The Catechins Profile of Green Tea Extracts Affects the Antioxidant Activity and Degradation of Catechins in DHA-Rich Oil

Effect of Ultrasound-Assisted Extraction and Drying Methods on Bioactive Compounds, Phenolic Composition, and Antioxidant Activity of Assam Tea Cultivar (Camellia sinensis var. assamica) Cultivated in Thailand

Tea is a rich source of phytochemicals; their composition in tea extracts varies depending on the cultivar, climate, production region, and processing and handling processes. The method of extraction plays a crucial role in determining the biological effects of the bioactive compounds in tea leaves. However, reports on the catechin profiles and antioxidant activities of the extracts obtained from leaves at different stages of maturity are limited. Here, we aimed to evaluate the effect of ultrasound-assisted extraction (UAE) and different drying methods, freeze drying (FD) and spray drying (SD), on the composition of bioactive compounds, phenolic composition, and antioxidant activity of extracts obtained from different part of leaves, top (TT), middle (ML), and mature (MT), of Assam tea cultivar (Camellia sinensis var. assamica) cultivated in Thailand (Thai Assam tea). High-performance liquid chromatography analysis showed that the extracts obtained by UAE with FD from TT leaves (UAEFD-TT) had the highest catechins (341.38 ± 0.11 mg/g extract) and caffeine (93.20 ± 0.36 mg CF/g extract) contents compared with those extracted from ML and MT using the same method as well those obtained by SD. The total phenolic and total flavonoid contents were the highest in UAEFD-TT extracts (456.78 ± 4.31 mg GAE/g extract and 333.98 ± 0.83 mg QE/g extract, respectively). In addition, UAEFD-TT exhibited the highest antioxidant activity; the IC50 values obtained by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays were 1.31 ± 0.02 and 7.51 ± 0.03 μg/mL, respectively. In the ferric-reducing antioxidant power (FRAP) assay, the UAEFD-TT extract demonstrated the highest antioxidant activity (324.54 ± 3.33 μM FeSO4/mg extract). These results suggest that extraction from TT using UAE followed by FD produced the highest amount of antioxidant compounds in Thai Assam tea extracts.

Potentialities of Tannase-Treated Green Tea Extract in Nutraceutical and Therapeutic Applications

Green tea has garnered widespread interest in the past decades due to its content of health-beneficial polyphenols and catechins, besides reportedly exhibiting activities for the prevention, and possibly treatment, of many modern-life-associated afflictions. Hence, the functional food potential of health-beneficial beverages such as green tea is widely and commercially promoted. Biotransformation of green tea extract using enzymes such as tannase ostensibly enhances its beneficial well-being properties and disease-preventing functionalities. The tannase-treated green tea catechins may exhibit enhanced, amongst others, antioxidant, anti-tumour, anti-wrinkle, anti-inflammatory, anti-obesity and anti-sarcopenia properties compared to native green tea extract. Nonetheless, the health benefits and therapeutic and toxicological effects associated with these compounds, before and after tannase treatment, present a scientific gap for detailed studies. Accordingly, the review surveys the literature from the late twentieth century until the year 2023 related to the aforementioned important aspects.

Effects of adding green tea extract on the oxidative stability and shelf life of sunflower oil during storage

This study aimed to compare different concentrations effect of green tea extract (GTE) (200, 400, and 800 ppm) with TBHQ (75 ppm) in extend the shelf-life of sunflower oil (SO) and to evaluate the protective effect of GTE on the oxidation of refined SO. The sample's peroxide value (PV), acidity value (AV), anisidine value (pAV), Totox value (TV), oxidative stability, and total phenol content (TPC) were analyzed at specific intervals during 12-month at 25 °C and 60-day at 60 °C. The optimum kinetic model corresponding to the first order for PV, TV, and pAV was obtained at 25, 35, and 45 °C. SO containing GTE (800 ppm) had a similar performance to TBHQ at 25 °C and 60 °C and possessed a longer shelf life than samples treated with TBHQ. Due to synthetic antioxidant's health risk and toxicity, GTE can be a good substitute for TBHQ in the edible oil industry.

Attenuation of heterocyclic amine formation and lipid and protein oxidation in air-fried fish fillets by marination with selected legume seed extracts

The present study aimed to investigate the potential of marination with extracts prepared from five legume seeds on heterocyclic amine (HA) formation in chemical models and air-fried fish fillets. In terms of total HAs, clove seed marinade (CSM) was found with the maximum inhibitory effect (43.98 %), followed by tamarind seed marinade (TSM) (40.26 %), fenugreek seed marinade (FSM) (39.07 %), acacia seed marinade (ASM) (37.99 %), and black bean seed marinade (BSM) (29.95 %). In particular, at higher levels (3 mg/mL, 4 mg/mL), CSM and FSM achieved the greatest mitigating effect against 4,8-DiMeIQx, 7,8-DiMeIQx, and MeIQx. Furthermore, all marinades were effective in lowering thiobarbituric acid-reactive substances (TBARS) and carbonyl and retaining thiol content relative to the control. PCA analysis revealed that higher levels of ASM, BSM, and FSM had better mitigating effect against IQ and MeIQx formation, whereas Pearson correlation shows that TBARS and carbonyl were positively correlated to HAs.

