Impact of the extraction procedure on the kinetics of anthocyanin and colour degradation of roselle extracts during storage

Effect of the roselle (Hibiscus sabdariffa L.) calyces drink on the physiological parameters of healthy adult subjects

The calyx of roselle (Hibiscus sabdariffa L.) has been the focus of attention of several studies, and although earlier studies on this plant showed it to possess antilipidemic and antidiabetic activities, none of these studies have assessed the effects of this plant on the physiological parameters of healthy subjects. The present study determined the effects of roselle calyx beverages on blood pressure, abdominal circumference, body mass index (BMI), hematological and urinary parameters, and the lipid profile of healthy subjects. Healthy subjects (n=30) were treated with a 200 ml roselle calyx beverage each morning and evening for 30 consecutive days. Every week the subjects were asked to perform some physical activity by following the Young Men's Christian Association step test. This study used a pre-post quasi-experimental design. Blood samples were taken before (day-0) and after the intervention (day-30). There was an increase in the levels of high-density lipoproteins (from 47.0 to 49.5 mg/dl; P=0.015), and a significant decrease in both systolic and diastolic (P=0.036 and P=0.030, respectively), and the abdominal circumference of the subjects (P=0.005). However, total cholesterol levels (191.2 to 191.9 mg/dl; P=0.821) and low-density lipoprotein levels (129.8 to 133.5 mg/dl; P=0.249) were slightly increased, although not significantly. A lower level of triglycerides (114.3 to 107.4 mg/dl; P=0.269) and very-low-density lipoprotein levels (22.8 to 21.4 mg/dl; P=0.681) was observed. No significant differences were detected in the BMI or the urinalysis parameters were identified. Based on these results, roselle (Hibiscus sabdariffa L.) may be used as a supplement to prospectively improve the health status of subjects. No serious adverse effects were observed during this trial.

Methodologies in the Analysis of Phenolic Compounds in Roselle (Hibiscus sabdariffa L.): Composition, Biological Activity, and Beneficial Effects on Human Health

Roselle (Hibiscus sabdariffa L.), as an edible flower, has long provided an array of positive effects on human health. This benefit is a result of phenolic compounds that are naturally present mainly in the calyx. Plentiful medicinal remedies and functional foods based on this flower are available worldwide, as supported by the studies of phenolic compounds in recent decades. This paper aims to provide a comprehensive review of the composition, biological activity, and beneficial effects on human health of phenolic compounds in roselle. This review was performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. A structured search in the published literature for phenolics compositions in roselle was required prior to the evaluation on the validity of the reported analytical methods. Reliable identification and quantification of phenolic compounds in roselle can be achieved by employing the proper extraction and separation methods. With ample alternative analytical methods discussed here, this review provided an aid for comprehending and selecting the most appropriate method for a particular study. The applications of the analytical methods highlighted indicated that phenolic acids, flavonoids, and their derivatives have been identified and quantified in roselle with a range of biological activities and beneficial effects on human health. It was also disclosed that the composition and concentration of phenolic compounds in roselle vary due to the growth factors, cultivars, and environmental influence. Finally, apart from the research progress carried out with roselle during the last ten years, this review also proposed relevant future works.

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.

Effects of sucrose and copigment sources on the major anthocyanins isolated from sour cherries

Cyanidin-3-O-glucosylrutinoside and cyanidin-3-O-rutinoside were isolated from sour cherry juice concentrate (SCJC). Sucrose and copigments [gallic acid (GA), cherry stem extract (CSE) and pomegranate rind extract (PRE)] were added to these anthocyanins. Effects of sucrose and copigments on the isolated anthocyanins were studied during storage at 20 °C for 140 days. All copigment sources provided protection against degradation effect of sucrose on the isolated anthocyanins before storage. Although GA increased the stabilities of both isolated anthocyanins, only CSE had copigmentation effect on both isolated anthocyanins. Copigmentation effect on cyanidin-3-O-glucosylrutinoside continued throughout storage. However, this effect on cyanidin-3-O-rutinoside continued for only 56 days of storage. Cyanidin-3-O-glucosylrutinoside containing three sugar moieties was more prone to copigmentation than cyanidine-3-rutinoside containing two sugar moieties. Results showed that the presence of more than one anthocyanin in a media changed stability of copigmentation. We recommend CSE for enhancement in colour density, but GA for enhancement in anthocyanin stability.

