The market size of varied carbonated teas and bottled ready-to-drink tea products in Taiwan has surpassed that of traditional Taiwan tea with hot infusion. The consumption behavior of Taiwanese ...consumers for new and varied types of cold infusion tea products has also differed from that of traditional hot infusion ones. More kinds of Taiwan tea with different fermentation levels are gradually being used as raw materials for various cold infusion tea products. Therefore, to study consumers’ responses towards cold-brewed tea has become more important for the market of tea in Taiwan. This study recruited Taiwanese consumers to taste seven Taiwanese specialty tea infusions with various degrees of fermentation, and their opinions were gathered by questionnaires composed of check-all-that-apply (CATA), and temporal check-all-that-apply (TCATA) questions and hedonic scales. We found that both CATA and TCATA data agreed that the sensory features of unfermented and lightly semi-fermented tea infusions could be plainly distinguished from the ones of heavily semi-fermented and fully fermented teas based on correspondence analyses. Through CATA and TCATA, the sensory characteristics of the cold-brewed tea of various fermentation degrees could be clearly identified. The first-hand information of cold tea beverages analyzed through this study could be useful for the development of the market in Taiwan. The proper level of bitterness, astringency, fresh tea leaf flavor, and late sweetness were the essential qualities of cold infusions brewed from lightly fermented teas, which could be the best raw materials for production of cold tea beverages to satisfy as many consumers as possible.
For hundreds of years, Taiwan has been famous for its various specialty teas. The sensory features of these teas have been well specialized and standardized through sensory evaluations performed by ...tea experts in yearly competitions throughout history. However, the question arises of whether young Taiwanese consumers, whose dietary behaviors have become Westernized, agree with the conventional sensory standards and association/postprandial concepts in the traditional tea market of Taiwan. To study young Taiwanese consumers' ideas towards traditional specialty teas, this research recruited 109 respondents, younger than the age of 30, to taste seven Taiwanese specialty tea infusions of various degrees of fermentation, and their opinions were gathered by questionnaires composed of check-all-that-apply (CATA) questions and hedonic scales. Through statistical analyses, we found that several tea sensory attributes which were emphasized in experts' descriptive sensory evaluations were not appreciated by the young Taiwanese people. Instead, tea aroma and late sweetness/palatable/smooth/refreshing mouthfeels were the most important sensory attributes contributing to their tea preference. Overall, there would generally be no problem in serving young Taiwanese consumers lightly-fermented oolong teas that generate the highest digestive and lowest heartburn postprandial perceptions.
The interrelationships between rheological characteristics and sensory attributes of commercial glutinous rice cake (mochi) have been investigated by using creep test, dynamic oscillatory ...measurements, texture profile analysis (TPA) and sensory evaluation. The water content of the mochi varied depending upon the addition of sugar. When no sugar was added, the water content could be as high as 55%. As sugar being added, the water content could be as low as 18%. Both water and sugar acted as plasticizer to soften the mochi. The mochi exhibited shear modulus (
G′) from 0.32 to 2.98
kPa with complex viscosity (
η
∗) from 0.06 to 0.51
kPa
s. From TPA, the products yielded hardness from 60 to 270
g
f. The creep data fitted well in the modified 4-element model with the coefficient of determination (
R
2) not less than 0.99. The interrelationships among the rheological properties have been discussed. Thirty-five panelists conducted a descriptive sensory evaluation on the mochi. The results from intensity test significantly correlated with the rheological characteristics. Nevertheless, the preference test did not show similar results.
The coronavirus disease 2019 (COVID-19) pandemic has brought about the unprecedented expansion of highly sensitive molecular diagnostics as a primary infection control strategy. At the same time, ...many laboratories have shifted focus to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) research and diagnostic development, leading to large-scale production of SARS-CoV-2 nucleic acids that can interfere with these tests. We have identified multiple instances, in independent laboratories, in which nucleic acids generated in research settings are suspected to have caused researchers to test positive for SARS-CoV-2 in surveillance testing. In some cases, the affected individuals did not work directly with these nucleic acids but were exposed via a contaminated surface or object. Though researchers have long been vigilant of DNA contaminants, the transfer of these contaminants to SARS-CoV-2 testing samples can result in anomalous test results. The impact of these incidents stretches into the public sphere, placing additional burdens on public health resources, placing affected researchers and their contacts in isolation and quarantine, removing them from the testing pool for 3 months, and carrying the potential to trigger shutdowns of classrooms and workplaces. We report our observations as a call for increased stewardship over nucleic acids with the potential to impact both the use and development of diagnostics. IMPORTANCE To meet the challenges imposed by the COVID-19 pandemic, research laboratories shifted their focus and clinical diagnostic laboratories developed and utilized new assays. Nucleic acid-based testing became widespread and, for the first time, was used as a prophylactic measure. We report 15 cases of researchers at two institutes testing positive for SARS-CoV-2 on routine surveillance tests, in the absence of any symptoms or transmission. These researchers were likely contaminated with nonhazardous nucleic acids generated in the laboratory in the course of developing new SARS-CoV-2 diagnostics. These contaminating nucleic acids were persistent and widespread throughout the laboratory. We report these findings as a cautionary tale to those working with nucleic acids used in diagnostic testing and as a call for careful stewardship of diagnostically relevant molecules. Our conclusions are especially relevant as at-home COVID-19 testing gains traction in the marketplace and these amplicons may impact on the general public.
