The effect of ageing temperature on the physicochemical properties, phytochemical profile and α-glucosidase inhibition of Hibiscus sabdariffa (roselle) wine

Characterization of Bitter Compounds in Shaoxing Huangjiu by Quantitative Measurements, Taste Recombination, and Omission Experiments

Excessive and uncoordinated bitterness of Shaoxing Huangjiu, a traditional Chinese rice wine, reduces its acceptance by consumers. To determine the compounds responsible for this bitterness, gas chromatography-mass spectrometry and high-performance liquid chromatography were performed on four types of Shaoxing Huangjiu (Yuanhong, Huadiao, Shanniang, and Xiangxue wine) for targeted quantitation of candidate compounds known to contribute to bitterness. Calculations of dose-over-threshold factors revealed that isoamyl alcohol, 1-hexanol, phenylethanol, ethyl butyrate, ethyl lactate, furfural, histidine, and arginine were important bitter compounds. Taste recombination experiments demonstrated that a recombination model constructed using the screened known bitter compounds showed good similarity with the original sample in bitter taste. Furthermore, omission experiments revealed that isobutanol, isoamyl alcohol, 1-hexanol, phenylethanol, ethyl acetate, ethyl butyrate, ethyl lactate, furfural, arginine, and valine were the compounds affecting the bitter taste perception. This study provides a certain guiding effect on the bitterness control and taste improvement of Shaoxing Huangjiu.

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.

Effect of sweeteners and storage on compositional and sensory properties of blackberry jams

Sweeteners of natural sources, such as sugar alcohols, are in the centre of growing interest. Their impact on the phytochemicals, antioxidant and sensory properties of blackberry jams were investigated during a 9-months storage period. Measurements on jams prepared with different sugars and sugar alcohols (sucrose, fructose, xylitol and erythritol) were performed at the date of preparation and in the 1st, 3rd, 6th, 9th month.

Total polyphenol content, individual polyphenols, antioxidant properties, anthocyanin content and CIE L*a*b* colour were determined. Sensory profiles were determined by a trained panel. Sensory attributes were compared by the results of the electronic tongue and nose.

Sweeteners had a significant impact on physicochemical properties and sensory attributes. Storage time also affected the sensory and compositional properties of jams. Changes in antioxidant properties did not follow a clear trend during the storage period, and antioxidant capacity was not affected significantly by the sweetening agent, but showed a significant decline from the 6th month. A positive effect of xylitol was observed in terms of a low degradation rate of anthocyanins, while their decomposition was the fastest in the fructose-containing preparation. Jams sweetened with erythritol reached significantly lower values for some sensory attributes (blackberry flavour and general taste intensity), however, they showed more intense red colour. Multiple factor analysis enabled the identification of the effect of sweetener and storage time on the pattern of the sensory data matrix. Classification according to individual sweeteners was performed successfully by the electronic tongue, but not by electronic nose.

Reversing UVB-induced photoaging with Hibiscus sabdariffa calyx aqueous extract

BACKGROUND

Hibiscus sabdariffa is commonly used in daily life and its extract is applied widely in food and cosmetics. However, it has not been evaluated for its anti-aging effects.

RESULTS

Hibiscus sabdariffa calyx aqueous extract (HSCAE) has shown potential collagenase activity suppression effects, together with tyrosinase activity inhibition, and anti-oxidation as a free radical scavenger. The current investigation demonstrated that HSCAE was not cytotoxic in skin fibroblasts, and it significantly decreased ultraviolet B (UVB)-induced reactive oxygen species (ROS) on a flow cytometry assay. Moreover, HSCAE reduced matrix metalloproteinase (MMP) expression, increased tissue inhibition of metalloproteinase (TIMP)-1 level, and enhanced collagen content by inhibiting collagenase activity. It also blocked mRNA and protein expressions of melanin production pathway key factors, including the microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 (TRP-1), and dopachrome tautomerase-2 (TRP-2).

CONCLUSION

These results demonstrated, for the first time, the potential of HSCAE as a natural antioxidant with the ability to maintain collagen production and to decrease melanin syntheses under UVB radiation, for anti-aging effects. © 2019 Society of Chemical Industry.

IR Thermography from UAVs to Monitor Thermal Anomalies in the Envelopes of Traditional Wine Cellars: Field Test

Infrared thermography (IRT) techniques for building inspection are currently becoming increasingly popular as non-destructive methods that provide valuable information about surface temperature (ST) and ST contrast (delta-T). With the advent of unmanned aerial vehicle (UAV)-mounted thermal cameras, IRT technology is now endowed with improved flexibility from an aerial perspective for the study of building envelopes. A case study cellar in Northwest (NW) Spain is used to assess the capability and reliability of low-altitude passive IRT in evaluating a typical semi-buried building. The study comparatively assesses the use of a pole-mounted FLIR B335 camera and a drone-mounted FLIR Vue Pro R camera for this purpose. Both tested IRT systems demonstrate good effectiveness in detecting thermal anomalies (e.g., thermal bridges, air leakages, constructive singularities, and moisture in the walls of the cellar) but pose some difficulties in performing accurate ST measurements under real operating conditions. Working with UAVs gives great flexibility for the inspection, but the angle of view strongly influences the radiometric data captured and must be taken into account to avoid disturbances due to specular reflections.

Roselle Anthocyanins: Antioxidant Properties and Stability to Heat and pH

Roselle is rich in anthocyanins and is traditionally used to prepare a bright red beverage by decoction. However, heat treatment and different pH environments are often encountered during food processing, and these factors are often detrimental to anthocyanins. Therefore, it is very important to understand the influence of pH and heat treatment on anthocyanins for the application of roselle. This study determined the antioxidant properties of roselle extract, explored changes in the color and anthocyanin content in different pH environments, and evaluated the thermal stability of roselle anthocyanins using kinetic equations. The results showed that the roselle extract is rich in anthocyanins and has good antioxidant capacity (DPPH IC50 = 4.06 mg/mL, ABTS IC50 = 3.7 mg/mL). The anthocyanins themselves exhibited a certain degree of heat resistance and good color stability in an acidic environment. In contrast, they degraded very quickly and exhibited significant changes in color in a low-acid environment. The activation energy (Ea) ranges of the anthocyanins in the acidic and low-acid environments were quite different at 55.8–95.7 and 31.4–74.9 kJ/mol, respectively. Thus, it can be concluded that roselle anthocyanins are susceptible to heat treatment in a low-acid environment, affecting their quality and appearance; however, they can serve as a good source of functional ingredients and color in an acidic environment.