Formulation and characterization of an optimized functional beverage from hibiscus (Hibiscus sabdariffaL.) and green tea (Camellia sinensisL.)

Hibiscus sabdariffa and Camellia sinensis are traditionally consumed as beverages and are good sources of health-promoting phenolic compounds. The objective of this work was to use response surface methodology to develop an optimized functional beverage with high total phenolic content, antioxidant capacity, and acceptable for potential consumers. Optimum infusion conditions were 4.9 g of hibiscus calyces or C. sinensis leaves/100 ml of water at 26 ℃ for 291 min. These conditions yielded a total phenolic content of 14.80 ± 1.4 and 33.02 ± 0.34 mg gallic acid equivalents/100 ml for hibiscus and green tea, respectively. The optimized beverages were combined in a 7:3 (hibiscus:green tea, v/v) ratio; a consumer preference test showed that this combination had an acceptable taste according to untrained panelists. A chromatographic analysis showed that this formulation contained flavonoids, phenolic acids, and anthocyanins as its main components. Our data suggested that hibiscus and green tea phenolic compounds were efficiently extracted using near-ambient temperature water for prolonged times, contrary to routine methods (high temperature, short time). Our method also preserved antioxidant capacity, possibly by avoiding chemical changes/degradation due to high temperatures. This process can be used to produce organoleptically acceptable functional beverages that deliver a varied phenolic compound profile to the consumer.

Monitoring anthocyanin degradation in Hibiscus sabdariffa extracts with multi-curve resolution on spectral measurement during storage

This study aims to monitor composition changes in an anthocyanin-rich beverage during storage by the means of UV-VIS measurements associated with a multi-curve resolution procedure. Hibiscus sabdariffa extract was stored at 37 °C for 50 days and UV-VIS spectra were measured on the extract and the fractions of the extract every 5 days. MCR was carried out in two steps, first with the fraction and then the extract spectra. The results enabled the main polyphenols initially present to be identified, anthocyanins and chlorogenic acid, but also found the nature of the main degradation products: the polymers from anthocyanin condensation and scission products. In addition, comparison with HPLC analysis results showed that the MCR procedure recovered the correct shapes of the concentration profiles particularly of anthocyanin and polymer kinetics during storage. This work gives perspective for the use of a rapid and efficient technique to monitor pigment-rich beverage processing or storage.

Evolution of Total Polyphenols Content and Antioxidant Activity in Broccoli Florets during Storage at Different Temperatures

Broccoli has great potential as functional food because of its high content of bioactive compounds. Polyphenols are to a great extent responsible for the high antioxidant activity of broccoli. An important challenge to keep the health promoting properties of broccoli is preservation, with freezing and refrigeration being the preferred methods. Despite storage at low temperature reduces the rate of deterioration reactions, some reactions still occur, thus affecting the content of bioactive compounds. In this work, we investigated the evolution of total polyphenols content and antioxidant activity in blanched and unprocessed broccoli florets during storage at different temperatures (−45°C to 20°C). Both antioxidant activity and total polyphenols content increased at the beginning of storage at −21, −1, 10, and 20°C, followed by a decrease. Storage at −45°C produced no significant variations. The uneven behavior of antioxidant activity precluded modeling. The evolution of polyphenols was well described by a two-consecutive-reaction model, with r≥0.86 and MSE ≤ 0.1. The Ea values obtained for polyphenols formation (27–32 kJ/mol) and degradation (26–38 kJ/mol) confirm that, in both unprocessed and blanched broccoli, the same reactions are responsible for the evolution of polyphenols content. Our results may contribute to design preservation strategies of broccoli.

