sábado, 6 de maio de 2017
Estudo mostrou que óleos essenciais podem ser seguros e eficazes na substituição de conservantes e antioxidantes sintéticos
No estudo, a incorporação de nanoemulsões em patê de frango não alterou as características físico-químicas do alimento – Foto: Katie Rotramel/Flickr-CC
Utilizados pelos chineses há mais de 4 mil anos, os óleos essenciais são compostos extraídos de plantas aromáticas por processos de destilação, compressão de frutos ou uso de solventes. Dentre seus diversos tipos, vários são inibidores eficazes de crescimento de patógenos de origem alimentar, ou seja, podem ser utilizados na conservação dos alimentos.
Entretanto, como notou uma pesquisa realizada na Faculdade de Zootecnia e Engenharia de Alimentos (FZEA) da USP, em Pirassununga, sua incorporação direta em alimentos apresenta diversos desafios, em especial porque há a possibilidade de ocorrer mudanças extremas em suas propriedades sensoriais como cor, sabor ou odor.
Em artigo publicado em abril deste ano pela revista Food Science and Technology, a pesquisadora Samantha Pinho, ao orientar a engenheira de alimentos Marília Moraes Lovison em sua tese de doutorado, investigou como essas possíveis desvantagens poderiam ser superadas por meio das chamadas técnicas de encapsulação, tais como nanoemulsification.
O estudo, realizado no Laboratório de Coloides e Funcionalidade de Macromoléculas da FZEA, produziu nanoemulsões encapsulando diferentes quantidades de óleo essencial de orégano, utilizando o método da temperatura de inversão de fase para avaliar sua estabilidade físico-química e atividade antibacteriana. A incorporação das tais nanoemulsões em patê de frango, alimento escolhido pelas pesquisadoras para o estudo, não alterou as características físico-químicas da carne.
“O motivo da escolha dos óleos essenciais foi o fato de serem potenciais substitutos de antimicrobianos e antioxidantes sintéticos normalmente utilizados na indústria de alimentos, e que são reconhecidos como potenciais causadores de problemas de saúde”, explica Samantha, engenheira química por formação.
Inovar na conservação de alimentos é uma necessidade devido à crescente demanda dos consumidores por formulações contendo ingredientes naturais e com baixos níveis de aditivos químicos. É esse interesse que tem constantemente movido pesquisadores a trabalhar com produtos e extratos vegetais com propriedades antimicrobianas.
“Neste trabalho, foi possível descobrir que, assim como na forma ‘livre’, o óleo essencial de orégano nanoemulsionado também apresentou potencial antioxidante e antimicrobiano in vitro e no produto cárneo, o patê de frango”, esclarece a especialista, destacando ainda que as nanoemulsões foram eficientes em preservar o alimento contra Staphylococcus aureus e Escherichia coli – ambas bactérias que podem causar infecções graves.
O óleo essencial de orégano nanoemulsionado, escolhido no estudo, apresentou potencial antioxidante e antimicrobiano – Foto: Marcos Santos/USP Imagens
De acordo com Samantha, para compreender como as nanoemulsões poderiam atuar na conservação do patê de frango, foi realizada uma contaminação “artificial” pelas bactérias e, posteriormente, a quantificação delas durante oito dias de armazenamento sob refrigeração.
Após determinar a atividade antimicrobiana das nanoemulsões, foram realizadas as análises para avaliação de seu potencial antioxidante in vitro. Na última etapa do trabalho foi avaliado se o óleo essencial “livre” ou nanoemulsionado afetaria as propriedades sensoriais do patê, e como era a aceitação do produto pelos consumidores.
Os resultados permitiram concluir que o óleo essencial é adequado para ser incorporado em formulações de alimentos e prolongar a sua vida de prateleira.
“Este trabalho mostrou que eles podem ser uma alternativa segura e eficaz na substituição, total ou parcial, dos conservantes e antioxidantes sintéticos empregados na indústria de produtos cárneos, proporcionando assim alimentos mais saudáveis e com maior qualidade aos consumidores”, resume a professora.
Além disso, conforme Samantha, a nanotecnologia pode ser considerada uma importante ferramenta para encapsular bioativos, protegendo-os de interações indesejáveis com os alimentos e permitindo a aplicação destes compostos em diversos tipos de alimentos, com a finalidade de diminuir ou mesmo evitar o uso de aditivos sintéticos.
O artigo Nanoemulsions encapsulating oregano essential oil: Production, stability, antibacterial activity and incorporation in chicken pate pode ser acessado neste link. A pesquisa tem apoio da Fundação de Amparo à Pesquisa do Estado de São Paulo (Fapesp).
