Carotenoid Degradation Research Articles

Application of spray drying, spray chilling and the combination of both methods to produce tucumã oil microparticles: characterization, stability, and β-carotene bioaccessibility

The aim of this work was to produce tucumã oil (PO) microparticles using different encapsulation methods, and to evaluate their properties, storage stability and bioaccessibility of the encapsulated β-carotene. Gum Arabic was used as carrier for spray drying (SD), while vegetable fat was the wall material for spray chilling (SC) and the combination of the methods (SDC). Powders were yellow (hue angle around 80°) and presented particles with small mean diameters (1.57–2.30 µm). PO and the microparticles possess high β-carotene contents (∼0.35–22 mg/g). However, some carotenoid loss was observed in the particles after encapsulation by SD and SDC (around 20%). After 90 days of storage, SDC particles presented the lowest degradation of total carotenoids (∼5%), while SD samples showed the highest loss (∼21%). Yet, the latter had the lowest contents of conjugated dienes (4.1–5.3 µmol/g) among treatments. At the end of simulated digestion, PO and the microparticles provided low β-carotene bioaccessibility (<10%), and only SC increased this parameter compared to the pure oil. In conclusion, carotenoid-rich microparticles with attractive color were obtained through microencapsulation of PO by SD, SC and SDC, revealing their potential as natural additives for the development of food products with improved nutritional properties. The SC method stood out for providing microparticles with high carotenoid content and retention, high oxidative stability, and improved β-carotene bioaccessibility.

Manufacture of active multilayer films made of functionalized pectin coated by polyhydroxyalkanoates: A fully renewable approach to active food packaging

Biodegradable active packaging, i.e. materials able to promote food preservation while avoiding plastic waste accumulation are expecting to play a key role fsor the manufacture of new generation materials.Bioactive films composed of citrus pectin (CP) added with extracts from spent coffee grounds (SCGs) were herein developed. To address the limitations of pectin-based materials, i.e. hydrophilicity and poor water barrier properties, an active multilayer film was prepared by coating the functionalized pectin by a two-steps dipping into polyhydroxyalkanoates (PHA) solutions characterized by different monomeric compositions. The PHA coating affected the stiffness of the film and its opacity, while improving its hydrophobicity and water vapor permeability. The dipping procedure did not compromise the stability of the bioactive compounds, rather it allowed to preserve their antioxidant and antimicrobial activities for longer times in comparison with uncoated functionalized film. Further, the multilayer material functionalized with extracts was able to delay the carotenoid degradation in mashed carrots likely because of the increased film opacity conferred by both phenols (caffeoylquinic acid isomers including chlorogenic acid) found in SCGs and PHAs layer suggesting that the new material may be used to extend the food shelf-life and potentially to enhance product health credentials.

Characterization of Carotenoid Cleavage Oxygenase Genes in Cerasus humilis and Functional Analysis of ChCCD1.

Carotenoid cleavage oxygenases (CCOs) are key enzymes that function in degrading carotenoids into a variety of apocarotenoids and some other compounds. In this study, we performed genome-wide identification and characterization analysis of CCO genes in Cerasus humilis. Totally, nine CCO genes could be classified into six subfamilies, including carotenoid cleavage dioxygenase 1 (CCD1), CCD4, CCD7, CCD8, CCD-like and nine-cis-epoxycarotenoid dioxygenase (NCED), were identified. Results of gene expression analysis showed that ChCCOs exhibited diverse expression patterns in different organs and in fruits at different ripening stages. To investigate the roles of ChCCOs in carotenoids degradation, enzyme assays of the ChCCD1 and ChCCD4 were performed in Escerichia coli BL21(DE3) that can accumulate lycopene, β-carotene and zeaxanthin. The prokaryotic expressed ChCCD1 resulted in obvious degradation of lycopene, β-carotene and zeaxanthin, but ChCCD4 did not show similar functions. To further determine the cleaved volatile apocarotenoids of these two proteins, headspace gas chromatography/mass spectrometer analysis was performed. Results showed that ChCCD1 could cleave lycopene at 5, 6 and 5', 6' positions to produce 6-methy-5-hepten-2-one and could catalyze β-carotene at 9, 10 and 9', 10' positions to generate β-ionone. Our study will be helpful for clarifying the roles of CCO genes especially ChCCD1 in regulating carotenoid degradation and apocarotenoid production in C. humilis.

