Sweet Potato Anthocyanins Research Articles

Effects and mechanism of natural phenolic acids/fatty acids on copigmentation of purple sweet potato anthocyanins

Anthocyanins are attractive alternatives to colorants; however, their low color stability hinders practical application. Copigmentation can enhance both the color intensity and color stability of complexes. Herein, we report an investigation of copigmentation reactions between purple sweet potato anthocyanins (PSA1) and phenolic acids (tannic, ferulic, and caffeic acids) or fatty acids (tartaric and malic acids) at pH 3.5. The effects of the mole ratios of the copigment and the reaction temperature were examined. In addition, quantum mechanical computations were performed to investigate molecular interactions. The optimum PSA:copigment molar ratio was found to be 1:100. The strongest bathochromic and hyperchromic effects were observed for copigmentation with tannic acid (Tan), which might be attributable to the fact that its HOMO-LUMO energy gap was the smallest among the investigated copigments, and because it has a greater number of phenolic aromatic and groups to form more van der Waals and hydrogen bond interactions. However, the formation of the PSA-caffeic acid (Caf) complex was accompanied by the greatest drop in enthalpy (−33.18 kJ/mol) and entropy (−74.55 kJ/mol), and this was the most stable complex at 90 °C. Quantum mechanical calculations indicated that hydrogen bonds and van der Waals force interactions contributed to the color intensification effect of copigmentation. These findings represent an advancement in our understanding of the properties of PSA, expanding the application scope of this natural product.

PERBEDAAN KADAR ANTOSIANIN UBI UNGU SEGAR DAN TEPUNG UBI UNGU VARIETAS LOKAL DAN ANTIN 3 PADA BEBERAPA ALAT PENGERINGAN

Background: Purple sweet potato is one of the local Asian food ingredients known as "people's food". Purple sweet potato is rich in anthocyanins which function as antioxidants and immunonutrients. In addition to being widely used as food or traditional snacks, purple sweet potato can be used as a functional food ingredient rich in anthocyanins. For example, purple sweet potato flour can be used as an essential ingredient for processed foods.Objectives: To analyze differences in anthocyanin levels in fresh purple sweet potato local varieties of Gunung Kawi and Antin 3 and purple sweet potato flour with different drying tools.Methods: This research consist of two research stages. The first phase analyzes differences in anthocyanin content in fresh purple sweet potatoes local varieties of Gunung Kawi and Antin 3 with a RAL research design (Completely Randomized Design) 3 repetitions. Then, the second stage of the research used a one-shot case study with 3 treatment groups: drying with an electric oven, cabinet dryer, and food dehydrator. Anthocyanin levels were tested using the UV-Vis spectrophotometry method. Differences in fresh purple sweet potato anthocyanins were analyzed using an independent t-test. Meanwhile, the different anthocyanin levels of purple sweet potato flour were analyzed using one-way ANOVA.Results: The first stage of the study showed that the anthocyanin content of fresh purple sweet potato Antin 3 was seven times higher than that of Gunung Kawi (53.94±25.6 v.s 7.59±2.4 mg/100 g) with p=0.036. The second stage of the study, showed no statistically significant difference in anthocyanin levels (p = 0.066) in 3 different drying equipment.Conclusion: Antin 3 purple sweet potato variety is purple sweet potato with the highest anthocyanin content. The purple sweet potato flour was dried with 3 different drying tools, resulting in anthocyanin levels that were not significantly different.Keywords: Anthocyanin; Gunung Kawi local purple sweet potato; Antin 3 purple sweet potato; Purple sweet potato flour; Drying equipment

Anthocyanin Extract from Purple Sweet Potato Exacerbate Mitophagy to Ameliorate Pyroptosis in Klebsiella pneumoniae Infection.

