Influence of drying conditions on colour, betacyanin content and antioxidant capacities in dried red-fleshed dragon fruit (Hylocereus polyrhizus )

Effect of kaolin impregnated with calico plant extract on properties of starch films

Starch film has poor tensile properties and poor water resistance. We aimed to improve these properties by adding kaolin impregnated with calico plant extract (CP-Kaolin). UV-Vis spectrophotometry showed that the calico plant extract (CPE) contained 4867.52 mg/L of total phenolic compounds and betacyanins were the predominant constituents. CP-Kaolin was characterized by Fourier transform infrared spectroscopy (FTIR), zeta potential, scanning electron microscopy (SEM) and x-ray diffraction (XRD) analysis. FTIR analysis showed that betacyanins were adsorbed on kaolin via hydrogen bonding. Zeta potential analysis confirmed the adsorption of betacyanins on kaolin. The intercalation of betacyanins between kaolin platelets was observed by XRD. SEM revealed that CP-Kaolin was well dispersed and embedded within the starch matrix. It was found that the addition of 10 wt% of CP-Kaolin increased the water resistance, tensile strength and thermal stability of starch film. Moreover, starch film containing 10 wt% of CP-Kaolin was sensitive to the change in pH of the fish during storage. Therefore, the addition of CP-Kaolin improved the properties of starch film and starch film composite with CP-Kaolin could be applied as a smart packaging in the food industry.

Bioactive compounds and antioxidant activity in garambullo fruit (Myrtillocactus geometrizans) at different ripening stages

Garambullo (Myrtillocactus geometrizans) is endemic in México, and although popularly consumed locally, its nutritional characteristics and value have not been studied in details. The objective of this work was to investigate the bioactive compounds and antioxidant activity in garambullo fruit from different sites at three ripening stages. Fruit from the three ripening stages (red, purple, and dark purple) were investigated for their physicochemical characteristics, hydrophilic (phenolic compounds, betalains, and ascorbic acid), and lipophilic (carotenoids, tocopherols, and fatty acids) bioactive compounds, using spectrophotometry, gas chromatography (GC-FID), and high-pressure liquid chromatography coupled to mass spectrometry (HPLC/DAD-ESI-MS). The antioxidant capacity was measured with the 2,2'-diphenyl-1-picrylhydrazyl and the ferric-ion-reducing antioxidant power assays. The color components of the fruit, chroma and a* values increased, whereas lightness (L*) and b* significantly decreased during ripening. Five betacyanins and four betaxanthins were tentatively identified with HPLC/DAD-ESI-MS, and betacyanins were more abundant than betaxanthins. Betalains content and antioxidant capacity of hydrophilic extracts significantly increased during ripening. Ten phenolic compounds were identified, with ferulic acid being the most abundant. Tocopherols were low (0.023-0.033 mg/100 g fw). Five fatty acids were abundant, and linoleic acid was the most important. Phenolic compounds, ascorbic acid, total carotenoids, and fatty acids decreased during fruit ripening. Garambullo fruit is rich in phytochemical compounds of importance for human nutrition and health. PRACTICAL APPLICATION: The physicochemical and bioactive compounds characterization in garambullo fruit is important to establish maturation and harvesting indices, postharvest strategies to preserve fruit quality and prolong postharvest life, promote the consumption and utilization of the fruit, and the designing of proper functional foods. In addition, the knowledge on the bioactive components might be useful to include this fruit in personalized nutritional approaches for patients with risks of certain chronic diseases. The methodology used in this study could be useful for the study of other fruits, especially those from the Cactaceae family.

Development of multifunctional packaging films based on arginine-modified chitosan/gelatin matrix and betacyanins from weed amaranth (A. hybridus)

Active and intelligent films with antioxidant, antimicrobial, and pH-responsive properties were developed by incorporating betacyanins-rich weed amaranth (A. hybridus) extract (AE) into chitosan/gelatin (Cs/Gn) and arginine-modified chitosan/gelatin (MCs/Gn) blend films. The microstructures, physical and functional properties of Cs/Gn, MCs/Gn, Cs/Gn-AE, and MCs/Gn-AE films were compared. Results showed the addition of AE into MCs/Gn film produced a compact inner microstructure through H-bonding and electrostatic interactions. Meanwhile, AE remarkably changed the colors of the film under alkaline pH mediums. However, AE significantly reduced the water vapor permeability of the films. By comparing different films, MCs/Gn-AE film presented the best UV-vis light and barrier ability as well as the highest mechanical strength. Moreover, MCs/Gn and MCs/Gn-AE films showed stronger microbial growth inhibition than Cs/Gn and Cs/Gn-AE films. Cs/Gn-AE and MCs/Gn-AE films possessed more potent free radical scavenging activity than Cs/Gn and MCs/Gn. Notably, MCs/Gn-AE film is suitable to monitor fish freshness and could be used as novel multifunctional packaging in the seafood industry.

