Effects of heat processing and storage on flavanols and sensory qualities of green tea beverage

Penthorum chinense Pursh leaf tea debittering mechanisms via green tea manufacturing process and its influence on NAFLD-alleviation activities

The green-tea manufacturing process showed good effect of flavor improving, debittering and shaping in making Penthorum chinensePursh leaf (PL) tea (PLT), which serves as a polyphenol dietary supplement and beverage raw material. GC-MS results showed that its unpleasant grassy odor decreased by 42.8% due to dodecanal, geranylacetone, and (E)-2-nonenal reduction, coupled with 1-hexadecanol increasing. UPLC-ESI-TOF-MS identified 95 compounds and showed that the debittering effect of green-tea manufacturing process was attributed to decreasing of flavonols and lignans, especially quercetins, kaempferols and luteolins, and increasing of dihydrochalcones which act as sweeteners bitterness-masking agents, while astringency was weakened by reducing delphinidin-3,5-O-diglucoside chloride, kaempferol-7-O-β-d-glucopyranoside, and tannins. The increase of pinocembrins and catechins in aqueous extracts of PLT, maintained its hepatoprotective, NAFLD-alleviation, and hepatofibrosis-prevention activities similar to PL in high fat-diet C57BL/6 mice, with flavonoids, tannins, tannic acids, and some newfound chemicals, including norbergenin, gomisin K2, pseudolaric acid B, tanshinol B, as functional ingredients.

Toxicological effects of the Curatella americana extract in embryo development of female pups from diabetic rats

Maternal diabetes can influence the development of offspring during fetal life and postnatally. Curatella americana is a plant used as a menstrual cycle regulator and to prevent diabetes. This study evaluates the effects of C. americana aqueous extract on the estrous cycle and preimplantation embryos of adult female pups from diabetic rats. Female Sprague Dawley newborn rats received Streptozotocin or vehicle (citrate buffer). At adulthood, were submitted to the Oral Glucose Tolerance Test, and mated. The female rats were obtained and were distributed into four experimental groups: OC and OC/T represent female pups of control mothers and received water or plant extract, respectively; OD and OD/T represent female pups of diabetic mothers and received water or plant extract, respectively. The estrous cycle was followed for 10 days, the rats were mated and on gestational day 4 was performed preimplantation embryo analysis. Phenolic composition and biogenic amines in the extract were analyzed about the influence of the thermal process. The female pups from diabetic dams exhibited glucose intolerance, irregular estral cycle and a higher percentage of pre-embryos in delayed development (morula stage). After C. americana treatment, OD/T group no present a regular estrous cycle. Furthermore, the infusion process increases phenolic compounds and biogenic amines levels, which can have anti-estrogenic effect, anticipates the early embryonic development, and impair pre-implantation embryos. Thus, the indiscriminate use of medicinal plants should be avoided in any life phases by women, especially during pregnancy.

Modeling of Sensory Properties of Poppy Sherbet by Turkish Consumers and Changes in Quality Properties during Storage Process

Poppy is an important edible plant containing bioactive components. This study aimed to produce good-tasting poppy sherbet by determining the content using a response surface methodology (RSM). At the same time, bioactive components, phenolic compounds, and color properties were investigated in optimum poppy sherbet during storage; 0.26 g of dried corn poppy flowers, 0.15 g of citric acid, and 4.29 g of sucrose values were the most promising, achieving high scores for color, smell, taste, and general acceptance from sensory properties (sensory score of 8.55 for color; 7.19 for smell; 8.38 for taste; 7.98 for general acceptability). A total of nine polyphenols were detected in the optimum poppy sherbet sample; gallic acid was the most common. There was no statistically significant difference between the samples stored on the 0th and 30th days regarding gallic acid content (23.886 ± 0.164 μg/mL, 23.403 ± 0.343 μg/mL) and protocatechuic acid (1.146 ± 0.048 μg/mL, 1.047 ± 0.038 μg/mL). Total flavonoid contents (TFC), total phenolic contents (TPC), CUPRAC (cupric ion reducing antioxidant capacity), DPPH (e free radical diphenylpicrylhydrazyl), total monomeric anthocyanin (TAC), and color values were found to decrease as the storage period increased. It was considered that a highly palatable and rich bioactive component product could be obtained.