Given the rise of morbidity and mortality caused by Klebsiella pneumoniae (KP), the increasing number of strains resistant to antibiotics, and the emergence of hypervirulent Klebsiella pneumonia, treatment of KP infection becomes difficult; thus, novel drugs are necessary for treatment. Anthocyanins, or natural flavonoids, have an extensive effect against bacterial infection. However, few studies on anti-KP are identified. Here, we evaluated the therapeutic effect of purple sweet potato anthocyanins (PSPAs) on KP, containing 98.7% delphinidin 3-sambubioside. Results showed that KP-infected mice after PSPAs treatment manifested decreased mortality, weakened lung injury, dampened inflammatory responses, and reduced bacterial systemic dissemination in vivo. In Vitro, PSPAs significantly suppressed pyroptosis and restricted NLRP3 inflammasome activation in alveolar macrophages infected with KP. As for the mechanism, PSPAs promote mitophagy by recruiting Parkin to the mitochondria. PSPAs-conferred mitophagy increased mitochondrial membrane potential and decreased mitochondrial reactive oxygen species and mitochondrial DNA, resulting in impaired NLRP3 inflammasome activation. In addition, the promotion of mitophagy by PSPAs required the Nrf2 signaling pathway. Collectively, these findings suggest that PSPAs are a potential option for the treatment of KP infection.

Preparation and dynamic response properties of colorimetric indicator films containing pH-sensitive anthocyanins

Colorimetric pH-responsive indicator capable of monitoring food freshness has received widespread attention in recent years. In this study, a novel colorimetric indicator film based on agarose matrix incorporated with purple sweet potato anthocyanins was prepared by a solution casting method. At the same time, dynamic response properties of the as-prepared indicator films were investigated by UV-vis absorption spectroscopy under a simulation environment. In order to overcome the defect of chromatic parameters, a new parameter, the relative ratio of the absorbance after and before exposure (A605nm/A535nm), was defined as Response in this work. The dynamic response fitting curve of the indicator film exposed to the volatile alkaline solution was established based on the newly defined response index, and the curve of Response vs. time showed a typical sigmoidal shape. The dynamic response model of the pH-responsive indicator was also surveyed through curve fitting and four classical mathematical models were verified to be the optimal models for dynamic response behavior. Moreover, the effects of dye concentration, pH of dye stock solution, relative humidity, and test temperature on dynamic response rate were separately researched. And the results indicated that dye concentration and pH of dye stock solution had a bigger impact on the response rate of indicator film than the remaining two factors. These findings could not only provide a new way for evaluating the response efficiency of pH-responsive indicators but also enlighten a valuable thought for developing colorimetric indicators with higher sensitivity and response efficiency.

Comparison of anthocyanin and polyphenolics in purple sweetpotato (Ipomoea batatas Lam.) grown in different locations in Japan

ABSTRACT The health benefits of purple sweetpotato, which is used as an edible food in its natural state and in processed foods and as a natural color pigment, have been recognized. In Japan, sweetpotato has been economically produced in regions below 36°4ʹN latitude; however, cultivation areas are beginning to expand further north. The anthocyanin and polyphenolics in three purple sweetpotatoes cultivated in different locations; I (42°92ʹN, 143°04ʹE) and II (31°72ʹN, 131°03ʹE), were compared over two years. Total anthocyanin and polyphenolic contents in purple sweetpotatoes tended to be high in location I. The anthocyanin and polyphenolic compositions differed between locations. The peonidin/cyanidin ratios were higher in location II compared with I in all varieties. The relative amount of 3,4- and 4,5-di-O-caffeoyolquinic acids were higher in location II. Their contents and composition also differed between years. These results suggest that the variability of the anthocyanin and polyphenolic content and composition was influenced by climate conditions, probably temperature during cultivation. This study indicates that northern areas in Japan are an alternative production area and may yield higher amounts of anthocyanin and polyphenolics.

Characterization of Anthocyanin Associated Purple Sweet Potato Starch and Peel-Based pH Indicator Films.