Changes in Physical and Chemical Parameters of Beetroot and Carrot Juices Obtained by Lactic Fermentation

Fermented foods have gained popularity recently, especially lactofermented vegetable juice products that provide a rich source of nutrients. This study analyzed the properties of fermented beetroot, carrot and beetroot-carrot juices fermented with bacterial strains Lactiplantibacillus plantarum or Levilactobacillus brevis. Density, extract, dry matter content, pH, total acidity, pigments (betalain or carotenoids), color and LAB count were measured. The results showed that the LAB strains used were capable of fermenting the analyzed juices. It was proven that Lactiplantibacillus plantarum was the better strain for fermentation of vegetable juice. This might have been influenced by the fermentation temperature and the duration time. The highest number of lactic acid bacteria was observed for carrot juice fermented with L. brevis on the 4th day (9.41 log CFU/mL), while for L. plantarum the highest numbers were observed on the 5th–6th day (8.9–9.1 log CFU/mL). For beetroot and its mixture with carrot juices, higher results were observed on the 5th day for L. plantarum (9.0 and 8.3 log CFU/mL, respectively). In most variants of this process, fermentation can be completed after 4–5 days. During the fermentation of carrot and mixed juice slow degradation of carotenoids was observed, while in mixed juice an increase of red pigment (betanin) was observed. In beetroot juices huge degradation was observed for fermentation with L. brevis, while the second bacteria kept the same level of red pigment almost until the last day, while yellow decreased from the 3rd day. It can be concluded that the mixed juice was most stable according to the bacteria count and the pigment content. In our opinion, L. plantarum was better for the fermentation of juices than L. brevis. However, in future tests the time of fermentation can be shortened to 5 days and other LAB strains can be tested.

Identification and Expression Pattern of the Carotenoid Cleavage Oxygenase Gene Family in Lycium Suggest CCOs Respond to Abiotic Stress and Promote Carotenoids Degradation

Carotenoids are key metabolites in goji (Lycium), a traditional Chinese medicine plant; however, the carotenoid content varies in fruits of different goji species, and the mechanism of this variation is not clear. Carotenoids participate in signal transduction and photosynthesis, and function as colorants and photoprotectors. Members of the carotenoid cleavage oxygenase (CCO) gene family are involved in the regulation of phytohormones, pigments, and aromatic substances, such as abscisic acid (ABA), β-carotenoid, and α-ionone, by degrading carotenoids. Some CCO genes are also related to an abiotic stress response. Here, a total of 12 LbCCO genes were identified and analyzed from the L. barbarum genome. CCO genes were divided into six subfamilies based on the constructed phylogenetic tree, including LbNCEDs, LbCCD1, LbCCD3, LbCCD4, LbCCD7, and LbCCD8. Among them, CCD3 was reported for the first time. The gene structure and motif analysis revealed the conservation of CCO subfamilies. Pseudogene generation and the importance of each subfamily in CCOs were revealed by collinearity analysis. The spatiotemporal transcriptomes of L. barbarum and L. ruthenicum were compared, suggesting that CCD4-1 may dominate carotenoid degradation in goji fruits. Cis-acting elements prediction and environment responsive gene expression analyses indicated that salt-alkali stress and photothermal conditions might influence the expression of CCOs in goji. The results of this study enhance our understanding of the carotenoid degradation pathway, and the functions and responses of CCOs in goji species.

Unraveling transcriptomics of sorghum grain carotenoids: a step forward for biofortification

