Stability and Quality of Anthocyanin in Purple Sweet Potato Extracts

Sweet potato protein hydrolysates solidified calcium-induced alginate gel for enhancing the encapsulation efficiency and long-term stability of purple sweet potato anthocyanins in beads

Based on the previous research, this work aimed to reveal the effect of sweet potato protein hydrolysates (SPPHs) with different molecular weights (1000, 3000, and 8000 Da) at 0.5 % on the gelation behavior of calcium-induced sodium alginate (SA), and the encapsulation efficiency and storage stability of purple sweet potato anthocyanins (PSPA) in calcium-induced alginate gel beads was determined. Results indicated that SPPHs with a molecular weight of 8000 Da formed hydrogen bonds and other interactions with SA, which strengthened the internal network connections of the gel, significantly enhanced the gel and effectively filled its pores. The highest encapsulation efficiency was achieved at 87.27 %, compared to 61.73 % without SPPHs. Additionally, stored at 37 °C for 21 days after commercial sterilization, the residual concentration of PSPA with SPPHs was 2.50 times higher than that without SPPHs. SPPHs can enhance the encapsulation efficiency of PSPA and retard their release in gel beads.

Phenolic profile, cheminformatics, and antiplatelet aggregation activity of orange and purple sweet potato (Ipomoea batatas L.) storage roots

Sweet potatoes are rich in cardioprotective phytochemicals with potential anti-platelet aggregation activity, although this benefit may vary among cultivars/genotypes. The phenolic profile [HPLC-ESI(-)-qTOF-MS2], cheminformatics (ADMET properties, affinity toward platelet proteins) and anti-PA activity of phenolic-rich hydroalcoholic extracts obtained from orange (OSP) and purple (PSP) sweet potato storage roots, was evaluated. The phenolic richness [Hydroxycinnamic acids> flavonoids> benzoic acids] was PSP > OSP. Their main chlorogenic acids could interact with platelet proteins (integrins/adhesins, kinases/metalloenzymes) but their bioavailability could be poor. Just OSP exhibited a dose-dependent anti-platelet aggregation activity [inductor (IC50, mg.ml-1): thrombin receptor activator peptide-6 (0.55) > Adenosine-5'-diphosphate (1.02) > collagen (1.56)] and reduced P-selectin expression (0.75-1.0 mg.ml-1) but not glycoprotein IIb/IIIa secretion. The explored anti-PA activity of OSP/PSP seems to be inversely related to their phenolic richness. The poor first-pass bioavailability of its chlorogenic acids (documented in silico) may represent a further obstacle for their anti-PA in vivo.

Proximate Composition, Health Benefits, and Food Applications in Bakery Products of Purple-Fleshed Sweet Potato (Ipomoea batatas L.) and Its By-Products: A Comprehensive Review

Ipomoea batatas (L.) Lam is a dicotyledonous plant originally from tropical regions, with China and Spain acting as the main producers from outside and within the EU, respectively. The root, including only flesh, is the edible part, and the peel, leaves, stems, or shoots are considered by-products, which are generated due to being discarded in the field and during processing. Therefore, this study aimed to perform a comprehensive review of the nutritional value, phytochemical composition, and health-promoting activities of purple-fleshed sweet potato and its by-products, which lead to its potential applications in bakery products for the development of functional foods. The methodology is applied to the selected topic and is used to conduct the search, review abstracts and full texts, and discuss the results using different general databases. The studies suggested that purple-fleshed sweet potato parts are characterized by a high content of essential minerals and bioactive compounds, including anthocyanins belonging to the cyanidin or the peonidin type. The flesh and leaves are also high in phenolic compounds and carotenoids such as lutein and β-carotene. The high content of phenolic compounds and anthocyanins provides the purple-fleshed sweet potato with high antioxidant and anti-inflammatory power due to the modulation effect of the transcription factor Nrf2 and NF-kB translocation, which may lead to protection against hepatic and neurological disorders, among others. Furthermore, purple-fleshed sweet potato and its by-products can play a dual role in food applications due to its attractive color and wide range of biological activities which enhance its nutritional profile. As a result, it is essential to harness the potential of the purple-fleshed sweet potato and its by-products that are generated during its processing through an appropriate agro-industrial valorization system.

Green Synthesis of Silver Nanoparticles from Anthocyanin Extracts of Peruvian Purple Potato INIA 328-Kulli papa

In this work, AgNPs were synthesized using an anthocyanin extract from Peruvian purple potato INIA 328-Kulli papa. The anthocyanin extract was obtained through a conventional extraction with acidified ethanolic aqueous solvent. This extract acted as both a reducing and stabilizing agent for the reduction of silver ions. Optimization of synthesis parameters, including pH, reaction time, and silver nitrate (AgNO3) concentration, led to the optimal formation of AgNPs at pH 10, with a reaction time of 30 min and an AgNO3 concentration of 5 mM. Characterization techniques such as X-ray diffraction (XRD) and dynamic light scattering (DLS) revealed that the AgNPs had a crystallite size of 9.42 nm and a hydrodynamic diameter of 21.6 nm, with a zeta potential of -42.03 mV, indicating favorable colloidal stability. Fourier Transform Infrared (FTIR) analysis confirmed the presence of anthocyanin functional groups on the surface of the AgNPs, contributing to their stability. Furthermore, the bacterial activity of the AgNPs was evaluated by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). For E. coli, the MIC was 0.5 mM (0.05 mg/mL) and the MBC was 4.5 mM (0.49 mg/mL). Similarly, for S. aureus, the MIC was 0.5 mM (0.05 mg/mL) and the MBC was 4.0 mM (0.43 mg/mL). These results highlight the potential benefits of AgNPs synthesized from Peruvian purple potato anthocyanin extract, both in biomedical and environmental contexts.