In food packaging, smart indicator films based on natural resources have greatly attracted researchers to minimize the environmental issues as well as to satisfy consumer preferences for food safety. In this research, pH-sensitive films were prepared using purple-fleshed sweet potato starch (SPS) and sweet potato peel (SPP). Two categories of the film (i) SPS and (ii) SPS/SPP, were fabricated via solvent casting technique, incorporating different concentrations of commercial purple sweet potato anthocyanin (CA) at 0%, 1%, 1.5%, and 2% (w/v) and the physicochemical, mechanical, thermal, and morphological properties of the films were investigated. The thickness, water solubility, and swelling degree of the films increased with the increment of CA, whereas there were no significant changes in the water content (WC) of the films. Water vapor permeability (WVP) was decreased for SPS films while statistically similar for SPS/SPP films. The addition of CA reduced the tensile strength (TS) and tensile modulus (TM) yet increased the elongation at break (EaB) of the films as compared to films without CA. The FTIR results confirmed the immobilization of anthocyanin into the film. In SEM images, roughness in the surfaces of the CA-associated films was observed. A reduction of thermal stability was found for the films with anthocyanin except for the SPS/SPP CA 2% film. Furthermore, the CA-associated films showed a remarkable color response when subjected to pH buffers (pH 1 to 12) and successfully monitored chicken freshness. The fastest color migration was observed in acidic conditions when the films were immersed into aqueous, acidic, low fat, and fatty food simulants. The findings of this work demonstrated that the developed pH indicator films have the potential to be implemented as smart packaging to monitor food freshness and quality for safe consumption.

Anthocyanins from purple sweet potato alleviate doxorubicin‐induced cardiotoxicity in vitro and in vivo

In this study, anthocyanins were extracted and purified from purple sweet potato anthocyanins (PSPA) and the alleviative effect of PSPA on doxorubicin (DOX)-induced cardiotoxicity was investigated. High Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS) results showed that 10 kinds of substances were identified in PSPA and the PSPA was mainly composed of cyanidin (62.9%) and peonidin (21.46%). In in vitro experiments, PSPA reduced the excessive release of inflammatory factors (NO and TNF-α) induced by DOX and decreased the secretion of trimethylamine oxide (TMAO), lactic dehydrogenase (LDH), and creatine kinase (CK) caused by myocardial injury. In in vivo experiments, PSPA inhibited the release of NO and MDA levels in heart tissue. Meanwhile, mice treated with PSPA decreased the levels of LDH, CK, TNF-α, and TMAO in serum and heart tissue when compared with the DOX group. In addition, the histopathological results of the heart tissue also showed a protective effect of PSPA on the pathological changes in heart. These results provide a reference for the application of PSPA as a functional food to intervene in DOX-induced cardiotoxicity. PRACTICAL APPLICATIONS: The effects of anthocyanins from purple sweet potato anthocyanins (PSPA) on doxorubicin (DOX)-induced cardiotoxicity were investigated in vitro and in vivo. The results indicated that PSPA could significantly ameliorate DOX-induced heart failure. The obtained results could provide the potential application of PSPA as an alternative therapy for cardiotoxicity caused by DOX in the functional food industry.

Purple sweet potato anthocyanins elicit calcium overload-induced cell death by inhibiting the calcium-binding protein S100A4 in acute lymphoblastic leukemia

This study aimed to evaluate the effects of purple sweet potato anthocyanins (PSPAs) on acute lymphoblastic leukemia (ALL) cells to elucidate the molecular mechanism underlying the anticancer properties of PSPAs. The results showed that PSPAs significantly suppressed cell proliferation by inducing obvious G2/M phase arrest. In addition, PSPAs dramatically increased the intracellular Ca2+ levels, thereby leading to calcium overload-induced cell death. Furthermore, to evaluate the relevant mechanism, bioinformatic, subcellular localization, molecular docking, and Western blot analyses were performed. PSPAs induced calcium overload by inhibiting the protein expression of S100A4. An additional assay combining S100A4 induction and PSPA treatment reconfirmed that S100A4 was the potential target of PSPAs and that PSPAs mainly exerted their antileukemic effects through the p38/c-Myc/CDK1-Cyclin B axis. Our findings indicate that PSPAs are promising therapeutic agents for ALL.