Changes in the Fruit Quality Parameters of Medlar Fruit (Mespilus germanica L.) after Heat Treatment, Storage, Freezing or Hoarfrost

The present study deals with the comparison of traditional fruit processing methods on medlar fruits and their effects on sugar content, organic acids, and phenolic composition in the medlar fruit variety 'Domača nešplja'. The study aimed to analyze which processing methods can be used to make technologically mature medlar fruits that are not yet suitable for consumption edible and to maintain their good chemical quality. The two major sugars in medlars are fructose (59.30 g/kg FW) and glucose (54.43 g/kg FW), and the most abundant organic acids present are malic (8.44 g/kg FW) and quinic acid (8.77 g/kg FW). A total of 38 different phenolic compounds were identified in the medlar fruits: 13 phenolic acids, 9 flavanols, 1 flavone, 3 flavanones, and 12 flavonol glycosides. To explicate: phenolic acids (532.85 mg/kg FW) and flavanols (375.21 mg/kg FW) predominated; neochlorogenic acid had the highest content among phenolic acids; and procyanidins were the most abundant flavanols. The analysis observed statistical differences in metabolite content amongst fruits treated differently (technologically ripe fruits (harvested from the three fruits), edible fruits (technologically ripe fruits stored at 8 °C for 25 days), fruits exposed to the hoarfrost (temperature -1 °C to -4 °C), fruits heated at 60 °C (3 h), and frozen fruits (at -20 °C for 2 months). The lowest levels of fructose (191.77-195.1 g/kg DW) and sorbitol (29.35-31.3 g/kg DW) were detected in the heated and edible fruits. Edible fruits had a 30% lower content of organic acids than technologically ripe fruits and a five times lower content of flavanols, whereas flavonols had an 18.7 times lower content of phenolic acids than technologically ripe fruits. Heating the fruits to 60 °C resulted in a 40% increase in total phenolic compounds in medlars. The results of the study indicate that exposure of medlar fruit to hoarfrost does not significantly affect the chemical quality of the fruit and only minimally alters the composition of sugars, acids, and phenolic compounds. The processing of medlar fruit with hoarfrost, therefore, remains the most suitable method of fruit bletting.

Analyzing the influence of withering degree on the dynamic changes in non-volatile metabolites and sensory quality of Longjing green tea by non-targeted metabolomics

Withering is an important processing stage in green tea, which contributes to the tea flavor quality. The aim of this work was to comprehensively investigate the changes of chemical features and flavor attributes in Longjing green teas produced with five different withering degrees (moisture content of 75.05, 72.53, 70.07, 68.00, and 64.78%, w.b.). Combined with human sensory evaluation, electronic tongue and chromatic differences analysis, an assessment of the relationship between the withering degree and the sensory quality of Longjing tea was obtained. By using a non-targeted metabolomics approach, 69 significantly differential metabolites were screened. As the withering degree increased, most free amino acids and catechin dimers were increased, largely attributed to the hydrolysis of proteins and catechin oxidative polymerization, respectively. The contents of organic acids as well as phenolic acids and derivatives were reduced. Interestingly, flavone C-glycosides decreased overall while flavonol O-glycosides increased. The correlation analysis revealed that metabolites such as theasinensin F, theasinensin B, theaflavin, theaflavin-3,3′-gallate, theaflavin-3′-gallate, malic acid, succinic acid, quinic acid, theanine glucoside and galloylglucose had a greater influence on the taste and color of tea infusion (|r| > 0.6, p < 0.05). Overall, an appropriate withering degree at a moisture content of around 70% is more favorable to enhance the Longjing tea quality. These results may enhance the understanding of green tea flavor chemistry associated with withering and provide a theoretical basis for green tea processing.

A New Substrate and Nitrogen Source for Traditional Kombucha Beverage: Stevia rebaudiana Leaves

Recently, the use of different herbal products as carbon sources instead of black and green tea in the preparation of traditional kombucha has been investigated. In this study, functional kombucha was prepared by adding Stevia rebaudiana Bertoni leaves, which have special organoleptic properties, to kombucha medium, and some properties of the beverage were analyzed. Tea blends were determined as 100% green tea (control = C), 75% green tea (GT) + 25% Stevia (ST), 50% GT + 50% ST, and 100% ST. On the 15th day of fermentation, gluconic acid (43.12 ± 0.01 g/L) was detected as dominant organic acid in GT75 + ST25 samples compared to group C (p < 0.05). According to physicochemical parameters that determine the drinkability properties of prepared teas, the best results were in GT25 + ST75 compared to group C (p < 0.05). It proved that the highest activity was in GT25 + ST75 on the 10th day in the groups that applied different antioxidant tests (DPPH, MCA, and CUPRAC). The antimicrobial activities of kombucha at 25, 50, 75, and 100% concentrations of GT and ST reached the highest levels in the GT25 + ST75 group in samples after 10 days of fermentation for all selected microorganisms. The results prove that GT25 + ST75 kombucha is a functional product with high drinkability on the 10th day of fermentation and also more beneficial for health due to the phenolic compounds from both green tea and Stevia. Stevia rebaudiana leaves can be suggested that be used as a new substrate and nitrogen source for kombucha production.