Stabilization effect and interaction mechanism of mannoprotein on anthocyanins in mulberry juice

This study aimed to investigate the problem of color instability in mulberry juice, examine the effect of mannoprotein (MP) dosage on improving the stability of anthocyanins in mulberry juice, and explore the molecular binding mechanism between them. As the mass ratio of anthocyanins to MP of 1.07 × 10-3: 1-1.65 × 10-3: 1, the retention rates of anthocyanins in mulberry juice and simulated system were significantly improved in the photostability experiment, with the highest increase of 128.89 % and 24.11 %, respectively. In the thermal stability experiment, it increased by 7.96 % and 18.49 %, respectively. The synergistic effect of combining MP with anthocyanins has been demonstrated to greatly enhance their antioxidant capacity, as measured by ABTS, FRAP, and potassium ferricyanide reduction method. Furthermore, MP stabilized more anthocyanins to reach the intestine in simulated in vitro digestion. MP and cyanidin-3-glucoside (C3G) interacted with each other through hydrogen bonding and hydrophobic interactions. Specific amino acid residues involved of MP in binding process were identified as threonine (THR), isoleucine (ILE) and arginine (ARG). The identification of the effective mass concentration ratio range and binding sites of MP and anthocyanins provided valuable insights for the application of MP in mulberry juice.

CaLAP1 and CaLAP2 orchestrate anthocyanin biosynthesis in the seed coat of Cicer arietinum

MAIN CONCLUSION

Our findings shed light on the regulation of anthocyanin and proanthocyanidin biosynthesis in chickpea seed coats. Expression of R2R3-MYB transcription factors CaLAP1 and CaLAP2 enhanced the anthocyanins and proanthocyanidins content in chickpea. The seed coat color is a major economic trait in leguminous crop chickpea (Cicer arietinum). Anthocyanins and proanthocyanidins (PAs) are two classes of flavonoids that mainly contribute to the flower, seed coat and color of Desi chickpea cultivars. Throughout the land plant lineage, the accumulation of anthocyanins and PAs is regulated by MYB and bHLH transcription factors (TFs), which form an MBW (MYB, bHLH, and WD40) complex. Here, we report two R2R3-MYB TFs in chickpea belonging to the anthocyanin-specific subgroup-6, CaLAP1 (Legume Anthocyanin Production 1), and CaLAP2 (Legume Anthocyanin Production 2), which are mainly expressed in the flowers and developmental stages of the seeds. CaLAP1 and CaLAP2 interact with TT8-like CabHLH1 and WD40, forming the MBW complex, and bind to the promoter sequences of anthocyanin- and PA biosynthetic genes CaCHS6, CaDFR2, CaANS, and CaANR, leading to anthocyanins and PA accumulation in the seed coat of chickpea. Moreover, these CaLAPs partially complement the anthocyanin-deficient phenotype in the Arabidopsis thaliana sextuple mutant seedlings. Overexpression of CaLAPs in chickpea resulted in significantly higher expression of anthocyanin and PA biosynthetic genes leading to a darker seed coat color with higher accumulation of anthocyanin and PA. Our findings show that CaLAPs positively modulate anthocyanin and PA content in seed coats, which might influence plant development and resistance to various biotic and abiotic stresses.

Image analysis and polyphenol profiling unveil red-flesh apple phenotype complexity

BACKGROUND

The genetic basis of colour development in red-flesh apples (Malus domestica Borkh) has been widely characterised; however, current models do not explain the observed variations in red pigmentation intensity and distribution. Available methods to evaluate the red-flesh trait rely on the estimation of an average overall colour using a discrete class notation index. However, colour variations among red-flesh cultivars are continuous while development of red colour is non-homogeneous and genotype-dependent. A robust estimation of red-flesh colour intensity and distribution is essential to fully capture the diversity among genotypes and provide a basis to enable identification of loci influencing the red-flesh trait.

RESULTS

In this study, we developed a multivariable approach to evaluate the red-flesh trait in apple. This method was implemented to study the phenotypic diversity in a segregating hybrid F1 family (91 genotypes). We developed a Python pipeline based on image and colour analysis to quantitatively dissect the red-flesh pigmentation from RGB (Red Green Blue) images and compared the efficiency of RGB and CIEL*a*b* colour spaces in discriminating genotypes previously classified with a visual notation. Chemical destructive methods, including targeted-metabolite analysis using ultra-high performance liquid chromatography with ultraviolet detection (UPLC-UV), were performed to quantify major phenolic compounds in fruits' flesh, as well as pH and water contents. Multivariate analyses were performed to study covariations of biochemical factors in relation to colour expression in CIEL*a*b* colour space. Our results indicate that anthocyanin, flavonol and flavanol concentrations, as well as pH, are closely related to flesh pigmentation in apple.

CONCLUSTION

Extraction of colour descriptors combined to chemical analyses helped in discriminating genotypes in relation to their flesh colour. These results suggest that the red-flesh trait in apple is a complex trait associated with several biochemical factors.

Design, Optimization, and Modeling Study of Ultrasound-Assisted Extraction of Bioactive Compounds from Purple-Fleshed Sweet Potatoes

This study focuses on optimizing the ultrasound-assisted extraction (UAE) of bioactive compounds from purple-fleshed sweet potatoes (PFSP) for potential use as natural colorants. Factors such as time, temperature, and solid-to-liquid ratio were varied using a Box-Behnken Design. The optimal conditions were determined as 75 min, 70 °C, and a 1:15 m/v solid-to-liquid ratio, resulting in 18.372 mg/100 g total anthocyanin (TA) and 151.160 mg GAE/100 g total phenolic content (TPC). The validation yielded 18.822 mg/100 g for total anthocyanin and 162.174 mg GAE/100 g for total phenolic content, showing a 7% difference from predictions. UAE significantly increased TA extraction by 81% and TPC by 93% compared with the conventional method, with a notable reduction in process time from 24 h to 75 min. Additionally, three kinetic models were tested to compare extraction mechanisms, confirming the efficiency of UAE for PFSP bioactive compound recovery. This study proposes the UAE technique as a highly effective means of extracting bioactive compounds from PFSP, offering promising applications across multiple industries.