Effects of water content and mucilage on physico-chemical characteristics of yam (
Discorea alata Purpurea) starch have been investigated. Particle size analysis by laser light scattering showed the ...size of the isolated yam starch granules to be mostly in the range of 10–80
μm, and about 1% of starch granules was smaller than 1
μm. Decreasing water content from 90% to 40% did not significantly alter the onset temperature (
T
o) and peak temperature (
T
p), but raised the conclusion temperature (
T
c). Mucilage exhibited greater storage modulus (
G′) and smaller loss modulus (
G″) than the isolated yam starch at water content of 90%. Water content also influenced the effect of mucilage on the rheological properties of starch–mucilage mixture, but did not significantly affect
T
o and
T
p. The swelling power measurement and scanning electron microscopy illustrated the presence of mucilage to retard the pasting of starch granules during heating.
The effects of three types of screw elements, forward, mixing disc, and pin-mixing element, on residence time distributions of glutinous rice flour in a single screw extruder with different die ...opening areas have been investigated. Both mixing disc and pin-mixing element yield longer residence time, higher specific mechanical energy (SME), and higher extrudate temperature compared with those for the forward screw element. The variation in die diameter did not significantly affect the mean residence time when the forward element was used. Nevertheless, increasing die diameter from 20 to 40 mm significantly reduced the mean residence time when mixing disc was used. Based on SME ranging from 3.6 to 20 kJ/kg, the extruder used in this study was classified as a low shear extruder. Due to the high moisture content (45%) and large die opening area, the die pressure was lower than 11.5 kPa. The utilization of mixing disc was found to raise the die pressure. The degree of starch gelatinization in extrudates was a function of the mean residence time. Three models were employed to fit the RTD data. The flow pattern in different screw profiles was discussed based on the model analysis.
Current therapy for chronic hepatitis B is suboptimal as a result of limited durable response rates, cumulative viral resistance, and/or poor tolerability. Telbivudine has potent antiviral activity ...against hepatitis B virus (HBV) in vitro and in the woodchuck model and has a promising preclinical safety profile. In this first clinical study of telbivudine, safety, antiviral activity, and pharmacokinetics were assessed in 43 adults with hepatitis B e antigen–positive chronic hepatitis B. This placebo‐controlled dose‐escalation trial investigated 6 telbivudine daily dosing levels (25, 50, 100, 200, 400, and 800 mg/d); treatment was given for 4 weeks, with 12 weeks' follow‐up. Serum HBV DNA levels were monitored via quantitative polymerase chain reaction. The results indicate that telbivudine was well tolerated at all dosing levels, with no dose‐related or treatment‐related clinical or laboratory adverse events. telbivudine plasma pharmacokinetics were dose‐proportional within the studied dose range. Marked dose‐related antiviral activity was evident, with a maximum at telbivudine doses of 400 mg/d or more. In the 800mg/d cohort, the mean HBV DNA reduction was 3.75 log10 copies/mL at week 4, comprising a 99.98% reduction in serum viral load. Correspondingly, posttreatment return of viral load was slowest in the high‐dose groups. Viral dynamic analyses suggested a high degree of efficiency of inhibition of HBV replication by telbivudine and helped refine selection of the optimal dose. In conclusion, these results support expanded clinical studies of this new agent for the treatment of hepatitis B. (HEPATOLOGY 2004;40:719–726.)
Large serine integrases (LSIs) offer tremendous potential for rapid genetic engineering as well as building biological systems capable of responding to stimuli and integrating information. Currently, ...there is no unified metric for directly measuring the enzymatic characteristics of LSI function, which hinders evaluation of their suitability to specific applications. Here, we present an experimental protocol for recording DNA recombination in HEK293 cells in real‐time through fluorophore expression and software which fits the kinetic data to a model tailored to LSI recombination dynamics. Our model captures the activity of LSIs as three parameters: expression level (Kexp), catalytic rate (kcat), and substrate affinity (Kd). The expression level and catalytic rate for phiC31 and Bxb1 varied greatly, suggesting disparate routes to high recombination efficiencies. Moreover, the expression level and substrate affinity jointly impacted downstream reporter expression, potentially by obstructing transcriptional machinery. We validated these observations by swapping between promoters and mutating key recombinase residues and DNA recognition sites to individually modulate each parameter. Our model for identifying key LSI parameters in cellulo provides insight into selecting the optimal recombinase for various applications as well as for guiding the engineering of improved LSIs.
Large serine integrases are a group of site‐specific recombinases that can modulate gene expression in living cells and report the transition through fluorescence, making them a potentially useful tool in a range of biological applications. However, endpoint readouts of fluorescence do not capture the whole story, as gene expression, protein‐DNA interaction, and recombination catalysis all factor into the rate and magnitude of the observed phenotypes. Here, George Church et al. present an experimental protocol that integrates fluorescence with DNA and protein concentrations and apply this model to identify three key parameters that can encapsulate the dynamics of the recombination process.
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