Study on production conditions, volatile composition, and chemical characteristics of herbal tea using Arapgir purple basil (Ocimum basilicum L.)

In this work, production of purple basil (Ocimum basilicum L.) herbal tea was studied. Purple basil is a medicinal and aromatic herb with many health benefits; it is commonly used for seasoning foods. Semi-shade and tray drying methods were used for drying purple basil for tea production. Physical, chemical, and sensory characteristics of samples were evaluated. Total polyphenol contents of samples increased with drying processes and were between 9.55 and 14.18 mg GAE/g. Colour values decreased with drying. Volatile composition of samples was determined using the SPME/GC-MS system. 2-Propenoic acid, 1,8-cineole (eucalyptol), and eugenol were the predominant volatile compounds in all samples. In sensory evaluation, samples produced by tray drying with added citric acid had the highest general acceptance. In conclusion, purple basil was evaluated as a suitable plant for herbal tea production due to its easy preparation, pleasant flavour and colour.

Quantitative Structure-Property Relationship (QSPR) of Plant Phenolic Compounds in Rapeseed Oil and Comparison of Antioxidant Measurement Methods

Natural antioxidants are known for their ability to scavenge free radicals and protect oils from oxidation. Our aim was to study the structural properties such as the number of hydroxyl groups and Bors criteria of phenolic substances leading to high antioxidant activity in oil in order to analyze common trends and differences in widespread in vitro antioxidant assays. Therefore, 20 different phenolic substances were incorporated into rapeseed oil and were measured using pressurized differential scanning calorimetry (P-DSC) and the Rancimat method. The Bors criteria had the highest influence on the antioxidant effect in rapeseed oil, which is why myricetin (MYR), fulfilling all Bors criteria, reached the highest result of the flavonoids. In the Rancimat test and P-DSC, MYR obtained an increase in oxidation induction time (OIT) of 231.1 ± 44.6% and 96.8 ± 1.8%, respectively. Due to differences in the measurement parameters, the results of the Rancimat test and P-DSC were only partially in agreement. Furthermore, we compared the results to in vitro assays (ABTS, DPPH, FC and ORAC) in order to evaluate their applicability as alternative rapid methods. These analysis showed the highest correlation of the oil methods with the results of the DPPH assay, which is, therefore, most suitable to predict the antioxidant behavior of oil.

Quince fruit Cydonia oblonga Mill nutritional composition, antioxidative properties, health benefits and consumers preferences towards some industrial quince products: A review

Quince fruit (Cydonia oblonga) that belongs to the Rosaceae family and native to the Mediterranean region has been studied for decades for its unique importance in food and medicine. This fruit is packed with vitamins, minerals as well as fibers, pectin and tannins. Quince is known by its many therapeutic effects that include antioxidant, anti-inflammatory, antimicrobial, anti-ulcerative, and anticancer actions. However, this fruit is underutilized at the level of food processing due to its sensory attributes and the limited appreciation of its benefits by both farmers and consumers. Other than jellies and jams, quince could be processed into various healthy sub-products. The aims of the current review are to present botanical and nutritive value of this fruit, review the available literature on its therapeutic effects in order to increase farmers and consumers awareness about the importance of quince fruit and showing the different ways of utilizing it.

Effects of Hydrogen Peroxide Produced by Catechins on the Aroma of Tea Beverages

Hydrogen peroxide has a significant effect on the flavor of tea beverages. In this study, the yield of hydrogen peroxide in (-)-epigallocatechin gallate (EGCG) solution was first investigated and found to be significantly enhanced under specific conditions, and the above phenomenon was amplified by the addition of linalool. Then, an aqueous hydrogen peroxide solution was added to a linalool solution and it was found that the concentration of linalool was significantly reduced in the above-reconstituted system. These findings were verified by extending the study system to the whole green tea infusions. The results suggested that the production of hydrogen peroxide in tea beverages may be dominated by catechins, with multiple factors acting synergistically, thereby leading to aroma deterioration and affecting the quality of tea beverages. The above results provided a feasible explanation for the deterioration of flavor quality of green tea beverages with shelf life.

Anti-obesity effects of heat-transformed green tea extract through the activation of adipose tissue thermogenesis

Background

Adipose tissue thermogenesis is a potential therapeutic target to increase energy expenditure and thereby combat obesity. The aim of the present study was to investigate the thermogenic and anti-obesity effects of heat-transformed green tea extract (HTGT) and enzymatically modified isoquercetin (EMIQ).