Edible film preparation by anthocyanin extract addition into acetylated cassava starch/sodium carboxymethyl cellulose matrix for oxidation inhibition of pumpkin seeds

In this study, an edible film was fabricated by incorporating anthocyanin extract from black rice (AEBR) into acetylated cassava starch (ACS)/carboxymethyl-cellulose (CMC) to enhance the shelf life of pumpkin seeds. The effects of AEBR on the rheological properties of film-forming solutions, as well as the structural characterization and physicochemical properties of the film, were evaluated. Rheological properties of solutions revealed that AEBR was evenly dispersed into polymer matrix and bound by hydrogen bonds, as confirmed by Fourier transform infrared spectroscopy analysis. The appropriate AEBR addition could be compatible with polymer matrix and formed a compact film structure, improving the mechanical properties, barrier properties, and opacity. However, with further addition of AEBR, the tensile strength and water vapor permeability decreased and the tight structure was destroyed. After being stored separately under thermal and UV light accelerated conditions for 20 days, the peroxide value and acid value of roasted pumpkin seeds coated with the AEBR film showed a significant reduction. Moreover, the storage stability of AEBR was improved through the embedding of ACS/CMC biopolymers. These results indicated that AEBR film could effectively delay pumpkin seeds oxidation and prolong their shelf life as an antioxidant material.

The Browning Properties, Antioxidant Activity, and α-Glucosidase Inhibitory Improvement of Aged Oranges (Citrus sinensis)

Oranges contain many natural active chemicals, organic acids, and polysaccharides. Aging processing is commonly used to modify the color, quality, functional components, and stability of fruits. This study assesses the preparation of aging black oranges using various pre-treatments and solid fermentation. Oranges were aged for six weeks in fresh, non-blanching, blanching, and hot air-assisted aging cycle (AA) groups. The oranges' shrinkage ratio, color difference values, and soluble solids content changed significantly (p < 0.05). Principal component analysis indicated that aging fermentation treatment accelerated glycolysis and increased the ratio of reducing sugars. The enhanced browning can be associated with the oxidation of ascorbic acid (0.66-0.47 mg/g) and the formation of 5-hydroxymethylfurfural (5-HMF) (0.09 mg/g). Furthermore, the presence of free polyphenols led to an increase in the total polyphenol and total flavonoid content. It also had a synergistic effect with 5-HMF in increasing the 2,2-diphenyl-1-picrylhydrazyl free radical-scavenging capacity and ferric ion-reducing antioxidant power (p < 0.05). AA had superior α-glucosidase inhibitory ability increasing from 67.31 to 80.48%. It also reduced the development time by 33%. Therefore, aging technology can enhance the bioactive compounds in oranges and provide a reference for future whole-fruit aging fermentation and health product creation.

A critical review on the stability of natural food pigments and stabilization techniques

This comprehensive review article delves into the complex world of natural edible pigments, with a primary focus on their stability and the factors that influence them. The study primarily explores four classes of pigments: anthocyanins, betalains, chlorophylls and carotenoids by investigating both their intrinsic and extrinsic stability factors. The review examines factors affecting the stability of anthocyanins which act as intrinsic factors like their structure, intermolecular and intramolecular interactions, copigmentation, and self-association as well as extrinsic factors such as temperature, light exposure, metal ions, and enzymatic activities. The scrutiny extends to betalains which are nitrogen-based pigments, and delves into intrinsic factors like chemical composition and glycosylation, as well as extrinsic factors like temperature, light exposure, and oxygen levels affecting for their stability. Carotenoids are analyzed concerning their intrinsic and extrinsic stability factors. The article emphasizes the role of chemical structure, isomerization, and copigmentation as intrinsic factors and discusses how light, temperature, oxygen, and moisture levels influence carotenoid stability. The impacts of food processing methods on carotenoid preservation are explored by offering guidance on maximizing retention and nutritional value. Chlorophyll is examined for its sensitivity to external factors like light, temperature, oxygen exposure, pH, metal ions, enzymatic actions, and the food matrix composition. In conclusion, this review article provides a comprehensive exploration of the stability of natural edible pigments, highlighting the intricate interplay of intrinsic and extrinsic factors. In addition, it is important to note that all the references cited in this review article are within the past five years, ensuring the most up-to-date and relevant sources have been considered in the analysis.

Hydrophobic Components in Light-Yellow Pulp Sweet Potato (Ipomoea batatas (L.) Lam.) Tubers Suppress LPS-Induced Inflammatory Responses in RAW264.7 Cells via Activation of the Nrf2 Pathway

Sweet potato is a crop that is widely consumed all over the world and is thought to contribute to health maintenance due to its abundant nutrients and phytochemicals. Previous studies on the functionality of sweet potatoes have focused on varieties that have colored pulp, such as purple and orange, which contain high levels of specific phytochemicals. Therefore, in the present study, we evaluated the anti-inflammatory effects of light-yellow-fleshed sweet potatoes, which have received little attention. After freeze-drying sweet potatoes harvested in 2020, extracts were prepared from the leaves, stems, roots, and tubers in 100% ethanol. Mouse macrophage-like cell line RAW264.7 cells were cultured with 10 µg/mL of the extracts and induced lipopolysaccharide (LPS)-stimulated inflammation. Of the extracts, the tuber extracts showed the highest suppression of LPS-induced interleukin-6 (IL-6) gene expression and production in RAW264.7, which was attributed to the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) oxidative stress response pathway. In addition, preparative high-performance liquid chromatography (HPLC) experiments suggested that hydrophobic components specific to the tuber were the main body of activity. In previous studies, it has been shown that the tubers and leaves of sweet potatoes with colored pulp exhibit anti-inflammatory effects due to their rich phytochemicals, and our results show that the tubers with light-yellow pulp also exhibit the effects. Furthermore, we were able to show a part of the mechanism, which may contribute to the fundamental understanding of the treatment and prevention of inflammation by food-derived components.