BackgroundSorghum (Sorghum bicolor [L.] Moench) is a promising target for pro-vitamin A biofortification as it is a global staple crop, particularly in regions where vitamin A deficiency is prevalent. As with most cereal grains, carotenoid concentrations are low in sorghum, and breeding could be a feasible strategy to increase pro-vitamin A carotenoids to biologically relevant concentrations. However, there are knowledge gaps in the biosynthesis and regulation of sorghum grain carotenoids, which can limit breeding effectiveness. The aim of this research was to gain an understanding of the transcriptional regulation of a priori candidate genes in carotenoid precursor, biosynthesis, and degradation pathways.ResultsWe used RNA sequencing of grain to compare the transcriptional profile of four sorghum accessions with contrasting carotenoid profiles through grain development. Most a priori candidate genes involved in the precursor MEP, carotenoid biosynthesis, and carotenoid degradation pathways were found to be differentially expressed between sorghum grain developmental stages. There was also differential expression of some of the a priori candidate genes between high and low carotenoid content groups at each developmental time point. Among these, we propose geranyl geranyl pyrophosphate synthase (GGPPS), phytoene synthase (PSY), and phytoene desaturase (PDS) as promising targets for pro-vitamin A carotenoid biofortification efforts in sorghum grain.ConclusionsA deeper understanding of the controls underlying biosynthesis and degradation of sorghum grain carotenoids is needed to advance biofortification efforts. This study provides the first insights into the regulation of sorghum grain carotenoid biosynthesis and degradation, suggesting potential gene targets to prioritize for molecular breeding.

Direct Solar Oven with and without UV Filter vs. Traditional Oven: Effect on Polyphenolic Antioxidants, Vitamins and Carotenoids of Food.

The use of efficient solar ovens can be a way for progressing ecofriendly technologies in the field of food preparation. In most performing direct solar ovens, the sun rays reach the foods directly, therefore, it becomes essential to check whether, in these conditions, foods can retain theirnutraceutical properties (antioxidants, vitamins and carotenoids). In the present research work, to investigate this issue, several foods (vegetables, meats, and a fish sample) were analyzed before and after cooking (traditional oven, solar oven, and solar oven with a UV filter). The content of lipophilic vitamins and carotenoids (analyzed via HPLC-MS) and the variation of total phenolic content (TPC), and antioxidant capacity (via Folin-Ciocalteu and DPPH assays) have evidenced that cooking with the direct solar oven allows to preserve some nutrients (i.e., tocopherols) and, sometimes, to enhance nutraceutical properties of vegetables (for example, solar oven-cooked eggplants showed 38% higher TPC compared to electric oven cooked sample) and meats. The specific isomerization of all-trans-β-carotene to 9-cis was also detected. The use of a UV filter is advisable to avoid UV drawbacks (for instance, a significant carotenoid degradation) without losing the beneficial effects of the other radiations.

Thermal Degradation of Carotenoids from Jambu Leaves (Acmella oleracea) during Convective Drying.

Jambu (Acmella oleracea) is a vegetable used in human food. Drying is an alternative to increase the shelf life of the product. High temperatures can induce the degradation of carotenoids and reduce the health benefits of these compounds. This study investigated the effect of the Jambu leaves' drying temperature on the carotenoid composition. It was performed previously by screening 16 plants from different localities based on the total carotenoid content. The process of drying by convection was carried out at temperatures of 35, 40, 50, and 60 °C in an air circulation oven, at an air velocity of 1.4 m/s-1 and a processing time of ~20 h. The drying data were fitted to six mathematical models and the quantification of the carotenoid retention was determined by HPLC-DAD. The study demonstrates that the carotenoid content among the samples collected from the 16 producers varied by 72% (lower-175 ± 16 μg/g, higher-618 ± 46 μg/g). Among the models, the Page model was found to be the most suitable model to explain the variation of the experimental data. The drying process at 40 °C reduces the Jambu leaves' carotenoid content significantly (p < 0.05) (All-trans-β-carotene-86 ± 2 μg/g, All-trans-lutein-141 ± 0.2 μg/g) but does not alter the carotenoid profile. The occurrence of similar reduction behavior was observed for the different carotenoids at all the temperatures studied. The drying process at 35 °C was the condition that ensured the highest retention of carotenoids, and also a product classified as a very high source of carotenoids (total carotenoids-748 ± 27 μg/g, vitamin A-17 ± 1 μg RAE/g). Thus, this study concludes that a temperature of 35 °C for 14 h (air velocity-1.4 m/s-1) is the best drying condition for Jambu leaves using a low-cost dryer and as a possibility for the preservation and marketing of this Amazonian raw material.

