Stability of chlorophyll–protein complex (photosystem II) in processed spinach: Effect of high hydrostatic pressure

Fabrication and characterization of curcumin-loaded composite nanoparticles based on high-hydrostatic-pressure-treated zein and pectin: Interaction mechanism, stability, and bioaccessibility

We successfully designed curcumin (Cur)-loaded composite nanoparticles consisting of high-hydrostatic-pressure-treated (HHP-treated) zein and pectin with a pressure of 150 MPa (zein-150 MPa-P-Cur), showing nano-spherical structure with high zeta-potential (-36.72 ± 1.14 mV) and encapsulation efficiency (95.64 ± 1.23 %). We investigated the interaction mechanism of the components in zein-150 MPa-P-Cur using fluorescence spectroscopy, molecular dynamics simulation, Fourier-transform infrared spectrometry and scanning electron microscopy techniques. Compared with zein-P-Cur, the binding sites and binding energy (-53.68 kcal/mol vs. - 44.22 kcal/mol) of HHP-treated zein and Cur were increased. Meanwhile, the interaction force among HHP-treated zein, pectin, and Cur was significantly enhanced, which formed a tighter and more stable particle structure to further improve package performance. Additionally, Cur showed the best chemical stability in zein-150 MPa-P-Cur. And the bioavailability of Cur was increased to 65.53 ± 1.70 %. Collectively, composite nanoparticles based on HHP-treated zein and pectin could be used as a promising Cur delivery system.

Effect of Heat Stress on Some Physiological and Anatomical Characteristics of Rice (Oryza sativa L.) cv. KDML105 Callus and Seedling

Simple Summary

Climate change is currently threatening agriculture all around the world, resulting in a lack of water and restricting the growth of plants, especially rice. Rice production decreases with the increase in temperature. An improvement in fundamental knowledge is necessary to comprehend plant adaptation mechanisms as responses to heat stress. Physiological and anatomical responses of Khao Dawk Mali 105 (KDML105) rice to artificial heat stress were studied. Our findings offer useful data for projects aimed at improving heat stress tolerance in rice to enhance long-term global food security.

Abstract

Global warming is a serious problem, with significant negative impacts on agricultural productivity. To better understand plant anatomical adaptation mechanisms as responses to heat stress, improved basic knowledge is required. This research studied the physiological and anatomical responses of Khao Dawk Mali 105 (KDML105) to artificial heat stress. Dehusked seeds were sterilized and cultured on Murashige and Skoog (MS) medium, supplemented with 3 mg/L 2,4-Dichlorophenoxyacetic acid (2,4-D) for callus induction. The cultures were maintained at 25 °C and 35 °C for 4 weeks, while the other culture was treated with heat shock at 42 °C for 1 week before further incubation at 25 °C for 3 weeks. Results revealed that elevated temperatures (35 °C and 42 °C) adversely impacted seedling growth. Plant height, root length, leaf number per plant, fresh and dry weight, chlorophyll a, chlorophyll b and total chlorophyll content decreased after heat stress treatment, while malondialdehyde (MDA) and electrolyte leakage percentage significantly increased, compared to the control. Heat stress induced ROS accumulation, leading to lipid peroxidation and membrane instability. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) results also confirmed negative correlations between MDA, electrolyte leakage and other parameters. MDA content and electrolyte leakage are effective indicators of heat stress in rice. Surface anatomical responses of rice seedlings to heat stress were studied but significant alterations were not observed, and heat stress had no significant negative effects on KDML105 calli. Size and mass of calli increased because heat stress stimulated gene expression that induced thermotolerance. Our results provide useful information for rice breeding and heat stress tolerance programs to benefit long-term global food security.

The Physicochemical Properties and Antioxidant Activity of Spirulina (Artrhospira platensis) Chlorophylls Microencapsulated in Different Ratios of Gum Arabic and Whey Protein Isolate

Spirulina (Artrhospira platensis) is rich in chlorophylls (CH) and is used as a potential natural additive in the food industry. In this study, the CH content was extracted from spirulina powder after ultrasound treatment. Microcapsules were then prepared at different ratios of gum Arabic (GA) and whey protein isolate (WPI) through freeze-drying to improve the chemical stability of CH. As a result, a* and C* values of the microcapsules prepared from GA:WPI ratios (3:7) were −8.94 ± 0.05 and 15.44 ± 0.08, respectively. The GA fraction increased from 1 to 9, and encapsulation efficiency (EE) of microcapsules also increased by 9.62%. Moreover, the absorption peaks of CH at 2927 and 1626 cm⁻¹ in microcapsules emerged as a redshift detected by FT-IR. From SEM images, the morphology of microcapsules changed from broken glassy to irregular porous flake-like structures when the GA ratio increased. In addition, the coated microcapsules (GA:WPI = 3:7) showed the highest DPPH free radical scavenging activity (SA_DPPH) (56.38 ± 0.19) due to low moisture content and better chemical stability through thermogravimetric analysis (TGA). Conclusively, GA and WPI coacervates as the wall material may improve the stability of CH extracted from spirulina.

Study the impact of ultra-sonication and pulsed electric field on the quality of wheat plantlet juice through FTIR and SERS

Pulsed electric field (PEF) and Ultrasound (US) are commonly used in food processing. We investigated the combined impact of pulsed electric field (PEF) and ultrasound (US) on the wheat plantlet juice. When compared with the individual treatments, the highest values of total phenolics, total flavonoids, chlorophyll, ORAC assay, and DPPH activities were obtained using the combined (US + PEF) methods. The US + PEF significantly decreased the peroxidase and polyphenol oxidase activities from 0.87 to 0.27 Abs min-1 and 0.031-0.016 Abs min-1. Also, the synergistic application significantly lowered the yeast and mold (3.92 to 2.11 log CFU/mL), E. coli/Coliform (1.95 to 0.96 log CFU/mL), and aerobics (4.41 to 2.01 log CFU/mL). Furthermore, Fourier Transform Infrared (FT-IR) and surface-enhanced Raman spectroscopy (SERS) was used to analyzing juice quality. Gold nanoparticles (AuNPs) were used as the SERS substrates, which provided stronger Raman peaks for the samples treated with US + PEF methods. The FT-IR analysis showed significant enhancement of the nutritional molecules. The enhanced quality of wheat plantlet juice combined with lower yeast and mold suggests the suitability of integrated methods for further research and applications.

Thermo-Ultrasound-Based Sterilization Approach for the Quality Improvement of Wheat Plantlets Juice

The impact of thermo–ultrasound (TU) on the quality of fresh wheat plantlets juice is described in this study. Fresh wheat plantlets juice was treated with TU using ultrasound (US) bath cleaner with different treatment variables, including power (70%, 420 W), frequency (40 kHz), processing time (20 and 40 min) and temperature (30, 45 and 60 °C) for the determination of free amino acids, minerals, microbial loads and bioactive compounds. The treatments have non-significant effects in ºBrix, pH, and titratable acidity while a significant increase in non-enzymatic browning, viscosity, and cloud value. The TU treatment at 30 °C for 20 and 40 min has achieved the highest value of total phenolics, flavonoids, total antioxidant capacity, 2, 2-diphenyl-1-picrylhydrazyl (DPPH), carotenoids, anthocyanin contents, chlorophyll (a + b), minerals and free amino acids than other treatments as well as untreated sample. A lightly visible variation in the color was observed among all treatments. TU treatments also showed a significant impact on the reduction of microbial loads at 60 °C for 40 min. The verdicts revealed that TU at low temperature a viable option to improve the quality of wheat plantlets juice at an industrial scale as compared to alone.