Methods

Immortalized brown pre-adipocytes and C3H10T1/2 cells were used for in vitro analyses. A high-fat diet (HFD)-induced obesity mouse model and CIDEA-reporter mice were used for in vivo experiments. The effects of HTGT and EMIQ on mitochondrial metabolism were evaluated by immunoblot, mitochondrial staining, and oxygen consumption rate analyses. In vivo anti-obesity effects of HTGT and EMIQ were measured using indirect calorimetry, body composition analyses, glucose tolerance tests, and histochemical analyses.

Results

Co-treatment with HTGT and EMIQ (50 μg/mL each) for 48 h increased brown adipocyte marker and mitochondrial protein levels (UCP1 and COXIV) in brown adipocytes by 2.9-fold, while the maximal and basal oxygen consumption rates increased by 1.57- and 1.39-fold, respectively. Consistently, HTGT and EMIQ treatment increased the fluorescence intensity of mitochondrial staining in C3H10T1/2 adipocytes by 1.68-fold. The combination of HTGT and EMIQ (100 mg/kg each) increased the expression levels of brown adipocyte markers and mitochondrial proteins in adipose tissue. Two weeks of HTGT and EMIQ treatment (100 mg/kg each) led to a loss of 3% body weight and 7.09% of body fat. Furthermore, the treatment increased energy expenditure by 8.95% and improved glucose tolerance in HFD-fed mice.

Conclusions

The current study demonstrated that HTGT and EMIQ have in vivo anti-obesity effects partly by increasing mitochondrial metabolism in adipocytes. Our findings suggest that a combination of HTGT and EMIQ is a promising therapeutic agent for the treatment of obesity and related metabolic diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-022-00648-6.

Effect of Temperatures on Polyphenols during Extraction

Background: Polyphenols are a set of bioactive compounds commonly found in plants. These compounds are of great interest, as they have shown high antioxidant power and are correlated to many health benefits. Hence, traditional methods of extraction such as solvent extraction, Soxhlet extraction and novel extraction technologies such as ultrasound-assisted extraction and subcritical water extraction (SWE) have been investigated for the extraction of polyphenols. Scope and Approach: Generally, for traditional extractions, the total phenolic content (TPC) is highest at an extraction temperature of 60–80 °C. For this reason, polyphenols are regularly regarded as heat-labile compounds. However, in many studies that investigated the optimal temperature for subcritical water extraction (SWE), temperatures as high as 100–200 °C have been reported. These SWE extractions showed extremely high yields and antioxidant capacities at these temperatures. This paper aimed to examine the relevant literature to identify and understand the mechanisms behind this discrepancy. Results: Thermal degradation is the most common explanation for the degradation of polyphenols. This may be the case for specific or sub-groups of phenolic acids. The different extraction temperatures may have also impacted the types of polyphenols extracted. At high extraction temperatures, the formation of new compounds known as Maillard reaction products may also influence the extracted polyphenols. The selection of source material for extraction, i.e., the plant matrix, and the effect of extraction conditions, i.e., oxidation and light exposure, are also discussed. The overestimation of total phenolic content by the Folin–Ciocâlteu assay is also discussed. There is also a lack of consensus in TPC’s correlation to antioxidant activity.

LC-MS based metabolomics and sensory evaluation reveal the critical compounds of different grades of Huangshan Maofeng green tea

Six grades of Huangshan Maofeng (HSMF) green tea were studied by LC-MS based metabolomics combined with sensory evaluation on bitterness, astringency and sweet aftertaste. Although there was no significant correlation (p > 0.05) between tea grades and the contents of total polyphenols and flavonoids, non-targeted metabolomics revealed that all grades of tea could be classified into two groups, group 1 (T1, T2) and group 2 (T3, 1, 2, 3). The main marker compounds responsible for distinguishing the two groups were procyanidins, flavonoid glycosides, and four hydrolysable tannins, including monogalloyl glucose, digalloyl glucose, trigalloyl glucose and galloyl-hexahydroxydiphenoyl-glucose. The Pearson correlation coefficients of these hydrolysable tannins with HSMF green tea grades were between 0.82 and 0.95. Furthermore, their Pearson correlation coefficients regarding sweet aftertaste were in the range of 0.73-0.83. This study suggested combination of metabolomics and sensory evaluation could provide an insight in searching for more potential taste-active components.

