Reclaim and Valorization of Sea Buckthorn (Hippophae rhamnoides) By-Product: Antioxidant Activity and Chemical Characterization

Analytical Strategies for Green Extraction, Characterization, and Bioactive Evaluation of Polyphenols, Tocopherols, Carotenoids, and Fatty Acids in Agri-Food Bio-Residues

Recent advancements in analytical strategies have enabled the efficient extraction and characterization of bioactive compounds from agri-food bio-residues, emphasizing green chemistry and circular economy principles. This review highlights the valorization of several agri-food bio-residues for the extraction of high-value-added bioactive compounds, particularly polyphenols, tocopherols, carotenoids, and fatty acids, as a biorefinery approach. To this end, the adoption of environmentally friendly extraction technologies is essential to improve performance, reduce energy consumption, and minimize costs. This study therefore examines emerging methodologies such as supercritical fluid extraction, pressurized liquid extraction, pulsed electric fields, and matrix solid-phase dispersion, highlighting their advantages and limitations. Additionally, the chemical characterization of these bioactive compounds is explored through spectrophotometric and high-resolution chromatographic techniques, crucial for their accurate identification and quantification. This is complemented by an analysis of bioactivity assays evaluating antioxidant, antimicrobial, anticancer, neuroprotective, and anti-inflammatory properties, with a focus on their applications in the food, pharmaceutical, and cosmetic industries. However, the analytical control of toxic compounds, such as alkaloids, in these bio-residues is undoubtedly needed. Ultimately, this approach not only promotes sustainability but also contributes to the development of eco-friendly solutions in various industries.

Growth and physiological response of Yulu Hippophae rhamnoides to drought stress and its omics analysis

Hippophae rhamnoides (H. rhamnoides) is the primary tree species known for its ecological and economic benefits in arid and semi-arid regions. Understanding the response of H. rhamnoides roots to drought stress is essential for promoting the development of varieties. One-year-old Yulu H. rhamnoides was utilized as the experimental material, and three water gradients were established: control (CK), moderate (T1) and severe (T2), over a period of 120 days. The phenotypic traits and physiological indies were assessed and analyzed, while the roots were subjected by RNA-Seq transcriptome and Tandem Mass Tags (TMT) proteome analysis. Drought stress significantly reduced the plant height, ground diameter, root biomass and superoxide dismutase activity; however, the main root length increased. In comparison with CK, a total of 5789 and 5594 differential genes, as well as 63 and 1012 differential proteins, were identified in T1 and T2, respectively. The combined analysis of transcriptome and proteome showed that the number of differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) associated with T1, T2 and CK was 28 and 126, respectively, with 7 and 36 genes achieving effective KEGG annotation. In T1 and T2, the differential genes were significantly enriched in the plant hormone signal transduction pathway, but there was no significant enrichment in the protein expression profile. In T2, 38 plant hormone signal transduction function genes and 10 peroxisome related genes were identified. With the increase of drought stress, the combined expression of DEGs and DEPs increased. Yulu H. rhamnoides may allocate more resources toward CAT while simultaneously decreasing SOD and POD to mitigate the oxidative stress induced by drought. Furthermore, the molecular mechanisms underlying plant hormone signal transduction and peroxisome-related genes in the roots of H. rhamnoides were discussed in greater detail.

The Effect of Including Sea Buckthorn Berry By-Products on White Chocolate Quality and Bioactive Characteristics under a Circular Economy Context

The by-products of the extraction of sea buckthorn (Hippophae rhamnoides L.) concentrated juice may represent a functional food ingredient for white chocolate production, as a rich source of bioactive compounds. The effects of six treatments derived from the factorial combination of two types of by-products (with oil or without oil) and three different concentrations (5%, 10%, and 15%), were assessed on rheological, quality, colour, antioxidant, and mineral properties of chocolate. The 15% addition of full powder led to the highest values of max firmness, total shear energy, shear energy, cohesiveness, gummosity, dry matter, and ABTS, compared to the untreated control, but the two highest concentrations of the oil-deprived powder resulted in the protein content increasing. The full powder addition always raised fat levels. Both the 'L' and 'a' colour component as well as total carotenoids, β-carotene, lycopene, and vitamin C increased with the rise of H. rhamnoides powder addition, compared to the untreated control. The opposite trend was shown by the 'b' colour component and pH, whereas polyphenols and antioxidant activity attained higher values with the oil-deprived powder. The content of potassium decreased upon the 15% addition of the Hippophae rhamnoides by-product powder, compared to the untreated control, whereas calcium and magnesium increased. The 15% H. rhamnoides full powder elicited the augmentation of phosphorus content in chocolate, compared to the untreated control, contrary to the effect of the oil-deprived powder on P and Zn. The employment of SBB by-products highlights the great potential for manufacturing innovative functional foods with high nutritional value, such as chocolate.