Anthocyanins degradation during storage of Hibiscus sabdariffa extract and evolution of its degradation products

Degradation parameters of two main anthocyanins from roselle extract (Hibiscus sabdariffa L.) stored at different temperatures (4-37°C) over 60days were determined. Anthocyanins and some of their degradation products were monitored and quantified using HPLC-MS and DAD. Degradation of anthocyanins followed first-order kinetics and reaction rate constants (k values), which were obtained by non-linear regression, showed that the degradation rate of delphinidin 3-O-sambubioside was higher than that of cyanidin 3-O-sambubioside with k values of 9.2·10(-7)s(-1) and 8.4·10(-7)s(-1) at 37°C respectively. The temperature dependence of the rate of anthocyanin degradation was modeled by the Arrhenius equation. Degradation of delphinidin 3-O-sambubioside (Ea=90kJmol(-1)) tended to be significantly more sensitive to an increase in temperature than cyanidin 3-O-sambubioside (Ea=80kJmol(-1)). Degradation of these anthocyanins formed scission products (gallic and protocatechuic acids respectively) and was accompanied by an increase in polymeric color index.

Effect of Temperature on Acidity and Hydration Equilibrium Constants of Delphinidin-3-O- and Cyanidin-3-O-sambubioside Calculated from Uni- and Multiwavelength Spectroscopic Data

Delphinidin-3-O-sambubioside and cyanidin-3-O-sambubioside are the main anthocyanins of Hibiscus sabdariffa calyces, traditionally used to make a bright red beverage by decoction in water. At natural pH, these anthocyanins are mainly in their flavylium form (red) in equilibrium with the quinonoid base (purple) and the hemiketal (colorless). For the first time, their acidity and hydration equilibrium constants were obtained from a pH-jump method followed by UV-vis spectroscopy as a function of temperature from 4 to 37 °C. Equilibrium constant determination was also performed by multivariate curve resolution (MCR). Acidity and hydration constants of cyanidin-3-O-sambubioside at 25 °C were 4.12 × 10(-5) and 7.74 × 10(-4), respectively, and were significantly higher for delphinidin-3-O-sambubioside (4.95 × 10(-5) and 1.21 × 10(-3), respectively). MCR enabled the obtaining of concentration and spectrum of each form but led to overestimated values for the equilibrium constants. However, both methods showed that formations of the quinonoid base and hemiketal were endothermic reactions. Equilibrium constants of anthocyanins in the hibiscus extract showed comparable values as for the isolated anthocyanins.

Extraction temperature affects the activities of antioxidation, carbohydrate-digestion enzymes, and angiotensin-converting enzyme of Pleurotus citrinopileatus extract

Extraction temperature can potentially affect the chemical compositions and bioactivities of the extracts obtained. The objective of this study was to investigate the effect of extraction temperature on the distribution of bioactive compounds and the bioactivities of Pleurotus citrinopileatus. The antioxidant activities (2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)⁺ scavenging capabilities) and the inhibitory capabilities on pancreatic α-amylase, intestinal α-glucosidase, and hypertension-linked angiotensin-converting enzyme of hot water P. citrinopileatus extract and cold water P. citrinopileatus extract were determined. The results showed that the antioxidant capabilities and inhibitory effects on α-amylase, α-glucosidase, and angiotensin-converting enzyme of cold water P. citrinopileatus extract were significantly higher than those of hot water P. citrinopileatus extract. The cold water P. citrinopileatus extracted was further precipitated with 100% ammonium sulfate to obtain a polysaccharide fraction or with 75% ethanol to obtain a protein fraction. The inhibitory activities of the protein fraction of the cold water P. citrinopileatus extract on α-amylase, α-glucosidase, and angiotensin-converting enzyme were significantly higher than those of the polysaccharide fraction. In conclusion, the protein fraction of the cold water P. citrinopileatus extract could be responsible for its bioactivities.