Mais informações: e-mail firstname.lastname@example.org, com Samantha Pinho
Já com pedido de patente, antisséptico bucal desenvolvido na USP não tem efeitos tóxicos
Já com pedido de patente, antisséptico bucal desenvolvido na USP não tem efeitos tóxicos
Produto com registro de patente confirmado é potente antimicrobiano de ação prolongada e atóxico – Foto: Wathriotu via Wikimedia Commons / CC BY-SA 3.0
Um antisséptico bucal à base de chá verde deve disputar espaço nas prateleiras de drogarias em breve. A fórmula do novo produto contém a catequina epigalocatequina-3-galato – substância extraída do chá verde, com comprovada ação antioxidante, antierosiva, anti-inflamatória, antimicrobiana, antitumoral e mineralizadora.
Por se tratar de um extrato natural, da planta Camellia sinensis, conhecida no mundo todo por seus benefícios à saúde, a catequina faz desse enxaguatório um substituto vantajoso aos existentes hoje no mercado. De acordo com pesquisadores da Faculdade de Odontologia de Ribeirão Preto (Forp) da USP, responsáveis pelo estudo, os antissépticos bucais mais recomendados trazem em suas fórmulas o digluconato de clorexidina, antimicrobiano eficiente, mas que não deve ser usado por longos períodos devido aos efeitos colaterais.
Aparência do chá verde em três diferentes etapas (da esquerda para direita): a infusão das folhas, as folhas secas, e o líquido – Foto: Alessandro Martini via Wikimedia Commons / CC0
Entre as ações indesejáveis causadas pela clorexidina estão a erosão e descoloração dos dentes e restaurações; alteração da cor da língua; descamação e sensibilidade oral, além de ser tóxica ao organismo. Com a utilização da catequina de chá verde, ao contrário, o antisséptico é atóxico, antierosivo e não causa malefícios à coloração dos dentes ou aos demais tecidos da boca.
Os primeiros resultados da formulação atóxica e antimicrobiana do enxaguatório da USP foram confirmados por Marina Moscardini Vilela em sua dissertação de mestrado, orientada pela professora Andiara De Rossi e apresentada à Forp em 2015. As pesquisadoras verificaram que o antisséptico de chá verde possui as mesmas propriedades dos já comercializados: redução da placa bacteriana que pode causar cárie e gengivite e é eficiente também nas aplicações antes de cirurgias bucais. A indicação deve ser feita sempre por profissionais da área de saúde.
Folhas secas e moídas de chá verde – Foto: Editor at Large via Wikimedia Commons / CC BY-SA 2.5
Nanotecnologia potencializa ação antimicrobiana
Marina, que agora estuda o uso do enxaguatório por crianças em seu doutorado, conta que o grupo de pesquisa resolveu inovar e acrescentou a nanotecnologia às propriedades da catequina. Ana Paula Dias Moreno, também orientada pela professora Andiara, foi responsável pelo desenvolvimento das “nanopartículas com quitosana” – fibra natural extraída de carapaças de crustáceos (camarão, lagosta) do tamanho de uma molécula. A pesquisadora deu às nanopartículas o formato de nanocápsulas que envolveram a catequina do chá verde.
Esse encapsulamento conferiu propriedade mucoadesiva às partículas e aumentou o poder antisséptico do novo produto. As nanopartículas literalmente “grudam nas bochechas e outros tecidos da boca, liberando princípios ativos antimicrobianos”, diz Ana Paula.
Ao avaliar o produto final, Ana Paula garante que ele mostrou “resultados microbiológicos e físico-químicos positivos, com alta eficiência de encapsulamento, estabilidade, tamanho de partícula adequado e ainda potencial elétrico, que conferiu mucoadesão e possibilitou efeito residual com liberação sustentada do princípio ativo”.
A técnica que incorpora a catequina em nanopartículas “proporcionou o aumento da atividade antimicrobiana deste componente”, afirma a pesquisadora.
O estudo e o desenvolvimento desse produto contaram com a colaboração dos professores Sergio Luiz Souza Salvador, Priscyla Danielly Marcato Gaspari e Roberto Santana da Silva e das especialistas químicas Marina Constante Gabriel Del Arco e Juliana Cristina Biazzoto de Moraes, da Faculdade de Ciências Farmacêuticas de Ribeirão Preto (FCFRP) da USP. O novo enxaguatório de chá verde teve pedido de patente confirmado em outubro do ano passado.
Rita Stella, de Ribeirão Preto
Mais informações: e-mail email@example.com
Increasing affordability expected to hamper efforts to address global obesity epidemic
Date: May 4, 2017
Source: American Cancer Society
A new study concludes that sugar-sweetened beverages have become more affordable around the globe, and are likely to become even more affordable and more widely consumed.