Product Characterization and Marketing Strategy of “BREM UNGU”: Rejuvenation of Indonesian Traditional Food with Local Purple Sweet Potato as the Source of Natural Colorant

Solid brem is an indigenous fermented food of Indonesia, which often has typical form of long thick bar, white to yellow in color, sweet-sour taste with cooling sensation, and it is easy to crumble by the presence of water. These unique characteristics are generated through alcoholic fermentation of glutinous rice, followed by filtration, concentration, whipping and dehydration. Although it is continuously produced and sold as regional specialties of Madiun, East Java, most people refuse to consume this solid brem due to its high sugar content and lack of information that describes its potential health benefits. The present study is attempting the possibility of combining glutinous rice with another local material having well-known health benefit. Here, we utilize the potency of local purple sweet potato (Ipomoea batatas var. Gunung Kawi), being rich in carbohydrate and anthocyanines, to partly substitute the glutinous rice while adding the health benefits of the final product. The present anthocyanins in sweet potato has been well-studied, exhibiting antioxidant, anti-inflammation, and hepatoprotective activities. The raw materials were subjected to yeast fermentation for 7 days, and subsequently extracted using manual mechanical press. A series of materials ratio (extract of fermented glutinous rice: purple sweet potato = 30:1, 15:1, 15:2) was determined prior to dehydration of brem, and then the color, sugar content, pH, antioxidant activity, and sensory properties of the resulted product were analyzed. Moreover, the competitive analysis and marketing strategy will also be discussed in order to make sure the sustainability of this new innovation.

Effect of Sweet Potato Anthocyanin (Ipomoea Batatas L.) on Levels of Follicle Stimulating Hormone and Folliculogenesis in Rattus Norvegicus Exposed to Cigarette Smoke

Cigarette smoke is one of the exogenous free radicals that can enter the blood circulation so that it candisrupt all body cells and tissues, including the reproductive organs. The anthocyanin in purple sweetpotato is one of the bioactive that can counter free radicals. This study was conducted to prove the effectof anthocyanin in purple sweet potato from Gunung Kawi cultivar on follicle-stimulating hormone (FSH),and folliculogenesis levels on Wistar rats (Rattus norvegicus) exposed to cigarette smoke. This study wasan experimental study with Randomized Post Test Only Control Group Design, using 30 female Wistar ratsaged 1-2 months weighing 150-200g. The rats were divided into three groups of where they were exposedto cigarette smoke and administered with anthocyanin (each group with the doses of 20, 40 and 80 mg/kgbw/day). One positive control group was exposed to cigarette smoke without being administered withanthocyanin for 56 days, and one more group served as a negative control. The FSH levels in the serum weremeasured by employing the ELISA method, and the folliculogenesis (follicle amount and number of ovaryfollicular granulosa cells) was measured from histopathological slides with Haematoxylin-Eosin staining.The results indicated that anthocyanin in purple sweet potato significantly increased the FSH levels, thefollicle amount and the number of primary follicular granulosa cell, secondary, and Graafian on femaleWistar rat ovaries exposed to cigarette smoke with a p-value of less than 0.05. To ensure the anthocyanindose that had maximum effect, more research is required with more dose variations and chronic toxicity testsfor the safety of the anthocyanin in purple sweet potato of Gunung Kawi cultivar.

Encapsulation of purple sweet potato's anthocyanin in CMC-PVA matrix for development of paper strips as a colorimetric biosensor

Bioactive compound from local resources such as anthocyanin has a high potential to develop as a biosensor for nitrite detection. As a biosensor, this compound shows instability to certain environmental conditions. To overcome this, bioactive compound may need to encapsulate. The aim of this work is to encapsulate of anthocyanin in the CMC-PVA matrix to improve its stability as paper strip for sodium nitrite detection. The result of this work shows that anthocyanin encapsulated by CMC/PVA matrix has well formed. Encapsulated anthocyanin has good homogeneity and it was strongly immobilized in the CMC/PVA matrix. Encapsulated anthocyanin is attached to the surface of the paper medium and penetrated into the matrix. The strip is shown changing color from red to yellow as it applied to nitrite. The selectivity of biosensor paper strip system is observed for various other chemicals including heavy metals such as Pb2+, Zn2+, Fe3+, Mg2+, NaCl, boric acid, monosodium glutamate, sodium benzoate, and formalin with a concentration of 10000 ppm, respectively, and the biosensor was selective towards nitrite. This work gives a basic information to development of a practical green sensor in the form of paper strips for nitrite detection with good stability and selectivity.

