjusted by altering the expression strength of the four genes using the ribosome binding sites (RBSs) library with specified strength to improve the inter-module balance. Three RBS libraries containing variably regulated MVK, PMK, MVD, and IDI were constructed based on different plasmid backbones with the variable promoter and replication origin. The RBS library was then transformed into engineered E. coli BL21(DE3) containing pCLES and pTrc-lyc to obtain a lycopene producer library and employed high-throughput screening based on lycopene color to obtain the required metabolic pathway. The shake flask culture of the selected high-yield strain resulted in a lycopene yield of 219.7 mg/g DCW, which was 4.6 times that of the reference strain.ConclusionA strain capable of producing 219.7 mg/g DCW with high lycopene metabolic flux was obtained by fine-tuning the expression of the four MVA pathway enzymes and visual selection. These results show that the strategy of optimizing the downstream MVA pathway through RBS library design can be effective, which can improve the metabolic flux and provide a reference for the synthesis of other terpenoids.

Metabolic engineering of Escherichia coli BL21 strain using simplified CRISPR-Cas9 and asymmetric homology arms recombineering

BackgroundThe recent CRISPR-Cas coupled with λ recombinase mediated genome recombineering has become a common laboratory practice to modify bacterial genomes. It requires supplying a template DNA with homology arms for precise genome editing. However, generation of homology arms is a time-consuming, costly and inefficient process that is often overlooked.ResultsIn this study, we first optimized a CRISPR-Cas genome engineering protocol in the Escherichia coli (E. coli) BL21 strain and successfully deleted 10 kb of DNA from the genome in one round of editing. To further simplify the protocol, asymmetric homology arms were produced by PCR in a single step with two primers and then purified using a desalting column. Unlike conventional homology arms that are prepared through overlapping PCR, cloning into a plasmid or annealing synthetic DNA fragments, our method significantly both shortened the time taken and reduced the cost of homology arm preparation. To test the robustness of the optimized workflow, we successfully deleted 26 / 27 genes across the BL21 genome. Noteworthy, gRNA design is important for the CRISPR-Cas system and a general heuristic gRNA design has been proposed in this study. To apply our established protocol, we targeted 16 genes and iteratively deleted 7 genes from BL21 genome. The resulting strain increased lycopene yield by ~ threefold.ConclusionsOur work has optimized the homology arms design for gene deletion in BL21. The protocol efficiently edited BL21 to improve lycopene production. The same workflow is applicable to any E. coli strain in which genome engineering would be useful to further increase metabolite production.

A Comprehensive Optimization of Ultrasound-Assisted Extraction for Lycopene Recovery from Tomato Waste and Encapsulation by Spray Drying

This study aimed to extract bioactive compounds from tomato waste through ultrasound-assisted extraction (UAE), using ethanol as solvent. Process optimization was carried out by a central composite design of 33 runs for response surface modelling, simultaneously analyzing the effect of temperature (T), time (t), volume (V), liquid-to-solid ratio (L/S), amplitude (A), the pulser duration (on), and their interaction. The best conditions found by the desirability method (T = 65 °C, t = 20 min, L/S = 72 mL/g, A = 65%, on = 33 s, V = 90 mL) were experimentally verified, leading to the production of an extract with interesting properties (total carotenoids of 1408 ±14 µglycopene equivalents/g, lycopene yield of 1536 ± 53 µg/g, 36.1 ± 0.9 µgtrolox equivalents/g as antiradical power). Due to the instability of lycopene, the extract encapsulation by spray drying was undertaken using inulin and maltodextrins as coating agents. The evaluation of wall material composition provided high product recovery (73%), a high content of encapsulated compared to superficial lycopene (15.3 ± 2.9 and 0.30 ± 0.02 µg/g), and a product with good water solubility. The novelty of this work concerned the simultaneous study of the effect and interdependences of the UAE parameters, and the use of inulin to enhance the properties of microparticles.

Upstream Activation Sequence Can Function as an Insulator for Chromosomal Regulation of Heterologous Pathways Against Position Effects in Saccharomyces cerevisiae.

Metabolic engineering of microbial cell factories through integrating the heterologous synthetic pathway into the chromosome is most commonly used for industrial applications. However, the position of the foreign gene in the chromosome can affect its transcriptional level. As a microorganism that is generally regarded as safe (GRAS) and commonly applied in industrial manufacture with large-scale operations, Saccharomyces cerevisiae is also confronted with this position effect. In this study, we characterized 12 different chromosome sites by inserting the lycopene biosynthetic pathway as a reporter cassette. Due to the different integration loci, the gene transcription and lycopene yield exhibited more than 58-fold and 3.8-fold differences, respectively. Furthermore, changing the gene order also revealed a remarkable influence (30-fold and 14-fold) on gene transcription and lycopene yield. Besides, the upstream activation sequence of a strong promoter (defined as an insulator) in S. cerevisiae could reduce the impact by gene order, and increased the gene transcription (tenfold) and lycopene yield (sevenfold). Taken together, our results demonstrated that gene order and insulator affected gene transcription and heterogeneous biosynthesis, opening the opportunity to regulate gene transcription by insulator against position effect in S. cerevisiae.

Astaxanthin overproduction of Phaffia rhodozyma PR106 under titanium dioxide stress by transcriptomics and metabolic regulation analysis

In this study, astaxanthin yield of Phaffia rhodozyma PR106 increased significantly under titanium dioxide (TiO2) stress, and the yield of lycopene and β-carotene also increased significantly, as well as the yield of violaxanthin and lutein significantly decreased; in addition, TiO2 stress promoted cell division and changed cell morphology of PR106. Then, the mechanism of increasing astaxanthin yield was studied by transcriptomics and related metabolic regulation. The results showed that astaxanthin accumulation in PR106 was not directly related to mRNA transcription and post-translational modifications regulation under TiO2 stress; TiO2 stress accelerated glucose uptake of yeast, promoted reuse of ethanol, and increased the formation of acetyl-CoA and ATP. The more carbon flux was shifted to astaxanthin synthesis pathway and weakened carotenoids accumulation in astaxanthin branch pathway to improve the astaxanthin production of PR106. The metabolism regulation of ROS could continue in the PR106 strain.

Process optimization for the supercritical carbondioxide extraction of lycopene from ripe grapefruit (Citrus paradisi) endocarp

In this study, an underutilized citrus family fruit named grapefruit was explored for the extraction of lycopene using supercritical carbon dioxide (CO2) extraction technique. An experimental design was developed using response surface methodology to investigate the effect of supercritical carbon dioxide (CO2) operating parameter viz., pressure, temperature, CO2 flow rate, and extraction time on the extraction yield of lycopene yield from grapefruit. A total of 30 sets of experiments were conducted with six central points. The statistical model indicated that extraction pressure and extraction time individually, and their interaction, significantly affected the lycopene yield. The central composite design showed that the polynomial regression models developed were in agreement with the experimental results, with R2 of 0.9885. The optimum conditions for extraction of lycopene from grapefruit were 305 bar pressure, 35 g/min CO2 flow rate, 135 min of extraction time, and 70 °C temperature.