Optimizing the Solvent Selection of the Ultrasound-Assisted Extraction of Sea Buckthorn (Hippophae rhamnoides L.) Pomace: Phenolic Profiles and Antioxidant Activity

Sea buckthorn pomace (SBP) is a by-product of sea buckthorn processing that is rich in bioactive compounds. In this study, different active ingredients were extracted by using different solvents (water, methanol, ethanol, glycerol, ethyl acetate, and petroleum ether) combined with an ultrasonic assisted method. The correlation between the active ingredients and antioxidant properties of the extract was studied, which provided a research basis for the comprehensive utilization of SBP. This study revealed that the 75% ethanol extract had the highest total phenolic content (TPC) of 42.86 ± 0.73 mg GAE/g, while the 75% glycerol extract had the highest total flavonoid content (TFC) of 25.52 ± 1.35 mg RTE/g. The ethanol extract exhibited the strongest antioxidant activity at the same concentration compared with other solvents. The antioxidant activity of the ethanol, methanol, and glycerol extracts increased in a concentration-dependent manner. Thirteen phenolic compounds were detected in the SBP extracts using UPLC-MS/MS analysis. Notably, the 75% glycerol extract contained the highest concentration of all identified phenolic compounds, with rutin (192.21 ± 8.19 μg/g), epigallocatechin (105.49 ± 0.69 μg/g), and protocatechuic acid (27.9 ± 2.38 μg/g) being the most abundant. Flavonols were found to be the main phenolic substances in SBP. A strong correlation was observed between TPC and the antioxidant activities of SBP extracts. In conclusion, the choice of solvent significantly influences the active compounds and antioxidant activities of SBP extracts. SBP extracts are a valuable source of natural phenolics and antioxidants.

In Search of Authenticity Biomarkers in Food Supplements Containing Sea Buckthorn: A Metabolomics Approach

Sea buckthorn (Hippophae rhamnoides L.) (SB) is increasingly consumed worldwide as a food and food supplement. The remarkable richness in biologically active phytochemicals (polyphenols, carotenoids, sterols, vitamins) is responsible for its purported nutritional and health-promoting effects. Despite the considerable interest and high market demand for SB-based supplements, a limited number of studies report on the authentication of such commercially available products. Herein, untargeted metabolomics based on ultra-high-performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry (UHPLC-QTOF-ESI+MS) were able to compare the phytochemical fingerprint of leaves, berries, and various categories of SB-berry herbal supplements (teas, capsules, tablets, liquids). By untargeted metabolomics, a multivariate discrimination analysis and a univariate approach (t-test and ANOVA) showed some putative authentication biomarkers for berries, e.g., xylitol, violaxanthin, tryptophan, quinic acid, quercetin-3-rutinoside. Significant dominant molecules were found for leaves: luteolin-5-glucoside, arginine, isorhamnetin 3-rutinoside, serotonin, and tocopherol. The univariate analysis showed discriminations between the different classes of food supplements using similar algorithms. Finally, eight molecules were selected and considered significant putative authentication biomarkers. Further studies will be focused on quantitative evaluation.

Effects of Different Drying Methods on Drying Characteristics and Quality of Glycyrrhiza uralensis (Licorice)

Large amounts of waste result from licorice mold rot; moreover, prompt drying directly influences product quality and value. This study compared various glycyrrhiza drying methods (Hot air drying (HAD), infrared combined hot air drying (IR-HAD), vacuum freeze drying (VFD), microwave vacuum drying (MVD), and vacuum pulsation drying (VPD)) that are used in the processing of traditional Chinese medicine. To investigate the effects of various drying methods on the drying characteristics and internal quality of licorice slices, their color, browning, total phenol, total flavonoid, and active components (liquiritin and glycyrrhizic acid) were chosen as qualitative and quantitative evaluation indices. Our results revealed that VFD had the longest drying time, but it could effectively maintain the contents of total phenol, total flavonoid, and liquiritin and glycyrrhizic acid. The results also showed that VFD samples had the best color and the lowest degree of browning, followed by HAD, IR-HAD, and VPD. We think that VFD is the best approach to ensure that licorice is dry.