Purple-fleshed sweet potato genotypes as the ingredients for crisps and noodle making

The presence of anthocyanins in purple-fleshed sweet potato has been intensively promoted as functional foods regarding its high antioxidant activity and essential health benefits. Therefore, a number of attractive and nutritious food products needs to be developed in order to diversify the utilization and increase the consumption. As selected promising purple-flesh sweet potato genotypes have been available, their suitability prepared for different food products needs to be studied. About 12 genotypes of sweet potato with varied purple color intensity or deepness were processed into crispy chips (crisps) and noodles and evaluated their physical properties (yield, lightness, hardness) and sensorial attributes (color, aroma, texture, taste) using a Hedonic test with 20 panelists. The results showed that sweet potato genotypes with purple flesh in combination with yellow/orange or white color, namely MSU 06046-74, Antin 1, and MSU 06044-05 were suitable for crisps making, followed by those with medium purple color, such as Aya Murasaki, MIS 0612-73, MIS 0614-02, MIS 0601-22, and MSU 06014-51. Conversely, sweet potato with deep purple color, namely MSU 06028-71 and MSU 06046-48 were tailored for the ingredients of noodles. This information would be useful for releasing new purple sweet potato varieties in addition to their excellent agronomic traits.

Anti-aging effects of the fermented anthocyanin extracts of purple sweet potato on Caenorhabditis elegans.

Anthocyanins have anti-inflammatory, anticarcinogenic and antioxidant properties and anti-aging effects as well as potential application as pigments. The metabolism of anthocyanins in fermented food has attracted increasing attention. However, the effect of lactic acid bacteria (LAB) fermentation on its anti-aging activity remains mostly unknown. The current study aimed to investigate the compositions, antioxidant activities and anti-aging effect of fermented purple sweet potato anthocyanins (FSPA) on aging Caenorhabditis elegans compared to raw purple sweet potato anthocyanins (PSPA). Results showed that anthocyanins were degraded into more bioavailable phenolic acids by Weissella confusa fermentation. PSPA and FSPA can extend the lifespan of C. elegans by 26.7% and 37.5%, respectively, through improving the activity of antioxidant enzymes as well as decreasing MDA content, ROS levels and lipofuscin accumulation. Pretreatment of the worms with PSPA and FSPA induced their potential to resist to thermal tolerance and oxidative stress, and FSPA exerted a higher anti-stress effect than PSPA. Moreover, FSPA supplementation upregulated the mRNA expressions of genes daf-16, hsp-16.2, sir-2.1, skn-1 and sod-3 and downregulated the expression of daf-2 in the nematodes, whereas PSPA only induced the increase in the expressions of sir-2.1, skn-1 and sod-3. Overall, FSPA can improve stress resistance and extend the lifespan of C. elegans by both insulin/IGF-1 signaling pathway and dietary restriction pathway, providing a theoretical basis for the application of PSPA in fermented food as functional pigments.

Anti-inflammatory effects of purple sweet potato anthocyanin extract in DSS-induced colitis: modulation of commensal bacteria and attenuated bacterial intestinal infection.

