Effects of cellulase from Aspergillus niger and solvent pretreatments on the extractability of organic green tea waste

Absorption, metabolism, bioactivity, and biotransformation of epigallocatechin gallate

Epigallocatechin gallate (EGCG), a typical flavone-3-ol polyphenol containing eight free hydroxyl groups, is associated with a variety of bioactivities, such as antioxidant, anti-inflammatory, anti-cancer, and antibacterial activities. However, the poor bioavailability of EGCG restricts its use. In this review, we discuss the processes involved in the absorption and metabolism of EGCG, with a focus on its metabolic interactions with the gut microbiota. Next, we summarize the bioactivities of some key metabolites, describe the biotransformation of EGCG by different microorganisms, and discuss its catabolism by specific bacteria. A deeper understanding of the absorption, metabolism, and biotransformation of EGCG may enable its disease-preventive and therapeutic properties to be better utilized. This review provides a theoretical basis for further development and utilization of EGCG and its metabolites for improving the gut microbiota and physiological health.

New insights into metabolomics profile generation in fermented tea: the relevance of bacteria and metabolites in Fuzhuan brick tea

BACKGROUND

The contribution of bacteria to fermented tea is not clear and the associated research is relatively limited. To reveal the role of microorganisms in fermented tea processing, the microbial community and metabolites of Fuzhuan brick tea (FBT), a Chinese traditional fermented tea, were revealed via high-throughput sequencing and liquid chromatography-mass spectrometry (LC-MS).

RESULTS

In FBT, bacterial communities had a higher abundance and diversity, Lactococcus and Bacillus were the main bacteria, and Eurotium was the predominant fungus. The predictive metabolic function indicated the pathways of cellular growth, environmental information, genetics and material metabolism of bacterial communities were abundant, whereas the fungal community predictive metabolic function was almost saprotroph. Using LC-MS, 1143 and 536 metabolites were defined in positive and negative ion mode, respectively. There were essential correlations between bacterial populations and metabolites, such that Bacillus was correlated significantly with 44 metabolites (P < 0.05) and Enterococcus was significantly associated with 15 metabolites (P < 0.05). Some of the main active components were significantly correlated with the bacteria, such as Enterococcus, Lactococcus and Carnobacterium.

CONCLUSION

Not only Eurotium, but also the bacteria were involved in the changes of metabolomics profile in fermented FBT. The present study assists in providing new insights into metabolomics profile generation in fermented tea. The present research lays a foundation for controlling the FBT fermentation by artificial inoculation to improve quality. © 2021 Society of Chemical Industry.

Status of the application of exogenous enzyme technology for the development of natural plant resources

Exogenous enzymes are extraneous enzymes that are not intrinsic to the subject. The exogenous enzyme industry has been rapidly developing recently. Successful application of recombinant DNA amplification, high-efficiency expression, and immobilization technology to genetically engineered bacteria provides a rich source of enzymes. Amylase, cellulase, protease, pectinase, glycosidase, tannase, and polyphenol oxidase are among the most widely used such enzymes. Currently, the application of exogenous enzyme technology in the development of natural plant resources mainly focuses on improving the taste and flavor of the product, enriching the active ingredient contents, deriving and transforming the structure of a chosen compound, and enhancing the biological activity and utilization of the functional ingredient. In this review, we discuss the application status of exogenous enzyme technology for the development of natural plant resources using typical natural active ingredients from plant, such as resveratrol, steviosides, catechins, mogrosides, and ginsenosides, as examples, to provide basis for further exploitation and utilization of exogenous enzyme technology.