Physiochemical and antioxidant properties of roselle-mango juice blends; effects of packaging material, storage temperature and time

A study was conducted to determine the effects of packaging materials, seasonality, storage temperature and time on physiochemical and antioxidant properties of roselle-mango juice blends. Roselle extract (20%, 40%, 60%, and 80%) was mixed with mango juice and stored in glass and plastic bottles at 4°C and 28°C. Total soluble solids, pH, titratable acidity, reducing sugar, color, vitamin C, total monomeric anthocyanins, total phenols, and antioxidant activity (FRAP) were evaluated in freshly prepared juice, and after, 2, 4, and 6 months of storage. The results showed that total soluble solids, reducing sugars, and pH increased with storage times under different storage time, irrespective of packaging materials. The acidity, color, total monomeric anthocyanin, vitamin C, total phenols, and antioxidant activity decreased during storage irrespective of storage temperature and packaging material. Loss of anthocyanins, total phenols, and vitamin C content were higher in blends stored at 28°C than 4°C.

Influence of storage temperature and time on the physicochemical and bioactive properties of roselle-fruit juice blends in plastic bottle

Roselle-fruit juice blends were made from roselle extract and mango, papaya, and guava juices at the ratio of 80:20, 60:40, 40:60, and 20:80, % roselle: fruit juice, respectively. The blends were pasteurized at 82.5°C for 20 min and stored in 100 mL plastic bottles at 28 and 4°C for 6 months. The effects of storage time and temperature on physicochemical and bioactive properties were evaluated. Total soluble solids, pH, and reducing sugars increased significantly (P < 0.05) in some blends while titratable acidity decrease with increasing storage time. Vitamin C, total monomeric anthocyanins (TMA), total phenols (TPC), and antioxidant activity (ferric reducing ability of plasma, FRAP) in all roselle-fruit blends (40% roselle) decreased significantly (P < 0.05) at 28 and 4°C as storage progressed. Vitamin C in all roselle-fruit blends (40% roselle) decreased from 58-55% to 43-42% when stored at 28 and 4°C, respectively. TMA losses were 86-65% at 28°C and 75-53% at 4°C while TPC losses were 66-58% at 28°C and 51-22% at 4°C. Loss of antioxidant capacity (FRAP) was 18-46% at 28°C and 17-35% at 4°C. A principal component analysis (PCA) differentiated roselle-juice fruit blends into two clusters with two principle components PC1 and PC2, which explained 97 and 3% (blends stored at ambient temperature) and 96 and 4% (blends stored at refrigerated temperature) of the variation, respectively. PC1 differentiated roselle-guava juice blends which were characterized by vitamin C, TPC, FRAP, and pH, while PC2 from another cluster of roselle-mango and roselle-papaya juice blends and was characterized by TSS, RS, and color parameters (L* a* b*). However, TMA was the main variable with the highest effect on all roselle-fruit juice blends regardless of the storage time and temperature.

Relationships between anthocyanins and other compounds and sensory acceptability of Hibiscus drinks

Chemical composition of Hibiscus drinks (Koor and Vimto varieties, commercial and traditional, infusions and syrups) (n=8) was related to sensory evaluation and acceptance. Significant correlations between chemical composition and sensory perception of drinks were found (i.e. anthocyanin content and Hibiscus taste) (p<0.05). Consumers (n=160) evaluated drink acceptability on a 9-point verbal hedonic scale. Three classes of behaviour were identified: (a) those who preferred syrup (43% of consumers); (b) those who preferred infusion (36%); and (c) those who preferred all of the samples (21%). Acceptability of 'syrup likers' was positively correlated to sweet taste, reducing sugar content and inversely correlated to acidic taste and titratable acidity (p<0.10). Acceptability of 'infusion likers' was positively correlated to the taste of Hibiscus drink and anthocyanin content. The study showed that the distinctions between the acceptability groups are very clear with respect to the chemical composition and rating of sensory attributes.