Correlation among Metabolic Changes in Tea Plant Camellia sinensis (L.) Shoots, Green Tea Quality and the Application of Cow Manure to Tea Plantation Soils

Traditionally, the supplement of organic manure in tea plantations has been a common approach to improving soil fertility and promoting terroir compounds, as manifested by the coordinated increase in yield and quality for the resulting teas. However, information regarding the effect of organic manure in the metabolome of tea plants is still inadequate. The metabolite profiles of tea shoots applied with cow manure, urea or no fertilizer were studied using gas chromatography–mass spectrometry (GC–MS). In total, 73 metabolites were detected, and the modulated metabolites included mainly amino acids, organic acids and fatty acids. In particular, glutamine, quinic acid and proline accumulated more in tea shoots in soils treated with cow manure, but octadecanoic acid, hexadecanoic acid and eicosanoic acid were drastically reduced. Pearson correlation analysis indicated that organic acids and amino acids in tea shoots were the two major metabolite groups among the three treatments. The analysis of metabolic pathways demonstrated that the cow manure treatment significantly changed the enrichment of pathways related to amino acids, sugars and fatty acids. Sensory evaluation showed that the quality of green teas was higher when the plants used to make the tea were grown in soil treated with cow manure rather than urea during spring and late summer. The results indicated that the application of cow manure in soils changed the metabolic characteristics of tea shoots and improved the qualities of the resulting teas.

Effect of Microwave Roasting and Extraction Solvents on the Bioactive Properties of Coffee Beans

Coffee is an intricate mixture of thousands of chemical compounds that are accountable for its flavor and aroma. Roasting is a key step in the processing of coffee beans. This study assessed the effect of microwave roasting (MW) and extraction solvents (ES) on the total polyphenol content, total flavonoid content, and antioxidant activity of coffee beans. The untreated and microwave-roasted (MR) coffee beans showed a total polyphenol content of 40.40 and 35.15 mg GAE/gm DW, respectively, when methanol was used as the solvent for extraction. Similarly, for the untreated coffee beans, the methanol extracted coffee had a significantly (p < 0.05) higher total flavonoid content (39.34 mg CE/g DW) as compared to ethanol (34.82 mg CE/g DW). The obtained IC₅₀ for the untreated and microwave-roasted samples as extracted by methanol were 4.13 and 5.68 mg/mL, respectively, while the IC₅₀ values of untreated and microwave-roasted samples extracted by ethanol were 4.59 and 6.24 mg/mL, respectively. Untreated coffee beans exhibited a higher reducing power (1.237) than that of the microwave-roasted ones (0.839) when extracted with methanol. Chlorogenic acid was the major (2.31–2.68%) phenolic compound found in all the coffee samples whether it was untreated or microwave-roasted. Vanillin demonstrated the lowest (0.118–0.166%) phenolic compound found in the coffee bean samples. These results might be helpful for obtaining the maximum health benefits from coffee.

Lactic Acid Fermented Green Tea with Levilactobacillus brevis Capable of Producing γ-Aminobutyric Acid

The antioxidative activity and bioactive compounds content of lactic acid fermented green tea (LFG) fermented with an outstanding GABA-producing strain under optimised fermentation conditions were evaluated. Levilactobacillus strain GTL 79 was isolated from green tea leaves and selected based on acid production, growth potential, catechin resistance, and GABA production to be applied to LFG. Through 16S rRNA gene sequence analysis, the strain was identified as Levilactobacillus brevis. The optimised conditions were defined as fermentation at 37 °C with supplementation of 1% fermentation alcohol, 6% glucose, and 1% MSG and was determined to be most effective in increasing the lactic acid, acetic acid, and GABA content in LFG by 522.20%, 238.72% and 232.52% (or 247.58%), respectively. Initial DPPH scavenging activity of LFG fermented under the optimised conditions was 88.96% and rose to 94.38% by day 5. Polyphenols may contribute to the initial DPPH scavenging activity, while GABA and other bioactive compounds may contribute to the activity thereafter. Consequently, as GABA and other bioactive compounds found in green tea have been reported to have health benefits, future studies may prove that optimally fermented LFG by L. brevis GTL 79 could be useful in the food and health industries.

(-)-Epigallocatechin Gallate Stability in Ready-To-Drink (RTD) Green Tea Infusions in TiO2 and Oleic-Acid-Modified TiO2 Polylactic Acid Film Packaging Stored under Fluorescent Light during Refrigerated Storage at 4 °C

The light-protective effectiveness of titanium dioxide polylactic acid (TiO₂ PLA) nanocomposite films (T-PLA) and oleic-acid-modified (OA_TiO₂PLA) nanocomposite films was investigated in ready-to-drink (RTD) green tea infusions in oxygen-impermeable glass packaging. The stability of (-)-epigallocatechin gallate (EGCG) was evaluated in RTD green tea infusions in glass packaging covered with PLA (polylactic acid), T-PLA and OT-PLA under fluorescent light during 20 days of storage at 4 °C. Levels of EGCG and color change of RTD green tea infusions were determined. In addition, sensory tests for difference were conducted on green tea infusions in glass packaging without and with complete light protection during 10 days of storage at 4 °C. Of the panelists, 60% noticed sensory differences in the RTD green tea infusion in two different packaging conditions during 10 days of storage under fluorescent light by a triangle test (p < 0.05). During 20 days of storage, levels of EGCG with complete light protection decreased by 10.8% (0.73 mg/mL), and there was a 42.2% loss of EGCG (0.48 mg/mL) in RTD green tea infusions in the glass packaging covered by PLA film. Finally, 3% T-PLA preserved higher levels of EGCG in RTD green tea infusions compared to 1% T-PLA and OT-PLA.