A new American Cancer Society study concludes that sugar-sweetened beverages have become more affordable in nearly every corner of the globe, and are likely to become even more affordable and more widely consumed. The study appears in the journal Preventing Chronic Disease, and concludes that without policy action to raise prices, global efforts to address the obesity epidemic will be hampered.
For the study researchers analyzed both real prices of sugar-sweetened beverages (SSBs) as well as relative income prices, based on annual per capita income in 40 high-income and 42 low-income and middle-income countries around the world between from 1990 to 2016. They used Coca-Cola as a proxy for all sugar-sweetened beverages because it is the most globally recognizable sugar-sweetened beverage brand and widely available worldwide, comprising more than one-fourth (25.8%) of the global market in 2014, more than double its closest competitor.
They found sugar-sweetened beverages became more affordable in 79 of 82 countries between 1990 and 2016, most often due to a combination of increases in income and decreases in price. Real prices dropped in 56 of the 82 countries.
"Overall in the countries we studied, a person in 2016 could buy 71 percent more sugar-sweetened beverages with the same share of their income than they could in 1990," said Jeffrey Drope, Ph.D., study co-author. "Sugary drinks became even more affordable in developing countries, where 2016's income could buy 89 percent more sugar-sweetened beverages than in 1990. That's essentially half-price."
"Although the increase in affordability is partly due to economic progress that resulted from rapid global economic development, it is also attributable to a lack of action taken by policy makers to affect the price of sugar-sweetened beverages," write the authors. "We argue and the scientific literature strongly suggests that this environment of increasingly affordable sugar-sweetened beverages will inevitably drive increased consumption of such products and will certainly hamper global efforts to address the overweight and obesity epidemic."
The authors also reviewed price trends for bottled water comparing them to SSBs to provide a control, and found that bottled water is typically more expensive and less affordable than sugar-sweetened beverages.
Because rising incomes are a positive sign of growth, the authors say "the logical intervention is for governments to affect prices through excise taxation, as they have done with other unhealthful products such as cigarettes."
Materials provided by American Cancer Society. Note: Content may be edited for style and length.
Evan Blecher, Alex C. Liber, Jeffrey M. Drope, Binh Nguyen, Michal Stoklosa. Global Trends in the Affordability of Sugar-Sweetened Beverages, 1990–2016. Preventing Chronic Disease, 2017; 14 DOI: 10.5888/pcd14.160406
Cite This Page:
American Cancer Society. "Sugar-sweetened beverages becoming more affordable around the world: Increasing affordability expected to hamper efforts to address global obesity epidemic." ScienceDaily. ScienceDaily, 4 May 2017. <www.sciencedaily.com/releases/2017/05/170504161456.htm>.
Date: May 6, 2017
Source: American Heart Association
Cinnamon may lessen the risk of cardiovascular damage of a high-fat diet by activating the body's antioxidant and anti-inflammatory systems and slowing the fat-storing process, according to a preliminary animal study.
Cinnamon may lessen the risk of cardiovascular damage of a high-fat diet by activating the body's antioxidant and anti-inflammatory systems and slowing the fat-storing process, according to a preliminary animal study presented at the American Heart Association's Arteriosclerosis, Thrombosis and Vascular Biology | Peripheral Vascular Disease 2017 Scientific Sessions.
In the study, researchers fed rats cinnamon supplements for 12 weeks along with a high-fat diet. They found:
The rats weighed less and had less belly fat and healthier levels of sugar, insulin and fat in their blood, compared to rats that did not receive cinnamon with their high-fat foods;
Rats fed cinnamon also had fewer molecules involved in the body's fat-storing process and more antioxidant and anti-inflammatory molecules that protect the body from the damages of stress.
The results suggest that cinnamon may reduce the effects of a high-fat diet, researchers said.
Cite This Page:
American Heart Association. "Cinnamon may lessen damage of high-fat diet in rats." ScienceDaily. ScienceDaily, 6 May 2017. <www.sciencedaily.com/releases/2017/05/170506103245.htm>.
Date: May 4, 2017
Source: Queen's University Belfast
Almost half of baby rice food products contain illegal levels of inorganic arsenic despite new regulations set by the EU, new research concludes.
50 per cent of baby rice food products still contain an illegal level of inorganic arsenic, say British researchers.
Credit: © jdjuanci / Fotolia
In January 2016, the EU imposed a maximum limit of inorganic arsenic on manufacturers in a bid to mitigate associated health risks. Researchers at the Institute for Global Food Security at Queen's have found that little has changed since this law was passed and that 50 per cent of baby rice food products still contain an illegal level of inorganic arsenic.