Identification and Characterization of CCD Gene Family in Rose (Rosa chinensis Jacq. ‘Old Blush’) and Gene Co-Expression Network in Biosynthesis of Flower Scent

Rose (Rosa sp.) is a widely used raw material for essential oil extraction and fragrance production. The carotenoid cleavage dioxygenases pathway is one of the main metabolic pathways for the degradation of carotenoids, which is located downstream of the terpenoids biosynthesis pathway and is closely related to the biosynthesis of volatile compounds. We performed a comprehensive genome-wide analysis of the rose CCD family genes (RcCCDs) in terms of phylogeny, sequence characterization, gene structure, gene duplication events, and transcriptome. Finally, 15 CCD family members were identified from the rose genome, and they were classified into three clades: nine for the CCD clade, four for the NCED clade, and two for the CCD-LIKE clade. The RcCCDs were distributed on chromosomes 1, 4, 5, 6, and 7, and were concentrated on both ends of the chromosomes. RcCCDs did not have paralogous genes or whole genome duplication events (WGD), eleven of them were single-copy genes, and their repetitive sequences were mainly dispersed and tandem. Ten RcCCDs were differentially expressed in the transcriptomes of different flowering stages. The expression of four of them increased and then decreased, which was the same process as the accumulation of volatile compounds, and it was speculated that these genes might be involved in the biosynthesis of volatile compounds. A total of fifteen modules were obtained by weighted gene co-expression network analysis of eighteen volatile compounds-related genes, of which six modules were a highly significant positive correlation with volatile compounds, and 20 hub genes in the modules were predicted. These hub genes all exercised their functions in the early flowering stage with strict temporal specificity. This study provided a theoretical basis for further exploring the biological functions of RcCCDs and hub genes regulating the synthesis and metabolism of volatile compounds in rose.

Uticaj plave svetlosti iz prirodnih i veštačkih izvora na kožu

Blue light includes rays of lower energy in comparison to UV radiation, but it has a greater power of penetrating the dermis, even to a depth of 1mm. The aim of this review article was to analyze the biological effects of natural and artificial blue light on the skin based on the available literature, as well as to propose preventive measures in order to protect the skin from its harmful effects. The latest research has shown that blue light has various direct and indirect effects on the skin. The direct effects of blue light on the skin are the excessive creation of reactive oxygen species, nitrogen and hyperpigmentation, and it indirectly affects the skin by disrupting the circadian rhythm and secreting melatonin. Blue light has a direct effect on chromophores that are present in the skin and leads to their activation. Their activation leads to the excessive production of reactive oxygen species and release of reactive nitrogen species, that is, nitrogen monoxide (NO), which triggers melanogenesis and hyperpigmentation. Also, there comes to the decrease in cell vitality and/or proliferation of keratinocytes and melanocytes, then increased synthesis of pro-inflammatory interleukins and tumor necrosis factor alpha and altered collagen metabolism. Blue light reduces the antioxidative protection of the skin by causing the degradation of present carotenoids. It can be used in clinical practice in the prevention and treatment of certain dermatoses, as well as in photorejuvenation treatments in aesthetic medicine. Further research in this field is necessary.

Transcriptome profiling reveals the roles of pigment formation mechanisms in yellow Paeonia delavayi flowers

The yellow colour of ornamental varieties of tree peony originated from Paeonia delavayi. However, but P. delavayi and Paeonia suffruticosa belong to different subgroups, so hybridization is difficult and results in a long breeding cycle. However, no comprehensive transcriptomic profiling has focused on the colour formation mechanisms of yellow tree peony petals. Analysing the colour formation mechanism of yellow petals in P. delavayi is very important for directional molecular breeding. In this study, the transcriptional map of yellow pigment development in petals was used to analyse the mechanism of petal colour formation. We analysed the genes related to the metabolism of flavonoids and carotenoids and the transcription factors (TFs) involved in P. delavayi var. lutea (pure yellow individual) yellow pigment development using transcriptome sequence profiling. Transcriptome sequence profiles revealed three and four differentially expressed transcripts (DETs) involved in flavonoid biosynthesis and carotenoid biosynthesis, respectively. An analysis of DETs in the flavonoid pathway showed that chalcone synthase (CHS) and chalcone 2´-glucosyltransferases (THC2’GT) act in synergy to synthesize isosalipurposide (ISP). CHS and flavonol synthase (FLS) synergistically synthesize quercetin and kaempferol. DEG analysis of the carotenoid pathway revealed that phytoene synthase (PSY), carotenoid isomerase (CRTISO) and β-carotene hydroxylases (CHYB) play a key role in regulating lutein formation, and carotenoid cleavage dioxygenase (CCD) plays an important role in the degradation of carotenoids. These two pathways may be regulated by TF families such as bHLH, ARF, and MYB. The results of the transient overexpression of genes showed that CHS and CHI are regulated by PdMYB2. In this study, the molecular mechanism of ISP synthesis was analysed in depth, and the complete metabolic pathway of carotenoids in Paeonia L. was reported for the first time. By studying the formation mechanism of yellow pigment in P. delavayi petals, a breeding strategy for improving flavonol and carotenoid contents and reducing anthocyanin synthesis by genetic engineering was suggested.