Photolysis kinetics of cartap and nereistoxin in water and tea beverages under irradiation of simulated sunlight and ultraviolet under laboratory conditions

Cartap applied widely in agricultural crops and tea plants is readily degraded into nereistoxin, resulting in a longer residual period and higher exposure risk to humans. The photolysis kinetics of cartap and nereistoxin in water and tea beverages was firstly investigated to explore the effect and mechanism of pesticide residue removal. Cartap and nereistoxin could be effectively photolyzed by ultraviolet and their photolysis rate increased with light intensity increasing. The photolysis percentage of cartap and nereistoxin in different solutions under ultraviolet irradiation of 200 W mercury lamp reached 81.8%-100.0% within 6 h. Relative to water solution, the water-soluble components in tea had an inhibition effect on the photodegradation of cartap and nereistoxin. This research provided a reference for the development of effective methods for the removal of cartap and its metabolite in water and tea beverages.

Effect of the roasting degree on flavor quality of large-leaf yellow tea

Roasting is crucial for producing large-leaf yellow tea (LYT) as it substantially affects chemical composition and sensory quality. However, the effect of roasting degree on LYT flavor quality is not clear. To investigate the effect of roasting degree on LYT flavor, the odor profiles and sensory evaluations of LYTs produced with small fire, medium fire and old fire roasting (OF) were determined. The OF was essential for the formation of LYT flavor with strong roasted, nutty, woody odors and weak fatty, fruity odors, and retaining high levels of GCG, total volatiles and heterocyclic compounds. Furthermore, the characteristic crispy-rice-like odor was only found in LYT with OF treatment and burnt flavor was missing. 2,3-Diethyl-5-methylpyrazine, trans-β-ionone with odor activity value above 1600 and 39 respectively offered roasted, floral odors, respectively in LYT. The current results provide a scientific basis for understanding the reactions that occur during the conventional production of LYT.

Roasting and Cryogenic Grinding Enhance the Antioxidant Property of Sword Beans (Canavalia gladiata)

The objective of this study was to optimize the conditions for enhancing the antioxidant properties of sword bean (Canavalia gladiata) as a coffee substitute in two processing methods, roasting and grinding. The optimum conditions for removing off-flavor of the bean and maximizing functionality and efficiency were light roasting and cryogenic grinding (< 53 μm). In these conditions, extraction yield was 16.75%, total phenolic content (TPC) was 69.82 ± 0.35 mg gallic acid equivalents/g, and total flavonoid content (TFC) was 168.81 ± 1.64 mg quercetin equivalents/100 g. The antioxidant properties were 77.58 ± 0.27% for DPPH radical scavenging activity and 58.02 ± 0.76 mg Trolox equivalents/g for ABTS radical scavenging activity. The values for TFC and ABTS radical scavenging activity were significantly higher (p < 0.05) than in other conditions, and TPC and DPPH radical scavenging activity were second highest in lightly roasted beans, following raw beans. HS-SPME/GCMS analysis confirmed that the amino acids and carbohydrates, which are the main components of sword bean, were condensed into other volatile flavor compounds, such as derivatives of furan, pyrazine, and pyrrole during roasting. Roasted and cryogenically ground (cryo-ground) sword beans showed higher functionality in terms of TFC, DPPH, and ABTS radical scavenging activities compared to those of coffee. Overall results showed that light roasting and cryogenic grinding are the most suitable processing conditions for enhancing the bioactivity of sword beans.

Effect of moderate thermal treatments on the inactivation of a strain of Listeria monocytogenes and physicochemical properties of soursop pulp