Professor Meharg, lead author of the study and Professor of Plant and Soil Sciences at Queen's, said: "This research has shown direct evidence that babies are exposed to illegal levels of arsenic despite the EU regulation to specifically address this health challenge. Babies are particularly vulnerable to the damaging effects of arsenic that can prevent the healthy development of a baby's growth, IQ and immune system to name but a few."
Rice has, typically, ten times more inorganic arsenic than other foods and chronic exposure can cause a range of health problems including developmental problems, heart disease, diabetes and nervous system damage.
As babies are rapidly growing they are at a sensitive stage of development and are known to be more susceptible to the damaging effects of arsenic, which can inhibit their development and cause long-term health problems. Babies and young children under the age of five also eat around three times more food on a body weight basis than adults, which means that, relatively, they have three times greater exposures to inorganic arsenic from the same food item.
The research findings, published in the PLOS ONE journal today, compared the level of arsenic in urine samples among infants who were breast-fed or formula-fed before and after weaning. A higher concentration of arsenic was found in formula-fed infants, particularly among those who were fed non-dairy formulas which includes rice-fortified formulas favoured for infants with dietary requirements such as wheat or dairy intolerance. The weaning process further increased infants' exposure to arsenic, with babies five times more exposed to arsenic after the weaning process, highlighting the clear link between rice-based baby products and exposure to arsenic.
In this new study, researchers at Queen's also compared baby food products containing rice before and after the law was passed and discovered that higher levels of arsenic were in fact found in the products since the new regulations were implemented. Nearly 75 per cent of the rice-based products specifically marketed for infants and young children contained more than the standard level of arsenic stipulated by the EU law.
Rice and rice-based products are a popular choice for parents, widely used during weaning, and to feed young children, due to its availability, nutritional value and relatively low allergic potential.
Professor Meharg explained: "Products such as rice-cakes and rice cereals are common in babies' diets. This study found that almost three-quarters of baby crackers, specifically marketed for children exceeded the maximum amount of arsenic."
Previous research led by Professor Meharg highlighted how a simple process of percolating rice could remove up to 85 per cent of arsenic. Professor Meharg adds: "Simple measures can be taken to dramatically reduce the arsenic in these products so there is no excuse for manufacturers to be selling baby food products with such harmful levels of this carcinogenic substance.
"Manufacturers should be held accountable for selling products that are not meeting the required EU standard. Companies should publish the levels of arsenic in their products to prevent those with illegal amounts from being sold. This will enable consumers to make an informed decision, aware of any risks associated before consuming products containing arsenic."
Antonio J. Signes-Pastor, Jayne V. Woodside, Paul McMullan, Karen Mullan, Manus Carey, Margaret R. Karagas, Andrew A. Meharg. Levels of infants’ urinary arsenic metabolites related to formula feeding and weaning with rice products exceeding the EU inorganic arsenic standard. PLOS ONE, 2017; 12 (5): e0176923 DOI: 10.1371/journal.pone.0176923
Cite This Page:
Queen's University Belfast. "New research shows illegal levels of arsenic found in baby foods." ScienceDaily. ScienceDaily, 4 May 2017. <www.sciencedaily.com/releases/2017/05/170504161538.htm>.
sexta-feira, 5 de maio de 2017
quinta-feira, 4 de maio de 2017
Date: March 16, 2017
Source: National University of Singapore
Tea drinking reduces the risk of cognitive impairment in older persons by 50 per cent and as much as 86 per cent for those who are genetically at risk of Alzheimer's, new research suggests.
NUS researchers found that regular consumption of tea brewed from tea leaves reduces elderly persons' risk of cognitive decline.
Credit: © Serhiy Shullye / Fotolia
A cup of tea a day can keep dementia away, and this is especially so for those who are genetically predisposed to the debilitating disease, according to a recent study led by Assistant Professor Feng Lei from the Department of Psychological Medicine at National University of Singapore's (NUS) Yong Loo Lin School of Medicine.
The longitudinal study involving 957 Chinese seniors aged 55 years or older has found that regular consumption of tea lowers the risk of cognitive decline in the elderly by 50 per cent, while APOE e4 gene carriers who are genetically at risk of developing Alzheimer's disease may experience a reduction in cognitive impairment risk by as much as 86 per cent.
The research team also discovered that the neuroprotective role of tea consumption on cognitive function is not limited to a particular type of tea -- so long as the tea is brewed from tea leaves, such as green, black or oolong tea.