Purple sweet potato anthocyanins have been acknowledged for their beneficial effects on human inflammatory bowel diseases (IBD). Although the ability of anthocyanins in modulating the gut microbiota has been reported, the relationship between the bacteria modulated by anthocyanins and intestinal inflammation has not been fully elucidated. We aimed to ascertain whether the purple sweet potato anthocyanin extract (PSPAE) modulation of gut microbiota in the dextran sodium sulphate (DSS) induced chronic colitis mouse model could result in the maintenance of intestinal homeostasis and protection against bacterial intestinal inflammation. Chronic colitis was induced by adding DSS in drinking water while administering the mice with PSPAE via gavage (20 mg kg-1). Effects on colon tissue damage, gut microbiota composition, tight junction protein, and cytokines were evaluated. PSPAE prevented the loss of Bifidobacterium and Lactobacillus and inhibited the increase of Gammaproteobacteria and Helicobacter upon DSS treatment. The non-pathogenic-dependent and pathogenic-dependent microenvironments were established upon treatment with broad-spectrum antibiotics. Both PSPAE treatment and non-pathogenic treatments modified the colonic expression of mouse tight junction proteins and maintained the architecture of the colon. However, the non-pathogenic treatment could not attenuate intestinal inflammation. Moreover, the pathogenic-dependent dysbiosis was exacerbated because of the increasing colonization of pathogens such as Helicobacter. The PSPAE exerted the modulation of gut microbiota to maintain the gut microbiome homeostasis in DSS-induced chronic colitis mice, which may help to propose a new treatment that combines efficacy and reduction of the possibility of bacterial intestinal infection.

Improvement of Malang Tahu Quality Using Sweet Potato Natural Dyes by Adsorption Technology

Tahu is a popular culinary product in Malang town. This product is produced from soyabean and rich of protein. Besides, tahu is also rich of water, so that surface of tahu tends to polar. Colorization of tahu by extract of yellow and sweet potatoes is interesting because both sweet potatoes contains different polarity molecular dyes, i.e. polar anthocyanin in the purple sweet potato but non-polar beta carotene in the yellow sweet potato. In this paper, changing of tahu’s color after colorization by extract of both sweet potatoes was observed at different times of adsorption process (2, 4, 6 h), different compositions of the sweet potato and water (100g/1L and 300g/1L), and effect of palm oil addition (250 mL oil/1L water). Result of observation showed that the higher time of adsorption process, the higher ratio of the sweet potato weight and water volume, the darker color of the colorized tahu. Addition of the palm oil just improved extraction of β - carotene from the yellow sweet potato but did not improve the adsorption of the dyes on the tahu surface. Results of this study are used for supporting program of community service DPP SPP 2020 of Inorganic lecturers, as application of adsorption technology using tahu food as adsorbent and application of intermolecular force theory as part of Inorganic Chemistry I course.

Efficacy of thermal treatment on the stability of total phenolic, flavonoid and anthocyanin in purple-fleshed sweet potato (Ipomoea batatas)

Efficacy of thermal treatment on the stability of total phenolic, flavonoid and anthocyanin in purple-fleshed sweet potato (Ipomoea batatas)

The influence of phenolic acyl groups on the color of purple sweet potato anthocyanins and their metal complexes

Anthocyanins from purple sweet potato (PSP) are peonidin and cyanidin glycosides acylated by p-hydroxycinnamic and p-hydroxybenzoic acids. For six individual PSP pigments, the thermodynamic constants of proton transfer and water addition were determined, from which the speciation diagrams for the colored and colorless forms and the UV–visible spectra of individual colored forms could be constructed. The data confirm that acylation by phenolic acids protects the chromophore against water addition (a consequence of acyl – anthocyanidin π-stacking interactions) and that this protection depends on the type and number of acyl residues, diacylation being much more efficient than monoacylation, and p-hydroxycinnamoyl more efficient than p-hydroxybenzoyl. Most PSP anthocyanins can bind metal ions (Fe2+, Al3+) through their cyanidin chromophore and/or their caffeoyl residue(s). At pH 7, a cyanidin glycoside bearing a caffeoyl residue can bind a single metal ion by simultaneous involvement of its two binding units. With Fe2+ a strong bluing effect was observed. Although the caffeoyl residues efficiently slow down color loss, their redox activity actually accelerates the thermal degradation of anthocyanins. Consistently, two-electron autoxidation of anthocyanins bearing caffeoyl residues could be evidenced by UPLC-MS/DAD analysis. These new pigments possibly stem from intramolecular coupling between the chromophore and o-quinones derived from the caffeoyl residues.