Raman imaging monitors the time-resolved response of A. thaliana to the artificial inhibition of PSII

The short-term (0–96 h) response of A. thaliana to the oxidative stress induced by PSII inhibitor metribuzin was examined using Raman spectroscopy. Whole leaves of wildtype (WT, Col-0) and ros1 mutant were scanned and changes in carotenoids were examined. Strong differences in Raman intensity distributions between WT and ros1 were observed. A stronger decrease of carotenoid v1(C=C) band intensity across the leaf was observed in ros1 after 48 h of exposure to metribuzin. It can be assumed that higher sensitivity to oxidative stress in ros1 mutant results in significantly faster degradation of carotenoids.

Transcriptome analysis reveals the potential mechanism of carotenoids change in hepatopancreas under low-temperature storage from swimming crab (Portunus trituberculatus)

The hepatopancreas of swimming crab (Portunus trituberculatus) rich in carotenoids would undergo serious color deterioration during cold storage, and then made portunid lose its commodity value. In this study, we firstly elucidated the change mechanism of its carotenoids during storage at the molecular level using transcriptome technology. We concluded that low-temperature would inhibit aerobic respiration of portunid, leading to a lower pH and inducing the degradation of carotenoids. After that, longer cold storage time would increase the oxidative stress in portunid, resulting in a further decrease in carotenoids content. Finally, the strong autolysis of portunid could release carotenoids stored in other parts such as ovary to the external environment, resulting in the increase of carotenoids detection content. This research could provide a basis for further developing the fresh-keeping technology of portunid during low-temperature storage.

Kinetics of Carotenoids Degradation during the Storage of Encapsulated Carrot Waste Extracts.

The encapsulates of carrot waste oil extract improved the antioxidant properties of durum wheat pasta. The aim of this research was to study the kinetics of carotenoids degradation in the freeze-dried (FDE) and spray-dried (SDE) encapsulates of carrot waste extract during storage at four different temperatures (+4, +21.3, +30, +37 °C) up to 413 days by HPLC. Carotenoids levels decreased as a function of time and temperature, following zero-order kinetics. At 4 °C carotenes were stable for at least 413 days, but their half-lives decreased with increasing temperatures: 8-12 months at 21 °C; 3-4 months at 30 °C; and 1.5-2 months at 37 °C. The freeze-drying technique was more effective against carotenes degradation. An initial lag-time with no or very limited carotenes degradation was observed: from one week at 37 °C up to 3 months (SDE) or more (FDE) at 21 °C. The activation energies (Ea) varied between 66.6 and 79.5 kJ/mol, and Ea values tended to be higher in FDE than in SDE.

Investigation on the changes of carotenoids and capsaicinoids in chili oil at different frying temperature by using 1H NMR