Carrageenan-based active and intelligent packaging films integrated with anthocyanin and TiO2-doped carbon dots derived from sweet potato peels

Carrageenan-based sustainable active and pH-dependent color-changing composite films were fabricated by blending anthocyanin extracted from sweet potato peel (SPA) with TiO2-doped carbon dots (Ti-CDs) prepared using the biowaste of SPA extraction. The SPA and Ti-CDs were compatible with the carrageenan matrix and were uniformly dispersed in the used polymer to form a homogeneous film with increased mechanical properties. The composite film added with SPA and 3 wt% Ti-CD showed 100 % UV protection, superb antioxidant (100 % DPPH and ABTS scavenging assay), and potent antibacterial activity (complete eradication of foodborne L.monocytogenes and E. coli strains after 3 h incubation). Additionally, the composite films showed distinguishable colorimetric responses to pH 7-12 buffers and volatile ammonia. The intelligent sensing ability of the composite film was assessed through shrimp freshness monitoring, and the film's hue shifted from pink (fresh shrimp) to yellow/brown (inedible shrimp) during storage. Shrimp packaging studies have shown that composite films retard the rate of food quality change during storage and are a good indicator of shrimp spoilage. Therefore, the designed film is expected to have high applicability as a chip, and quick on-site sensor that detects seafood quality in real-time, and a highly effective multifunctional film for better product quality preservation.

Effect of purple sweet potato-derived anthocyanins on heat stress response in Wenchang chickens and preliminary mechanism study

This study was conducted to investigate the beneficial effect of purple sweet potato anthocyanins (PSPA) on growth performance, oxidative status, immune response, intestinal morphology, and intestinal flora homeostasis in heat-stressed Wenchang chickens. A total of 100 Wenchang chickens (50-day-old) were randomly assigned to 5 groups, including the thermoneutral environment (TN) group (26°C); high-temperature stressed (HS) group (33°C ± 1°C); low-dose PSPA treatment (L_HS) group (8 mg/kg body weight, 33°C ± 1°C); medium-dose PSPA treatment (M_HS) group and high-dose PSPA treatment (H_HS) group (16 mg/kg and 32 mg/kg body weight, respectively, 33°C ± 1°C). The results showed that PSPA reversed the adverse effects of heat stress on growth performance, meat quality, and carcass characteristics. And the effect was associated with the concentration of PSPA partially. Heat stress increased the serum lipids of Wenchang chickens. LDL-C, TG, TC, and FFA in the serum were significantly decreased, and HDL-C and LPS in the serum were increased by PSPA treatment. The digestive enzymes in duodenal chyme were significantly (P < 0.05) increased by PSPA treatment. And PSPA treatment significantly (P < 0.05) enhanced the redox status by improving antioxidant parameters (GSH-Px and SOD) and decreasing the MDA level in the serum and liver. Moreover, the level of inflammatory cytokines was significantly (P < 0.05) regulated by PSPA treatment compared to the HS group. The villus length and goblet cell numbers after PSPA treatment were significantly higher than HS group. Furthermore, PSPA also played protection on the intestine structure by decreasing the level of D-LA and DAO. 16S rRNA sequencing revealed the microbial composition was altered by PSPA, and Acetanaerobacterium and Oscillibacter were dominant in the H_HS group. Microbial functional prediction indicated that function pathways based on KEGG and metacyc database were regulated by PSPA, and intestinal flora correlated with metabolic function significantly. The spearman correlation analysis showed that Saccharibacteria and Clostridium_IV correlated with the serum lipids, antioxidant, and inflammatory cytokines. Collectively, these findings suggest that PSPA has a positive effect against heat stress in poultry.

Metabolic engineering of plant secondary metabolites: prospects and its technological challenges

Plants produce a wide range of secondary metabolites that play vital roles for their primary functions such as growth, defence, adaptations or reproduction. Some of the plant secondary metabolites are beneficial to mankind as nutraceuticals and pharmaceuticals. Metabolic pathways and their regulatory mechanism are crucial for targeting metabolite engineering. The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated system has been widely applied in genome editing with high accuracy, efficiency, and multiplex targeting ability. Besides its vast application in genetic improvement, the technique also facilitates a comprehensive profiling approach to functional genomics related to gene discovery involved in various plant secondary metabolic pathways. Despite these wide applications, several challenges limit CRISPR/Cas system applicability in genome editing in plants. This review highlights updated applications of CRISPR/Cas system-mediated metabolic engineering of plants and its challenges.

Pharmacological Activities and Chemical Stability of Natural and Enzymatically Acylated Anthocyanins: A Comparative Review

Anthocyanins (ANCs) are naturally occurring water-soluble pigments responsible for conferring red, blue, and purple colors to fruits, vegetables, flowers, and grains. Due to their chemical structure, they are highly susceptible to degradation by external factors, such as pH, light, temperature, and oxygen. Naturally acylated anthocyanins have proven to be more stable in response to external factors and exhibit superior biological effects as compared with their non-acylated analogues. Therefore, synthetic acylation represents a viable alternative to make the application of these compounds more suitable for use. Enzyme-mediated synthetic acylation produces derivatives that are highly similar to those obtained through the natural acylation process, with the main difference between these two pathways being the catalytic site of the enzymes involved in the synthesis; acyltransferases catalyze natural acylation, while lipases catalyze synthetic acylation. In both cases, their active sites perform the addition of carbon chains to the hydroxyl groups of anthocyanin glycosyl moieties. Currently, there is no comparative information regarding natural and enzymatically acylated anthocyanins. In this sense, the aim of this review is to compare natural and enzyme-mediated synthetic acylated anthocyanins in terms of chemical stability and pharmacological activity with a focus on inflammation and diabetes.