Maturation Process, Nutritional Profile, Bioactivities and Utilisation in Food Products of Red Pitaya Fruits: A Review

Red pitaya (Hylocereus polyrhizus, red pulp with pink peel), also known as dragon fruit, is a well-known species of pitaya fruit. Pitaya seeds and peels have been reported to exhibit higher concentrations of total polyphenols, beta-cyanins and amino acid than pulp, while anthocyanins (i.e., cyanidin 3-glucoside, delphinidin 3-glucoside and pelargonidin 3-glucoside) were only detected in the pulp extracts. Beta-cyanins, phenolics and flavonoids were found to increase gradually during fruit maturation and pigmentation appeared earlier in the pulp than peel. The phytochemicals were extracted and purified by various techniques and broadly used as natural, low-cost, and beneficial healthy compounds in foods, including bakery, wine, dairy, meat and confectionery products. These bioactive components also exhibit regulative influences on the human gut microbiota, glycaemic response, lipid accumulation, inflammation, growth of microbials and mutagenicity, but the mechanisms are yet to be understood. The objective of this study was to systematically summarise the effect of red pitaya’s maturation process on the nutritional profile and techno-functionality in a variety of food products. The findings of this review provide valuable suggestions for the red pitaya fruit processing industry, leading to novel formulations supported by molecular research.

Phytoconstituents and pharmaco-therapeutic benefits of pitaya: A wonder fruit

Dragon fruit has caught the attention of many researchers in the last few years because of its vast therapeutic potential. The fruit is enriched with several phytochemical constituents having tremendous pharmacological properties. It is traditionally used as a coloring agent. Some newly explored therapeutic applications include its use as an antioxidant, antimicrobial, antidiabetic, anticancer, and nutraceutical. The phytoconstituents can be extracted from flesh, peel, and seeds of the fruit. The fruit is known to be a rich source of betacyanin, vitamin C, and lycopene. The current review is focused on phytochemical constituents of dragon fruit along with its pharmacological activities. It also sheds light on the safety aspects of the fruit. The review will pave a path for researchers to study this marvel fruit further for societal benefit. Advanced research on dragon fruit will unleash many more therapeutic benefits and can give mechanistic insight about its activities. PRACTICAL APPLICATIONS: Phytoconstituents play a vital role in the treatment of various diseases and for the improvement of human health, in general. Dragon fruit is known to be having antioxidant, anti-microbial, anti-diabetic, anti-cancer applications. The fruit can also be used as a nutraceutical (functional food). To grab all the benefits from this fruit, its phytoconstituents and pharmaco-therapeutic aspect have to be thoroughly studied. This review can be very useful for researchers across different fields like botany, agriculture, pharmacy, etc., to bridge the gap for collaborative work on dragon fruit, which will help in finding solutions for many modern diseases.

Green biosynthesis of gold nanoparticles using Chenopodium formosanum shell extract and analysis of the particles' antibacterial properties

BACKGROUND

Various physical and chemical methods for synthesis of metal nanoparticles have had some drawbacks. Therefore, green synthesis of gold nanoparticles (Au NPs) has became one of the most crucial emerging areas of nanobiotechnology. In the present study, plant-mediated synthesis of Au NPs was performed using Djulis (Chenopodium formosanum) shell extract as a reducing and stabilizing agent.

RESULTS

Reaction parameters were manipulated to optimize the Au NPs using a UV-visible spectrophotometer. Optimized Au NPs with a surface plasmon resonance band at 533 nm were prepared using a 744 µg mL^-1 extract and a solution of pH 2.62 chloroauric acid (HAuCl₄ ·3H₂ O) at 40 °C. High-resolution transmission electron microscopy (HR-TEM) results indicated that most of the resultant Au NPs were spherical in shape and exhibited a mean size of 8 ± 6 nm. Energy-dispersive X-ray spectroscopy (EDS), and selected area electron diffraction (SAED), and X-ray diffraction (XRD) confirmed the elemental gold and crystalline nature of the resultant NPs. FTIR spectrum analysis indicated the critical role of phenolic groups in the reduction of Au³⁺ ions and stabilization of the formed Au NPs. Moreover, the synthesized Au NPs possessed antibacterial activity for Escherichia coli and Staphylococcus aureus.

CONCLUSION

In this study, Au NPs were synthesized with high efficiency and stability using Djulis shell extract, and related antibacterial applications were demonstrated. © 2019 Society of Chemical Industry.