The color and pungency are important indicators for evaluating the quality of chili oil, which are mainly determined by the carotenoids and capsaicinoids, respectively. In this study, the effect of frying temperature on the changes of carotenoids and capsaicinoids in chili oil was qualitatively and quantitatively analyzed by 1H NMR. The increasing frying temperature caused the thermal degradation of carotenoids to be intensified, and the degradation of red carotenoids was greater than that of yellow carotenoids. After 10 min of frying at 130, 150, 170 and 190 °C, the contents of capsanthin in chili oil were 40.3, 15.4, 9.6 and 6.2 mg/kg, respectively. Meanwhile, the contents of total carotenoids were 63.0, 25.5, 17.7 and 13.3 mg/kg, respectively. The observed change of R/Y values correlated well with the degradation of carotenoids. The contents of capsaicinoids were 14.8, 20.9, 19.4 and 7.4 mg/kg, respectively. The best frying temperature for the extraction of carotenoids was 130 °C, and over 90% of the carotenoids were dissolved in the frying oil at this frying condition. However, capsaicinoids were more stable than carotenoids, and the best frying temperature for capsaicinoids was 150–170 °C with over 90% extraction rate. Therefore, the temperature fried at 130–150 °C was suitable for the quality of chili oil, considering the higher extraction rates of both total carotenoids and capsaicinoids. This study is of great significance for the quality control of chili oil.

Oscillating flower colour changes of Causonis japonica (Thunb.) Raf. (Vitaceae) linked to sexual phase changes

Flower colour change may represent an ‘honest signal’ for pollinators, denoting flowers with good conditions for rewards and pollination. All previously reported flower colour changes are unidirectional, except for an incomplete case in one Fabaceae species. In this study, we discovered a very rare example of complete oscillating flower colour change associated with sexual phase changes in Causonis japonica (Vitaceae). More specifically, flower discs of C. japonica exhibit an orange colour in the initial male phase then soon fade into pink with desorption of the stamens. Several hours later in the daytime of the same or the following day, with stigma maturation and style elongation, the orange flower disc colour is recovered before fading into pink again. Importantly, we found that the colour change is caused by the accumulation and the degradation of carotenoids. Moreover, nectar secretion was roughly correlated with the abovementioned colour changes. This is the first example of an apparent oscillating colour change mediated by carotenoid content alteration in flowers.

Influence of exposure history on the particle retention capacity and physiological responses of Euonymus japonicus Thunb. var. aurea-marginatus Hort.

Green plants in urban environments experience cyclical particulate matter stress. And this history of exhaust exposure may generate stress memory in plants, which may alter their subsequent response. Studies combining urban pollution characteristics and stress memory are limited. Therefore, we selected E. japonicus var. aurea-marginatus, a common urban greening tree species in the Yangtze River Delta, and conducted an experiment in three periods: the initial pollution period (S1: 28 days), the recovery period (R: 14 days) and the secondary pollution period (S2: 28 days). The experimental design consisted of an elevated pollution treatment (173 μg•cm−3) and an ambient control (34 μg•cm−3) with three replicates. In S2, the net total particle retention and saturated particle retention decreased by 11.5% and 19.3%, respectively, while PM10 and PM2.5 did not change significantly. E. japonicus var. aurea-marginatus exhibited recovery of chlorophyll levels, slower degradation of carotenoid, faster accumulation of ASA, lower accumulation of MDA, reduced activity of SOD under the second pollution period, and the period had a significant effect on the physiological indicators. Collectively, the effect of autoexhaust exposure history on the particle retention capacity of selected plant varied across particle sizes, and stress memory may confer plant resistance to recurrent exhaust pollution via combined regulations of physiological responses. Fine particles which pose a great risk to human health arise predominantly from vehicular traffic and energy production. So, E. japonicus tends to play a stabilising role in particle retention in industrial, traffic and residential areas.

Effects of Cadmium on metabolism of photosynthetic pigment and photosynthetic system in Lactuca sativa L. revealed by physiological and proteomics analysis