"While the study was conducted on Chinese elderly, the results could apply to other races as well. Our findings have important implications for dementia prevention. Despite high quality drug trials, effective pharmacological therapy for neurocognitive disorders such as dementia remains elusive and current prevention strategies are far from satisfactory. Tea is one of the most widely consumed beverages in the world. The data from our study suggests that a simple and inexpensive lifestyle measure such as daily tea drinking can reduce a person's risk of developing neurocognitive disorders in late life," explained Asst Prof Feng.
He added, "Based on current knowledge, this long term benefit of tea consumption is due to the bioactive compounds in tea leaves, such as catechins, theaflavins, thearubigins and L-theanine. These compounds exhibit anti-inflammatory and antioxidant potential and other bioactive properties that may protect the brain from vascular damage and neurodegeneration. Our understanding of the detailed biological mechanisms is still very limited so we do need more research to find out definitive answers."
In this study, tea consumption information were collected from the participants, who are community-living elderly, from 2003 to 2005. At regular intervals of two years, these seniors were assessed on their cognitive function using standardised tools until 2010. Information on lifestyles, medical conditions, physical and social activities were also collected. Those potential confounding factors were carefully controlled in statistical models to ensure the robustness of the findings.
The research team published their findings in scientific journal The Journal of Nutrition, Health & Aging in December 2016.
Asst Prof Feng and his team are planning to embark on further studies to better understand the impact of Asian diet on cognitive health in aging. They are also keen to investigate the effects of the bioactive compounds in tea and test them more rigorously through the assessment of their biological markers and by conducting randomised controlled trials or studies that assign participants into experimental groups or control groups randomly to eliminate biased results.
Materials provided by National University of Singapore. Note: Content may be edited for style and length.
L. Feng, M. -S. Chong, W. -S. Lim, Q. Gao, M. S. Z. Nyunt, T. -S. Lee, S. L. Collinson, T. Tsoi, E. -H. Kua, T. -P. Ng. Tea consumption reduces the incidence of neurocognitive disorders: Findings from the Singapore longitudinal aging study. The Journal of Nutrition, Health & Aging, 2016; 20 (10): 1002 DOI: 10.1007/s12603-016-0687-0
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National University of Singapore. "Daily consumption of tea may protect the elderly from cognitive decline, study suggests." ScienceDaily. ScienceDaily, 16 March 2017. <www.sciencedaily.com/releases/2017/03/170316093412.htm>.
Date: April 13, 2017
After more than a decade of declining cholera incidence, Vietnam faced an increase in cases of the diarrheal disease during 2007-2010. Risk factors for contracting cholera in Ben Tre province of Vietnam include drinking iced tea or unboiled water and having a water source near a toilet, researchers report.
After more than a decade of declining cholera incidence, Vietnam faced an increase in cases of the diarrheal disease during 2007-2010. Risk factors for contracting cholera in Ben Tre province of Vietnam include drinking iced tea or unboiled water and having a water source near a toilet, researchers report in PLOS Neglected Tropical Diseases.
Around the world, more than a million people a year suffer from cholera and tens of thousands die from the disease. Cholera transmission is closely linked to inadequate access to clean water and is often spread through contaminated drinking water. In the Ben Tre province of the Mekong Delta region in the southern part of Vietnam, no cholera cases were reported from 2005 until an outbreak in 2010.
In the new work, Thuong Vu Nguyen, of the Pasteur Institute Ho Chi Minh City, Vietnam and colleagues interviewed 60 people who were confirmed to have been infected with cholera during the 2010 outbreak in Ben Tre, as well as 240 subcommune-, 5-year age group- and sex-matched controls. Information about each person's eating and drinking behaviors and living environment was recorded. The researchers also collected samples of nearby river water, drinking water, wastewater samples, and local seafood to test for Vibrio cholerae, the bacteria which spreads the disease.
The researchers found that drinking iced tea, not always boiling drinking water, having a main water source near a toilet, living with other who have diarrhea, and having little or no education were all associated with an increased risk of cholera, while drinking stored rainwater, eating cooked seafood or steamed vegetables were protective against the disease. 22% of people with cholera reported drinking iced tea in the week prior to their disease, whereas only 3% of controls had drank iced tea in the week before being interviewed. Patients with cholera were also more likely to always put ice in their water and to use sedimented river water for drinking, bathing, cooking, and brushing their teeth. More work is needed to determine why iced tea boosts the risk of cholera, but the researchers hypothesize that the bacteria may be found in ice, which is often bought from street vendors.
"This present study has important implications for Vietnam's cholera responses," the researchers say. "Along with traditional approaches that focus on enhancement of safe water, sanitation, and food safety, combined with periodic provision of oral cholera vaccines, a water quality monitoring system at ice-making plants should be established."