Evaluation of physicochemical properties of anthocyanin extracts and powders from purple sweet potato (Ipomoea batatas L.)

Purple sweet potato (Ipomoea batatas L.) is one of the food commodities that contain anthocyanin. This research aimed to evaluate the physicochemical properties of anthocyanin extracts and powders from purple sweet potato. Purple sweet potato anthocyanin was extracted using a water solvent with the addition of citric acid in different concentrations (0, 2, 4, and 6 g/100 mL). Ethanol solvent was used as a control. Foam mat drying was performed using variations of egg white composition (10 and 20 mg/100 mL). The result showed that extraction using a water solvent with 2 g/100 mL of citric acid was the most effective condition to obtain the highest total anthocyanin content (p < 0.05). However, its total phenolic, flavonoid, and antioxidant activity were lower compared to others. Total anthocyanin content of foam mat dried purple sweet potato powder made from the citric acid-water extract was significantly higher than the powder made from the citric acid-ethanol extract (p < 0.05). There was no effect in the total phenolic, flavonoid, viscosity, and yellowish-red color of the powder obtained from citric acid-water extract as the increase of egg white concentration. The use of 20 g/100 mL egg white in both powders produced from citric acid-water and ethanol extracts resulted in higher total anthocyanins and solubilities than powders using 10 g/100 mL egg white. The color of the powder obtained from citric acid-water extract had a lower brightness level and higher yellowish-red color intensity compared to the powder made from citric acidethanol extract.

Enhanced water extraction with high-pressure carbon dioxide on purple sweet potato pigments: Comparison to traditional aqueous and ethanolic extraction

The high pressure carbon dioxide (HPCD) technology has been used in separation for a while, but its application was relatively limited to several classes of functional compounds. Not to repeat traditional investigation on kinetics or improvement on yield, this study was designed to evaluate HPCD impact on the quality properties of purple sweet potato anthocyanins extraction, comparing to classical water and ethanol extraction. Pigments relative yield, color properties, pigment HPLC profiles were characterized. Application of 10 MPa HPCD to water increased the anthocyanins relative yield from 45.58%–83.20% in 20 min. Unlike alcoholic solvent brought higher polymeric color and bluer hue, the HPCD technique maintained around 10 % polymeric color without altering the extract shade. Moreover, HPCD significantly improved the extract quality by extending the monomeric anthocyanins half-life from 79 to 315 days (stored at dark, 25 °C). This study indicated HPCD could modify solvent polarity during process, the highest proportion of mono-acylated pigments was found in HPCD extract, while the highest non-acylated was in water and the highest di-acylated was in ethanolic. This study presented HPCD would be an efficient novel technique for green production of high quality natural pigments.

Effects of β-cyclodextrin, whey protein, and soy protein on the thermal and storage stability of anthocyanins obtained from purple-fleshed sweet potatoes

The effects of β-cyclodextrin (β-CD), whey protein (WP), and soy protein (SP) on the color loss and degradation of anthocyanins in purple-fleshed sweet potato anthocyanin extracts (PFSPAEs) during thermal treatment and shelf-life storage in model beverage systems by performing chromaticity, degradation kinetics, and principal component analysis. Results showed that WP and SP improved the thermal stability of the PFSPAE, but WP accelerated the color loss of the extract. However, the addition of 25 mg/L SP improved the color and thermal stability of the anthocyanins when heated at 100 °C for 30 min. With regard to the shelf-life storage, the addition of SP and WP showed non-significant effect on the storage stability of the PFSPAE. However, the addition of 2500 mg/L β-CD significantly improved the storage stability of the PFSPAE. In summary, our findings provide useful information on improving the thermal and storage stability of PFSPAEs in beverage systems using food biopolymers.