Cadmium stress stunted lettuce growth, resulting in phenotypic changes such as leaf yellowing and shrinkage, as well as physiological changes such as reduced chlorophyll and photosynthesis. However, the molecular mechanism by which this metal inhibits lettuce development and plant stress response remains unclear. The effects of 20 μmol/L Cd treatment on chlorophyll and carotenoids contents as well as photosynthetic function of lettuce leaves was investigated to explore the mechanism of action of Cd on photosynthetic function. Using an IBT-based proteomics technique, the key proteins in these physiological processes were quantified. It was found that the expression of important enzymes in the chlorophyll synthesis pathway in leaves, such as HemB, POR and DVR, was shown to be hindered by Cd stress, resulting in a reduction in chlorophyll content. Meanwhile, Cd promoted the degradation of carotenoids and up-regulated the expression of degradation enzymes NCED4 and CCD8, resulting in a reduction in carotenoids content. Furthermore, the expression of the xanthophyll cycle-regulating enzymes ZEP and VDE was dramatically reduced. This means that lettuce's inherent antioxidant defensive mechanisms, such as the xanthophyll cycle and the NPQ-dependent energy dissipation process, are impaired. Moreover, the decrease in chlorophyll and carotenoids content reduced the stability of LHC, where the protein expression of Lhca4, Lhcb1, Lhcb3, Lhcb4 and Lhcb6 was significantly reduced. Additionally, Cd not only reduced the expression of PSII receptor-side proteins (PsbL, PsbP, and PsbR) and core of PSI response center (psaC, psaD, psaE, psaL and psaN), but also electron transport-related proteins (Cyt b6/f complex, Fd and H+-ATPase), carbon fixation-related ATPase subunits and Rubisco subunits expression were all significantly reduced, then the supply of carbon assimilation power was inhibited. Therefore, on one hand, Cd stress inhibited the synthesis of photosynthetic pigments and photosynthesis-related proteins or subunits, eventually affected the fixation of CO2, as manifested by the decreased Pn and plant biomass. On the other hand, Cd stress directly affected the protective mechanism of the photosynthetic apparatus, such as xanthophyll cycle and antioxidant capacity, which ultimately leads to the photodamaged of the photosynthetic apparatus. This study delves into the target sites of Cd attack on lettuce and provides an accurate reference for our research on Cd mitigants.

Comparison of energy consumption, color, ascorbic acid and carotenoid degradation in guava (Psidium guajava) pulp during conventional and ohmic heating.

This study aimed to compare the effect of ohmic and conventional heat treatments on red guava pulp, evaluating the effects on pulp color, degradation kinetics of ascorbic acid and carotenoids, together with the thermal efficiency of both treatments. Samples were heated by conventional heating (water bath) and ohmic heating (platinum electrodes) using alternating voltage of 21.2 V/m and average frequency of 60 Hz at temperatures of 60, 70 and 80 °C for 110 min. In general, the ascorbic acid degradation followed a first order kinetics, for both heat treatments, the pulp color showed no significant variation (p < 0.05) according to the type and time of heating applied, whereas the carotenoid content was favored by ohmic heating, at the two lowest temperatures tested. As for the heat transfer process, the ohmic treatment showed an average thermal efficiency of 40.93%, while the conventional heating, 2.62%, proving to be a promising emerging technology for processing viscous foods with suspended particles like fruit pulps.

Changes in volatile and fatty acid compositions of selected microalgal suspensions with high pressure homogenization

This is the first report on the fatty acid and volatile analysis of high pressure homogenization (HPH)-treated microalgal suspensions using chemometrics methods to increase insight into the complex (bio)chemical changes. Four microalgal suspensions, namely Arthrospira , Isochrysis , Nannochloropsis , and Tetraselmis species, were processed by HPH at 300, 600, and 900 bar. While cell disruption due to HPH seemed to have a minimal impact on the fatty acid profile, the high number of discriminating volatiles suggest several (bio)chemical reactions that the treatment may have triggered. Alterations in terpene and ketones indicate the induction of carotenoid degradation. Lipid oxidation could also have occurred during HPH, as noted in the changes in furans in Arthrospira sp. and aldehydes in Nannochloropsis sp. and Tetraselmis sp. Maillard reaction may have likewise been triggered by HPH as shown by the pyrazines in Arthrospira sp. and Tetraselmis sp. Sulphur compounds were only significantly changing in Isochrysis sp. and are typically associated with the degradation of sulphur-containing amino acids. The abundance of hydrocarbons as discriminant volatiles suggests that HPH can induce the synthesis of long-chain fatty acids. This study provides insight into how the volatile profile of microalgae can potentially be manipulated by applying specific pressure levels of HPH. • The effect of HPH on the volatile and fatty acid profile was investigated. • HPH (especially at 900 bar) modified the volatile fraction of microalgal suspensions. • Changes in furans and pyrazines show a possible effect on the Maillard reactions. • HPH triggered the degradation of sulphur-containing amino acids and carotenoids. • A microalgal volatile profile can be modified by applying specific pressure-levels.