Utilization of Pectinase Cocktail and High Hydrostatic Pressure for the Production of Aged Black Garlic Juice with Improved Nutritional Value

In comparison with raw garlic, aged black garlic has been shown to display multiple pharmacological activities. We recently reported that pretreatment of pectinase cocktail with high hydrostatic pressure (HHP) before the process of aging garlic juice improves its antidiabetic activity and increases S-allylcysteine (SAC) content. Thus, this study was designed to investigate the influence of pectinase cocktail with HHP on the quality of aged black garlic juice formation and to identify the optimal manufacturing conditions. In the pretreatment step, garlic juice is heated at 55°C for 24 h. The contents of SAC and total polyphenols were increased with treatment of pectinase cocktail; this increase was greater under HHP processing. In contrast, the total flavonoid content was decreased in all pretreatment conditions. Garlic juice pretreated with pectinase cocktail and HHP had a significantly higher content of SAC in the early phase of aging than raw garlic juice, and the SAC was increased over time in both treatment groups. The total polyphenol content of garlic juice was significantly higher in the pretreatment group during the aging period, and the antioxidant activity of garlic juice showed a positive correlation with polyphenol content. Interestingly, HHP increased the enzymatic activity of the pectinase cocktail.

Green and Sustainable Separation of Natural Products from Agro-Industrial Waste: Challenges, Potentialities, and Perspectives on Emerging Approaches

New generations of biorefinery combine innovative biomass waste resources from different origins, chemical extraction and/or synthesis of biomaterials, biofuels, and bioenergy via green and sustainable processes. From the very beginning, identifying and evaluating all potentially high value-added chemicals that could be removed from available renewable feedstocks requires robust, efficient, selective, reproducible, and benign analytical approaches. With this in mind, green and sustainable separation of natural products from agro-industrial waste is clearly attractive considering both socio-environmental and economic aspects. In this paper, the concepts of green and sustainable separation of natural products will be discussed, highlighting the main studies conducted on this topic over the last 10 years. The principal analytical techniques (such as solvent, microwave, ultrasound, and supercritical treatments), by-products (e.g., citrus, coffee, corn, and sugarcane waste) and target compounds (polyphenols, proteins, essential oils, etc.) will be presented, including the emerging green and sustainable separation approaches towards bioeconomy and circular economy contexts.

Preparation of S-Allylcysteine-Enriched Black Garlic Juice and Its Antidiabetic Effects in Streptozotocin-Induced Insulin-Deficient Mice

S-Allylcysteine (SAC), produced in large amounts during the aging process of garlic via enzymatic hydrolysis, is known as a key compound responsible for the multiple pharmacological activities of aged black garlic. This study investigated the effects of enzyme- and high hydrostatic pressure (HHP)-assisted extraction on the content of the bioactive compounds, including SAC, in black garlic juice (BGJ) and evaluated the antidiabetic effects of SAC-enriched BGJ in streptozotocin (STZ)-treated mice. The aging process increased the contents of SAC, total polyphenols, and total flavonoids in garlic juice. More importantly, pretreatment of pectinase cocktail with HHP resulted in a greater increase in those compounds during aging. Enzyme-treated BGJ reduced hyperglycemia and improved islet architecture and β-cell function in STZ-treated mice. Moreover, these effects were more potent than those of BGJ prepared by the conventional aging process. These findings provide useful information for the production of black garlic with improved bioactivities.

Synergistic effect of Trichoderma reesei cellulases on agricultural tea waste for adsorption of heavy metal Cr(VI)

This is the first attempt to study the synergistic effect between Trichoderma reesei cellulases and the abundant agricultural tea waste in absorption of heavy metal Cr(VI) as well as its kinetic model development. The properties of tea waste were first analyzed by near infrared spectroscopy (NIR), particle size distribution (PSD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) examination with EDX for comparison between its original (UN-TW) and cellulase-hydrolyzed (TRCEL-TW) conditions. Then, an advanced kinetic model in the form of -d[Cr(VI)]/dt = A[H+](n)e(-Ea/RT) [Cr(VI)](m)(0), which can successfully predict the time-dependent Cr(VI) concentration of various pHs, initial Cr(VI) concentrations and temperatures was developed. The demonstrated synergistic effects of T. reesei cellulases on tea waste suggested that cellulosic material provides more accessibility area for absorption of heavy metal. This study also provides an alternative approach to remove toxic Cr(VI) from aqueous solutions and extend the utilization of agricultural tea waste.