Materials provided by PLOS. Note: Content may be edited for style and length.
Thuong V. Nguyen, Quang D. Pham, Quoc K. Do, Tai T. Diep, Hung C. Phan, Thang V. Ho, Hong T. Do, Lan T. Phan, Huu N. Tran. Cholera returns to southern Vietnam in an outbreak associated with consuming unsafe water through iced tea: A matched case-control study. PLOS Neglected Tropical Diseases, 2017; 11 (4): e0005490 DOI: 10.1371/journal.pntd.0005490
Cite This Page:
PLOS. "Drinking iced tea may boost cholera risk in endemic countries." ScienceDaily. ScienceDaily, 13 April 2017. <www.sciencedaily.com/releases/2017/04/170413141128.htm>.
Date: March 1, 2016
Source: University of Illinois at Urbana-Champaign
A new study has examined the dietary habits of more than 18,300 US adults, and found the majority of people who increased their consumption of plain water by 1 percent reduced their total daily calorie intake as well as their consumption of saturated fat, sugar, sodium and cholesterol.
Drinking water (stock image).
Credit: © ampyang / Fotolia
For people who want to control their weight or reduce their intakes of sugar, sodium and saturated fat, tap water may be what the doctor ordered.
A new study that examined the dietary habits of more than 18,300 U.S. adults found the majority of people who increased their consumption of plain water -- tap water or from a cooler, drinking fountain or bottle -- by 1 percent reduced their total daily calorie intake as well as their consumption of saturated fat, sugar, sodium and cholesterol.
People who increased their consumption of water by one, two or three cups daily decreased their total energy intake by 68 to 205 calories daily and their sodium intake by 78 to 235 milligrams, according to a paper by University of Illinois kinesiology and community health professor Ruopeng An. They also consumed 5 grams to nearly 18 grams less sugar and decreased their cholesterol consumption by 7 to 21 milligrams daily.
"The impact of plain water intake on diet was similar across race/ethnicity, education and income levels and body weight status," An said. "This finding indicates that it might be sufficient to design and deliver universal nutrition interventions and education campaigns that promote plain water consumption in replacement of beverages with calories in diverse population subgroups without profound concerns about message and strategy customization."
An examined data from four waves (2005-12) of the National Health and Nutrition Examination Survey, conducted by the National Center for Health Statistics. Participants were asked to recall everything they ate or drank over the course of two days that were three to 10 days apart.
An calculated the amount of plain water each person consumed as a percentage of their daily dietary water intake from food and beverages combined. Beverages such as unsweetened black tea, herbal tea and coffee were not counted as sources of plain water, but their water content was included in An's calculations of participants' total dietary water consumption.
On average, participants consumed about 4.2 cups of plain water on a daily basis, accounting for slightly more than 30 percent of their total dietary water intake. Participants' average calorie intake was 2,157 calories, including 125 calories from sugar-sweetened beverages and 432 calories from discretionary foods, which are low-nutrition, calorie-dense foods such as desserts, pastries and snack mixes that add variety to but are not necessary for a healthy diet.
A small but statistically significant 1 percent increase in participants' daily consumption of plain water was associated with an 8.6-calorie decrease in daily energy intake, as well as slight reductions in participants' intake of sugar-sweetened beverages and discretionary foods along with their consumption of fat, sugar, sodium and cholesterol.
While An found that the decreases were greater among men and among young and middle-aged adults, he suggested they could have been associated with these groups' higher daily calorie intakes.
The study was published in the Journal of Human Nutrition and Dietetics.
Materials provided by University of Illinois at Urbana-Champaign. Original written by Sharita Forrest. Note: Content may be edited for style and length.
R. An, J. McCaffrey. Plain water consumption in relation to energy intake and diet quality among US adults, 2005-2012. Journal of Human Nutrition and Dietetics, 2016; DOI: 10.1111/jhn.12368
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University of Illinois at Urbana-Champaign. "Drinking more water associated with numerous dietary benefits, study finds." ScienceDaily. ScienceDaily, 1 March 2016. <www.sciencedaily.com/releases/2016/03/160301174759.htm>.
Date: May 1, 2017
Source: Cell Press
The most popular varieties of tea -- including black tea, green tea, Oolong tea, white tea, and chai -- all come from the leaves of the evergreen shrub Camellia sinensis, otherwise known as the tea tree. Despite tea's cultural and economic significance, relatively little is known about the shrub behind the tea leaves. However, the first draft of the tea tree genome may help explain why tea leaves are so rich in antioxidants and caffeine.
Camellia sinensis shrub.