Soursop (Annona muricata L.) is a commercially important tropical fruit, whether fresh or processed as a pasteurized or frozen pulp used to prepare juice, drinks, nectar, ice cream, popsicles, and desserts. Besides preserving quality, another preoccupation in the processing of fruit pulps is product safety. Several studies show the association between pulp processing and the development of various microorganisms; however, few have focused on the association between L. monocytogenes and the pulp of sour fruits. The objective was to evaluate the effect of moderate thermal treatments on the inactivation of L. monocytogenes and the physicochemical properties in soursop pulp in order to determine the best processing conditions that will allow to maintain quality as well as to achieve an adequate level of safety. Thermal inactivation kinetics were obtained for L. monocytogenes inoculated in soursop pulp at five levels of temperature (50, 52.5, 55, 57.5, and 60 ℃) and different exposure times (0-60 min). The survival curves did not suggest a log-linear relationship, and were, consequently, fitted to the modified Gompertz equation. The results indicated that the modified Gompertz equation provided an acceptable goodness of fit. Five-log₁₀ cycles reductions of L. monocytogenes were achieved at 50 ℃/60 min, 52.5 ℃/16 min, 55 ℃/10 min, 57.5 ℃/5 min, and 60 ℃/1.25 min. These 5-log₁₀ treatments applied to the soursop pulp indicated that the soursop pulp showed changes in the color parameters and a decrease in the content of total sugars, reducing sugars, ascorbic acid, total phenols, and pH.

A Comparative Study of Antioxidant Potential and Phenolic Content in White (Silver Needle), Green and Black Tea

Background:

White, green and black are the major tea types obtained from the same tea plant (Camellia sinensis). The differences in processing result in different types of tea, of which green tea (20%) and black tea (78%) are the most consumed worldwide and also white tea is gaining popularity due to its subtle taste and recent evidences about its health benefits. Silver needle is a sub type of white tea, made purely from buds whereas green tea is procured from leaves that are steamed or panfried, and to produce black tea, the tea leaves are withered, fully oxidized and then dried.

Objective:

The present study was undertaken to analyze and compare the antioxidant activity and phenolic composition of white (silver needle), green and black teas of same brand.

Method:

The radical scavenging ability of different tea types was measured using various antioxidant assays. The total phenolic content was also estimated using Folin-Ciocalteu’s method.

Results:

The white tea (silver needle) demonstrated highest radical scavenging activity followed by green and then black tea in various antioxidant assays performed. The total phenolic content of different types of tea exhibited the following order: white tea (133.30mg/g) > green tea (118.37mg/g) > black tea (101.8mg/g). A strong correlation was observed between the total phenolic content and antioxidant activity of different tea types, the correlation coefficient ranged from 0.87-0.97.

Conclusion:

White tea (silver needle) manifested highest antioxidant activity followed by green and least in black tea. The pronounced antioxidant ability of WT (silver needle) may be ascribed to the different parts of the plant (unopened buds) and the least processing it undergoes, followed by obtaining green tea and black tea from different parts of the plant (leaves), and variation in degree of processing.

Effects of heat treatment on the phenolic compounds and antioxidant capacity of quince fruit and its tisane's sensory properties

The quince fruit can be an alternative for producing healthy tea because it is a rich source of bioactive compounds. This study was conducted to evaluate the effects of heating (for 20, 40 and 60 min) on the bioactive compounds of quince and quality attributes its tisanes. To this aim, phenolic content of the treated sample (for 40 min according to sensory analysis) was evaluated by HPLC and antioxidant activity was measured using DPPH method. The analysis of sensory evaluation data demonstrated that the heating process significantly improved the color and taste of the quince tisanes. Thermal treatment (180 °C) for 40 min had maximum acceptability. Although, results confirmed negative effects of the heating process on phenolic content, it showed an increase in antioxidant activity. The HPLC data displayed significant reduction in total amount of five identified phenolic compounds from 460.51 to 25.49 mg/25 g extract by heat treatment. In contrast the roasted sample exhibited lower IC50 (663.88 µg/ml) than the unprocessed sample (1098.66 µg/ml). Considering the elevated antioxidant activity achieved through the heating process, the quince tisane can be considered as a healthy beverage.

Metabolomics Investigation Reveals That 8-C N-Ethyl-2-pyrrolidinone-Substituted Flavan-3-ols Are Potential Marker Compounds of Stored White Teas

White teas of different stored ages have varied flavor, bioactivity, and commercial value. In this study, a liquid chromatography-mass spectrometry-based metabolomics investigation revealed that there are distinct differences among the compound patterns of Baihaoyinzhen (BHYZ) and Baimudan (BMD) white teas with various storage durations. The levels of flavan-3-ols, procyanidins, theasinensins, theaflavins, flavonol- O-glycosides, flavone- C-glycosides, and most of the amino acids were reduced after long-term (>4 years) storage. More importantly, 8-C N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (EPSFs), including seven novel compounds discovered in white teas for the first time, were formed from theanine and flavan-3-ols during storage, and their contents were positively correlated with the storage duration. These findings were further confirmed by the linearly increasing formation of EPSFs in reaction solution and BMD white teas stored in an environment-controlled cabinet. In conclusion, EPSFs were detected in white teas for the first time and were discovered as marker compounds and potential indicators for long-term storage of white tea.