Phytochemicals Derived from Agricultural Residues and Their Valuable Properties and Applications

Billions of tons of agro-industrial residues are produced worldwide. This is associated with the risk of pollution as well as management and economic problems. Simultaneously, non-edible portions of many crops are rich in bioactive compounds with valuable properties. For this reason, developing various methods for utilizing agro-industrial residues as a source of high-value by-products is very important. The main objective of the paper is a review of the newest studies on biologically active compounds included in non-edible parts of crops with the highest amount of waste generated annually in the world. The review also provides the newest data on the chemical and biological properties, as well as the potential application of phytochemicals from such waste. The review shows that, in 2020, there were above 6 billion tonnes of residues only from the most popular crops. The greatest amount is generated during sugar, oil, and flour production. All described residues contain valuable phytochemicals that exhibit antioxidant, antimicrobial and very often anti-cancer activity. Many studies show interesting applications, mainly in pharmaceuticals and food production, but also in agriculture and wastewater remediation, as well as metal and steel industries.

Regulatory network characterization of anthocyanin metabolites in purple sweetpotato via joint transcriptomics and metabolomics

INTRODUCTION

Sweet potato is an important staple food crop in the world and contains abundant secondary metabolites in its underground tuberous roots. The large accumulation of several categories of secondary metabolites result in colorful pigmentation of the roots. Anthocyanin, is a typical flavonoid compound present in purple sweet potatoes and it contributes to the antioxidant activity.

METHODS

In this study, we developed joint omics research via by combing the transcriptomic and metabolomic analysis to explore the molecular mechanisms underlying the anthocyanin biosynthesis in purple sweet potato. Four experimental materials with different pigmentation phenotypes, 1143-1 (white root flesh), HS (orange root flesh), Dianziganshu No.88 (DZ88, purple root flesh), and Dianziganshu No.54 (DZ54, dark purple root flesh) were comparably studied.

RESULTS AND DISCUSSION

We identified 38 differentially accumulated pigment metabolites and 1214 differentially expressed genes from a total of 418 metabolites and 50893 genes detected. There were 14 kinds of anthocyanin detected in DZ88 and DZ54, with glycosylated cyanidin and peonidin as the major components. The significantly enhanced expression levels of multiple structural genes involved in the central anthocyanin metabolic network, such as chalcone isomerase (CHI), flavanone 3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR), anthocyanidin synthase/leucocyanidin oxygenase (ANS), and glutathione S-transferase (GST) were manifested to be the primary reason why the purple sweet potatoes had a much higher accumulation of anthocyanin. Moreover, the competition or redistribution of the intermediate substrates (i.e. dihydrokaempferol and dihydroquercetin) between the downstream production of anthocyanin products and the flavonoid derivatization (i.e. quercetin and kaempferol) under the regulation of the flavonol synthesis (FLS) gene, might play a crucial role in the metabolite flux repartitioning, which further led to the discrepant pigmentary performances in the purple and non-purple materials. Furthermore, the substantial production of chlorogenic acid, another prominent high-value antioxidant, in DZ88 and DZ54 seemed to be an interrelated but independent pathway differentiated from the anthocyanin biosynthesis. Collectively, these data from the transcriptomic and metabolomic analysis of four kinds of sweet potatoes provide insight to understand the molecular mechanisms of the coloring mechanism in purple sweet potatoes.

Sharif MS, Md Nor N. The Physicochemical Analysis and Anthocyanin Level of Malaysian Purple Sweet Potato Cracker

Purple Sweet Potato (PSP) in Malaysia is an abandoned crop. Even though it has various health benefits and nutritional values, consumers, especially Malaysians, still lack purple sweet potato consumption. It has a high dietary fibre content, a low glycemic index, and contains proteins, minerals, polyphenols, and anthocyanin. The National Health Morbidity Survey (Malaysia) in 2019 reported that 94% of Malaysian adults lack fiber consumption in their dietary patterns. As a result, it may become an alternative crop for individuals who consume less nutrients and fibre as a result of dietary choices and health issues. This one-of-a-kind crop also contains anti-oxidative, hepatoprotective, anti-inflammatory, anti-tumor, anti-diabetic, anti-microbial, anti-obesity, and anti-aging qualities. Due to the lack of a commercial food product based on this crop, it has become an unpopular crop among Malaysians. Purple sweet potato makes only a few Malaysian sweets and traditional snacks. Nonetheless, Malaysian customers continue to ignore it. Thus, Purple Sweet Potato Cracker was made, and a proximate analysis was conducted to examine its physicochemical content. It was found that the newly developed PSP crackers were high in fiber, vitamins, and minerals, as well as in calcium (1332.08 mg/kg) and contained anthocyanins of 6.68 mg/L. Besides that, this special cracker is free from food preservatives without coloring agents and additives. The processing of Purple Sweet Potato Cracker carries important features for small-medium entrepreneurs, which will contribute to the Malaysian economy perspectives, as it has a good potential to be marketed in domestic and international commercial food outlets.

High-Performance Extraction Process of Anthocyanins from Jussara (Euterpe edulis) Using Deep Eutectic Solvents

New strategies for obtaining target bioactive compounds and natural pigments with the use of “green solvents” are consistently being developed, and deep eutectic solvents are (DES) a great alternative. This work established the significant variables and models for anthocyanin extraction, using DES and experimental design, of Euterpe edulis Mart. (jussara) fruit pulp, an endangered palm tree from the Brazilian Atlantic Forest. From a screening of seven initially tested DES, choline chloride/xylitol-based solvents had the best results with up to 42% increase in the total anthocyanin yield compared to methanolic extraction. Antioxidant assays also revealed a maximum antioxidant capacity of 198.93 mmol Trolox/100 g dry weight basis. The DES extract showed slower degradation to heat at 60° and 90 °C (2.5 times) and indoor constant light source (1.9 times) than methanolic extracts. The optimal extract also revealed slight inhibition of S. enterica and S. aureus growth in the agar plate.