Credit: LiZhi Gao Lab
The most popular varieties of tea -- including black tea, green tea, Oolong tea, white tea, and chai -- all come from the leaves of the evergreen shrub Camellia sinensis, otherwise known as the tea tree. Despite tea's immense cultural and economic significance, relatively little is known about the shrub behind the tea leaves. However, the first draft of the tea tree genome published May 1 in the journal Molecular Plant may help explain why tea leaves are so rich in antioxidants and caffeine.
Understanding how the tea tree genetically differs from its close relatives may help tea growers figure out what makes Camellia sinensis leaves so special. The genus Camellia contains over 100 species -- including several popular decorative garden plants and C. oleifera, which produces "tea tree" oil -- but only two major varieties (C. sinensis var. assamica and C. sinensis var. sinensis) are grown commercially for making tea. "There are many diverse flavors, but the mystery is what determines or what is the genetic basis of tea flavors?" says plant geneticist Lizhi Gao of Kunming Institute of Botany in China.
Previous studies have suggested that tea owes much of its flavor to a group of antioxidants called flavonoids, molecules that are thought to help plants survive in their environments. One, a bitter-tasting flavonoid called catechin, is particularly associated with tea flavor. Levels of catechin and other flavonoids vary among Camellia species, as does caffeine. Gao and his colleagues found that C. sinensis leaves not only contain high levels of catechins, caffeine, and flavonoids, but also have multiple copies of the genes that produce caffeine and flavonoids.
Caffeine and flavonoids such as catechins are not proteins (and therefore not encoded in the genome directly), but genetically encoded proteins in the tea leaves manufacture them. All Camellia species have genes for the caffeine- and flavonoid-producing pathways, but each species expresses those genes at different levels. That variation may explain why C. sinensis leaves are suitable for making tea, while other Camellia species' leaves aren't.
Gao and his colleagues estimate that more than half of the base pairs (67%) in the tea tree genome are part of retrotransposon sequences, or "jumping genes," which have copied-and-pasted themselves into different spots in the genome numerous times. The large number of retrotransposons resulted in a dramatic expansion in genome size of tea tree, and possibly many, many duplicates of certain genes, including the disease-resistant ones. The researchers think that these "expanded" gene families must have helped tea trees adapt to different climates and environmental stresses, as tea trees grow well on several continents in a wide range of climate conditions. Since much of the retrotransposon copying & pasting seems to have happened relatively recently in the tea tree's evolutionary history, the researchers as theorize that at least some of the duplications are responses to cultivation.
However, these duplicated genes and the large number of repeat sequences also turned assembling a tea tree genome into an uphill battle. "Our lab has successfully sequenced and assembled more than twenty plant genomes," says Gao. "But this genome, the tea tree genome, was tough."
For one thing, the tea tree genome turned out to be much larger than initially expected. At 3.02 billion base pairs in length, the tea tree genome is more than four times the size of the coffee plant genome and much larger than most sequenced plant species. Further complicating the picture is the fact that many of those genes are duplicates or near-duplicates. Whole genomes are too long to sequence in one piece, so instead, scientists must copy thousands upon thousands of genome fragments, sequence them, and identify overlapping sequences that appear in multiple fragments. Those overlap sites become sign posts for lining up the fragments in the correct order. However, when the genome itself contains sequences that are repeated hundreds or thousands of times, those overlaps disappear into the crowd of repeats; it's like assembling a million piece puzzle where all the middle pieces look almost exactly alike.
All told, even with modern sequencing, assembling the genome took the team over 5 years.
And still, there is more work to do, both in terms of double-checking the genome draft and in terms of sequencing different tea tree varieties from around the world. "Together with the construction of genetic maps and new sequencing technologies, we are working on an updated tea tree genome that will investigate some of the flavor," says Gao. "We will look at gene copy number variation to see how they affect tea properties, like flavor. We want to get a map of different tea tree variation and answer how it was domesticated, cultivated, and dispersed to different continents of the world."
Materials provided by Cell Press. Note: Content may be edited for style and length.
Xia et al. The tea tree genome provides insights into tea flavor and independent evolution of caffeine biosynthesis. Molecular Plant, 2017 DOI: 10.1016/j.molp.2017.04.002
Cite This Page:
Cell Press. "Tea tree genome contains clues about how one leaf produces so many flavors." ScienceDaily. ScienceDaily, 1 May 2017. <www.sciencedaily.com/releases/2017/05/170501141648.htm>.
quarta-feira, 3 de maio de 2017
Marcos Roberto Furlan - Engenheiro Agrônomo
Jessica Tiyoko Yamashita - acadêmica de Engenharia Agronômica
Algumas espécies são identificadas facilmente pelo aroma. No entanto, essa característica não é garantia para acertar na identificação, pois há plantas com aromas bem semelhantes, devido à presença de mesmas substâncias em concentrações predominantes, como, por exemplo, o eucalipto-citriodora (Corymbia citriodora) e a citronela (Cymbopogon winterianus), que possuem citronelal, o que justifica aromas semelhantes. O mesmo acontece com o funcho (Foeniculum vulgare), a anis (Pimpinella anisum) e a anis-estrelado (Illicium verum), por possuírem o anetol como componente majoritário em seu óleo essencial.