Effect of edible coatings and films enriched with plant extracts and essential oils on the preservation of animal-derived foods

Edible coatings and films for food preservation are becoming more popular thanks to their environmentally friendly properties and active ingredient-carrying ability. Their application can be effective in contrasting quality decay by limiting oxidation and deterioration of foods. Many reviews analyze the different compounds with which films and coatings can be created, their characteristics, and the effect when applied to food. However, the possibility of adding plant extracts and essential oils in edible coatings and films to preserve processed animal-derived products has been not exhaustively explored. The aim of this review is to summarize how edible coatings and films enriched with plant extracts (EXs) and essential oils (EOs) influence the physico-chemical and sensory features as well as the shelf-life of cheese, and processed meat and fish. Different studies showed that various EXs and EOs limited both oxidation and microbial growth after processing and during food preservation. Moreover, encapsulation has been found to be a valid technology to improve the solubility and stability of EOs and EXs, limiting strong flavor, controlling the release of bioactive compounds, and maintaining their stability during storage. Overall, the incorporation of EXs and EOs in edible coating and film to preserve processed foods can offer benefits for improving the shelf-life, limiting food losses, and creating a food sustainable chain.

Evaluation of the Phenolic Composition and Biological Activities of Six Aqueous Date (Phoenix dactylifera L.) Seed Extracts Originating from Different Countries: A Comparative Analysis

Date seeds, which are the main by-products of date fruit consumption, were shown to possess promising biological activities and health benefits with minimal human use. The present investigation analyzed and compared the phenolic content of six date seed varieties from four different origins (Khudari, Sakai, and Safawi from Saudi Arabia, Majdool from Jordan, Zahdi from Iraq, and Kabkab from Iran). The aqueous extracts were examined for possible antioxidant, antibacterial, and anti-tumor potential. Date seed oil was extracted, and fatty acid profiles were compared. The results revealed that date seeds are a rich source of polyphenols, which have been linked to biological activities. Furthermore, the phenolic content seemed highly dependent on the variety, where Kabkab had the highest TPC value (271.2 mg GAE/g DM) while Majdool had the lowest value (63.2 mg GAE/g DM). Antioxidant activities of all varieties were highly correlated with the total phenolic content. The antibacterial investigation demonstrated that the Sakai variety possessed the dominant activity, whereas Majdool showed no activity. The results further indicated the sensitivity of both Staphylococcus aureus and Bacillus cereus, with a stronger effect against B. cereus, while no effect was observed against Gram-negative strains (Salmonella Typhi and Escherichia coli). All varieties were able to decrease colon and lung cancer cell viability, especially Khudari and Sakai, with stronger effects against colon cancer cells. Analysis of date seed oil showed high oleic acid content, especially in Sakai. The findings suggest that date seeds are promising candidates for future pharmaceutical applications as nutraceuticals to help combat certain illnesses, as well as functional foods and natural additives that boost the nutritional value of food products, increase their shelf lives, and improve the overall health of consumers.

Epigallocatechin Gallate: pH-Dependent Redox Properties and Effect on Respiration, Photosynthesis, and Cell Death in Pea Plants

In vitro redox properties of the green tea component epigallocatechin gallate (EGCG) and its effect on pea plant cells were investigated. EGCG was found to exhibit both pro- and antioxidant properties. In solutions, EGCG was oxidized by oxygen at physiological (slightly alkaline) pH values with the generation of O2-• and H2O2, the reaction being slowed down by a decrease in the medium pH. On the other hand, EGCG functioned as an electron donor for peroxidase, resulting in the H2O2 utilization. EGCG suppressed respiration, reduced mitochondrial transmembrane potential difference and inhibited electron transfer in the photosynthetic electron transport chain in pea leaf cells (leaf cuttings and epidermis). Among components of the photosynthetic redox chain, Photosystem II was the least sensitive to the EGCG action. In the epidermis, EGCG reduced the rate of reactive oxygen species formation that was induced by NADH. EGCG at the concentrations from 10 μM to 1 mM suppressed the KCN-induced death of guard cells in the epidermis, which was determined from the destruction of cell nuclei. EGCG at a concentration of 10 mM disrupted the barrier function of the guard cell plasma membrane, increasing its permeability to propidium iodide.