Identification of azaphilone derivatives of Monascus colorants from Talaromyces amestolkiae and their halochromic properties

Currently, the ability to produce several kinds of water-soluble red natural colorants makes the genus Talaromyces particularly important to the dye industry, which can be an alternative to the use of harmful synthetic colorants. In this study, colored compounds produced by Talaromyces amestolkiae were extracted, characterized chemically and the color stability of the fermented broth without any extraction procedure was further evaluated over pH variation. Five azaphilones compounds were detected by Ultrahigh Performance Liquid Chromatography-Mass Spectrometry system, all being complexes of the fatty acid amino-hexanedioic acid and azaphilone Monascus colorants. The color of the fermented broth was stable at a wide range of pH (3-9). Furthermore, T. amestolkiae colorants precipitated through hydrolysis of key chemical groups at extremely acidic (pH 1) and lose red color in extremely basic (pH 13) medium, showing negative halochromism. Nevertheless, these findings enhance the industrial relevance of azaphilone colorants produced by biotechnological process.

Sources and relative stabilities of acylated and nonacylated anthocyanins in beverage systems

Anthocyanins are considered as the largest group of water-soluble pigments found in the vacuole of plant cells, displaying range of colors from pink, orange, red, purple and blue. They belong to flavonoids, a polyphenolic subgroup. Application of anthocyanins in food systems as natural food colourants is limited due to the lack of stability under different environmental conditions such as light, pH, heat etc. Anthocyanins esterified with one or more acid groups are referred as acylated anthocyanins. Based on the presence or absence of acyl group, anthocyanins are categorized as acylated and nonacylated anthocyanins. Acylated anthocyanins are further classified as mono, di, tri, tetra acylated anthocyanins according to the number of acyl groups present in the anthocyanin. This review classifies common anthocyanin sources into non-acylated, mono-, di-, tri- and tetra-acylated anthocyanins based on the major anthocyanins present in these sources. The relative stabilities of these anthocyanins with respect to thermal, pH and photo stress in beverage systems are specifically discussed. Common anthocyanin sources such as elderberry, blackberry, and blackcurrant mainly contain nonacylated anthocyanins. Red radish, purple corn, black carrot also mainly contain mono acylated anthocyanins. Red cabbage and purple sweet potato have both mono and diacylated anthocyanins. Poly acylated anthocyanins show relatively higher stability compared with nonacylated and monoacylated anthocyanins. Several techniques such as addition of sweeteners, co-pigmentation and acylation techniques could enhance the stability of nonacylated anthocyanins. Flowers are main sources of polyacylated anthocyanins having higher stability, yet they have not been commercially exploited for their anthocyanins.

Purple sweet potato leaf extracts suppress adipogenic differentiation of human bone marrow-derived mesenchymal stem cells

Purple sweet potato (Ipomoea batatas L.) leaf extract (PSPLE) is known to exhibit various biological effects. However, the anti-adipogenic effects of PSPLE on mesenchymal stem cells (MSCs) remain unknown. In the present study, we investigated the effect of PSPLE on the adipogenic differentiation of human bone marrow MSCs. PSPLE treatment significantly reduced lipid accumulation and triglyceride levels during adipogenic differentiation. PSPLE suppressed the expression of PPARγ and C/EBPα, which are the master transcription factors orchestrating adipogenesis; moreover, it inhibited the expression of adiponectin, adipocyte protein 2 (aP2), and lipoprotein lipase (LPL), which are downstream target genes involved in adipogenic differentiation. Furthermore, PSPLE treatment suppressed glucose transporter 4 expression and intracellular glucose uptake and significantly inhibited the adipogenic differentiation induced factor-stimulated Akt signaling activation. These results indicate that PSPLE suppresses the differentiation of undifferentiated MSCs into adipocyte lineages and inhibits the terminal differentiation from preadipocytes into mature adipocytes. PRACTICAL APPLICATION: The increase in the prevalence of obesity worldwide is a problem today. Obesity is induced by an excessive accumulation of adipocytes and causes obesity-related diseases, such as diabetes, hypertension, and hyperlipidemia. Natural compounds derived from plants and fruits have a variety of biological activities and are expected to exert therapeutic effects against various diseases. This study shows that purple sweet potato (Ipomoea batatas L.) leaf extract (PSPLE) suppresses adipogenesis of bone marrow-derived mesenchymal stem cells. Thus, PSPLE may be a novel functional food for controlling obesity.

Natural and Synthetic Flavylium-Based Dyes: The Chemistry Behind the Color

Flavylium compounds are a well-known family of pigments because they are prevalent in the plant kingdom, contributing to colors over a wide range from shades of yellow-red to blue in fruits, flowers, leaves, and other plant parts. Flavylium compounds include a large variety of natural compound classes, namely, anthocyanins, 3-deoxyanthocyanidins, auronidins, and their respective aglycones as well as anthocyanin-derived pigments (e.g., pyranoanthocyanins, anthocyanin-flavan-3-ol dimers). During the past few decades, there has been increasing interest among chemists in synthesizing different flavylium compounds that mimic natural structures but with different substitution patterns that present a variety of spectroscopic characteristics in view of their applications in different industrial fields. This Review provides an overview of the chemistry of flavylium-based compounds, in particular, the synthetic and enzymatic approaches and mechanisms reported in the literature for obtaining different classes of pigments, their physical-chemical properties in relation to their pH-dependent equilibria network, and their chemical and enzymatic degradation. The development of flavylium-based systems is also described throughout this Review for emergent applications to explore some of the physical-chemical properties of the multistate of species generated by these compounds.

Extraction and deproteinization process of polysaccharide from purple sweet potato

Extraction and deproteinization process of polysaccharide from purple sweet potato (PPSP) were optimized via the response surface methodology (RSM). The results indicated that the optimal conditions of extraction in hot water of PPSP were as follows: The extraction temperature was 120℃, the extraction time was 2.5 hr, and the solid-liquid ratio was 1∶10 (g/ml). The optimal conditions of Sevage deproteinization were as under the oscillation time was 20 min, the deproteinization times was twice, and polysaccharide solution-Sevage reagent ratio was 1:1 (ml/ml). The extraction yield of PPSP was 3.32%, and the protein removal rate was 93.14% in such a condition.