Effect of Green Tea Phytochemicals on Mood and Cognition

BACKGROUND

Green tea is traditionally known to induce mental clarity, cognitive function, physical activation and relaxation. Recently, a special green tea, matcha tea, is rapidly gaining popularity throughout the world and is frequently referred to as a mood- and brain food. Matcha tea consumption leads to much higher intake of green tea phytochemicals compared to regular green tea. Previous research on tea constituents caffeine, L-theanine, and epigallocatechin gallate (EGCG) repeatedly demonstrated benefits on mood and cognitive performance. These effects were observed when these phytochemicals were consumed separately and in combination.

METHODS

A review was conducted on 49 human intervention studies to summarize the research on acute psychoactive effects of caffeine, L-theanine, and EGCG on different dimensions of mood and cognitive performance.

CONCLUSION

Caffeine was found to mainly improve performance on demanding long-duration cognitive tasks and self-reported alertness, arousal, and vigor. Significant effects already occurred at low doses of 40 mg. L-theanine alone improved self-reported relaxation, tension, and calmness starting at 200 mg. L-theanine and caffeine combined were found to particularly improve performance in attention-switching tasks and alertness, but to a lesser extent than caffeine alone. No conclusive evidence relating to effects induced by EGCG could be given since the amount of intervention studies was limited. These studies provided reliable evidence showing that L-theanine and caffeine have clear beneficial effects on sustained attention, memory, and suppression of distraction. Moreover, L-theanine was found to lead to relaxation by reducing caffeine induced arousal.

Relative content of gallic acid over 5-galloylquinic acid as an index for the baking intensity of oolong teas

Phenolic compounds in a series of old oolong teas prepared by baking annually were monitored and compared. The results showed that the relative content of gallic acid over 5-galloylquinic acid was subsequently elevated during this preparatory process. To reveal the effect was mainly resulted from baking or aging, two sets of oolong teas were collected and examined; one set was generated from fresh oolong tea via continually daily baking and the other set was composed of aged oolong teas with no or light baking in the storage period. The relative content of gallic acid over 5-galloylquinic acid was observed to be subsequently elevated when oolong tea was continually baked at 90, 100, 110, and 120 °C for 8 h day after day. In contrast, the relative contents of gallic acid over 5-galloylquinic acid in aged oolong teas with no or light baking were found to be similar to or slightly higher than that in fresh oolong tea. The results suggest that the relative content of gallic acid over 5-galloylquinic acid seems to be a suitable index for the baking intensity of oolong tea in different preparations.

Evaluation and application of prebiotic and probiotic ingredients for development of ready to drink tea beverage

Ready-to-drink (RTD) ice tea is a ready prepared tea, produced from green and black tea originating from same plant Camellia sinensis. The objective of this study was to determine the effect of prebiotics [galacto-oligosaccharide (GOS), fructo-oligosaccharide (FOS), and inulin] or synbiotic ingredients (GOS, FOS, inulin, and Lactobacillus acidophilus) on the sensory properties and consumer acceptability of RTD. The quality of green tea extract (GTE) and black tea extract (BTE) was improved with pretreatment of cellulase and pectinase enzymes. The combined enzymatic extraction amplified total extractives up to 76% in GTE and 72% in BTE. Total polyphenol was found to be enhanced to 24% in GTE and 19% in BTE. GTE was further selected for development of RTD in two different formats; synbiotic RTD and prebiotic RTD premix and analyzed for sensory attributes (colour, aroma, taste, and acceptability). Synbiotic RTD was also evaluated for stability over a period of 28 days at 4 °C. Synbiotic RTD developed an unpleasant flavor and aroma during the shelf life. Premix format of RTD developed using spray drying was reconstituted and found to be functionally and sensorially acceptable.

Green Tea Polyphenols Decrease Strecker Aldehydes and Bind to Proteins in Lactose-Hydrolyzed UHT Milk

The effect of epigallocatechin gallate enriched green tea extract (GTE) on flavor, Maillard reactions and protein modifications in lactose-hydrolyzed (LH) ultrahigh temperature (UHT) processed milk was examined during storage at 40 °C for up to 42 days. Addition of GTE inhibited the formation of Strecker aldehydes by up to 95% compared to control milk, and the effect was similar when GTE was added either before or after UHT treatment. Release of free amino acids, caused by proteolysis, during storage was also decreased in GTE-added milk either before or after UHT treatment compared to control milk. Binding of polyphenols to milk proteins was observed in both fresh and stored milk samples. The inhibition of Strecker aldehyde formation by GTE may be explained by two different mechanisms; inhibition of proteolysis during storage by GTE or binding of amino acids and proteins to the GTE polyphenols.