Dependendo da região há ocorrência de uma planta com um cheiro que a diferencia de todas as demais de sua vizinhança. Seu nome popular “pau d’alho” já indica que exala cheiro que lembra alho. Sua denominação científica é Gallesia integrifolia, pertencente à família Phytolaccaceae, podendo receber outras denominações populares, como: ibirarema, ubaeté e guararema. Nem precisa tocar ou apertar partes da planta, pois em dias quentes, o aroma sai naturalmente. De todas as partes da planta sai um forte cheiro que lembra alho.
O pau d’alho também se destaca pelo rápido crescimento e pela altura, que pode ultrapassar 30 m; pelo largo tronco, com até 1,5 m de diâmetro, e pelas folhas lisas e brilhantes. Sua distribuição no Brasil é bem ampla, pois pode ser encontrada no Sul, no Sudeste e em alguns estados do Nordeste e do Norte.
Como é planta pioneira, pode ser utilizada em reflorestamento. Tradicionalmente, sua madeira é utilizada em construções rurais, para fabrico de caixotes e outros tipos de embalagens mais leves. Serve, ainda, para paisagismo, pois além de bonita, proporciona uma ótima sombra.
Do ponto de vista medicinal, ainda há poucas pesquisas que comprovam seus usos. Popularmente, o chá das folhas é considerado eficaz contra gripe e resfriado, e as raízes são consideradas vermífugas. Também há referências contra reumatismo e antimicrobiano. Esta última ação já há estudos que comprovam, como o realizado por Arunachalam et al. (2016).
Na agricultura há estudos que comprovam sua ação alelopática e contra nematoides (FERREIRA, ÁQUILA, 2000; SILVA et al., 2011; MARCONDES et al., 2011).
ARUNACHALAM, K.; ASCÊNCIO, S. D.; SOARES, I. M.; SOUZA AGUIAR, R. W.; DA SILVA, L. I.; DE OLIVEIRA, R. G.; BALOGUN, S. O.; DE OLIVEIRA MARTINS, D. T. Gallesia integrifolia (Spreng.) Harms: in vitro and in vivo antibacterial activities and mode of action. Journal of Ethnopharmacology, v. 1, p. 128-137, 2016. Disponível em: https://www.ncbi.nlm.nih.gov/pubmed/26945980. Acesso: 1 mai 2017. https://www.ncbi.nlm.nih.gov/pubmed/26945980
CARVALHO, P.E.R. Espécies Arbóreas Brasileiras. vol. 1. Brasília, DF: Embrapa Informação Tecnológica; Colombo, PR: Embrapa Florestas, 2003.
FERREIRA, A. G.; AQUILA, M. E. A. Alelopatia: uma área emergente da Ecofisiologia. Revista Brasileira de Fisiologia Vegetal, v. 12, p. 175-204, 2000.
LORENZI, H. Árvores Brasileiras: manual de identificação e cultivo de plantas arbóreas do Brasil, vol. 1. 4.ed. Nova Odessa, SP: Instituto Plantarum, 2002.
MARCHIORETTO, M.S. 2012. Phytolaccaceae. In: Lista de Espécies da Flora do Brasil. Jardim Botânico do Rio de Janeiro. Disponível em: <http://floradobrasil.jbrj.gov.br/2012/FB012578>. Acesso em: 2 mai 2017.
MARCONDES, M. M.; FERREIRA, S. G. M.; SCISLOSKI, S. F.; MATEUS, M. A. F.; FARIA, C. M. D. R. Efeito de diferentes concentrações de hidrolatos da eclosão de juvenis de Meloidogyne sp..Tropical Plant Phatology, v. 36, 2011.
SILVA, B. F.; LAMEIRÃO, V. G.; AZEVEDO, I. H. F.; GOI, S. R. Efeito alelopático de estrato aquoso de Gallesia integrifolia (Spreng.) Harms e Schinus terebinthifolius Raddi sobre a germinação e desenvolvimento de Lactuca sativa L. e Bidens pilosa L. Anais... X Congresso de Ecologia do Brasil, 2011.
Foto: Pau d'alho
Jessica Tiyoko Yamashita