Adsorption and Desorption Characteristics of Total Flavonoids from Acanthopanax senticosus on Macroporous Adsorption Resins

We examined the application of six different resins with the aim of selecting a macroporous resin suitable for purifying Acanthopanax senticosus total flavonoids (ASTFs) from Acanthopanax senticosus crude extract (EAS) by comparing their adsorption/desorption capacities, which led to the selection of HPD-600. Research on the adsorption mechanism showed that the adsorption process had pseudo-second-order kinetics and fit the Freundlich adsorption model. Moreover, the analysis of thermodynamic parameters indicated that the adsorption process is spontaneous and endothermic. The optimal conditions for purification of ASTFs were determined as sample pH of 3, 60% ethanol concentration, and 3 BV·h⁻¹ flow rate, for both adsorption and desorption, using volumes of 2.5 and 4 BV, respectively. The application of macroporous resin HPD-600 to enrich ASTFs resulted in an increase in the purity of total flavonoids, from 28.79% to 50.57%. Additionally, the antioxidant capacity of ASTFs was higher than that of EAS, but both were lower than that of L-ascorbic acid. The changes in ASTFs compositions were determined using ultra-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS), with the results illustrating that the levels of seven major flavonoids of ASTFs were increased compared to that in the crude extract.

Optimization of the Drum Drying Parameters and Citric Acid Level to Produce Purple Sweet Potato (Ipomoea batatas L.) Powder Using Response Surface Methodology

Purple sweet potato (PSP) is a rich source of anthocyanins, but the anthocyanin content and color can be affected by the drying method and processing condition. Response surface methodology (RSM) with a Box-Behnken design (BBD) was used to investigate the effects of citric acid (CA) concentration, steam pressure (SP) and rotation speed (DS) on the physicochemical and functional properties of drum-dried purple sweet potato powder (PSPP). The anthocyanins of the PSPP were analyzed using mass spectrometry with electrospray ionization and twelve anthocyanins were identified. The results indicated that the moisture content (4.80 ± 0.17-9.97 ± 0.03%) and water activity (0.290 ± 0.004-0.47 ± 0.001) (p < 0.05) decreased with increasing drum temperature as well as with reduced drum rotating speed. CA had a significant (p < 0.05) effect on the color and total anthocyanin content (101.83 ± 2.20-124.09 ± 2.89 mg/100 g) of the PSPP. High SP and low DS negatively affected the antioxidant properties of the PSPP. DPPH value of the PSPP ranged from 20.41 ± 0.79 to 30.79 ± 1.00 μmol TE/g. The optimal parameters were achieved at 0.59% CA, 499.8 kPa SP and 3 rpm DS.

Visual pH Sensors: From a Chemical Perspective to New Bioengineered Materials

Many human activities and cellular functions depend upon precise pH values, and pH monitoring is considered a fundamental task. Colorimetric and fluorescence sensors for pH measurements are chemical and biochemical tools able to sense protons and produce a visible signal. These pH sensors are gaining widespread attention as non-destructive tools, visible to the human eye, that are capable of a real-time and in-situ response. Optical “visual” sensors are expanding researchers’ interests in many chemical contexts and are routinely used for biological, environmental, and medical applications. In this review we provide an overview of trending colorimetric, fluorescent, or dual-mode responsive visual pH sensors. These sensors include molecular synthetic organic sensors, metal organic frameworks (MOF), engineered sensing nanomaterials, and bioengineered sensors. We review different typological chemical entities of visual pH sensors, three-dimensional structures, and signaling mechanisms for pH sensing and applications; developed in the past five years. The progression of this review from simple organic molecules to biological macromolecules seeks to benefit beginners and scientists embarking on a project of pH sensing development, who needs background information and a quick update on advances in the field. Lessons learned from these tools will aid pH determination projects and provide new ways of thinking for cell bioimaging or other cutting-edge in vivo applications.

Anthocyanins extraction from Hibiscus sabdariffa and identification of phenolic compounds associated with their stability

BACKGROUND

One of the main disadvantages of red pigments used in foods is their low extraction yield and storage stability. Roselle flowers are sources of anthocyanins; however, these are unstable during storage, but this could be improved with phenolic compounds, which establish bonds with the anthocyanins. The aim of this work was to identify conditions to improve the extraction efficiency and color stability of Hibiscus sabdariffa extract and, furthermore, to identify the phenolic compounds associated with color stability of roselle.

RESULTS

The temperature of extraction (35 and 75 °C), the time of extraction (15 and 60 min), type of acid (acetic and citric), percentage of acid (0.5 and 2.0%) and the water:ethanol ratio (20:80 and 80:20) did not affect the yield of anthocyanins; only the solid:solvent ratio had an effect in the anthocyanin extraction yield. The extraction with 80% ethanol decreased up to 50% the anthocyanin degradation in the extracts stored at 4, 25, 35, 45, and 80 °C. Phenolic acids and flavonoids were quantified by ultrahigh-performance liquid chromatography coupled with triple quadrupole electrospray ionization mass spectrometry. These compounds were analyzed using principal component analysis, and the H. sabdariffa extract, with greater stability, was found to be associated with the presence of quercetin, myricetin, kaempferol 3-O-glucose, ellagic acid, and rutin.

CONCLUSION

H. sabdariffa extract with increased color stability was extracted with a higher proportion of ethanol and the improvement in the color stability was attributed to the co-extraction of phenolic compounds, principally flavonoids that could interact with anthocyanins and stabilize them. © 2020 Society of Chemical Industry.

Purple Sweet Potato Extract extends lifespan by activating autophagy pathway in male Drosophila melanogaster

INTRODUCTION

Purple sweet potato is a nutritive food rich in anthocyanins that possess antioxidant effects. Drosophila melanogaster owns short growth cycle, fast reproduction, less chromosomes, more mutants, small individuals, therefore, which is an appropriate genetic model organism.

OBJECTIVE

To investigate the anti-aging activity of Purple Sweet Potato Extract (PSPE) in male Drosophila melanogaster and explore the underlying mechanism.

