Characteristics and Relationships between Total Polyphenol and Flavonoid Contents, Antioxidant Capacities, and the Content of Caffeine, Gallic Acid, and Major Catechins in Wild/Ancient and Cultivated Teas in Vietnam

Phytochemical Profiles and Biological Activities of Five Wild Camellia Species from Ta Dung, Vietnam

The C. luuana Orel & Curry (TD3), C. furfuracea (Merr.) Cohen-Stuard (TD4), C. bidoupensis Truong, Luong & Tran (TD6), C. sinensis (L.) Kuntze (TD7), and C. kissii var. spp (TD8), have been traditionally used as a health-promoting beverage by local people in Ta Dung, Dak Nong. Despite their potential health benefits, further scientific data on biological and phytochemical properties of these plants is needed. To address this issue, this study was conducted to investigate phytochemical and biological properties of five Camellia species extracts, using DPPH, ABTS radical scavenging, copper chelating (Cu-chelator), and tyrosinase inhibition (TI), α-amylase (Al-AI), and α-glucosidase (Al-GI) analyses. As results, ten compounds were identified using UPLC method, in which catechins (mainly EGCG and catechin (Cat)), were the most prevalent, and followed by chlorogenic acid (ChlA), quercitrin (Querci), rutin, and quercetin (Querce). Additionally, multiple factor analysis (MFA) also revealed that TD7, TD3, and TD4 containing high TPC, TFC, high concentrations of EGCG, ChlA, and caffeine were responsible for their high DPPH, ABTS radical scavenging activities, as well asTI, Al-AI and Al-GI. Furthemore, TD6 and TD8, possessing elevated levels of Apig, Querci, Rutin, Querce, Cat, and EA, exhibited a high Cu-chelator property, but a weak enzyme inhibition. From all above-mentioned results, the antioxidative and enzyme inhibitory potentials of Camellia species extracts collected in Dak Nong province in Vietnam were scientifically demonstrated paving a pathway to develop health supplement in further studies.

Antioxidant and cholesterol regulatory effect of flavonoid-rich silk sericin

Cholesterol is a component of cell membranes and a precursor of hormones, and excess levels are associated with disease development; therefore, it must be maintained within the normal range. Silkworm cocoons are known to contain bioactive substances. Therefore, we compared the bioactivities of pigmented and white silkworm cocoons. Sericin extract of the Yeonnokjam (YN) variety, which contained a high flavonoid content, showed the highest antioxidant activity and inhibited cholesterol biosynthetic enzyme activity. YN-fed mice showed a 26% reduction in serum low-density lipoprotein cholesterol level. In addition, a 27% decrease in cholesterol accumulation in the liver was observed. Mechanistically, YN reduced the expression of 3-hydroxy-3-methylglutaryl-CoA reductase and acetyl-CoA acetyltransferase 2 proteins by 34 and 13%, respectively. In conclusion, YN suppresses cholesterol synthesis in the liver and stimulates bile acid secretion, which contributes to reduction in cholesterol levels, suggesting its potential as a cholesterol-lowering agent.

Thermal fixation technologies affect phenolic profile, ginkgolides, bilobalide, product quality, and ginkgolic acids in Ginkgo biloba leaf tea

Ginkgo biloba leaves (GBLs) contain high phytoconstituents, but ginkgolic acids (GAs, the main toxic compound in GBLs) have limited its applications. Processing Ginkgo biloba dark tea (GBDT) using fixation technology could decrease the toxic compounds; retain flavonoids, ginkgolides, and bilobalide; and improve the product quality. For the first time, various thermal fixations (hot air fixation [HAF], iron pot fixation [IPF], and boiled water fixation [BWF]) followed by rolling, fermentation, and drying were applied to produce GBDT. A comprehensive analysis of the toxicants (GAs), main bioactive compounds (ginkgolides and bilobalide, flavonoids, antioxidants, and phenolic profiles), and product qualities (moisture content, reducing sugar [RS], free amino acids [FAAs], enzyme activity, color properties, antioxidant capacity, etc.) were evaluated. The results revealed that thermal fixations BWF and HAF significantly reduced the GA contents (41.1%-34.6%). Most terpene lactones showed significant differences in control, IPF, and HAF. The HAF had lower total flavonoid content (TFC) than BWF and IPF. The control group (unfixated) had the highest toxic components (GA), terpene trilactones, and TFC compared with various fixations. Adding different fixations to rolling, fermentation, and drying had various impacts on GBDT, and principal component analysis supported the results. Among four thermal fixations, HAF yielded the best results in RS, FAA, total phenolic content, and antioxidant activities, while IPF had the highest TFC. BWF had the lowest content for GA. In conclusion, HAF (6) was chosen as the best technique for producing GBDT since it preserved GBDT's bioactive components while lowering its toxic components.

Developing the procedure-enhanced model of ginger-infused sesame oil based on its flavor and functional properties

Ginger-infused sesame oil enriches the nutrition and provides enhanced flavor for the foods. An original processing procedure and module for evaluation were established in this study, using different raw materials (Guangdong and Chu ginger) and treatments (ginger powder, extract, and both). The quality, functionality, and flavor of the infused oils were evaluated. Ginger-infused sesame oil contained 0.58-3.22 µg/g of 6-gingerol, 0.21-0.88 µg/g of 6-shogaol. The number range of volatile compounds from 48 to 55 identified by gas chromatography-mass spectrometry varies depending on different process procedures. Agglomerative hierarchical clustering analysis revealed the flavor profiles were clustered by different varieties, while gingerol and phytosterol was by different treatments. In conclusion, sesame oil was an appropriate carrier for gingerol and phytosterol, which are characterized by higher antioxidant capacities (p < 0.05). These results show the benefits of developing infused oil products with enhanced functional and sensory properties.

Comparative Analysis of Hot and Cold Brews from Single-Estate Teas (Camellia sinensis) Grown across Europe: An Emerging Specialty Product

Tea is grown around the world under extremely diverse geographic and climatic conditions, namely, in China, India, the Far East and Africa. However, recently, growing tea also appears to be feasible in many regions of Europe, from where high-quality, chemical-free, organic, single-estate teas have been obtained. Hence, the aim of this study was to characterize the health-promoting properties in terms of the antioxidant capacity of traditional hot brews as well as cold brews of black, green and white teas produced across the European territory using a panel of antioxidant assays. Total polyphenol/flavonoid contents and metal chelating activity were also determined. For differentiating the characteristics of the different tea brews, ultraviolet-visible (UV-Vis) spectroscopy and ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry were employed. Overall, our findings demonstrate for the first time that teas grown in Europe are good quality teas that are endowed with levels of health-promoting polyphenols and flavonoids and that have an antioxidant capacity similar to those grown in other parts of the world. This research is a vital contribution to the characterization of European teas, providing essential and important information for both European tea growers and consumers, and could be of guidance and support for the selection of teas grown in the old continent, along with having the best brewing conditions for maximizing the health benefits of tea.