RESULTS

PSPE-induced longevity was associated with improvements in climbing ability and tolerance to stressors such as paraquat and hydrogen peroxide (H₂O₂). Furthermore, PSPE supplementation increased the activity of superoxide dismutase (SOD) and catalase (CAT), as well as expression of SOD and CAT genes, but decreased malondialdehyde (MDA) content. Meanwhile, PSPE decreased the intestinal stem cells (ISCs) proliferation and improved intestinal homeostasis, which was measured by Smurf assay and colony-forming units (CFUs) measurement in aging flies. Additionally, PSPE markedly inhibited the expression of upstream genes AKT-1, PI3K and mTOR and elevated the downstream gene 4E-BP, which further activated the expression of autophagy-related genes (Atg1, Atg5, Atg8a and Atg8b). Moreover, the production of lysosomes increased, indicating that the autophagy pathway was activated.

CONCLUSION

The results provided direct evidence of PSPE anti-aging effects on an organism level, indicating PSPE could be developed for use in effective anti-aging products.

STABILITY OF CHITOSAN-TRIPOLYPHOSPHATE COMPLEX-ENCAPSULATED ANTHOCYANIN AT HIGH WATER ACTIVITY

Previous study successfully conducted encapsulation of the purple-fleshed sweet potato’s anthocyanin but the study has yet to reveal the stability of encapsulated anthocyanin. Therefore, this research aims to observe the stability of encapsulated anthocyanin regarding the characteristic of low anthocyanin stability, which depends on environmental factors, such as temperature, pH, humidity, and water activity. The kinetic parameters of stability, including kinetic constant (k), reaction order, and half-life (t1/2), were also studied. Stability testing was conducted in high water activity of 0.75 and various in-cubation temperatures at 16, 25, 35, and 45°C. Un-encapsulated anthocyanin extract was also tested for its stability in the same condition in order to be compared with encapsulated anthocyanin. This study re-vealed that the encapsulated anthocyanin had lower stability than un-encapsulated anthocyanin extract. It was proven by higher kinetic constant and lower half-life of encapsulated anthocyanin for every incubation temperature which was induced by higher pH of encapsulated anthocyanin compared with anthocyanin extract. Besides, high water activity reduced glass transition temperature (Tg), in which encapsulated anthocyanin was in rubbery state. Both encapsulated anthocyanin and anthocyanin extract were degraded following the first order kinetic. Using the Arrhenius equation, it was obtained that the degradation kinetic constant of encapsulated anthocyanin was stated as k= 420.44 exp (-23.33/RT). Meanwhile, k= 1.12x106 exp (-46.70/RT) described degradation of kinetic constant of anthocyanin extract. The stability test re-vealed that the application of encapsulated anthocyanin was not suitable for wet-type food product.

Exploring the Applications of the Photoprotective Properties of Anthocyanins in Biological Systems

Due to their physical and chemical characteristics, anthocyanins are amongst the most versatile groups of natural compounds. Such unique signature makes these compounds a focus in several different areas of research. Anthocyanins have well been reported as bioactive compounds in a myriad of health disorders such as cardiovascular diseases, cancer, and obesity, among others, due to their anti-inflammatory, antioxidant, anti-diabetic, anti-bacterial, and anti-proliferative capacities. Such a vast number of action mechanisms may be also due to the number of structurally different anthocyanins plus their related derivatives. In this review, we highlight the recent advances on the potential use of anthocyanins in biological systems with particular focus on their photoprotective properties. Topics such as skin aging and eye degenerative diseases, highly influenced by light, and the action of anthocyanins against such damages will be discussed. Photodynamic Therapy and the potential role of anthocyanins as novel photosensitizers will be also a central theme of this review.

Effect of Cutting Styles on Quality and Antioxidant Activity of Stored Fresh-Cut Sweet Potato (Ipomoea batatas L.) Cultivars

The effect of cutting styles (slice, pie, and shred) on the quality characteristics and antioxidant activity of purple and yellow flesh sweet potato cultivars during six days of storage at 4 °C was investigated. The results indicated that the sliced and pie samples showed no significant difference (p > 0.05) on the firmness, weight loss, and vitamin C content compared with the whole sweet potato in both cultivars during storage. The pie sample exhibited the highest wound-induced phenolic, flavonoid, and carotenoid accumulation and DPPH radical scavenging activity among the cuts in both cultivars. Moreover, the shredded sample showed significantly (p < 0.05) higher polyphenol oxidase (PPO) activity but lower total phenolic and flavonoid content and the lowest antioxidant activity among the samples. Thus, the finding of this study revealed that pie-cut processing has potential in improving the quality and increasing the antioxidant activity of fresh-cut purple and yellow flesh sweet potato cultivars while shredding accelerated the quality deterioration of both sweet potato cultivars.

Anthocyanins-Nature's Bold, Beautiful, and Health-Promoting Colors

Anthocyanins are among the most interesting and vigorously studied plant compounds, representing a large class of over 700 polyphenolic pigments within the flavonoid family that exist ubiquitously in the human diet. They are "nature's colors," responsible for providing the beautiful red-orange to blue-violet hues present in many leaves, flowers, vegetables, and fruits, especially berries. The beginning of the 21st century has witnessed a renaissance in research activities on anthocyanins in several areas, mainly related to their potential health-promoting properties and their increased use as alternatives to synthetic food colors. There is increasingly convincing scientific evidence that supports both a preventative and therapeutic role of anthocyanins towards certain chronic disease states. Many anthocyanin-based extracts and juice concentrates from crop and/or food processing waste have become commercially available as colorants and/or value-added food ingredients. There is a large and evolving peer-reviewed literature on how anthocyanin chemistry and concentration may affect their coloring properties in food. Equally as important is the food matrix, which can have large impacts on anthocyanin color expression, stability and degradation, particularly regarding the applications of anthocyanins as food colorants and their health-promoting properties. This Special Edition of Foods, titled "Anthocyanins in Foods," presents original research that extends our understanding of these exciting and complex compounds.